Wallet LMDB backend (#1151)

* Migrate main node store to LMDB

In preparation to using LMDB as a wallet database, migrate the
node db. There's no point in having 2 key-value stores.
In addition LMDB provides a few advantages as a node db, namely a
much faster build (compared to RocksDb), lesser dependencies and
transactions.

* Migrated p2p store to lmdb, stuff compiles

* More fixes, chain tests starting to pass

* Fixed txhashset rollback messing with block save and general batch delimitation. Chain tests passing.

* rustfmt

* LMDB max map size of 10MB isn't really workable. Half TB seems reasonable.

* Fix wallet tests

* Rather crucial commit was missing

* rustfmt

* Fixing new merged tests following lmdb changes

* rustfmt

* * Make txhashset validation read-only on fast sync to avoid having
a really long open transaction.
* Fix deadlock in new block processing, batch should always be
created within a txhashset lock (when they interact).

* Comment about batch and txhashset interlacing

* Fix store tests to use batch

* Externalize wallet config and seed

* Converted direct read access to file outputs map to an iterator

* Cleaned up and simplified wallet Backend trait:

* No more direct mutable access to internal structures (HashMap)
* Batch interface for all writes
* Remove unneeded read wrapper (read_wallet)

* rustfmt

* First (incomplete) pass at wallet LMDB backend

* Progressing on lmdb backent iml

* Added batch impl for LMDB wallet backend. Pretty much done with it, but not sure how to deal with commit (owned).

* rustfmt

* Wrapping LMDB batch around a refcell to work around borrow rules

* Compilation up to grin chain

api/src/handlers.rs

@@ -496,21 +496,6 @@ impl Handler for ChainValidationHandler {
 	}
 }
 
-/// Temporary - fix header by height index.
-/// POST /v1/chain/height-index
-pub struct HeaderByHeightHandler {
-	pub chain: Weak<chain::Chain>,
-}
-
-impl Handler for HeaderByHeightHandler {
-	fn handle(&self, _req: &mut Request) -> IronResult<Response> {
-		match w(&self.chain).rebuild_header_by_height() {
-			Ok(_) => Ok(Response::with((status::Ok, ""))),
-			Err(_) => Ok(Response::with((status::InternalServerError, ""))),
-		}
-	}
-}
-
 /// Chain compaction handler. Trigger a compaction of the chain state to regain
 /// storage space.
 /// GET /v1/chain/compact
@@ -733,9 +718,6 @@ pub fn start_rest_apis<T>(
 			let chain_compact_handler = ChainCompactHandler {
 				chain: chain.clone(),
 			};
-			let header_height_handler = HeaderByHeightHandler {
-				chain: chain.clone(),
-			};
 			let chain_validation_handler = ChainValidationHandler {
 				chain: chain.clone(),
 			};
@@ -795,7 +777,6 @@ pub fn start_rest_apis<T>(
 				chain_compact: get "/chain/compact" => chain_compact_handler,
 				chain_validate: get "/chain/validate" => chain_validation_handler,
 				chain_outputs: get "/chain/outputs/*" => output_handler,
-				header_height: post "/chain/height-index" => header_height_handler,
 				status: get "/status" => status_handler,
 				txhashset_roots: get "/txhashset/*" => txhashset_handler,
 				pool_info: get "/pool" => pool_info_handler,

chain/Cargo.toml

@@ -8,6 +8,7 @@ publish = false
 [dependencies]
 bitflags = "1"
 byteorder = "1"
+lmdb-zero = "0.4.4"
 croaring = "0.3"
 slog = { version = "~2.2", features = ["max_level_trace", "release_max_level_trace"] }
 serde = "1"

chain/src/chain.rs

@@ -20,17 +20,19 @@ use std::fs::File;
 use std::sync::{Arc, Mutex, RwLock};
 use std::time::{Duration, Instant};
 
-use core::core::Committed;
+use lmdb;
+
 use core::core::hash::{Hash, Hashed};
 use core::core::merkle_proof::MerkleProof;
 use core::core::target::Difficulty;
-use core::core::{Block, BlockHeader, Output, OutputIdentifier, Transaction, TxKernel};
+use core::core::{Block, BlockHeader, Output, OutputIdentifier, Transaction,
+                 TxKernel};
 use core::global;
 use grin_store::Error::NotFoundErr;
 use pipe;
 use store;
 use txhashset;
-use types::{BlockMarker, ChainAdapter, ChainStore, Error, Options, Tip};
+use types::{BlockMarker, ChainAdapter, Error, Options, Tip};
 use util::LOGGER;
 use util::secp::pedersen::{Commitment, RangeProof};
 
@@ -123,7 +125,7 @@ impl OrphanBlockPool {
 /// maintains locking for the pipeline to avoid conflicting processing.
 pub struct Chain {
 	db_root: String,
-	store: Arc<ChainStore>,
+	store: Arc<store::ChainStore>,
 	adapter: Arc<ChainAdapter>,
 
 	head: Arc<Mutex<Tip>>,
@@ -139,107 +141,28 @@ unsafe impl Sync for Chain {}
 unsafe impl Send for Chain {}
 
 impl Chain {
-	/// Check whether the chain exists. If not, the call to 'init' will
-	/// expect an already mined genesis block. This keeps the chain free
-	/// from needing to know about the mining implementation
-	pub fn chain_exists(db_root: String) -> bool {
-		let chain_store = store::ChainKVStore::new(db_root).unwrap();
-		match chain_store.head() {
-			Ok(_) => true,
-			Err(NotFoundErr) => false,
-			Err(_) => false,
-		}
-	}
-
 	/// Initializes the blockchain and returns a new Chain instance. Does a
 	/// check on the current chain head to make sure it exists and creates one
 	/// based on the genesis block if necessary.
 	pub fn init(
 		db_root: String,
+		db_env: Arc<lmdb::Environment>,
 		adapter: Arc<ChainAdapter>,
 		genesis: Block,
 		pow_verifier: fn(&BlockHeader, u8) -> bool,
 	) -> Result<Chain, Error> {
-		let chain_store = store::ChainKVStore::new(db_root.clone())?;
+		let chain_store = store::ChainStore::new(db_env)?;
 
 		let store = Arc::new(chain_store);
 
-		// check if we have a head in store, otherwise the genesis block is it
-		let head = store.head();
-
 		// open the txhashset, creating a new one if necessary
 		let mut txhashset = txhashset::TxHashSet::open(db_root.clone(), store.clone(), None)?;
 
-		match head {
+		setup_head(genesis, store.clone(), &mut txhashset)?;
-			Ok(head) => {
-				// TODO - consolidate head vs head_header here.
-				let head_header = store.head_header()?;
-
-				let mut head = head;
-				loop {
-					// Use current chain tip if we have one.
-					// Note: We are rewinding and validating against a writeable extension.
-					// If validation is successful we will truncate the backend files
-					// to match the provided block header.
-					let header = store.get_block_header(&head.last_block_h)?;
-					let res = txhashset::extending(&mut txhashset, |extension| {
-						debug!(
-							LOGGER,
-							"chain: init: rewinding and validating before we start... {} at {}",
-							header.hash(),
-							header.height,
-						);
-
-						extension.rewind(&header, &head_header)?;
-						extension.validate_roots(&header)?;
-
-						Ok(())
-					});
-
-					if res.is_ok() {
-						break;
-					} else {
-						// We may have corrupted the MMR backend files
-						// last time we stopped the node.
-						// If this appears to be the case
-						// revert the head to the previous header and try again
-
-						let _ = store.delete_block(&header.hash());
-						let prev_header = store.get_block_header(&head.prev_block_h)?;
-						let _ = store.setup_height(&prev_header, &head)?;
-						head = Tip::from_block(&prev_header);
-						store.save_head(&head)?;
-					}
-				}
-			}
-			Err(NotFoundErr) => {
-				let tip = Tip::from_block(&genesis.header);
-				store.save_block(&genesis)?;
-				store.setup_height(&genesis.header, &tip)?;
-				txhashset::extending(&mut txhashset, |extension| {
-					extension.apply_block(&genesis)?;
-					Ok(())
-				})?;
-
-				// saving a new tip based on genesis
-				store.save_head(&tip)?;
-				info!(
-					LOGGER,
-					"chain: init: saved genesis block: {:?}, nonce: {:?}, pow: {:?}",
-					genesis.hash(),
-					genesis.header.nonce,
-					genesis.header.pow,
-				);
-			}
-			Err(e) => return Err(Error::StoreErr(e, "chain init load head".to_owned())),
-		};
 
 		// Now reload the chain head (either existing head or genesis from above)
 		let head = store.head()?;
 
-		// Initialize header_head and sync_head as necessary for chain init.
-		store.init_head()?;
-
 		debug!(
 			LOGGER,
 			"Chain init: {} @ {} [{}]",
@@ -291,9 +214,9 @@ impl Chain {
 		let head = self.store
 			.head()
 			.map_err(|e| Error::StoreErr(e, "chain load head".to_owned()))?;
-		let ctx = self.ctx_from_head(head, opts);
+		let mut ctx = self.ctx_from_head(head, opts)?;
 
-		let res = pipe::process_block(&b, ctx);
+		let res = pipe::process_block(&b, &mut ctx);
 
 		match res {
 			Ok(Some(ref tip)) => {
@@ -378,8 +301,8 @@ impl Chain {
 	/// Process a block header received during "header first" propagation.
 	pub fn process_block_header(&self, bh: &BlockHeader, opts: Options) -> Result<(), Error> {
 		let header_head = self.get_header_head()?;
-		let ctx = self.ctx_from_head(header_head, opts);
+		let mut ctx = self.ctx_from_head(header_head, opts)?;
-		pipe::process_block_header(bh, ctx)
+		pipe::process_block_header(bh, &mut ctx)
 	}
 
 	/// Attempt to add a new header to the header chain.
@@ -387,19 +310,24 @@ impl Chain {
 	pub fn sync_block_header(&self, bh: &BlockHeader, opts: Options) -> Result<Option<Tip>, Error> {
 		let sync_head = self.get_sync_head()?;
 		let header_head = self.get_header_head()?;
-		let sync_ctx = self.ctx_from_head(sync_head, opts);
+		let mut sync_ctx = self.ctx_from_head(sync_head, opts)?;
-		let header_ctx = self.ctx_from_head(header_head, opts);
+		let mut header_ctx = self.ctx_from_head(header_head, opts)?;
-		pipe::sync_block_header(bh, sync_ctx, header_ctx)
+		let mut batch = self.store.batch()?;
+		let res = pipe::sync_block_header(bh, &mut sync_ctx, &mut header_ctx, &mut batch);
+		if res.is_ok() {
+			batch.commit()?;
+		}
+		res
 	}
 
-	fn ctx_from_head(&self, head: Tip, opts: Options) -> pipe::BlockContext {
+	fn ctx_from_head<'a>(&self, head: Tip, opts: Options) -> Result<pipe::BlockContext, Error> {
-		pipe::BlockContext {
+		Ok(pipe::BlockContext {
 			opts: opts,
 			store: self.store.clone(),
 			head: head,
 			pow_verifier: self.pow_verifier,
 			txhashset: self.txhashset.clone(),
-		}
+		})
 	}
 
 	/// Check if hash is for a known orphan.
@@ -497,39 +425,36 @@ impl Chain {
 
 		let mut txhashset = self.txhashset.write().unwrap();
 
-		// Now create an extension from the txhashset and validate
+		// Now create an extension from the txhashset and validate against the
-		// against the latest block header.
+		// latest block header. Rewind the extension to the specified header to
-		// Rewind the extension to the specified header to ensure the view is
+		// ensure the view is consistent.
-		// consistent.
 		txhashset::extending_readonly(&mut txhashset, |extension| {
 			// TODO - is this rewind guaranteed to be redundant now?
-			extension.rewind(&header, &header)?;
+			extension.rewind(&header, &header, true, true, true)?;
 			extension.validate(&header, skip_rproofs)?;
 			Ok(())
 		})
 	}
 
-	/// Sets the txhashset roots on a brand new block by applying the block on
+/// Sets the txhashset roots on a brand new block by applying the block on
-	/// the current txhashset state.
+/// the current txhashset state.
-	pub fn set_block_roots(&self, b: &mut Block, is_fork: bool) -> Result<(), Error> {
+pub fn set_txhashset_roots(&self, b: &mut Block, is_fork: bool) -> Result<(), Error> {
 	let mut txhashset = self.txhashset.write().unwrap();
 	let store = self.store.clone();
 
-		let (roots, sizes) = txhashset::extending_readonly(&mut txhashset, |extension| {
+	let roots = txhashset::extending_readonly(&mut txhashset, |extension| {
 		if is_fork {
 			pipe::rewind_and_apply_fork(b, store, extension)?;
 		}
 		extension.apply_block(b)?;
-			Ok((extension.roots(), extension.sizes()))
+		Ok(extension.roots())
 	})?;
 
 	b.header.output_root = roots.output_root;
 	b.header.range_proof_root = roots.rproof_root;
 	b.header.kernel_root = roots.kernel_root;
-		b.header.output_mmr_size = sizes.0;
-		b.header.kernel_mmr_size = sizes.2;
 	Ok(())
-	}
+}
 
 	/// Return a pre-built Merkle proof for the given commitment from the store.
 	pub fn get_merkle_proof(
@@ -580,7 +505,7 @@ impl Chain {
 
 			let mut txhashset = self.txhashset.write().unwrap();
 			txhashset::extending_readonly(&mut txhashset, |extension| {
-				extension.rewind(&header, &head_header)?;
+				extension.rewind(&header, &head_header, true, true, true)?;
 				extension.snapshot(&header)?;
 				Ok(())
 			})?;
@@ -612,34 +537,29 @@ impl Chain {
 		let header = self.store.get_block_header(&h)?;
 		txhashset::zip_write(self.db_root.clone(), txhashset_data)?;
 
+		{
 			// write the block marker so we can safely rewind to
 			// the pos for that block when we validate the extension below
+			let batch = self.store.batch()?;
 			let marker = BlockMarker {
 				output_pos: rewind_to_output,
 				kernel_pos: rewind_to_kernel,
 			};
-		self.store.save_block_marker(&h, &marker)?;
+			batch.save_block_marker(&h, &marker)?;
-
+			batch.commit()?;
-		debug!(
+		}
-			LOGGER,
-			"Going to validate new txhashset, might take some time..."
-		);
 
 		let mut txhashset =
 			txhashset::TxHashSet::open(self.db_root.clone(), self.store.clone(), Some(&header))?;
 
-		// first read-only extension, for validation only
+		// all good, prepare a new batch and update all the required records
-		txhashset::extending_readonly(&mut txhashset, |extension| {
+		let mut batch = self.store.batch()?;
-			extension.rewind(&header)?;
+		// Note: we are validataing against a writeable extension.
-			extension.validate(&header, false)?;
+		txhashset::extending(&mut txhashset, &mut batch, |extension| {
-			Ok(())
-		})?;
-		// second real extension to commit the rewind and indexes
-		txhashset::extending(&mut txhashset, |extension| {
 			// TODO do we need to rewind here? We have no blocks to rewind
 			// (and we need them for the pos to unremove)
-			extension.rewind(&header, &header)?;
+			extension.rewind(&header, &header, true, true, true)?;
-			extension.validate(&header, false)?;
+			let (_output_sum, _kernel_sum) = extension.validate(&header, false)?;
 			extension.rebuild_index()?;
 			Ok(())
 		})?;
@@ -649,18 +569,17 @@ impl Chain {
 			let mut txhashset_ref = self.txhashset.write().unwrap();
 			*txhashset_ref = txhashset;
 		}
-
 		// setup new head
 		{
 			let mut head = self.head.lock().unwrap();
 			*head = Tip::from_block(&header);
-			let _ = self.store.save_body_head(&head);
+			batch.save_body_head(&head)?;
-			self.store.save_header_height(&header)?;
+			batch.save_header_height(&header)?;
-			self.store.build_by_height_index(&header, true)?;
+			batch.build_by_height_index(&header, true)?;
 		}
+		batch.commit()?;
 
 		self.check_orphans(header.height + 1);
-
 		Ok(())
 	}
 
@@ -710,15 +629,14 @@ impl Chain {
 		);
 		let mut count = 0;
 		let mut current = self.store.get_header_by_height(head.height - horizon - 1)?;
+		let batch = self.store.batch()?;
 		loop {
 			match self.store.get_block(&current.hash()) {
 				Ok(b) => {
 					count += 1;
-
+					batch.delete_block(&b.hash())?;
-					// TODO - consider wrapping these up in a single fn call?
+					batch.delete_block_marker(&b.hash())?;
-					self.store.delete_block(&b.hash())?;
+					batch.delete_block_input_bitmap(&b.hash())?;
-					self.store.delete_block_marker(&b.hash())?;
-					self.store.delete_block_input_bitmap(&b.hash())?;
 				}
 				Err(NotFoundErr) => {
 					break;
@@ -734,6 +652,7 @@ impl Chain {
 				Err(e) => return Err(From::from(e)),
 			}
 		}
+		batch.commit()?;
 		debug!(LOGGER, "Compaction removed {} blocks, done.", count);
 		Ok(())
 	}
@@ -799,9 +718,12 @@ impl Chain {
 
 	/// Reset header_head and sync_head to head of current body chain
 	pub fn reset_head(&self) -> Result<(), Error> {
-		self.store
+		let batch = self.store.batch()?;
+		batch
 			.reset_head()
-			.map_err(|e| Error::StoreErr(e, "chain reset_head".to_owned()))
+			.map_err(|e| Error::StoreErr(e, "chain reset_head".to_owned()))?;
+		batch.commit()?;
+		Ok(())
 	}
 
 	/// Get the tip that's also the head of the chain
@@ -882,12 +804,75 @@ impl Chain {
 			.block_exists(&h)
 			.map_err(|e| Error::StoreErr(e, "chain block exists".to_owned()))
 	}
-
+}
-	/// Rebuilds height index. Reachable as endpoint POST /chain/height-index
+
-	pub fn rebuild_header_by_height(&self) -> Result<(), Error> {
+fn setup_head(
-		let head = self.head_header()?;
+	genesis: Block,
-		self.store
+	store: Arc<store::ChainStore>,
-			.build_by_height_index(&head, true)
+	txhashset: &mut txhashset::TxHashSet,
-			.map_err(|e| Error::StoreErr(e, "rebuild header by height index".to_owned()))
+) -> Result<(), Error> {
-	}
+	// check if we have a head in store, otherwise the genesis block is it
+	let head_res = store.head();
+	let mut batch = store.batch()?;
+	let mut head: Tip;
+	match head_res {
+		Ok(h) => {
+			head = h;
+			let head_header = store.head_header()?;
+			loop {
+				// Use current chain tip if we have one.
+				// Note: We are rewinding and validating against a writeable extension.
+				// If validation is successful we will truncate the backend files
+				// to match the provided block header.
+				let header = store.get_block_header(&head.last_block_h)?;
+
+
+				let res = txhashset::extending(txhashset, &mut batch, |extension| {
+					extension.rewind(&header, &head_header, true, true, true)?;
+					extension.validate_roots(&header)?;
+					debug!(
+						LOGGER,
+						"chain: init: rewinding and validating before we start... {} at {}",
+						header.hash(),
+						header.height,
+					);
+					Ok(())
+				});
+
+				if res.is_ok() {
+					break;
+				} else {
+					// We may have corrupted the MMR backend files last time we stopped the
+					// node. If this appears to be the case revert the head to the previous
+					// header and try again
+					let prev_header = store.get_block_header(&head.prev_block_h)?;
+					let _ = batch.delete_block(&header.hash());
+					let _ = batch.setup_height(&prev_header, &head)?;
+					head = Tip::from_block(&prev_header);
+					batch.save_head(&head)?;
+				}
+			}
+		}
+		Err(NotFoundErr) => {
+			let tip = Tip::from_block(&genesis.header);
+			batch.save_block(&genesis)?;
+			batch.setup_height(&genesis.header, &tip)?;
+			txhashset::extending(txhashset, &mut batch, |extension| {
+				extension.apply_block(&genesis)?;
+				Ok(())
+			})?;
+
+			// saving a new tip based on genesis
+			batch.save_head(&tip)?;
+			head = tip;
+			info!(LOGGER, "chain: init: saved genesis: {:?}", genesis.hash());
+		}
+		Err(e) => return Err(Error::StoreErr(e, "chain init load head".to_owned())),
+	};
+
+	// Initialize header_head and sync_head as necessary for chain init.
+	batch.init_sync_head(&head)?;
+	batch.commit()?;
+
+	Ok(())
 }

chain/src/lib.rs

@@ -23,6 +23,7 @@
 #[macro_use]
 extern crate bitflags;
 extern crate byteorder;
+extern crate lmdb_zero as lmdb;
 extern crate croaring;
 extern crate lru_cache;
 extern crate serde;
@@ -46,4 +47,5 @@ pub mod types;
 // Re-export the base interface
 
 pub use chain::{Chain, MAX_ORPHAN_SIZE};
-pub use types::{ChainAdapter, ChainStore, Error, Options, Tip};
+pub use store::ChainStore;
+pub use types::{BlockSums, ChainAdapter, Error, Options, Tip};

chain/src/pipe.rs

@@ -26,7 +26,7 @@ use core::global;
 use grin_store;
 use store;
 use txhashset;
-use types::{ChainStore, Error, Options, Tip};
+use types::{Error, Options, Tip};
 use util::LOGGER;
 
 /// Contextual information required to process a new block and either reject or
@@ -35,7 +35,7 @@ pub struct BlockContext {
 	/// The options
 	pub opts: Options,
 	/// The store
-	pub store: Arc<ChainStore>,
+	pub store: Arc<store::ChainStore>,
 	/// The head
 	pub head: Tip,
 	/// The POW verification function
@@ -45,9 +45,9 @@ pub struct BlockContext {
 }
 
 /// Runs the block processing pipeline, including validation and finding a
-/// place for the new block in the chain. Returns the new
+/// place for the new block in the chain. Returns the new chain head if
-/// chain head if updated.
+/// updated.
-pub fn process_block(b: &Block, mut ctx: BlockContext) -> Result<Option<Tip>, Error> {
+pub fn process_block(b: &Block, ctx: &mut BlockContext) -> Result<Option<Tip>, Error> {
 	// TODO should just take a promise for a block with a full header so we don't
 	// spend resources reading the full block when its header is invalid
 
@@ -60,9 +60,9 @@ pub fn process_block(b: &Block, mut ctx: BlockContext) -> Result<Option<Tip>, Er
 		b.outputs.len(),
 		b.kernels.len(),
 	);
-	check_known(b.hash(), &mut ctx)?;
+	check_known(b.hash(), ctx)?;
 
-	validate_header(&b.header, &mut ctx)?;
+	validate_header(&b.header, ctx)?;
 
 	// now check we actually have the previous block in the store
 	// not just the header but the block itself
@@ -84,8 +84,8 @@ pub fn process_block(b: &Block, mut ctx: BlockContext) -> Result<Option<Tip>, Er
 	}
 
 	// validate the block itself
-	// we can do this now before interact with the txhashset
+	// we can do this now before interacting with the txhashset
-	validate_block(b, &mut ctx)?;
+	let _sums = validate_block(b, ctx)?;
 
 	// header and block both valid, and we have a previous block
 	// so take the lock on the txhashset
@@ -97,9 +97,11 @@ pub fn process_block(b: &Block, mut ctx: BlockContext) -> Result<Option<Tip>, Er
 		.head()
 		.map_err(|e| Error::StoreErr(e, "pipe reload head".to_owned()))?;
 
+	let mut batch = ctx.store.batch()?;
+
 	// start a chain extension unit of work dependent on the success of the
 	// internal validation and saving operations
-	let result = txhashset::extending(&mut txhashset, |mut extension| {
+	let _ = txhashset::extending(&mut txhashset, &mut batch, |mut extension| {
 		// First we rewind the txhashset extension if necessary
 		// to put it into a consistent state for validating the block.
 		// We can skip this step if the previous header is the latest header we saw.
@@ -108,30 +110,33 @@ pub fn process_block(b: &Block, mut ctx: BlockContext) -> Result<Option<Tip>, Er
 		}
 		validate_block_via_txhashset(b, &mut extension)?;
 
+		if !block_has_more_work(b, &ctx.head) {
+			extension.force_rollback();
+		}
+		Ok(())
+	});
+
 	trace!(
 		LOGGER,
 		"pipe: process_block: {} at {} is valid, save and append.",
 		b.hash(),
 		b.header.height,
 	);
-
+	add_block(b, &mut batch)?;
-		add_block(b, &mut ctx)?;
+	let res = update_head(b, &ctx, &mut batch);
-		let h = update_head(b, &mut ctx)?;
+	if res.is_ok() {
-		if h.is_none() {
+		batch.commit()?;
-			extension.force_rollback();
 	}
-		Ok(h)
+	res
-	});
-
-	result
 }
 
 /// Process the block header.
 /// This is only ever used during sync and uses a context based on sync_head.
 pub fn sync_block_header(
 	bh: &BlockHeader,
-	mut sync_ctx: BlockContext,
+	sync_ctx: &mut BlockContext,
-	mut header_ctx: BlockContext,
+	header_ctx: &mut BlockContext,
+	batch: &mut store::Batch,
 ) -> Result<Option<Tip>, Error> {
 	debug!(
 		LOGGER,
@@ -140,20 +145,20 @@ pub fn sync_block_header(
 		bh.height
 	);
 
-	validate_header(&bh, &mut sync_ctx)?;
+	validate_header(&bh, sync_ctx)?;
-	add_block_header(bh, &mut sync_ctx)?;
+	add_block_header(bh, batch)?;
 
 	// now update the header_head (if new header with most work) and the sync_head
 	// (always)
-	update_header_head(bh, &mut header_ctx)?;
+	update_header_head(bh, header_ctx, batch)?;
-	update_sync_head(bh, &mut sync_ctx)
+	update_sync_head(bh, sync_ctx, batch)
 }
 
 /// Process block header as part of "header first" block propagation.
 /// We validate the header but we do not store it or update header head based
 /// on this. We will update these once we get the block back after requesting
 /// it.
-pub fn process_block_header(bh: &BlockHeader, mut ctx: BlockContext) -> Result<(), Error> {
+pub fn process_block_header(bh: &BlockHeader, ctx: &mut BlockContext) -> Result<(), Error> {
 	debug!(
 		LOGGER,
 		"pipe: process_block_header at {} [{}]",
@@ -161,8 +166,8 @@ pub fn process_block_header(bh: &BlockHeader, mut ctx: BlockContext) -> Result<(
 		bh.hash()
 	); // keep this
 
-	check_header_known(bh.hash(), &mut ctx)?;
+	check_header_known(bh.hash(), ctx)?;
-	validate_header(&bh, &mut ctx)
+	validate_header(&bh, ctx)
 }
 
 /// Quick in-memory check to fast-reject any block header we've already handled
@@ -362,19 +367,19 @@ fn validate_block_via_txhashset(b: &Block, ext: &mut txhashset::Extension) -> Re
 }
 
 /// Officially adds the block to our chain.
-fn add_block(b: &Block, ctx: &mut BlockContext) -> Result<(), Error> {
+fn add_block(b: &Block, batch: &store::Batch) -> Result<(), Error> {
-	ctx.store
+	batch
 		.save_block(b)
 		.map_err(|e| Error::StoreErr(e, "pipe save block".to_owned()))?;
-	ctx.store
+	batch
 		.save_block_input_bitmap(&b)
 		.map_err(|e| Error::StoreErr(e, "pipe save block input bitmap".to_owned()))?;
 	Ok(())
 }
 
 /// Officially adds the block header to our header chain.
-fn add_block_header(bh: &BlockHeader, ctx: &mut BlockContext) -> Result<(), Error> {
+fn add_block_header(bh: &BlockHeader, batch: &mut store::Batch) -> Result<(), Error> {
-	ctx.store
+	batch
 		.save_block_header(bh)
 		.map_err(|e| Error::StoreErr(e, "pipe save header".to_owned()))
 }
@@ -382,103 +387,73 @@ fn add_block_header(bh: &BlockHeader, ctx: &mut BlockContext) -> Result<(), Erro
 /// Directly updates the head if we've just appended a new block to it or handle
 /// the situation where we've just added enough work to have a fork with more
 /// work than the head.
-fn update_head(b: &Block, ctx: &mut BlockContext) -> Result<Option<Tip>, Error> {
+fn update_head(b: &Block, ctx: &BlockContext, batch: &store::Batch) -> Result<Option<Tip>, Error> {
 	// if we made a fork with more work than the head (which should also be true
 	// when extending the head), update it
-	let tip = Tip::from_block(&b.header);
+	if block_has_more_work(b, &ctx.head) {
-	if tip.total_difficulty > ctx.head.total_difficulty {
 		// update the block height index
-		ctx.store
+		batch
 			.setup_height(&b.header, &ctx.head)
 			.map_err(|e| Error::StoreErr(e, "pipe setup height".to_owned()))?;
 
 		// in sync mode, only update the "body chain", otherwise update both the
 		// "header chain" and "body chain", updating the header chain in sync resets
 		// all additional "future" headers we've received
+		let tip = Tip::from_block(&b.header);
 		if ctx.opts.contains(Options::SYNC) {
-			ctx.store
+			batch
 				.save_body_head(&tip)
 				.map_err(|e| Error::StoreErr(e, "pipe save body".to_owned()))?;
 		} else {
-			ctx.store
+			batch
 				.save_head(&tip)
 				.map_err(|e| Error::StoreErr(e, "pipe save head".to_owned()))?;
 		}
-		ctx.head = tip.clone();
-		if b.header.height % 100 == 0 {
-			info!(
-				LOGGER,
-				"pipe: chain head reached {} @ {} [{}]",
-				b.header.height,
-				b.header.total_difficulty,
-				b.hash()
-			);
-		} else {
 		debug!(
 			LOGGER,
-				"pipe: chain head reached {} @ {} [{}]",
+			"pipe: chain head {} @ {}",
-				b.header.height,
+			b.hash(),
-				b.header.total_difficulty,
+			b.header.height
-				b.hash()
 		);
-		}
 		Ok(Some(tip))
 	} else {
 		Ok(None)
 	}
 }
 
+// Whether the provided block totals more work than the chain tip
+fn block_has_more_work(b: &Block, tip: &Tip) -> bool {
+	let block_tip = Tip::from_block(&b.header);
+	block_tip.total_difficulty > tip.total_difficulty
+}
+
 /// Update the sync head so we can keep syncing from where we left off.
-fn update_sync_head(bh: &BlockHeader, ctx: &mut BlockContext) -> Result<Option<Tip>, Error> {
+fn update_sync_head(
+	bh: &BlockHeader,
+	ctx: &mut BlockContext,
+	batch: &mut store::Batch,
+) -> Result<Option<Tip>, Error> {
 	let tip = Tip::from_block(bh);
-	ctx.store
+	batch
 		.save_sync_head(&tip)
 		.map_err(|e| Error::StoreErr(e, "pipe save sync head".to_owned()))?;
 	ctx.head = tip.clone();
-	if bh.height % 100 == 0 {
+	debug!(LOGGER, "sync head {} @ {}", bh.hash(), bh.height);
-		info!(
-			LOGGER,
-			"sync head {} @ {} [{}]",
-			bh.total_difficulty,
-			bh.height,
-			bh.hash()
-		);
-	} else {
-		debug!(
-			LOGGER,
-			"sync head {} @ {} [{}]",
-			bh.total_difficulty,
-			bh.height,
-			bh.hash()
-		);
-	}
 	Ok(Some(tip))
 }
 
-fn update_header_head(bh: &BlockHeader, ctx: &mut BlockContext) -> Result<Option<Tip>, Error> {
+fn update_header_head(
+	bh: &BlockHeader,
+	ctx: &mut BlockContext,
+	batch: &mut store::Batch,
+) -> Result<Option<Tip>, Error> {
 	let tip = Tip::from_block(bh);
 	if tip.total_difficulty > ctx.head.total_difficulty {
-		ctx.store
+		batch
 			.save_header_head(&tip)
 			.map_err(|e| Error::StoreErr(e, "pipe save header head".to_owned()))?;
 		ctx.head = tip.clone();
-		if bh.height % 100 == 0 {
+		debug!(LOGGER, "header head {} @ {}", bh.hash(), bh.height);
-			info!(
-				LOGGER,
-				"header head {} @ {} [{}]",
-				bh.total_difficulty,
-				bh.height,
-				bh.hash()
-			);
-		} else {
-			debug!(
-				LOGGER,
-				"header head {} @ {} [{}]",
-				bh.total_difficulty,
-				bh.height,
-				bh.hash()
-			);
-		}
 		Ok(Some(tip))
 	} else {
 		Ok(None)
@@ -491,7 +466,7 @@ fn update_header_head(bh: &BlockHeader, ctx: &mut BlockContext) -> Result<Option
 /// the expected state.
 pub fn rewind_and_apply_fork(
 	b: &Block,
-	store: Arc<ChainStore>,
+	store: Arc<store::ChainStore>,
 	ext: &mut txhashset::Extension,
 ) -> Result<(), Error> {
 	// extending a fork, first identify the block where forking occurred
@@ -522,7 +497,7 @@ pub fn rewind_and_apply_fork(
 	);
 
 	// rewind the sum trees up to the forking block
-	ext.rewind(&forked_header, &head_header)?;
+	ext.rewind(&forked_header, &head_header, true, true, true)?;
 
 	trace!(
 		LOGGER,

chain/src/store.rs

@@ -16,6 +16,7 @@
 
 use std::sync::{Arc, RwLock};
 
+use lmdb;
 use croaring::Bitmap;
 use lru_cache::LruCache;
 
@@ -25,8 +26,9 @@ use core::consensus::TargetError;
 use core::core::hash::{Hash, Hashed};
 use core::core::target::Difficulty;
 use core::core::{Block, BlockHeader};
-use grin_store::{self, option_to_not_found, to_key, Error, u64_to_key};
+use grin_store as store;
-use types::{BlockMarker, ChainStore, Tip};
+use grin_store::{option_to_not_found, to_key, Error, u64_to_key};
+use types::{BlockMarker, BlockSums, Tip};
 
 const STORE_SUBPATH: &'static str = "chain";
 
@@ -38,28 +40,254 @@ const SYNC_HEAD_PREFIX: u8 = 's' as u8;
 const HEADER_HEIGHT_PREFIX: u8 = '8' as u8;
 const COMMIT_POS_PREFIX: u8 = 'c' as u8;
 const BLOCK_MARKER_PREFIX: u8 = 'm' as u8;
+const BLOCK_SUMS_PREFIX: u8 = 'M' as u8;
 const BLOCK_INPUT_BITMAP_PREFIX: u8 = 'B' as u8;
 
-/// An implementation of the ChainStore trait backed by a simple key-value
+/// All chain-related database operations
-/// store.
+pub struct ChainStore {
-pub struct ChainKVStore {
+	db: store::Store,
-	db: grin_store::Store,
 	header_cache: Arc<RwLock<LruCache<Hash, BlockHeader>>>,
-	block_input_bitmap_cache: Arc<RwLock<LruCache<Hash, Vec<u8>>>>,
 }
 
-impl ChainKVStore {
+impl ChainStore {
 	/// Create new chain store
-	pub fn new(root_path: String) -> Result<ChainKVStore, Error> {
+	pub fn new(db_env: Arc<lmdb::Environment>) -> Result<ChainStore, Error> {
-		let db = grin_store::Store::open(format!("{}/{}", root_path, STORE_SUBPATH).as_str())?;
+		let db = store::Store::open(db_env, STORE_SUBPATH);
-		Ok(ChainKVStore {
+		Ok(ChainStore {
 			db,
 			header_cache: Arc::new(RwLock::new(LruCache::new(1_000))),
+		})
+	}
+}
+
+#[allow(missing_docs)]
+impl ChainStore {
+	pub fn head(&self) -> Result<Tip, Error> {
+		option_to_not_found(self.db.get_ser(&vec![HEAD_PREFIX]))
+	}
+
+	pub fn head_header(&self) -> Result<BlockHeader, Error> {
+		self.get_block_header(&self.head()?.last_block_h)
+	}
+
+	pub fn get_header_head(&self) -> Result<Tip, Error> {
+		option_to_not_found(self.db.get_ser(&vec![HEADER_HEAD_PREFIX]))
+	}
+
+	pub fn get_sync_head(&self) -> Result<Tip, Error> {
+		option_to_not_found(self.db.get_ser(&vec![SYNC_HEAD_PREFIX]))
+	}
+
+	pub fn get_block(&self, h: &Hash) -> Result<Block, Error> {
+		option_to_not_found(self.db.get_ser(&to_key(BLOCK_PREFIX, &mut h.to_vec())))
+	}
+
+	pub fn block_exists(&self, h: &Hash) -> Result<bool, Error> {
+		self.db.exists(&to_key(BLOCK_PREFIX, &mut h.to_vec()))
+	}
+
+	pub fn get_block_header(&self, h: &Hash) -> Result<BlockHeader, Error> {
+		{
+			let mut header_cache = self.header_cache.write().unwrap();
+
+			// cache hit - return the value from the cache
+			if let Some(header) = header_cache.get_mut(h) {
+				return Ok(header.clone());
+			}
+		}
+
+		let header: Result<BlockHeader, Error> = option_to_not_found(
+			self.db
+				.get_ser(&to_key(BLOCK_HEADER_PREFIX, &mut h.to_vec())),
+		);
+
+		// cache miss - so adding to the cache for next time
+		if let Ok(header) = header {
+			{
+				let mut header_cache = self.header_cache.write().unwrap();
+				header_cache.insert(*h, header.clone());
+			}
+			Ok(header)
+		} else {
+			header
+		}
+	}
+
+	// We are on the current chain if -
+	// * the header by height index matches the header, and
+	// * we are not ahead of the current head
+	pub fn is_on_current_chain(&self, header: &BlockHeader) -> Result<(), Error> {
+		let head = self.head()?;
+
+		// check we are not out ahead of the current head
+		if header.height > head.height {
+			return Err(Error::NotFoundErr);
+		}
+
+		let header_at_height = self.get_header_by_height(header.height)?;
+		if header.hash() == header_at_height.hash() {
+			Ok(())
+		} else {
+			Err(Error::NotFoundErr)
+		}
+	}
+
+	pub fn get_header_by_height(&self, height: u64) -> Result<BlockHeader, Error> {
+		option_to_not_found(self.db.get_ser(&u64_to_key(HEADER_HEIGHT_PREFIX, height)))
+			.and_then(|hash| self.get_block_header(&hash))
+	}
+
+	pub fn get_output_pos(&self, commit: &Commitment) -> Result<u64, Error> {
+		option_to_not_found(
+			self.db
+				.get_ser(&to_key(COMMIT_POS_PREFIX, &mut commit.as_ref().to_vec())),
+		)
+	}
+
+	pub fn get_block_marker(&self, bh: &Hash) -> Result<BlockMarker, Error> {
+		option_to_not_found(
+			self.db
+				.get_ser(&to_key(BLOCK_MARKER_PREFIX, &mut bh.to_vec())),
+		)
+	}
+
+	pub fn get_block_sums(&self, bh: &Hash) -> Result<BlockSums, Error> {
+		option_to_not_found(
+			self.db
+				.get_ser(&to_key(BLOCK_SUMS_PREFIX, &mut bh.to_vec())),
+		)
+	}
+
+	/// Builds a new batch to be used with this store.
+	pub fn batch(&self) -> Result<Batch, Error> {
+		Ok(Batch {
+			store: self,
+			db: self.db.batch()?,
 			block_input_bitmap_cache: Arc::new(RwLock::new(LruCache::new(1_000))),
 		})
 	}
+}
 
-	fn get_block_header_db(&self, h: &Hash) -> Result<BlockHeader, Error> {
+/// An atomic batch in which all changes can be committed all at once or
+/// discarded on error.
+pub struct Batch<'a> {
+	store: &'a ChainStore,
+	db: store::Batch<'a>,
+	block_input_bitmap_cache: Arc<RwLock<LruCache<Hash, Vec<u8>>>>,
+}
+
+#[allow(missing_docs)]
+impl<'a> Batch<'a> {
+	pub fn save_head(&self, t: &Tip) -> Result<(), Error> {
+		self.db.put_ser(&vec![HEAD_PREFIX], t)?;
+		self.db.put_ser(&vec![HEADER_HEAD_PREFIX], t)
+	}
+
+	pub fn save_body_head(&self, t: &Tip) -> Result<(), Error> {
+		self.db.put_ser(&vec![HEAD_PREFIX], t)
+	}
+
+	pub fn save_header_head(&self, t: &Tip) -> Result<(), Error> {
+		self.db.put_ser(&vec![HEADER_HEAD_PREFIX], t)
+	}
+
+	pub fn save_sync_head(&self, t: &Tip) -> Result<(), Error> {
+		self.db.put_ser(&vec![SYNC_HEAD_PREFIX], t)
+	}
+
+	pub fn init_sync_head(&self, t: &Tip) -> Result<(), Error> {
+		let header_tip = match self.store.get_header_head() {
+			Ok(hh) => hh,
+			Err(store::Error::NotFoundErr) => {
+				self.save_header_head(t)?;
+				t.clone()
+			}
+			Err(e) => return Err(e),
+		};
+		self.save_sync_head(&header_tip)
+	}
+
+	// Reset both header_head and sync_head to the current head of the body chain
+	pub fn reset_head(&self) -> Result<(), Error> {
+		let tip = self.store.head()?;
+		self.save_header_head(&tip)?;
+		self.save_sync_head(&tip)
+	}
+
+	/// get block
+	fn get_block(&self, h: &Hash) -> Result<Block, Error> {
+		option_to_not_found(self.db.get_ser(&to_key(BLOCK_PREFIX, &mut h.to_vec())))
+	}
+
+	/// Save the block and its header
+	pub fn save_block(&self, b: &Block) -> Result<(), Error> {
+		self.db
+			.put_ser(&to_key(BLOCK_PREFIX, &mut b.hash().to_vec())[..], b)?;
+		self.db.put_ser(
+			&to_key(BLOCK_HEADER_PREFIX, &mut b.hash().to_vec())[..],
+			&b.header,
+		)
+	}
+
+	/// Delete a full block. Does not delete any record associated with a block
+	/// header.
+	pub fn delete_block(&self, bh: &Hash) -> Result<(), Error> {
+		self.db.delete(&to_key(BLOCK_PREFIX, &mut bh.to_vec())[..])
+	}
+
+	pub fn save_block_header(&self, bh: &BlockHeader) -> Result<(), Error> {
+		let hash = bh.hash();
+		self.db
+			.put_ser(&to_key(BLOCK_HEADER_PREFIX, &mut hash.to_vec())[..], bh)?;
+		Ok(())
+	}
+
+	pub fn save_header_height(&self, bh: &BlockHeader) -> Result<(), Error> {
+		self.db
+			.put_ser(&u64_to_key(HEADER_HEIGHT_PREFIX, bh.height), &bh.hash())
+	}
+
+	pub fn delete_header_by_height(&self, height: u64) -> Result<(), Error> {
+		self.db.delete(&u64_to_key(HEADER_HEIGHT_PREFIX, height))
+	}
+
+	pub fn save_output_pos(&self, commit: &Commitment, pos: u64) -> Result<(), Error> {
+		self.db.put_ser(
+			&to_key(COMMIT_POS_PREFIX, &mut commit.as_ref().to_vec())[..],
+			&pos,
+		)
+	}
+
+	pub fn get_output_pos(&self, commit: &Commitment) -> Result<u64, Error> {
+		option_to_not_found(
+			self.db
+				.get_ser(&to_key(COMMIT_POS_PREFIX, &mut commit.as_ref().to_vec())),
+		)
+	}
+
+	pub fn delete_output_pos(&self, commit: &[u8]) -> Result<(), Error> {
+		self.db
+			.delete(&to_key(COMMIT_POS_PREFIX, &mut commit.to_vec()))
+	}
+
+	pub fn get_block_marker(&self, bh: &Hash) -> Result<BlockMarker, Error> {
+		option_to_not_found(
+			self.db
+				.get_ser(&to_key(BLOCK_MARKER_PREFIX, &mut bh.to_vec())),
+		)
+	}
+
+	pub fn save_block_marker(&self, bh: &Hash, marker: &BlockMarker) -> Result<(), Error> {
+		self.db
+			.put_ser(&to_key(BLOCK_MARKER_PREFIX, &mut bh.to_vec())[..], &marker)
+	}
+
+	pub fn delete_block_marker(&self, bh: &Hash) -> Result<(), Error> {
+		self.db
+			.delete(&to_key(BLOCK_MARKER_PREFIX, &mut bh.to_vec()))
+	}
+
+	pub fn get_block_header_db(&self, h: &Hash) -> Result<BlockHeader, Error> {
 		option_to_not_found(
 			self.db
 				.get_ser(&to_key(BLOCK_HEADER_PREFIX, &mut h.to_vec())),
@@ -93,192 +321,8 @@ impl ChainKVStore {
 			}
 		}
 	}
-}
 
-impl ChainStore for ChainKVStore {
+	pub fn get_block_input_bitmap(&self, bh: &Hash) -> Result<Bitmap, Error> {
-	fn head(&self) -> Result<Tip, Error> {
-		option_to_not_found(self.db.get_ser(&vec![HEAD_PREFIX]))
-	}
-
-	fn head_header(&self) -> Result<BlockHeader, Error> {
-		self.get_block_header(&self.head()?.last_block_h)
-	}
-
-	fn save_head(&self, t: &Tip) -> Result<(), Error> {
-		self.db
-			.batch()
-			.put_ser(&vec![HEAD_PREFIX], t)?
-			.put_ser(&vec![HEADER_HEAD_PREFIX], t)?
-			.write()
-	}
-
-	fn save_body_head(&self, t: &Tip) -> Result<(), Error> {
-		self.db.put_ser(&vec![HEAD_PREFIX], t)
-	}
-
-	fn get_header_head(&self) -> Result<Tip, Error> {
-		option_to_not_found(self.db.get_ser(&vec![HEADER_HEAD_PREFIX]))
-	}
-
-	fn save_header_head(&self, t: &Tip) -> Result<(), Error> {
-		self.db.put_ser(&vec![HEADER_HEAD_PREFIX], t)
-	}
-
-	fn get_sync_head(&self) -> Result<Tip, Error> {
-		option_to_not_found(self.db.get_ser(&vec![SYNC_HEAD_PREFIX]))
-	}
-
-	fn save_sync_head(&self, t: &Tip) -> Result<(), Error> {
-		self.db.put_ser(&vec![SYNC_HEAD_PREFIX], t)
-	}
-
-	fn init_head(&self) -> Result<(), Error> {
-		if self.get_header_head().is_err() {
-			let tip = self.head()?;
-			self.save_header_head(&tip)?;
-		}
-		let header_tip = self.get_header_head()?;
-		self.save_sync_head(&header_tip)
-	}
-
-	// Reset both header_head and sync_head to the current head of the body chain
-	fn reset_head(&self) -> Result<(), Error> {
-		let tip = self.head()?;
-		self.save_header_head(&tip)?;
-		self.save_sync_head(&tip)
-	}
-
-	fn get_block(&self, h: &Hash) -> Result<Block, Error> {
-		option_to_not_found(self.db.get_ser(&to_key(BLOCK_PREFIX, &mut h.to_vec())))
-	}
-
-	fn block_exists(&self, h: &Hash) -> Result<bool, Error> {
-		self.db.exists(&to_key(BLOCK_PREFIX, &mut h.to_vec()))
-	}
-
-	fn get_block_header(&self, h: &Hash) -> Result<BlockHeader, Error> {
-		{
-			let mut header_cache = self.header_cache.write().unwrap();
-
-			// cache hit - return the value from the cache
-			if let Some(header) = header_cache.get_mut(h) {
-				return Ok(header.clone());
-			}
-		}
-
-		// cache miss - get it from db and cache it for next time (if we found one in
-		// db)
-		let res = self.get_block_header_db(h);
-		if let Ok(header) = res {
-			let mut header_cache = self.header_cache.write().unwrap();
-			header_cache.insert(*h, header.clone());
-			return Ok(header);
-		}
-		res
-	}
-
-	/// Save the block and its header
-	fn save_block(&self, b: &Block) -> Result<(), Error> {
-		let batch = self.db
-			.batch()
-			.put_ser(&to_key(BLOCK_PREFIX, &mut b.hash().to_vec())[..], b)?
-			.put_ser(
-				&to_key(BLOCK_HEADER_PREFIX, &mut b.hash().to_vec())[..],
-				&b.header,
-			)?;
-		batch.write()
-	}
-
-	/// Delete a full block. Does not delete any record associated with a block
-	/// header.
-	fn delete_block(&self, bh: &Hash) -> Result<(), Error> {
-		self.db.delete(&to_key(BLOCK_PREFIX, &mut bh.to_vec())[..])
-	}
-
-	// We are on the current chain if -
-	// * the header by height index matches the header, and
-	// * we are not ahead of the current head
-	fn is_on_current_chain(&self, header: &BlockHeader) -> Result<(), Error> {
-		let head = self.head()?;
-
-		// check we are not out ahead of the current head
-		if header.height > head.height {
-			return Err(Error::NotFoundErr);
-		}
-
-		let header_at_height = self.get_header_by_height(header.height)?;
-		if header.hash() == header_at_height.hash() {
-			Ok(())
-		} else {
-			Err(Error::NotFoundErr)
-		}
-	}
-
-	fn save_block_header(&self, bh: &BlockHeader) -> Result<(), Error> {
-		let hash = bh.hash();
-		self.db
-			.put_ser(&to_key(BLOCK_HEADER_PREFIX, &mut hash.to_vec())[..], bh)?;
-
-		// Write the block_header to the cache also.
-		{
-			let mut header_cache = self.header_cache.write().unwrap();
-			header_cache.insert(hash, bh.clone());
-		}
-
-		Ok(())
-	}
-
-	fn get_header_by_height(&self, height: u64) -> Result<BlockHeader, Error> {
-		option_to_not_found(self.db.get_ser(&u64_to_key(HEADER_HEIGHT_PREFIX, height)))
-			.and_then(|hash| self.get_block_header(&hash))
-	}
-
-	fn save_header_height(&self, bh: &BlockHeader) -> Result<(), Error> {
-		self.db
-			.put_ser(&u64_to_key(HEADER_HEIGHT_PREFIX, bh.height), &bh.hash())
-	}
-
-	fn delete_header_by_height(&self, height: u64) -> Result<(), Error> {
-		self.db.delete(&u64_to_key(HEADER_HEIGHT_PREFIX, height))
-	}
-
-	fn save_output_pos(&self, commit: &Commitment, pos: u64) -> Result<(), Error> {
-		self.db.put_ser(
-			&to_key(COMMIT_POS_PREFIX, &mut commit.as_ref().to_vec())[..],
-			&pos,
-		)
-	}
-
-	fn get_output_pos(&self, commit: &Commitment) -> Result<u64, Error> {
-		option_to_not_found(
-			self.db
-				.get_ser(&to_key(COMMIT_POS_PREFIX, &mut commit.as_ref().to_vec())),
-		)
-	}
-
-	fn delete_output_pos(&self, commit: &[u8]) -> Result<(), Error> {
-		self.db
-			.delete(&to_key(COMMIT_POS_PREFIX, &mut commit.to_vec()))
-	}
-
-	fn save_block_marker(&self, bh: &Hash, marker: &BlockMarker) -> Result<(), Error> {
-		self.db
-			.put_ser(&to_key(BLOCK_MARKER_PREFIX, &mut bh.to_vec())[..], &marker)
-	}
-
-	fn get_block_marker(&self, bh: &Hash) -> Result<BlockMarker, Error> {
-		option_to_not_found(
-			self.db
-				.get_ser(&to_key(BLOCK_MARKER_PREFIX, &mut bh.to_vec())),
-		)
-	}
-
-	fn delete_block_marker(&self, bh: &Hash) -> Result<(), Error> {
-		self.db
-			.delete(&to_key(BLOCK_MARKER_PREFIX, &mut bh.to_vec()))
-	}
-
-	fn get_block_input_bitmap(&self, bh: &Hash) -> Result<Bitmap, Error> {
 		{
 			let mut cache = self.block_input_bitmap_cache.write().unwrap();
 
@@ -299,7 +343,7 @@ impl ChainStore for ChainKVStore {
 		res
 	}
 
-	fn save_block_input_bitmap(&self, block: &Block) -> Result<Bitmap, Error> {
+	pub fn save_block_input_bitmap(&self, block: &Block) -> Result<Bitmap, Error> {
 		let hash = block.hash();
 		let bitmap = self.build_block_input_bitmap(block)?;
 		self.db.put(
@@ -313,7 +357,7 @@ impl ChainStore for ChainKVStore {
 		Ok(bitmap)
 	}
 
-	fn delete_block_input_bitmap(&self, bh: &Hash) -> Result<(), Error> {
+	pub fn delete_block_input_bitmap(&self, bh: &Hash) -> Result<(), Error> {
 		self.db
 			.delete(&to_key(BLOCK_INPUT_BITMAP_PREFIX, &mut bh.to_vec()))
 	}
@@ -325,7 +369,7 @@ impl ChainStore for ChainKVStore {
 	/// We need to handle the case where we have no index entry for a given
 	/// height to account for the case where we just switched to a new fork and
 	/// the height jumped beyond current chain height.
-	fn setup_height(&self, header: &BlockHeader, old_tip: &Tip) -> Result<(), Error> {
+	pub fn setup_height(&self, header: &BlockHeader, old_tip: &Tip) -> Result<(), Error> {
 		// remove headers ahead if we backtracked
 		for n in header.height..old_tip.height {
 			self.delete_header_by_height(n + 1)?;
@@ -333,24 +377,40 @@ impl ChainStore for ChainKVStore {
 		self.build_by_height_index(header, false)
 	}
 
-	fn build_by_height_index(&self, header: &BlockHeader, force: bool) -> Result<(), Error> {
+	pub fn build_by_height_index(&self, header: &BlockHeader, force: bool) -> Result<(), Error> {
 		self.save_header_height(&header)?;
 
 		if header.height > 0 {
-			let mut prev_header = self.get_block_header(&header.previous)?;
+			let mut prev_header = self.store.get_block_header(&header.previous)?;
 			while prev_header.height > 0 {
 				if !force {
-					if let Ok(_) = self.is_on_current_chain(&prev_header) {
+					if let Ok(_) = self.store.is_on_current_chain(&prev_header) {
 						break;
 					}
 				}
 				self.save_header_height(&prev_header)?;
 
-				prev_header = self.get_block_header(&prev_header.previous)?;
+				prev_header = self.store.get_block_header(&prev_header.previous)?;
 			}
 		}
 		Ok(())
 	}
+
+	/// Commits this batch. If it's a child batch, it will be merged with the
+	/// parent, otherwise the batch is written to db.
+	pub fn commit(self) -> Result<(), Error> {
+		self.db.commit()
+	}
+
+	/// Creates a child of this batch. It will be merged with its parent on
+	/// commit, abandoned otherwise.
+	pub fn child(&mut self) -> Result<Batch, Error> {
+		Ok(Batch {
+			store: self.store,
+			db: self.db.child()?,
+			block_input_bitmap_cache: Arc::new(RwLock::new(LruCache::new(1_000))),
+		})
+	}
 }
 
 /// An iterator on blocks, from latest to earliest, specialized to return

chain/src/txhashset.rs

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//! Utility structs to handle the 3 hashtrees (output, range proof, kernel) more
+//! Utility structs to handle the 3 hashtrees (output, range proof,
-//! conveniently and transactionally.
+//! kernel) more conveniently and transactionally.
 
 use std::collections::HashMap;
 use std::fs;
@@ -39,8 +39,9 @@ use core::ser::{PMMRIndexHashable, PMMRable};
 use grin_store;
 use grin_store::pmmr::PMMRBackend;
 use grin_store::types::prune_noop;
-use types::{BlockMarker, ChainStore, Error, TxHashSetRoots};
+use store::{Batch, ChainStore};
-use util::{zip, LOGGER};
+use types::{BlockMarker, Error, TxHashSetRoots};
+use util::{secp_static, zip, LOGGER};
 
 const TXHASHSET_SUBDIR: &'static str = "txhashset";
 const OUTPUT_SUBDIR: &'static str = "output";
@@ -241,9 +242,11 @@ impl TxHashSet {
 		let rewind_rm_pos =
 			input_pos_to_rewind(self.commit_index.clone(), &horizon_header, &head_header)?;
 
+		let batch = self.commit_index.batch()?;
+		{
 			let clean_output_index = |commit: &[u8]| {
 				// do we care if this fails?
-			let _ = commit_index.delete_output_pos(commit);
+				let _ = batch.delete_output_pos(commit);
 			};
 
 			self.output_pmmr_h.backend.check_compact(
@@ -259,6 +262,8 @@ impl TxHashSet {
 				&rewind_rm_pos,
 				&prune_noop,
 			)?;
+		}
+		batch.commit()?;
 
 		Ok(())
 	}
@@ -274,24 +279,19 @@ pub fn extending_readonly<'a, F, T>(trees: &'a mut TxHashSet, inner: F) -> Resul
 where
 	F: FnOnce(&mut Extension) -> Result<T, Error>,
 {
-	let sizes: (u64, u64, u64);
 	let res: Result<T, Error>;
 	{
 		let commit_index = trees.commit_index.clone();
+		let commit_index2 = trees.commit_index.clone();
+		let batch = commit_index.batch()?;
 
 		trace!(LOGGER, "Starting new txhashset (readonly) extension.");
-		let mut extension = Extension::new(trees, commit_index);
+		let mut extension = Extension::new(trees, &batch, commit_index2);
 		extension.force_rollback();
 		res = inner(&mut extension);
-
-		sizes = extension.sizes();
 	}
 
-	trace!(
+	trace!(LOGGER, "Rollbacking txhashset (readonly) extension.");
-		LOGGER,
-		"Rollbacking txhashset (readonly) extension. sizes {:?}",
-		sizes
-	);
 
 	trees.output_pmmr_h.backend.discard();
 	trees.rproof_pmmr_h.backend.discard();
@@ -309,7 +309,11 @@ where
 ///
 /// If the closure returns an error, modifications are canceled and the unit
 /// of work is abandoned. Otherwise, the unit of work is permanently applied.
-pub fn extending<'a, F, T>(trees: &'a mut TxHashSet, inner: F) -> Result<T, Error>
+pub fn extending<'a, F, T>(
+	trees: &'a mut TxHashSet,
+	batch: &'a mut Batch,
+	inner: F,
+) -> Result<T, Error>
 where
 	F: FnOnce(&mut Extension) -> Result<T, Error>,
 {
@@ -317,11 +321,14 @@ where
 	let res: Result<T, Error>;
 	let rollback: bool;
 
+	// create a child transaction so if the state is rolled back by itself, all
+	// index saving can be undone
+	let child_batch = batch.child()?;
 	{
 		let commit_index = trees.commit_index.clone();
 
 		trace!(LOGGER, "Starting new txhashset extension.");
-		let mut extension = Extension::new(trees, commit_index);
+		let mut extension = Extension::new(trees, &child_batch, commit_index);
 		res = inner(&mut extension);
 
 		rollback = extension.rollback;
@@ -347,6 +354,7 @@ where
 				trees.kernel_pmmr_h.backend.discard();
 			} else {
 				trace!(LOGGER, "Committing txhashset extension. sizes {:?}", sizes);
+				child_batch.commit()?;
 				trees.output_pmmr_h.backend.sync()?;
 				trees.rproof_pmmr_h.backend.sync()?;
 				trees.kernel_pmmr_h.backend.sync()?;
@@ -373,6 +381,11 @@ pub struct Extension<'a> {
 	new_output_commits: HashMap<Commitment, u64>,
 	new_block_markers: HashMap<Hash, BlockMarker>,
 	rollback: bool,
+
+	/// Batch in which the extension occurs, public so it can be used within
+	/// and `extending` closure. Just be careful using it that way as it will
+	/// get rolled back with the extension (i.e on a losing fork).
+	pub batch: &'a Batch<'a>,
 }
 
 impl<'a> Committed for Extension<'a> {
@@ -407,7 +420,11 @@ impl<'a> Committed for Extension<'a> {
 
 impl<'a> Extension<'a> {
 	// constructor
-	fn new(trees: &'a mut TxHashSet, commit_index: Arc<ChainStore>) -> Extension<'a> {
+	fn new(
+		trees: &'a mut TxHashSet,
+		batch: &'a Batch,
+		commit_index: Arc<ChainStore>,
+	) -> Extension<'a> {
 		Extension {
 			output_pmmr: PMMR::at(
 				&mut trees.output_pmmr_h.backend,
@@ -421,10 +438,11 @@ impl<'a> Extension<'a> {
 				&mut trees.kernel_pmmr_h.backend,
 				trees.kernel_pmmr_h.last_pos,
 			),
-			commit_index: commit_index,
+			commit_index,
 			new_output_commits: HashMap::new(),
 			new_block_markers: HashMap::new(),
 			rollback: false,
+			batch,
 		}
 	}
 
@@ -440,7 +458,7 @@ impl<'a> Extension<'a> {
 		let rewind_add_pos: Bitmap = ((output_pos + 1)..(latest_output_pos + 1))
 			.map(|x| x as u32)
 			.collect();
-		self.rewind_to_pos(output_pos, kernel_pos, &rewind_add_pos, rewind_rm_pos)?;
+		self.rewind_to_pos(output_pos, kernel_pos, &rewind_add_pos, rewind_rm_pos, true, true, true)?;
 		Ok(())
 	}
 
@@ -465,8 +483,7 @@ impl<'a> Extension<'a> {
 		// Build bitmap of output pos spent (as inputs) by this tx for rewind.
 		let rewind_rm_pos = tx.inputs
 			.iter()
-			.filter_map(|x| self.get_output_pos(&x.commitment()).ok())
+			.filter_map(|x| self.get_output_pos(&x.commitment()).ok()) .map(|x| x as u32)
-			.map(|x| x as u32)
 			.collect();
 
 		for ref output in &tx.outputs {
@@ -595,6 +612,8 @@ impl<'a> Extension<'a> {
 			output_pos: self.output_pmmr.unpruned_size(),
 			kernel_pos: self.kernel_pmmr.unpruned_size(),
 		};
+		//TODO: This doesn't look right
+		self.batch.save_block_marker(&b.hash(), &marker)?;
 		self.new_block_markers.insert(b.hash(), marker);
 		Ok(())
 	}
@@ -603,17 +622,17 @@ impl<'a> Extension<'a> {
 	// Also store any new block_markers.
 	fn save_indexes(&self) -> Result<(), Error> {
 		for (commit, pos) in &self.new_output_commits {
-			self.commit_index.save_output_pos(commit, *pos)?;
+			self.batch.save_output_pos(commit, *pos)?;
 		}
 		for (bh, marker) in &self.new_block_markers {
-			self.commit_index.save_block_marker(bh, marker)?;
+			self.batch.save_block_marker(bh, marker)?;
 		}
 		Ok(())
 	}
 
 	fn apply_input(&mut self, input: &Input) -> Result<(), Error> {
 		let commit = input.commitment();
-		let pos_res = self.get_output_pos(&commit);
+		let pos_res = self.batch.get_output_pos(&commit);
 		if let Ok(pos) = pos_res {
 			let output_id_hash = OutputIdentifier::from_input(input).hash_with_index(pos - 1);
 			if let Some(read_hash) = self.output_pmmr.get_hash(pos) {
@@ -649,7 +668,8 @@ impl<'a> Extension<'a> {
 
 	fn apply_output(&mut self, out: &Output) -> Result<(), Error> {
 		let commit = out.commitment();
-		if let Ok(pos) = self.get_output_pos(&commit) {
+
+		if let Ok(pos) = self.batch.get_output_pos(&commit) {
 			// we need to check whether the commitment is in the current MMR view
 			// as well as the index doesn't support rewind and is non-authoritative
 			// (non-historical node will have a much smaller one)
@@ -668,6 +688,7 @@ impl<'a> Extension<'a> {
 		let pos = self.output_pmmr
 			.push(OutputIdentifier::from_output(out))
 			.map_err(&Error::TxHashSetErr)?;
+		self.batch.save_output_pos(&out.commitment(), pos)?;
 		self.new_output_commits.insert(out.commitment(), pos);
 
 		// push range proofs in their MMR and file
@@ -705,10 +726,10 @@ impl<'a> Extension<'a> {
 
 		// rewind to the specified block for a consistent view
 		let head_header = self.commit_index.head_header()?;
-		self.rewind(block_header, &head_header)?;
+		self.rewind(block_header, &head_header, true, true, true)?;
 
 		// then calculate the Merkle Proof based on the known pos
-		let pos = self.get_output_pos(&output.commit)?;
+		let pos = self.batch.get_output_pos(&output.commit)?;
 		let merkle_proof = self.output_pmmr
 			.merkle_proof(pos)
 			.map_err(&Error::TxHashSetErr)?;
@@ -737,6 +758,9 @@ impl<'a> Extension<'a> {
 		&mut self,
 		block_header: &BlockHeader,
 		head_header: &BlockHeader,
+		rewind_utxo: bool,
+		rewind_kernel: bool,
+		rewind_rangeproof: bool,
 	) -> Result<(), Error> {
 		let hash = block_header.hash();
 		trace!(
@@ -748,7 +772,7 @@ impl<'a> Extension<'a> {
 
 		// Rewind our MMRs to the appropriate positions
 		// based on the block_marker.
-		let marker = self.commit_index.get_block_marker(&hash)?;
+		let marker = self.batch.get_block_marker(&hash)?;
 
 		// We need to build bitmaps of added and removed output positions
 		// so we can correctly rewind all operations applied to the output MMR
@@ -766,6 +790,9 @@ impl<'a> Extension<'a> {
 			marker.kernel_pos,
 			&rewind_add_pos,
 			&rewind_rm_pos,
+			rewind_utxo,
+			rewind_kernel,
+			rewind_rangeproof
 		)?;
 
 		Ok(())
@@ -779,6 +806,9 @@ impl<'a> Extension<'a> {
 		kernel_pos: u64,
 		rewind_add_pos: &Bitmap,
 		rewind_rm_pos: &Bitmap,
+		rewind_utxo: bool,
+		rewind_kernel: bool,
+		rewind_rproof: bool,
 	) -> Result<(), Error> {
 		trace!(
 			LOGGER,
@@ -792,15 +822,21 @@ impl<'a> Extension<'a> {
 		// been sync'd to disk.
 		self.new_output_commits.retain(|_, &mut v| v <= output_pos);
 
+		if rewind_utxo {
 			self.output_pmmr
 				.rewind(output_pos, rewind_add_pos, rewind_rm_pos)
 				.map_err(&Error::TxHashSetErr)?;
+		}
+		if rewind_rproof {
 			self.rproof_pmmr
 				.rewind(output_pos, rewind_add_pos, rewind_rm_pos)
 				.map_err(&Error::TxHashSetErr)?;
+		}
+		if rewind_kernel {
 			self.kernel_pmmr
 				.rewind(kernel_pos, rewind_add_pos, rewind_rm_pos)
 				.map_err(&Error::TxHashSetErr)?;
+		}
 
 		Ok(())
 	}
@@ -864,18 +900,26 @@ impl<'a> Extension<'a> {
 	}
 
 	/// Validate the txhashset state against the provided block header.
-	pub fn validate(&mut self, header: &BlockHeader, skip_rproofs: bool) -> Result<(), Error> {
+	pub fn validate(
+		&mut self,
+		header: &BlockHeader,
+		skip_rproofs: bool,
+	) -> Result<((Commitment, Commitment)), Error> {
 		self.validate_mmrs()?;
 		self.validate_roots(header)?;
 
 		if header.height == 0 {
-			return Ok(());
+			let zero_commit = secp_static::commit_to_zero_value();
+			return Ok((zero_commit.clone(), zero_commit.clone()));
 		}
 
 		// The real magicking happens here.
 		// Sum of kernel excesses should equal sum of
 		// unspent outputs minus total supply.
-		self.verify_kernel_sums(header.total_overage(), header.total_kernel_offset())?;
+		let (output_sum, kernel_sum) = self.verify_kernel_sums(
+			header.total_overage(),
+			header.total_kernel_offset(),
+		)?;
 
 		// This is an expensive verification step.
 		self.verify_kernel_signatures()?;
@@ -890,7 +934,7 @@ impl<'a> Extension<'a> {
 		// a lot without resetting
 		self.verify_kernel_history(header)?;
 
-		Ok(())
+		Ok((output_sum, kernel_sum))
 	}
 
 	/// Rebuild the index of MMR positions to the corresponding Output and
@@ -901,7 +945,7 @@ impl<'a> Extension<'a> {
 			// non-pruned leaves only
 			if pmmr::bintree_postorder_height(n) == 0 {
 				if let Some(out) = self.output_pmmr.get_data(n) {
-					self.commit_index.save_output_pos(&out.commit, n)?;
+					self.batch.save_output_pos(&out.commit, n)?;
 				}
 			}
 		}
@@ -1015,10 +1059,9 @@ impl<'a> Extension<'a> {
 			if current.height == 0 {
 				break;
 			}
+			let head_header = self.commit_index.head_header()?;
 			// rewinding further and further back
-			self.kernel_pmmr
+			self.rewind(&current, &head_header, false, true, false)?;
-				.rewind(current.kernel_mmr_size, current.height as u32)
-				.map_err(&Error::TxHashSetErr)?;
 			if self.kernel_pmmr.root() != current.kernel_root {
 				return Err(Error::InvalidTxHashSet(format!(
 					"Kernel root at {} does not match",
@@ -1095,7 +1138,7 @@ fn input_pos_to_rewind(
 		// I/O should be minimized or eliminated here for most
 		// rewind scenarios.
 		let current_header = commit_index.get_block_header(&current)?;
-		let input_bitmap = commit_index.get_block_input_bitmap(&current)?;
+		let input_bitmap = commit_index.batch()?.get_block_input_bitmap(&current)?;
 
 		bitmap.or_inplace(&input_bitmap);
 		current = current_header.previous;

chain/src/types.rs

@@ -16,10 +16,9 @@
 
 use std::{error, fmt, io};
 
-use croaring::Bitmap;
-
 use util::secp;
 use util::secp::pedersen::Commitment;
+use util::secp_static;
 
 use core::core::committed;
 use core::core::hash::{Hash, Hashed};
@@ -256,112 +255,6 @@ impl ser::Readable for Tip {
 	}
 }
 
-/// Trait the chain pipeline requires an implementor for in order to process
-/// blocks.
-pub trait ChainStore: Send + Sync {
-	/// Get the tip that's also the head of the chain
-	fn head(&self) -> Result<Tip, store::Error>;
-
-	/// Block header for the chain head
-	fn head_header(&self) -> Result<BlockHeader, store::Error>;
-
-	/// Save the provided tip as the current head of our chain
-	fn save_head(&self, t: &Tip) -> Result<(), store::Error>;
-
-	/// Save the provided tip as the current head of the body chain, leaving the
-	/// header chain alone.
-	fn save_body_head(&self, t: &Tip) -> Result<(), store::Error>;
-
-	/// Gets a block header by hash
-	fn get_block(&self, h: &Hash) -> Result<Block, store::Error>;
-
-	/// Check whether we have a block without reading it
-	fn block_exists(&self, h: &Hash) -> Result<bool, store::Error>;
-
-	/// Gets a block header by hash
-	fn get_block_header(&self, h: &Hash) -> Result<BlockHeader, store::Error>;
-
-	/// Save the provided block in store
-	fn save_block(&self, b: &Block) -> Result<(), store::Error>;
-
-	/// Delete a full block. Does not delete any record associated with a block
-	/// header.
-	fn delete_block(&self, bh: &Hash) -> Result<(), store::Error>;
-
-	/// Save the provided block header in store
-	fn save_block_header(&self, bh: &BlockHeader) -> Result<(), store::Error>;
-
-	/// Get the tip of the header chain
-	fn get_header_head(&self) -> Result<Tip, store::Error>;
-
-	/// Save the provided tip as the current head of the block header chain
-	fn save_header_head(&self, t: &Tip) -> Result<(), store::Error>;
-
-	/// Get the tip of the current sync header chain
-	fn get_sync_head(&self) -> Result<Tip, store::Error>;
-
-	/// Save the provided tip as the current head of the sync header chain
-	fn save_sync_head(&self, t: &Tip) -> Result<(), store::Error>;
-
-	/// Initialize header_head if necessary and set sync_head to header_head.
-	fn init_head(&self) -> Result<(), store::Error>;
-
-	/// Reset header_head and sync_head to head of current body chain
-	fn reset_head(&self) -> Result<(), store::Error>;
-
-	/// Gets the block header at the provided height
-	fn get_header_by_height(&self, height: u64) -> Result<BlockHeader, store::Error>;
-
-	/// Save a header as associated with its height
-	fn save_header_height(&self, header: &BlockHeader) -> Result<(), store::Error>;
-
-	/// Delete the block header at the height
-	fn delete_header_by_height(&self, height: u64) -> Result<(), store::Error>;
-
-	/// Is the block header on the current chain?
-	/// Use the header_by_height index to verify the block header is where we
-	/// think it is.
-	fn is_on_current_chain(&self, header: &BlockHeader) -> Result<(), store::Error>;
-
-	/// Saves the position of an output, represented by its commitment, in the
-	/// Output MMR. Used as an index for spending and pruning.
-	fn save_output_pos(&self, commit: &Commitment, pos: u64) -> Result<(), store::Error>;
-
-	/// Gets the position of an output, represented by its commitment, in the
-	/// Output MMR. Used as an index for spending and pruning.
-	fn get_output_pos(&self, commit: &Commitment) -> Result<u64, store::Error>;
-
-	/// Deletes the MMR position of an output.
-	fn delete_output_pos(&self, commit: &[u8]) -> Result<(), store::Error>;
-
-	/// Saves a marker associated with a block recording the MMR positions of
-	/// its last elements.
-	fn save_block_marker(&self, bh: &Hash, marker: &BlockMarker) -> Result<(), store::Error>;
-
-	/// Retrieves a block marker from a block hash.
-	fn get_block_marker(&self, bh: &Hash) -> Result<BlockMarker, store::Error>;
-
-	/// Deletes a block marker associated with the provided hash
-	fn delete_block_marker(&self, bh: &Hash) -> Result<(), store::Error>;
-
-	/// Get the bitmap representing the inputs for the specified block.
-	fn get_block_input_bitmap(&self, bh: &Hash) -> Result<Bitmap, store::Error>;
-
-	/// Save the bitmap representing the inputs for the specified block.
-	fn save_block_input_bitmap(&self, b: &Block) -> Result<Bitmap, store::Error>;
-
-	/// Delete the bitmap representing the inputs for the specified block.
-	fn delete_block_input_bitmap(&self, bh: &Hash) -> Result<(), store::Error>;
-
-	/// Saves the provided block header at the corresponding height. Also check
-	/// the consistency of the height chain in store by assuring previous
-	/// headers are also at their respective heights.
-	fn setup_height(&self, bh: &BlockHeader, old_tip: &Tip) -> Result<(), store::Error>;
-
-	/// Similar to setup_height but without handling fork
-	fn build_by_height_index(&self, header: &BlockHeader, force: bool) -> Result<(), store::Error>;
-}
-
 /// Bridge between the chain pipeline and the rest of the system. Handles
 /// downstream processing of valid blocks by the rest of the system, most
 /// importantly the broadcasting of blocks to our peers.
@@ -414,3 +307,45 @@ impl Default for BlockMarker {
 		}
 	}
 }
+
+/// The output_sum and kernel_sum for a given block.
+/// This is used to validate the next block being processed by applying
+/// the inputs, outputs, kernels and kernel_offset from the new block
+/// and checking everything sums correctly.
+#[derive(Debug, Clone)]
+pub struct BlockSums {
+	/// The total output sum so far.
+	pub output_sum: Commitment,
+	/// The total kernel sum so far.
+	pub kernel_sum: Commitment,
+}
+
+impl Writeable for BlockSums {
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ser::Error> {
+		writer.write_fixed_bytes(&self.output_sum)?;
+		writer.write_fixed_bytes(&self.kernel_sum)?;
+		Ok(())
+	}
+}
+
+impl Readable for BlockSums {
+	fn read(reader: &mut Reader) -> Result<BlockSums, ser::Error> {
+		Ok(BlockSums {
+			output_sum: Commitment::read(reader)?,
+			kernel_sum: Commitment::read(reader)?,
+		})
+	}
+}
+
+impl Default for BlockSums {
+	fn default() -> BlockSums {
+		let zero_commit = secp_static::commit_to_zero_value();
+		BlockSums {
+			output_sum: zero_commit.clone(),
+			kernel_sum: zero_commit.clone(),
+		}
+	}
+}
+
+
+

chain/tests/data_file_integrity.rs

@@ -16,6 +16,7 @@ extern crate env_logger;
 extern crate grin_chain as chain;
 extern crate grin_core as core;
 extern crate grin_keychain as keychain;
+extern crate grin_store as store;
 extern crate grin_util as util;
 extern crate grin_wallet as wallet;
 extern crate rand;
@@ -43,8 +44,10 @@ fn setup(dir_name: &str) -> Chain {
 	clean_output_dir(dir_name);
 	global::set_mining_mode(ChainTypes::AutomatedTesting);
 	let genesis_block = pow::mine_genesis_block().unwrap();
+	let db_env = Arc::new(store::new_env(dir_name.to_string()));
 	chain::Chain::init(
 		dir_name.to_string(),
+		db_env,
 		Arc::new(NoopAdapter {}),
 		genesis_block,
 		pow::verify_size,
@@ -52,8 +55,10 @@ fn setup(dir_name: &str) -> Chain {
 }
 
 fn reload_chain(dir_name: &str) -> Chain {
+	let db_env = Arc::new(store::new_env(dir_name.to_string()));
 	chain::Chain::init(
 		dir_name.to_string(),
+		db_env,
 		Arc::new(NoopAdapter {}),
 		genesis::genesis_dev(),
 		pow::verify_size,

chain/tests/mine_simple_chain.rs

@@ -12,10 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-extern crate env_logger;
 extern crate grin_chain as chain;
 extern crate grin_core as core;
 extern crate grin_keychain as keychain;
+extern crate grin_store as store;
 extern crate grin_util as util;
 extern crate grin_wallet as wallet;
 extern crate rand;
@@ -38,25 +38,23 @@ fn clean_output_dir(dir_name: &str) {
 	let _ = fs::remove_dir_all(dir_name);
 }
 
-fn setup(dir_name: &str) -> Chain {
+fn setup(dir_name: &str, genesis: Block) -> Chain {
-	match env_logger::try_init() {
+	util::init_test_logger();
-		Ok(_) => println!("Initializing env logger"),
-		Err(e) => println!("env logger already initialized: {:?}", e),
-	};
 	clean_output_dir(dir_name);
-	global::set_mining_mode(ChainTypes::AutomatedTesting);
+	let db_env = Arc::new(store::new_env(dir_name.to_string()));
-	let genesis_block = pow::mine_genesis_block().unwrap();
 	chain::Chain::init(
 		dir_name.to_string(),
+		db_env,
 		Arc::new(NoopAdapter {}),
-		genesis_block,
+		genesis,
 		pow::verify_size,
 	).unwrap()
 }
 
 #[test]
 fn mine_empty_chain() {
-	let chain = setup(".grin");
+	global::set_mining_mode(ChainTypes::AutomatedTesting);
+	let chain = setup(".grin", pow::mine_genesis_block().unwrap());
 	let keychain = ExtKeychain::from_random_seed().unwrap();
 
 	for n in 1..4 {
@@ -105,7 +103,8 @@ fn mine_empty_chain() {
 
 #[test]
 fn mine_forks() {
-	let chain = setup(".grin2");
+	global::set_mining_mode(ChainTypes::AutomatedTesting);
+	let chain = setup(".grin2", pow::mine_genesis_block().unwrap());
 	let kc = ExtKeychain::from_random_seed().unwrap();
 
 	// add a first block to not fork genesis
@@ -147,8 +146,9 @@ fn mine_forks() {
 
 #[test]
 fn mine_losing_fork() {
+	global::set_mining_mode(ChainTypes::AutomatedTesting);
 	let kc = ExtKeychain::from_random_seed().unwrap();
-	let chain = setup(".grin3");
+	let chain = setup(".grin3", pow::mine_genesis_block().unwrap());
 
 	// add a first block we'll be forking from
 	let prev = chain.head_header().unwrap();
@@ -178,12 +178,14 @@ fn mine_losing_fork() {
 
 #[test]
 fn longer_fork() {
+	global::set_mining_mode(ChainTypes::AutomatedTesting);
 	let kc = ExtKeychain::from_random_seed().unwrap();
 	// to make it easier to compute the txhashset roots in the test, we
 	// prepare 2 chains, the 2nd will be have the forked blocks we can
 	// then send back on the 1st
-	let chain = setup(".grin4");
+	let genesis = pow::mine_genesis_block().unwrap();
-	let chain_fork = setup(".grin5");
+	let chain = setup(".grin4", genesis.clone());
+	let chain_fork = setup(".grin5", genesis);
 
 	// add blocks to both chains, 20 on the main one, only the first 5
 	// for the forked chain
@@ -193,9 +195,8 @@ fn longer_fork() {
 		let bh = b.header.clone();
 
 		if n < 5 {
-			let b_fork = b.clone();
 			chain_fork
-				.process_block(b_fork, chain::Options::SKIP_POW)
+				.process_block(b.clone(), chain::Options::SKIP_POW)
 				.unwrap();
 		}
 
@@ -227,8 +228,9 @@ fn longer_fork() {
 
 #[test]
 fn spend_in_fork_and_compact() {
+	global::set_mining_mode(ChainTypes::AutomatedTesting);
 	util::init_test_logger();
-	let chain = setup(".grin6");
+	let chain = setup(".grin6", pow::mine_genesis_block().unwrap());
 	let prev = chain.head_header().unwrap();
 	let kc = ExtKeychain::from_random_seed().unwrap();
 
@@ -435,8 +437,10 @@ where
 fn actual_diff_iter_output() {
 	global::set_mining_mode(ChainTypes::AutomatedTesting);
 	let genesis_block = pow::mine_genesis_block().unwrap();
+	let db_env = Arc::new(store::new_env(".grin".to_string()));
 	let chain = chain::Chain::init(
 		"../.grin".to_string(),
+		db_env,
 		Arc::new(NoopAdapter {}),
 		genesis_block,
 		pow::verify_size,

chain/tests/store_indices.rs

@@ -16,10 +16,12 @@ extern crate env_logger;
 extern crate grin_chain as chain;
 extern crate grin_core as core;
 extern crate grin_keychain as keychain;
+extern crate grin_store as store;
 extern crate grin_wallet as wallet;
 extern crate rand;
 
 use std::fs;
+use std::sync::Arc;
 
 use chain::{ChainStore, Tip};
 use core::core::hash::Hashed;
@@ -45,27 +47,34 @@ fn test_various_store_indices() {
 
 	let keychain = ExtKeychain::from_random_seed().unwrap();
 	let key_id = keychain.derive_key_id(1).unwrap();
+	let db_env = Arc::new(store::new_env(chain_dir.to_string()));
 
-	let chain_store =
+	let chain_store = chain::store::ChainStore::new(db_env).unwrap();
-		&chain::store::ChainKVStore::new(chain_dir.to_string()).unwrap() as &ChainStore;
-
 	global::set_mining_mode(ChainTypes::AutomatedTesting);
 	let genesis = pow::mine_genesis_block().unwrap();
-	chain_store.save_block(&genesis).unwrap();
-	chain_store
-		.setup_height(&genesis.header, &Tip::new(genesis.hash()))
-		.unwrap();
-
 	let reward = libtx::reward::output(&keychain, &key_id, 0, 1).unwrap();
 
 	let block = Block::new(&genesis.header, vec![], Difficulty::one(), reward).unwrap();
 	let block_hash = block.hash();
 
-	chain_store.save_block(&block).unwrap();
+	{
-	chain_store
+		let batch = chain_store.batch().unwrap();
+		batch.save_block(&genesis).unwrap();
+		batch
+			.setup_height(&genesis.header, &Tip::new(genesis.hash()))
+			.unwrap();
+		batch.commit().unwrap();
+	}
+	{
+		let batch = chain_store.batch().unwrap();
+		batch.save_block(&block).unwrap();
+		batch
 			.setup_height(&block.header, &Tip::from_block(&block.header))
 			.unwrap();
 
+		batch.commit().unwrap();
+	}
+
 	let block_header = chain_store.get_block_header(&block_hash).unwrap();
 	assert_eq!(block_header.hash(), block_hash);
 
@@ -82,19 +91,27 @@ fn test_store_header_height() {
 	let chain_dir = ".grin_idx_2";
 	clean_output_dir(chain_dir);
 
-	let chain_store =
+	let db_env = Arc::new(store::new_env(chain_dir.to_string()));
-		&chain::store::ChainKVStore::new(chain_dir.to_string()).unwrap() as &ChainStore;
+	let chain_store = chain::store::ChainStore::new(db_env).unwrap();
 
 	let mut block_header = BlockHeader::default();
 	block_header.height = 1;
 
-	chain_store.save_block_header(&block_header).unwrap();
+	{
-	chain_store.save_header_height(&block_header).unwrap();
+		let batch = chain_store.batch().unwrap();
+		batch.save_block_header(&block_header).unwrap();
+		batch.save_header_height(&block_header).unwrap();
+		batch.commit().unwrap();
+	}
 
 	let stored_block_header = chain_store.get_header_by_height(1).unwrap();
 	assert_eq!(block_header.hash(), stored_block_header.hash());
 
-	chain_store.delete_header_by_height(1).unwrap();
+	{
+		let batch = chain_store.batch().unwrap();
+		batch.delete_header_by_height(1).unwrap();
+		batch.commit().unwrap();
+	}
 
 	let result = chain_store.get_header_by_height(1);
 	assert_eq!(result.is_err(), true);

chain/tests/test_coinbase_maturity.rs

@@ -16,6 +16,7 @@ extern crate env_logger;
 extern crate grin_chain as chain;
 extern crate grin_core as core;
 extern crate grin_keychain as keychain;
+extern crate grin_store as store;
 extern crate grin_wallet as wallet;
 extern crate rand;
 extern crate time;
@@ -43,8 +44,10 @@ fn test_coinbase_maturity() {
 
 	let genesis_block = pow::mine_genesis_block().unwrap();
 
+	let db_env = Arc::new(store::new_env(".grin".to_string()));
 	let chain = chain::Chain::init(
 		".grin".to_string(),
+		db_env,
 		Arc::new(NoopAdapter {}),
 		genesis_block,
 		pow::verify_size,

chain/tests/test_txhashset_raw_txs.rs

@@ -15,13 +15,13 @@
 extern crate grin_chain as chain;
 extern crate grin_core as core;
 extern crate grin_keychain as keychain;
+extern crate grin_store as store;
 extern crate grin_wallet as wallet;
 
 use std::fs;
 use std::sync::Arc;
 
-use chain::ChainStore;
+use chain::store::ChainStore;
-use chain::store::ChainKVStore;
 use chain::txhashset::{self, TxHashSet};
 use chain::types::Tip;
 use core::core::merkle_proof::MerkleProof;
@@ -39,6 +39,7 @@ fn test_some_raw_txs() {
 	let db_root = format!(".grin_txhashset_raw_txs");
 	clean_output_dir(&db_root);
 
+	let db_env = Arc::new(store::new_env(db_root.clone()));
 	let store = Arc::new(ChainKVStore::new(db_root.clone()).unwrap());
 	let mut txhashset = TxHashSet::open(db_root.clone(), store.clone(), None).unwrap();
 
@@ -60,11 +61,15 @@ fn test_some_raw_txs() {
 	// Note: this results in an output MMR with a single leaf node.
 	// We need to be careful with pruning while processing the txs below
 	// as we cannot prune a tree with a single node in it (no sibling or parent).
-	txhashset::extending(&mut txhashset, |extension| extension.apply_block(&block)).unwrap();
+	let mut batch = store.batch().unwrap();
+	txhashset::extending(&mut txhashset, &mut batch, |extension| {
+		extension.apply_block(&block)
+	}).unwrap();
 
 	// Make sure we setup the head in the store based on block we just accepted.
 	let head = Tip::from_block(&block.header);
-	store.save_head(&head).unwrap();
+	batch.save_head(&head).unwrap();
+	batch.commit().unwrap();
 
 	let coinbase_reward = 60_000_000_000;
 

core/src/core/block.rs

@@ -702,17 +702,17 @@ impl Block {
 				vec![prev_kernel_offset.clone()],
 			)?
 		};
-		let sum = self.verify_kernel_sums(self.header.overage(), block_kernel_offset)?;
+		let (_utxo_sum, kernel_sum) = self.verify_kernel_sums(self.header.overage(), block_kernel_offset)?;
 
 		// check the block header's total kernel sum
-		let total_sum = committed::sum_commits(vec![sum, prev_kernel_sum.clone()], vec![])?;
+		let total_sum = committed::sum_commits(vec![kernel_sum, prev_kernel_sum.clone()], vec![])?;
 		if total_sum != self.header.total_kernel_sum {
 			return Err(Error::InvalidTotalKernelSum);
 		}
 
 		self.verify_rangeproofs()?;
 		self.verify_kernel_signatures()?;
-		Ok(sum)
+		Ok(kernel_sum)
 	}
 
 	fn verify_weight(&self) -> Result<(), Error> {

core/src/core/committed.rs

@@ -117,7 +117,7 @@ pub trait Committed {
 		&self,
 		overage: i64,
 		kernel_offset: BlindingFactor,
-	) -> Result<(Commitment), Error> {
+	) -> Result<((Commitment, Commitment)), Error> {
 		// Sum all input|output|overage commitments.
 		let utxo_sum = self.sum_commitments(overage)?;
 
@@ -128,7 +128,7 @@ pub trait Committed {
 			return Err(Error::KernelSumMismatch);
 		}
 
-		Ok(kernel_sum)
+		Ok((utxo_sum, kernel_sum))
 	}
 }
 

p2p/Cargo.toml

@@ -9,6 +9,7 @@ publish = false
 bitflags = "1"
 bytes = "0.4"
 enum_primitive = "0.1"
+lmdb-zero = "0.4.4"
 net2 = "0.2"
 num = "0.1"
 rand = "0.3"

p2p/src/lib.rs

@@ -25,6 +25,7 @@ extern crate bitflags;
 extern crate bytes;
 #[macro_use]
 extern crate enum_primitive;
+extern crate lmdb_zero as lmdb;
 
 #[macro_use]
 extern crate grin_core as core;

p2p/src/serv.rs

@@ -19,6 +19,8 @@ use std::sync::{Arc, RwLock};
 use std::time::Duration;
 use std::{io, thread};
 
+use lmdb;
+
 use core::core;
 use core::core::hash::Hash;
 use core::core::target::Difficulty;
@@ -46,7 +48,7 @@ unsafe impl Send for Server {}
 impl Server {
 	/// Creates a new idle p2p server with no peers
 	pub fn new(
-		db_root: String,
+		db_env: Arc<lmdb::Environment>,
 		mut capab: Capabilities,
 		config: P2PConfig,
 		adapter: Arc<ChainAdapter>,
@@ -80,7 +82,7 @@ impl Server {
 			config: config.clone(),
 			capabilities: capab,
 			handshake: Arc::new(Handshake::new(genesis, config.clone())),
-			peers: Arc::new(Peers::new(PeerStore::new(db_root)?, adapter, config)),
+			peers: Arc::new(Peers::new(PeerStore::new(db_env)?, adapter, config)),
 			stop: stop,
 		})
 	}

p2p/src/store.rs

@@ -17,6 +17,9 @@
 use num::FromPrimitive;
 use rand::{thread_rng, Rng};
 use std::net::SocketAddr;
+use std::sync::Arc;
+
+use lmdb;
 
 use core::ser::{self, Readable, Reader, Writeable, Writer};
 use grin_store::{self, option_to_not_found, to_key, Error};
@@ -101,15 +104,17 @@ pub struct PeerStore {
 
 impl PeerStore {
 	/// Instantiates a new peer store under the provided root path.
-	pub fn new(root_path: String) -> Result<PeerStore, Error> {
+	pub fn new(db_env: Arc<lmdb::Environment>) -> Result<PeerStore, Error> {
-		let db = grin_store::Store::open(format!("{}/{}", root_path, STORE_SUBPATH).as_str())?;
+		let db = grin_store::Store::open(db_env, STORE_SUBPATH);
 		Ok(PeerStore { db: db })
 	}
 
 	pub fn save_peer(&self, p: &PeerData) -> Result<(), Error> {
 		debug!(LOGGER, "save_peer: {:?} marked {:?}", p.addr, p.flags);
 
-		self.db.put_ser(&peer_key(p.addr)[..], p)
+		let batch = self.db.batch()?;
+		batch.put_ser(&peer_key(p.addr)[..], p)?;
+		batch.commit()
 	}
 
 	pub fn get_peer(&self, peer_addr: SocketAddr) -> Result<PeerData, Error> {
@@ -123,12 +128,15 @@ impl PeerStore {
 	/// TODO - allow below added to avoid github issue reports
 	#[allow(dead_code)]
 	pub fn delete_peer(&self, peer_addr: SocketAddr) -> Result<(), Error> {
-		self.db.delete(&peer_key(peer_addr)[..])
+		let batch = self.db.batch()?;
+		batch.delete(&peer_key(peer_addr)[..])?;
+		batch.commit()
 	}
 
 	pub fn find_peers(&self, state: State, cap: Capabilities, count: usize) -> Vec<PeerData> {
 		let mut peers = self.db
 			.iter::<PeerData>(&to_key(PEER_PREFIX, &mut "".to_string().into_bytes()))
+			.unwrap()
 			.filter(|p| p.flags == state && p.capabilities.contains(cap))
 			.collect::<Vec<_>>();
 		thread_rng().shuffle(&mut peers[..]);
@@ -138,9 +146,8 @@ impl PeerStore {
 	/// List all known peers
 	/// Used for /v1/peers/all api endpoint
 	pub fn all_peers(&self) -> Vec<PeerData> {
-		self.db
+		let key = to_key(PEER_PREFIX, &mut "".to_string().into_bytes());
-			.iter::<PeerData>(&to_key(PEER_PREFIX, &mut "".to_string().into_bytes()))
+		self.db.iter::<PeerData>(&key).unwrap().collect::<Vec<_>>()
-			.collect::<Vec<_>>()
 	}
 
 	/// Convenience method to load a peer data, update its status and save it

p2p/tests/peer_handshake.rs

@@ -14,6 +14,8 @@
 
 extern crate grin_core as core;
 extern crate grin_p2p as p2p;
+extern crate grin_pool as pool;
+extern crate grin_store as store;
 extern crate grin_util as util;
 
 use std::net::{SocketAddr, TcpListener, TcpStream};
@@ -47,9 +49,10 @@ fn peer_handshake() {
 		..p2p::P2PConfig::default()
 	};
 	let net_adapter = Arc::new(p2p::DummyAdapter {});
+	let db_env = Arc::new(store::new_env(".grin".to_string()));
 	let server = Arc::new(
 		p2p::Server::new(
-			".grin".to_owned(),
+			db_env,
 			p2p::Capabilities::UNKNOWN,
 			p2p_config.clone(),
 			net_adapter.clone(),

pool/Cargo.toml

@@ -15,6 +15,7 @@ time = "0.1"
 
 grin_core = { path = "../core" }
 grin_keychain = { path = "../keychain" }
+grin_store = { path = "../store" }
 grin_util = { path = "../util" }
 
 [dev-dependencies]

pool/tests/block_building.rs

@@ -55,11 +55,15 @@ fn test_transaction_pool_block_building() {
 		let block = Block::new(&BlockHeader::default(), vec![], Difficulty::one(), reward).unwrap();
 
 		let mut txhashset = chain.txhashset.write().unwrap();
-		txhashset::extending(&mut txhashset, |extension| extension.apply_block(&block)).unwrap();
+		let mut batch = chain.store.batch().unwrap();
+		txhashset::extending(&mut txhashset, &mut batch, |extension| {
+			extension.apply_block(&block)
+		}).unwrap();
 
 		let tip = Tip::from_block(&block.header);
-		chain.store.save_block_header(&block.header).unwrap();
+		batch.save_block_header(&block.header).unwrap();
-		chain.store.save_head(&tip).unwrap();
+		batch.save_head(&tip).unwrap();
+		batch.commit().unwrap();
 
 		block.header
 	};
@@ -126,11 +130,13 @@ fn test_transaction_pool_block_building() {
 	}.unwrap();
 
 	{
+		let mut batch = chain.store.batch().unwrap();
 		let mut txhashset = chain.txhashset.write().unwrap();
-		txhashset::extending(&mut txhashset, |extension| {
+		txhashset::extending(&mut txhashset, &mut batch, |extension| {
 			extension.apply_block(&block)?;
 			Ok(())
 		}).unwrap();
+		batch.commit().unwrap();
 	}
 
 	// Now reconcile the transaction pool with the new block

pool/tests/block_reconciliation.rs

@@ -53,12 +53,16 @@ fn test_transaction_pool_block_reconciliation() {
 		let reward = libtx::reward::output(&keychain, &key_id, 0, height).unwrap();
 		let block = Block::new(&BlockHeader::default(), vec![], Difficulty::one(), reward).unwrap();
 
+		let mut batch = chain.store.batch().unwrap();
 		let mut txhashset = chain.txhashset.write().unwrap();
-		txhashset::extending(&mut txhashset, |extension| extension.apply_block(&block)).unwrap();
+		txhashset::extending(&mut txhashset, &mut batch, |extension| {
+			extension.apply_block(&block)
+		}).unwrap();
 
 		let tip = Tip::from_block(&block.header);
-		chain.store.save_block_header(&block.header).unwrap();
+		batch.save_block_header(&block.header).unwrap();
-		chain.store.save_head(&tip).unwrap();
+		batch.save_head(&tip).unwrap();
+		batch.commit().unwrap();
 
 		block.header
 	};
@@ -76,17 +80,19 @@ fn test_transaction_pool_block_reconciliation() {
 		let reward = libtx::reward::output(&keychain, &key_id, fees, 0).unwrap();
 		let block = Block::new(&header, vec![initial_tx], Difficulty::one(), reward).unwrap();
 
+		let mut batch = chain.store.batch().unwrap();
 		{
 			let mut txhashset = chain.txhashset.write().unwrap();
-			txhashset::extending(&mut txhashset, |extension| {
+			txhashset::extending(&mut txhashset, &mut batch, |extension| {
 				extension.apply_block(&block)?;
 				Ok(())
 			}).unwrap();
 		}
 
 		let tip = Tip::from_block(&block.header);
-		chain.store.save_block_header(&block.header).unwrap();
+		batch.save_block_header(&block.header).unwrap();
-		chain.store.save_head(&tip).unwrap();
+		batch.save_head(&tip).unwrap();
+		batch.commit().unwrap();
 
 		block.header
 	};
@@ -174,16 +180,20 @@ fn test_transaction_pool_block_reconciliation() {
 		let block = Block::new(&header, block_txs, Difficulty::one(), reward).unwrap();
 
 		{
+			let mut batch = chain.store.batch().unwrap();
 			let mut txhashset = chain.txhashset.write().unwrap();
-			txhashset::extending(&mut txhashset, |extension| {
+			txhashset::extending(&mut txhashset, &mut batch, |extension| {
 				extension.apply_block(&block)?;
 				Ok(())
 			}).unwrap();
+			batch.commit().unwrap();
 		}
 
 		let tip = Tip::from_block(&block.header);
-		chain.store.save_block_header(&block.header).unwrap();
+		let batch = chain.store.batch().unwrap();
-		chain.store.save_head(&tip).unwrap();
+		batch.save_block_header(&block.header).unwrap();
+		batch.save_head(&tip).unwrap();
+		batch.commit().unwrap();
 
 		block
 	};

pool/tests/common/mod.rs

@@ -19,6 +19,7 @@ extern crate grin_chain as chain;
 extern crate grin_core as core;
 extern crate grin_keychain as keychain;
 extern crate grin_pool as pool;
+extern crate grin_store as store;
 extern crate grin_util as util;
 extern crate grin_wallet as wallet;
 
@@ -30,7 +31,7 @@ use std::sync::{Arc, RwLock};
 
 use core::core::{BlockHeader, Transaction};
 
-use chain::store::ChainKVStore;
+use chain::store::ChainStore;
 use chain::txhashset;
 use chain::txhashset::TxHashSet;
 use core::core::hash::Hashed;
@@ -46,14 +47,15 @@ use pool::types::*;
 #[derive(Clone)]
 pub struct ChainAdapter {
 	pub txhashset: Arc<RwLock<TxHashSet>>,
-	pub store: Arc<ChainKVStore>,
+	pub store: Arc<ChainStore>,
 }
 
 impl ChainAdapter {
 	pub fn init(db_root: String) -> Result<ChainAdapter, String> {
 		let target_dir = format!("target/{}", db_root);
-		let chain_store = ChainKVStore::new(target_dir.clone())
+		let db_env = Arc::new(store::new_env(target_dir.clone()));
-			.map_err(|e| format!("failed to init chain_store, {}", e))?;
+		let chain_store =
+			ChainStore::new(db_env).map_err(|e| format!("failed to init chain_store, {:?}", e))?;
 		let store = Arc::new(chain_store);
 		let txhashset = TxHashSet::open(target_dir.clone(), store.clone(), None)
 			.map_err(|e| format!("failed to init txhashset, {}", e))?;

pool/tests/transaction_pool.rs

@@ -54,11 +54,15 @@ fn test_the_transaction_pool() {
 		let block = Block::new(&BlockHeader::default(), vec![], Difficulty::one(), reward).unwrap();
 
 		let mut txhashset = chain.txhashset.write().unwrap();
-		txhashset::extending(&mut txhashset, |extension| extension.apply_block(&block)).unwrap();
+		let mut batch = chain.store.batch().unwrap();
+		txhashset::extending(&mut txhashset, &mut batch, |extension| {
+			extension.apply_block(&block)
+		}).unwrap();
 
 		let tip = Tip::from_block(&block.header);
-		chain.store.save_block_header(&block.header).unwrap();
+		batch.save_block_header(&block.header).unwrap();
-		chain.store.save_head(&tip).unwrap();
+		batch.save_head(&tip).unwrap();
+		batch.commit().unwrap();
 
 		block.header
 	};

servers/Cargo.toml

@@ -8,6 +8,7 @@ publish = false
 [dependencies]
 hyper = "0.10"
 itertools = "0.7"
+lmdb-zero = "0.4.4"
 rand = "0.3"
 router = "0.6"
 slog = { version = "~2.2", features = ["max_level_trace", "release_max_level_trace"] }

servers/src/grin/server.rs

@@ -35,6 +35,7 @@ use mining::stratumserver;
 use mining::test_miner::Miner;
 use p2p;
 use pool;
+use store;
 use util::LOGGER;
 
 /// Grin server holding internal structures.
@@ -130,8 +131,10 @@ impl Server {
 
 		info!(LOGGER, "Starting server, genesis block: {}", genesis.hash());
 
+		let db_env = Arc::new(store::new_env(config.db_root.clone()));
 		let shared_chain = Arc::new(chain::Chain::init(
 			config.db_root.clone(),
+			db_env.clone(),
 			chain_adapter.clone(),
 			genesis.clone(),
 			pow::verify_size,
@@ -156,7 +159,7 @@ impl Server {
 		};
 
 		let p2p_server = Arc::new(p2p::Server::new(
-			config.db_root.clone(),
+			db_env,
 			config.capabilities,
 			config.p2p_config.clone(),
 			net_adapter.clone(),

servers/src/lib.rs

@@ -25,6 +25,7 @@ extern crate bufstream;
 extern crate hyper;
 extern crate itertools;
 extern crate jsonrpc_core;
+extern crate lmdb_zero as lmdb;
 extern crate rand;
 extern crate serde;
 #[macro_use]
@@ -48,6 +49,6 @@ pub mod common;
 mod grin;
 mod mining;
 
-pub use grin::server::Server;
-pub use common::types::{Seeding, ServerConfig, StratumServerConfig};
 pub use common::stats::{DiffBlock, PeerStats, ServerStats, StratumStats, WorkerStats};
+pub use common::types::{Seeding, ServerConfig, StratumServerConfig};
+pub use grin::server::Server;

src/bin/grin.rs

@@ -51,7 +51,7 @@ use daemonize::Daemonize;
 use config::GlobalConfig;
 use core::core::amount_to_hr_string;
 use core::global;
-use keychain::ExtKeychain;
+use keychain::{self, ExtKeychain};
 use tui::ui;
 use util::{init_logger, LoggingConfig, LOGGER};
 use wallet::{libwallet, FileWallet};
@@ -446,8 +446,8 @@ fn server_command(server_args: Option<&ArgMatches>, mut global_config: GlobalCon
 		let _ = thread::Builder::new()
 			.name("wallet_listener".to_string())
 			.spawn(move || {
-				let wallet: FileWallet<ExtKeychain> = FileWallet::new(wallet_config.clone(), "")
+				let wallet: FileWallet<keychain::ExtKeychain> =
-					.unwrap_or_else(|e| {
+					FileWallet::new(wallet_config.clone(), "").unwrap_or_else(|e| {
 						panic!("Error creating wallet: {:?} Config: {:?}", e, wallet_config)
 					});
 				wallet::controller::foreign_listener(wallet, &wallet_config.api_listen_addr())
@@ -586,8 +586,8 @@ fn wallet_command(wallet_args: &ArgMatches, global_config: GlobalConfig) {
 
 	// Handle listener startup commands
 	{
-		let wallet: FileWallet<ExtKeychain> = FileWallet::new(wallet_config.clone(), passphrase)
+		let wallet: FileWallet<keychain::ExtKeychain> =
-			.unwrap_or_else(|e| {
+			FileWallet::new(wallet_config.clone(), passphrase).unwrap_or_else(|e| {
 				panic!("Error creating wallet: {:?} Config: {:?}", e, wallet_config)
 			});
 		match wallet_args.subcommand() {
@@ -617,7 +617,7 @@ fn wallet_command(wallet_args: &ArgMatches, global_config: GlobalConfig) {
 
 	// Handle single-use (command line) owner commands
 	{
-		let mut wallet: FileWallet<ExtKeychain> =
+		let mut wallet: FileWallet<keychain::ExtKeychain> =
 			FileWallet::new(wallet_config.clone(), passphrase).unwrap_or_else(|e| {
 				panic!("Error creating wallet: {:?} Config: {:?}", e, wallet_config)
 			});

store/Cargo.toml

@@ -10,9 +10,8 @@ byteorder = "1"
 croaring = "0.3"
 env_logger = "0.5"
 libc = "0.2"
+lmdb-zero = "0.4.4"
 memmap = { git = "https://github.com/danburkert/memmap-rs", tag = "0.6.2" }
-rand = "0.3"
-rocksdb = "0.10"
 serde = "1"
 serde_derive = "1"
 slog = { version = "~2.2", features = ["max_level_trace", "release_max_level_trace"] }
@@ -22,3 +21,4 @@ grin_util = { path = "../util" }
 
 [dev-dependencies]
 time = "0.1"
+rand = "0.3"

store/src/lib.rs

@@ -23,16 +23,18 @@
 extern crate byteorder;
 extern crate croaring;
 extern crate env_logger;
-#[macro_use]
-extern crate grin_core as core;
-extern crate grin_util as util;
 extern crate libc;
+extern crate lmdb_zero;
 extern crate memmap;
-extern crate rocksdb;
 extern crate serde;
 #[macro_use]
 extern crate slog;
 
+#[macro_use]
+extern crate grin_core as core;
+extern crate grin_util as util;
+
+mod lmdb;
 pub mod leaf_set;
 pub mod pmmr;
 pub mod rm_log;
@@ -40,209 +42,34 @@ pub mod types;
 
 const SEP: u8 = ':' as u8;
 
-use std::fmt;
-use std::iter::Iterator;
-use std::marker;
-use std::sync::RwLock;
-
 use byteorder::{BigEndian, WriteBytesExt};
-use rocksdb::{DBCompactionStyle, DBIterator, Direction, IteratorMode, WriteBatch, DB};
 
-use core::ser;
+pub use lmdb::*;
-
-/// Main error type for this crate.
-#[derive(Debug)]
-pub enum Error {
-	/// Couldn't find what we were looking for
-	NotFoundErr,
-	/// Wraps an error originating from RocksDB (which unfortunately returns
-	/// string errors).
-	RocksDbErr(String),
-	/// Wraps a serialization error for Writeable or Readable
-	SerErr(ser::Error),
-}
-
-impl fmt::Display for Error {
-	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-		match self {
-			&Error::NotFoundErr => write!(f, "Not Found"),
-			&Error::RocksDbErr(ref s) => write!(f, "RocksDb Error: {}", s),
-			&Error::SerErr(ref e) => write!(f, "Serialization Error: {}", e.to_string()),
-		}
-	}
-}
-
-impl From<rocksdb::Error> for Error {
-	fn from(e: rocksdb::Error) -> Error {
-		Error::RocksDbErr(e.to_string())
-	}
-}
-
-/// Thread-safe rocksdb wrapper
-pub struct Store {
-	rdb: RwLock<DB>,
-}
-
-unsafe impl Sync for Store {}
-unsafe impl Send for Store {}
-
-impl Store {
-	/// Opens a new RocksDB at the specified location.
-	pub fn open(path: &str) -> Result<Store, Error> {
-		let mut opts = rocksdb::Options::default();
-		opts.create_if_missing(true);
-		opts.set_compaction_style(DBCompactionStyle::Universal);
-		opts.set_max_open_files(256);
-		opts.set_use_fsync(false);
-		let db = DB::open(&opts, &path)?;
-		Ok(Store {
-			rdb: RwLock::new(db),
-		})
-	}
-
-	/// Writes a single key/value pair to the db
-	pub fn put(&self, key: &[u8], value: Vec<u8>) -> Result<(), Error> {
-		let db = self.rdb.write().unwrap();
-		db.put(key, &value[..]).map_err(&From::from)
-	}
-
-	/// Writes a single key and its `Writeable` value to the db. Encapsulates
-	/// serialization.
-	pub fn put_ser<W: ser::Writeable>(&self, key: &[u8], value: &W) -> Result<(), Error> {
-		let ser_value = ser::ser_vec(value);
-		match ser_value {
-			Ok(data) => self.put(key, data),
-			Err(err) => Err(Error::SerErr(err)),
-		}
-	}
-
-	/// Gets a value from the db, provided its key
-	pub fn get(&self, key: &[u8]) -> Result<Option<Vec<u8>>, Error> {
-		let db = self.rdb.read().unwrap();
-		db.get(key)
-			.map(|r| r.map(|o| o.to_vec()))
-			.map_err(From::from)
-	}
-
-	/// Gets a `Readable` value from the db, provided its key. Encapsulates
-	/// serialization.
-	pub fn get_ser<T: ser::Readable>(&self, key: &[u8]) -> Result<Option<T>, Error> {
-		self.get_ser_limited(key, 0)
-	}
-
-	/// Gets a `Readable` value from the db, provided its key, allowing to
-	/// extract only partial data. The underlying Readable size must align
-	/// accordingly. Encapsulates serialization.
-	pub fn get_ser_limited<T: ser::Readable>(
-		&self,
-		key: &[u8],
-		len: usize,
-	) -> Result<Option<T>, Error> {
-		let data = self.get(key)?;
-		match data {
-			Some(val) => {
-				let mut lval = if len > 0 { &val[..len] } else { &val[..] };
-				let r = ser::deserialize(&mut lval).map_err(Error::SerErr)?;
-				Ok(Some(r))
-			}
-			None => Ok(None),
-		}
-	}
-
-	/// Whether the provided key exists
-	pub fn exists(&self, key: &[u8]) -> Result<bool, Error> {
-		let db = self.rdb.read().unwrap();
-		db.get(key).map(|r| r.is_some()).map_err(From::from)
-	}
-
-	/// Deletes a key/value pair from the db
-	pub fn delete(&self, key: &[u8]) -> Result<(), Error> {
-		let db = self.rdb.write().unwrap();
-		db.delete(key).map_err(From::from)
-	}
-
-	/// Produces an iterator of `Readable` types moving forward from the
-	/// provided
-	/// key.
-	pub fn iter<T: ser::Readable>(&self, from: &[u8]) -> SerIterator<T> {
-		let db = self.rdb.read().unwrap();
-		SerIterator {
-			iter: db.iterator(IteratorMode::From(from, Direction::Forward)),
-			_marker: marker::PhantomData,
-		}
-	}
-
-	/// Builds a new batch to be used with this store.
-	pub fn batch(&self) -> Batch {
-		Batch {
-			store: self,
-			batch: WriteBatch::default(),
-		}
-	}
-
-	fn write(&self, batch: WriteBatch) -> Result<(), Error> {
-		let db = self.rdb.write().unwrap();
-		db.write(batch).map_err(From::from)
-	}
-}
-
-/// Batch to write multiple Writeables to RocksDb in an atomic manner.
-pub struct Batch<'a> {
-	store: &'a Store,
-	batch: WriteBatch,
-}
-
-impl<'a> Batch<'a> {
-	/// Writes a single key and its `Writeable` value to the batch. The write
-	/// function must be called to "commit" the batch to storage.
-	pub fn put_ser<W: ser::Writeable>(mut self, key: &[u8], value: &W) -> Result<Batch<'a>, Error> {
-		let ser_value = ser::ser_vec(value);
-		match ser_value {
-			Ok(data) => {
-				self.batch.put(key, &data[..])?;
-				Ok(self)
-			}
-			Err(err) => Err(Error::SerErr(err)),
-		}
-	}
-
-	/// Delete a single key from the batch. The write function
-	/// must be called to "commit" the batch to storage.
-	pub fn delete(mut self, key: &[u8]) -> Result<Batch<'a>, Error> {
-		self.batch.delete(key)?;
-		Ok(self)
-	}
-
-	/// Writes the batch to RocksDb.
-	pub fn write(self) -> Result<(), Error> {
-		self.store.write(self.batch)
-	}
-}
 
 /// An iterator thad produces Readable instances back. Wraps the lower level
 /// DBIterator and deserializes the returned values.
-pub struct SerIterator<T>
+// pub struct SerIterator<T>
-where
+// where
-	T: ser::Readable,
+// 	T: ser::Readable,
-{
+// {
-	iter: DBIterator,
+// 	iter: DBIterator,
-	_marker: marker::PhantomData<T>,
+// 	_marker: marker::PhantomData<T>,
-}
+// }
-
+//
-impl<T> Iterator for SerIterator<T>
+// impl<T> Iterator for SerIterator<T>
-where
+// where
-	T: ser::Readable,
+// 	T: ser::Readable,
-{
+// {
-	type Item = T;
+// 	type Item = T;
-
+//
-	fn next(&mut self) -> Option<T> {
+// 	fn next(&mut self) -> Option<T> {
-		let next = self.iter.next();
+// 		let next = self.iter.next();
-		next.and_then(|r| {
+// 		next.and_then(|r| {
-			let (_, v) = r;
+// 			let (_, v) = r;
-			ser::deserialize(&mut &v[..]).ok()
+// 			ser::deserialize(&mut &v[..]).ok()
-		})
+// 		})
-	}
+// 	}
-}
+// }
 
 /// Build a db key from a prefix and a byte vector identifier.
 pub fn to_key(prefix: u8, k: &mut Vec<u8>) -> Vec<u8> {
@@ -261,12 +88,3 @@ pub fn u64_to_key<'a>(prefix: u8, val: u64) -> Vec<u8> {
 	u64_vec.insert(0, prefix);
 	u64_vec
 }
-
-/// unwraps the inner option by converting the none case to a not found error
-pub fn option_to_not_found<T>(res: Result<Option<T>, Error>) -> Result<T, Error> {
-	match res {
-		Ok(None) => Err(Error::NotFoundErr),
-		Ok(Some(o)) => Ok(o),
-		Err(e) => Err(e),
-	}
-}

store/src/lmdb.rs

@@ -0,0 +1,270 @@
+// Copyright 2018 The Grin Developers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Storage of core types using LMDB.
+
+use std::fs;
+use std::marker;
+use std::sync::Arc;
+
+use lmdb_zero as lmdb;
+use lmdb_zero::LmdbResultExt;
+use lmdb_zero::traits::CreateCursor;
+
+use core::ser;
+
+/// Main error type for this lmdb
+#[derive(Debug)]
+pub enum Error {
+	/// Couldn't find what we were looking for
+	NotFoundErr,
+	/// Wraps an error originating from RocksDB (which unfortunately returns
+	/// string errors).
+	LmdbErr(lmdb::error::Error),
+	/// Wraps a serialization error for Writeable or Readable
+	SerErr(ser::Error),
+}
+
+impl From<lmdb::error::Error> for Error {
+	fn from(e: lmdb::error::Error) -> Error {
+		Error::LmdbErr(e)
+	}
+}
+
+/// unwraps the inner option by converting the none case to a not found error
+pub fn option_to_not_found<T>(res: Result<Option<T>, Error>) -> Result<T, Error> {
+	match res {
+		Ok(None) => Err(Error::NotFoundErr),
+		Ok(Some(o)) => Ok(o),
+		Err(e) => Err(e),
+	}
+}
+
+/// Create a new LMDB env under the provided directory to spawn various
+/// databases from.
+pub fn new_env(path: String) -> lmdb::Environment {
+	let full_path = path + "/lmdb";
+	fs::create_dir_all(&full_path).unwrap();
+	unsafe {
+		let mut env_builder = lmdb::EnvBuilder::new().unwrap();
+		env_builder.set_maxdbs(8).unwrap();
+		// half a TB should give us plenty room, will be an issue on 32 bits
+		// (which we don't support anyway)
+		env_builder.set_mapsize(549755813888).unwrap_or_else(|e| {
+			panic!("Unable to allocate LMDB space: {:?}", e);
+		});
+
+		env_builder
+			.open(&full_path, lmdb::open::Flags::empty(), 0o600)
+			.unwrap()
+	}
+}
+
+/// LMDB-backed store facilitating data access and serialization. All writes
+/// are done through a Batch abstraction providing atomicity.
+pub struct Store {
+	env: Arc<lmdb::Environment>,
+	db: Arc<lmdb::Database<'static>>,
+}
+
+impl Store {
+	/// Creates a new store with the provided name under the specified
+	/// environment
+	pub fn open(env: Arc<lmdb::Environment>, name: &str) -> Store {
+		let db = Arc::new(
+			lmdb::Database::open(
+				env.clone(),
+				Some(name),
+				&lmdb::DatabaseOptions::new(lmdb::db::CREATE),
+			).unwrap(),
+		);
+		Store { env, db }
+	}
+
+	/// Gets a value from the db, provided its key
+	pub fn get(&self, key: &[u8]) -> Result<Option<Vec<u8>>, Error> {
+		let txn = lmdb::ReadTransaction::new(self.env.clone())?;
+		let access = txn.access();
+		let res = access.get(&self.db, key);
+		res.map(|res: &[u8]| res.to_vec())
+			.to_opt()
+			.map_err(From::from)
+	}
+
+	/// Gets a `Readable` value from the db, provided its key. Encapsulates
+	/// serialization.
+	pub fn get_ser<T: ser::Readable>(&self, key: &[u8]) -> Result<Option<T>, Error> {
+		let txn = lmdb::ReadTransaction::new(self.env.clone())?;
+		let access = txn.access();
+		self.get_ser_access(key, &access)
+	}
+
+	fn get_ser_access<T: ser::Readable>(
+		&self,
+		key: &[u8],
+		access: &lmdb::ConstAccessor,
+	) -> Result<Option<T>, Error> {
+		let res: lmdb::error::Result<&[u8]> = access.get(&self.db, key);
+		match res.to_opt() {
+			Ok(Some(mut res)) => match ser::deserialize(&mut res).map_err(Error::SerErr) {
+				Ok(res) => Ok(Some(res)),
+				Err(e) => Err(From::from(e)),
+			},
+			Ok(None) => Ok(None),
+			Err(e) => Err(From::from(e)),
+		}
+	}
+
+	/// Whether the provided key exists
+	pub fn exists(&self, key: &[u8]) -> Result<bool, Error> {
+		let txn = lmdb::ReadTransaction::new(self.env.clone())?;
+		let access = txn.access();
+		let res: lmdb::error::Result<&lmdb::Ignore> = access.get(&self.db, key);
+		res.to_opt().map(|r| r.is_some()).map_err(From::from)
+	}
+
+	/// Produces an iterator of `Readable` types moving forward from the
+	/// provided key.
+	pub fn iter<T: ser::Readable>(&self, from: &[u8]) -> Result<SerIterator<T>, Error> {
+		let txn = Arc::new(lmdb::ReadTransaction::new(self.env.clone())?);
+		let cursor = Arc::new(txn.cursor(self.db.clone()).unwrap());
+		Ok(SerIterator {
+			tx: txn,
+			cursor: cursor,
+			seek: false,
+			prefix: from.to_vec(),
+			_marker: marker::PhantomData,
+		})
+	}
+
+	/// Builds a new batch to be used with this store.
+	pub fn batch(&self) -> Result<Batch, Error> {
+		let txn = lmdb::WriteTransaction::new(self.env.clone())?;
+		Ok(Batch {
+			store: self,
+			tx: txn,
+		})
+	}
+}
+
+/// Batch to write multiple Writeables to db in an atomic manner.
+pub struct Batch<'a> {
+	store: &'a Store,
+	tx: lmdb::WriteTransaction<'a>,
+}
+
+impl<'a> Batch<'a> {
+	/// Writes a single key/value pair to the db
+	pub fn put(&self, key: &[u8], value: Vec<u8>) -> Result<(), Error> {
+		self.tx
+			.access()
+			.put(&self.store.db, key, &value, lmdb::put::Flags::empty())?;
+		Ok(())
+	}
+
+	/// Writes a single key and its `Writeable` value to the db. Encapsulates
+	/// serialization.
+	pub fn put_ser<W: ser::Writeable>(&self, key: &[u8], value: &W) -> Result<(), Error> {
+		let ser_value = ser::ser_vec(value);
+		match ser_value {
+			Ok(data) => self.put(key, data),
+			Err(err) => Err(Error::SerErr(err)),
+		}
+	}
+
+	/// gets a value from the db, provided its key
+	pub fn get(&self, key: &[u8]) -> Result<Option<Vec<u8>>, Error> {
+		self.store.get(key)
+	}
+
+	/// Gets a `Readable` value from the db, provided its key, taking the
+	/// content of the current batch into account.
+	pub fn get_ser<T: ser::Readable>(&self, key: &[u8]) -> Result<Option<T>, Error> {
+		let access = self.tx.access();
+		self.store.get_ser_access(key, &access)
+	}
+
+	/// Deletes a key/value pair from the db
+	pub fn delete(&self, key: &[u8]) -> Result<(), Error> {
+		self.tx.access().del_key(&self.store.db, key)?;
+		Ok(())
+	}
+
+	/// Writes the batch to db
+	pub fn commit(self) -> Result<(), Error> {
+		self.tx.commit()?;
+		Ok(())
+	}
+
+	/// Creates a child of this batch. It will be merged with its parent on
+	/// commit, abandoned otherwise.
+	pub fn child(&mut self) -> Result<Batch, Error> {
+		Ok(Batch {
+			store: self.store,
+			tx: self.tx.child_tx()?,
+		})
+	}
+}
+
+/// An iterator thad produces Readable instances back. Wraps the lower level
+/// DBIterator and deserializes the returned values.
+pub struct SerIterator<T>
+where
+	T: ser::Readable,
+{
+	tx: Arc<lmdb::ReadTransaction<'static>>,
+	cursor: Arc<lmdb::Cursor<'static, 'static>>,
+	seek: bool,
+	prefix: Vec<u8>,
+	_marker: marker::PhantomData<T>,
+}
+
+impl<T> Iterator for SerIterator<T>
+where
+	T: ser::Readable,
+{
+	type Item = T;
+
+	fn next(&mut self) -> Option<T> {
+		let access = self.tx.access();
+		let kv = if self.seek {
+			Arc::get_mut(&mut self.cursor).unwrap().next(&access)
+		} else {
+			self.seek = true;
+			Arc::get_mut(&mut self.cursor)
+				.unwrap()
+				.seek_range_k(&access, &self.prefix[..])
+		};
+		self.deser_if_prefix_match(kv)
+	}
+}
+
+impl<T> SerIterator<T>
+where
+	T: ser::Readable,
+{
+	fn deser_if_prefix_match(&self, kv: Result<(&[u8], &[u8]), lmdb::Error>) -> Option<T> {
+		match kv {
+			Ok((k, v)) => {
+				let plen = self.prefix.len();
+				if plen == 0 || k[0..plen] == self.prefix[..] {
+					ser::deserialize(&mut &v[..]).ok()
+				} else {
+					None
+				}
+			}
+			Err(_) => None,
+		}
+	}
+}

util/src/logger.rs

@@ -12,12 +12,12 @@
 // limitations under the License.
 
 //! Logging wrapper to be used throughout all crates in the workspace
-use std::fs::OpenOptions;
-use std::sync::Mutex;
-use std::ops::Deref;
 use slog::{Discard, Drain, Duplicate, Level, LevelFilter, Logger};
-use slog_term;
 use slog_async;
+use slog_term;
+use std::fs::OpenOptions;
+use std::ops::Deref;
+use std::sync::Mutex;
 
 use backtrace::Backtrace;
 use std::{panic, thread};
@@ -110,7 +110,6 @@ pub fn init_test_logger() {
 	let mut config_ref = LOGGING_CONFIG.lock().unwrap();
 	*config_ref = LoggingConfig::default();
 	*was_init_ref = true;
-	send_panic_to_log();
 }
 
 /// hook to send panics to logs as well as stderr

wallet/Cargo.toml

@@ -30,8 +30,10 @@ urlencoded = "0.5"
 grin_api = { path = "../api" }
 grin_core = { path = "../core" }
 grin_keychain = { path = "../keychain" }
+grin_store = { path = "../store" }
 grin_util = { path = "../util" }
 
 [dev-dependencies]
 grin_chain = { path = "../chain" }
+grin_store = { path = "../store" }
 time = "0.1"

wallet/src/file_wallet.rs

@@ -12,10 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use blake2;
-use rand::{thread_rng, Rng};
-use std::cmp::min;
 use std::collections::HashMap;
+use std::collections::hash_map::Values;
 use std::fs::{self, File};
 use std::io::{Read, Write};
 use std::path::{Path, MAIN_SEPARATOR};
@@ -27,9 +25,9 @@ use tokio_retry::strategy::FibonacciBackoff;
 
 use failure::ResultExt;
 
-use keychain::{self, Keychain};
+use keychain::{self, Identifier, Keychain};
+use util::LOGGER;
 use util::secp::pedersen;
-use util::{self, LOGGER};
 
 use error::{Error, ErrorKind};
 
@@ -37,7 +35,8 @@ use client;
 use libtx::slate::Slate;
 use libwallet;
 use libwallet::types::{BlockFees, BlockIdentifier, CbData, MerkleProofWrapper, OutputData,
-                       TxWrapper, WalletBackend, WalletClient, WalletDetails};
+                       TxWrapper, WalletBackend, WalletClient, WalletDetails, WalletOutputBatch};
+use types::{WalletConfig, WalletSeed};
 
 const DETAIL_FILE: &'static str = "wallet.det";
 const DET_BCK_FILE: &'static str = "wallet.detbck";
@@ -46,123 +45,70 @@ const BCK_FILE: &'static str = "wallet.bck";
 const LOCK_FILE: &'static str = "wallet.lock";
 const SEED_FILE: &'static str = "wallet.seed";
 
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug)]
-pub struct WalletConfig {
+struct FileBatch<'a> {
-	// Right now the decision to run or not a wallet is based on the command.
+	/// List of outputs
-	// This may change in the near-future.
+	outputs: &'a mut HashMap<String, OutputData>,
-	// pub enable_wallet: bool,
+	/// Data file path
-
+	data_file_path: String,
-	// The api interface/ip_address that this api server (i.e. this wallet) will run
+	/// lock file path
-	// by default this is 127.0.0.1 (and will not accept connections from external clients)
+	lock_file_path: String,
-	pub api_listen_interface: String,
-	// The port this wallet will run on
-	pub api_listen_port: u16,
-	// The api address of a running server node against which transaction inputs
-	// will be checked during send
-	pub check_node_api_http_addr: String,
-	// The directory in which wallet files are stored
-	pub data_file_dir: String,
 }
 
-impl Default for WalletConfig {
+impl<'a> WalletOutputBatch for FileBatch<'a> {
-	fn default() -> WalletConfig {
+	fn save(&mut self, out: OutputData) -> Result<(), libwallet::Error> {
-		WalletConfig {
+		let _ = self.outputs.insert(out.key_id.to_hex(), out);
-			// enable_wallet: false,
+		Ok(())
-			api_listen_interface: "127.0.0.1".to_string(),
-			api_listen_port: 13415,
-			check_node_api_http_addr: "http://127.0.0.1:13413".to_string(),
-			data_file_dir: ".".to_string(),
 	}
+
+	fn get(&self, id: &Identifier) -> Result<OutputData, libwallet::Error> {
+		self.outputs
+			.get(&id.to_hex())
+			.map(|od| od.clone())
+			.ok_or(libwallet::ErrorKind::Backend("not found".to_string()).into())
+	}
+
+	fn delete(&mut self, id: &Identifier) -> Result<(), libwallet::Error> {
+		let _ = self.outputs.remove(&id.to_hex());
+		Ok(())
+	}
+
+	fn lock_output(&mut self, out: &mut OutputData) -> Result<(), libwallet::Error> {
+		if let Some(out_to_lock) = self.outputs.get_mut(&out.key_id.to_hex()) {
+			if out_to_lock.value == out.value {
+				out_to_lock.lock()
+			}
+		}
+		Ok(())
+	}
+
+	fn commit(&self) -> Result<(), libwallet::Error> {
+		let mut data_file = File::create(self.data_file_path.clone())
+			.context(libwallet::ErrorKind::CallbackImpl("Could not create"))?;
+		let mut outputs = self.outputs.values().collect::<Vec<_>>();
+		outputs.sort();
+		let res_json = serde_json::to_vec_pretty(&outputs).context(
+			libwallet::ErrorKind::CallbackImpl("Error serializing wallet data"),
+		)?;
+		data_file
+			.write_all(res_json.as_slice())
+			.context(libwallet::ErrorKind::CallbackImpl(
+				"Error writing wallet file",
+			))
+			.map_err(|e| e.into())
 	}
 }
 
-impl WalletConfig {
+impl<'a> Drop for FileBatch<'a> {
-	pub fn api_listen_addr(&self) -> String {
+	fn drop(&mut self) {
-		format!("{}:{}", self.api_listen_interface, self.api_listen_port)
+		// delete the lock file
-	}
+		if let Err(e) = fs::remove_dir(&self.lock_file_path) {
-}
-
-#[derive(Clone, PartialEq)]
-pub struct WalletSeed([u8; 32]);
-
-impl WalletSeed {
-	pub fn from_bytes(bytes: &[u8]) -> WalletSeed {
-		let mut seed = [0; 32];
-		for i in 0..min(32, bytes.len()) {
-			seed[i] = bytes[i];
-		}
-		WalletSeed(seed)
-	}
-
-	fn from_hex(hex: &str) -> Result<WalletSeed, Error> {
-		let bytes =
-			util::from_hex(hex.to_string()).context(ErrorKind::GenericError("Invalid hex"))?;
-		Ok(WalletSeed::from_bytes(&bytes))
-	}
-
-	pub fn to_hex(&self) -> String {
-		util::to_hex(self.0.to_vec())
-	}
-
-	pub fn derive_keychain<K: Keychain>(&self, password: &str) -> Result<K, Error> {
-		let seed = blake2::blake2b::blake2b(64, &password.as_bytes(), &self.0);
-		let result = K::from_seed(seed.as_bytes())?;
-		Ok(result)
-	}
-
-	pub fn init_new() -> WalletSeed {
-		let seed: [u8; 32] = thread_rng().gen();
-		WalletSeed(seed)
-	}
-
-	pub fn init_file(wallet_config: &WalletConfig) -> Result<WalletSeed, Error> {
-		// create directory if it doesn't exist
-		fs::create_dir_all(&wallet_config.data_file_dir).context(ErrorKind::IO)?;
-
-		let seed_file_path = &format!(
-			"{}{}{}",
-			wallet_config.data_file_dir, MAIN_SEPARATOR, SEED_FILE,
-		);
-
-		debug!(LOGGER, "Generating wallet seed file at: {}", seed_file_path,);
-
-		if Path::new(seed_file_path).exists() {
-			Err(ErrorKind::WalletSeedExists)?
-		} else {
-			let seed = WalletSeed::init_new();
-			let mut file = File::create(seed_file_path).context(ErrorKind::IO)?;
-			file.write_all(&seed.to_hex().as_bytes())
-				.context(ErrorKind::IO)?;
-			Ok(seed)
-		}
-	}
-
-	pub fn from_file(wallet_config: &WalletConfig) -> Result<WalletSeed, Error> {
-		// create directory if it doesn't exist
-		fs::create_dir_all(&wallet_config.data_file_dir).context(ErrorKind::IO)?;
-
-		let seed_file_path = &format!(
-			"{}{}{}",
-			wallet_config.data_file_dir, MAIN_SEPARATOR, SEED_FILE,
-		);
-
-		debug!(LOGGER, "Using wallet seed file at: {}", seed_file_path,);
-
-		if Path::new(seed_file_path).exists() {
-			let mut file = File::open(seed_file_path).context(ErrorKind::IO)?;
-			let mut buffer = String::new();
-			file.read_to_string(&mut buffer).context(ErrorKind::IO)?;
-			let wallet_seed = WalletSeed::from_hex(&buffer)?;
-			Ok(wallet_seed)
-		} else {
 			error!(
 				LOGGER,
-				"wallet seed file {} could not be opened (grin wallet init). \
+				"Could not remove wallet lock file. Maybe insufficient rights? "
-				 Run \"grin wallet init\" to initialize a new wallet.",
-				seed_file_path
 			);
-			Err(ErrorKind::WalletSeedDoesntExist)?
 		}
+		info!(LOGGER, "... released wallet lock");
 	}
 }
 
@@ -220,113 +166,38 @@ where
 		self.keychain.as_mut().unwrap()
 	}
 
-	/// Return the outputs directly
+	fn iter<'a>(&'a self) -> Box<Iterator<Item = OutputData> + 'a> {
-	fn outputs(&mut self) -> &mut HashMap<String, OutputData> {
+		Box::new(self.outputs.values().cloned())
-		&mut self.outputs
 	}
 
-	/// Allows for reading wallet data (without needing to acquire the write
+	fn get(&self, id: &Identifier) -> Result<OutputData, libwallet::Error> {
-	/// lock).
+		self.outputs
-	fn read_wallet<T, F>(&mut self, f: F) -> Result<T, libwallet::Error>
+			.get(&id.to_hex())
-	where
+			.map(|o| o.clone())
-		F: FnOnce(&mut Self) -> Result<T, libwallet::Error>,
+			.ok_or(libwallet::ErrorKind::Backend("not found".to_string()).into())
-	{
-		self.read_or_create_paths()
-			.context(libwallet::ErrorKind::CallbackImpl("Error reading wallet"))?;
-		f(self)
 	}
 
-	/// Allows the reading and writing of the wallet data within a file lock.
+	fn batch<'a>(&'a mut self) -> Result<Box<WalletOutputBatch + 'a>, libwallet::Error> {
-	/// Just provide a closure taking a mutable FileWallet. The lock should
+		self.lock()?;
-	/// be held for as short a period as possible to avoid contention.
-	/// Note that due to the impossibility to do an actual file lock easily
-	/// across operating systems, this just creates a lock file with a "should
-	/// not exist" option.
-	fn with_wallet<T, F>(&mut self, f: F) -> Result<T, libwallet::Error>
-	where
-		F: FnOnce(&mut Self) -> T,
-	{
-		// create directory if it doesn't exist
-		fs::create_dir_all(self.config.data_file_dir.clone()).unwrap_or_else(|why| {
-			info!(LOGGER, "! {:?}", why.kind());
-		});
-
-		info!(LOGGER, "Acquiring wallet lock ...");
-
-		let lock_file_path = self.lock_file_path.clone();
-		let action = || {
-			trace!(LOGGER, "making lock file for wallet lock");
-			fs::create_dir(&lock_file_path)
-		};
-
-		// use tokio_retry to cleanly define some retry logic
-		let mut core = reactor::Core::new().unwrap();
-		let retry_strategy = FibonacciBackoff::from_millis(1000).take(10);
-		let retry_future = Retry::spawn(core.handle(), retry_strategy, action);
-		let retry_result = core.run(retry_future)
-			.context(libwallet::ErrorKind::CallbackImpl(
-				"Failed to acquire lock file",
-			));
-
-		match retry_result {
-			Ok(_) => {}
-			Err(e) => {
-				error!(
-					LOGGER,
-					"Failed to acquire wallet lock file (multiple retries)",
-				);
-				return Err(e.into());
-			}
-		}
 
 		// We successfully acquired the lock - so do what needs to be done.
 		self.read_or_create_paths()
 			.context(libwallet::ErrorKind::CallbackImpl("Lock Error"))?;
 		self.write(&self.backup_file_path, &self.details_bak_path)
 			.context(libwallet::ErrorKind::CallbackImpl("Write Error"))?;
-		let res = f(self);
-		self.write(&self.data_file_path, &self.details_file_path)
-			.context(libwallet::ErrorKind::CallbackImpl("Write Error"))?;
 
-		// delete the lock file
+		Ok(Box::new(FileBatch {
-		fs::remove_dir(&self.lock_file_path).context(libwallet::ErrorKind::CallbackImpl(
+			outputs: &mut self.outputs,
-			&"Could not remove wallet lock file. Maybe insufficient rights? ",
+			data_file_path: self.data_file_path.clone(),
-		))?;
+			lock_file_path: self.lock_file_path.clone(),
-
+		}))
-		info!(LOGGER, "... released wallet lock");
-
-		Ok(res)
-	}
-
-	/// Append a new output data to the wallet data.
-	/// TODO - we should check for overwriting here - only really valid for
-	/// unconfirmed coinbase
-	fn add_output(&mut self, out: OutputData) {
-		self.outputs.insert(out.key_id.to_hex(), out.clone());
-	}
-
-	// TODO - careful with this, only for Unconfirmed (maybe Locked)?
-	fn delete_output(&mut self, id: &keychain::Identifier) {
-		self.outputs.remove(&id.to_hex());
-	}
-
-	/// Lock an output data.
-	/// TODO - we should track identifier on these outputs (not just n_child)
-	fn lock_output(&mut self, out: &OutputData) {
-		if let Some(out_to_lock) = self.outputs.get_mut(&out.key_id.to_hex()) {
-			if out_to_lock.value == out.value {
-				out_to_lock.lock()
-			}
-		}
-	}
-
-	/// get a single output
-	fn get_output(&self, key_id: &keychain::Identifier) -> Option<&OutputData> {
-		self.outputs.get(&key_id.to_hex())
 	}
 
 	/// Next child index when we want to create a new output.
-	fn next_child(&mut self, root_key_id: keychain::Identifier) -> u32 {
+	fn next_child<'a>(
+		&'a mut self,
+		root_key_id: keychain::Identifier,
+	) -> Result<u32, libwallet::Error> {
 		let mut max_n = 0;
 		for out in self.outputs.values() {
 			if max_n < out.n_child && out.root_key_id == root_key_id {
@@ -339,7 +210,7 @@ where
 		} else {
 			self.details.last_child_index += 1;
 		}
-		self.details.last_child_index
+		Ok(self.details.last_child_index)
 	}
 
 	/// Select spendable coins from the wallet.
@@ -530,6 +401,41 @@ where
 		}
 	}
 
+	fn lock(&self) -> Result<(), libwallet::Error> {
+		// create directory if it doesn't exist
+		fs::create_dir_all(self.config.data_file_dir.clone()).unwrap_or_else(|why| {
+			info!(LOGGER, "! {:?}", why.kind());
+		});
+
+		info!(LOGGER, "Acquiring wallet lock ...");
+
+		let lock_file_path = self.lock_file_path.clone();
+		let action = || {
+			trace!(LOGGER, "making lock file for wallet lock");
+			fs::create_dir(&lock_file_path)
+		};
+
+		// use tokio_retry to cleanly define some retry logic
+		let mut core = reactor::Core::new().unwrap();
+		let retry_strategy = FibonacciBackoff::from_millis(1000).take(10);
+		let retry_future = Retry::spawn(core.handle(), retry_strategy, action);
+		let retry_result = core.run(retry_future)
+			.context(libwallet::ErrorKind::CallbackImpl(
+				"Failed to acquire lock file",
+			));
+
+		match retry_result {
+			Ok(_) => Ok(()),
+			Err(e) => {
+				error!(
+					LOGGER,
+					"Failed to acquire wallet lock file (multiple retries)",
+				);
+				Err(e.into())
+			}
+		}
+	}
+
 	/// Read the wallet data or create brand files if the data
 	/// files don't yet exist
 	fn read_or_create_paths(&mut self) -> Result<(), Error> {
@@ -570,7 +476,7 @@ where
 		let outputs = self.read_outputs()?;
 		self.outputs = HashMap::new();
 		for out in outputs {
-			self.add_output(out);
+			self.outputs.insert(out.key_id.to_hex(), out.clone());
 		}
 		Ok(())
 	}

wallet/src/lib.rs

@@ -44,6 +44,7 @@ extern crate tokio_retry;
 extern crate grin_api as api;
 extern crate grin_core as core;
 extern crate grin_keychain as keychain;
+extern crate grin_store as store;
 extern crate grin_util as util;
 
 mod client;
@@ -52,9 +53,12 @@ mod error;
 pub mod file_wallet;
 pub mod libtx;
 pub mod libwallet;
+pub mod lmdb_wallet;
+mod types;
 
 pub use client::create_coinbase;
 pub use error::{Error, ErrorKind};
-pub use file_wallet::{FileWallet, WalletConfig, WalletSeed};
+pub use file_wallet::FileWallet;
 pub use libwallet::controller;
 pub use libwallet::types::{BlockFees, CbData, WalletInfo};
+pub use types::{WalletConfig, WalletSeed};

wallet/src/libwallet/error.rs

@@ -77,6 +77,10 @@ pub enum ErrorKind {
 	#[fail(display = "Trait Implementation error")]
 	CallbackImpl(&'static str),
 
+	/// Wallet backend error
+	#[fail(display = "Wallet store error")]
+	Backend(String),
+
 	/// Callback implementation error conversion
 	#[fail(display = "Restore Error")]
 	Restore,

wallet/src/libwallet/internal/keys.rs

@@ -17,38 +17,29 @@ use keychain::{Identifier, Keychain};
 use libwallet::error::Error;
 use libwallet::types::WalletBackend;
 
-/// Get our next available key
-pub fn new_output_key<T, K>(wallet: &mut T) -> Result<(Identifier, u32), Error>
-where
-	T: WalletBackend<K>,
-	K: Keychain,
-{
-	wallet.with_wallet(|wallet_data| next_available_key(wallet_data))
-}
-
 /// Get next available key in the wallet
-pub fn next_available_key<T, K>(wallet: &mut T) -> (Identifier, u32)
+pub fn next_available_key<T, K>(wallet: &mut T) -> Result<(Identifier, u32), Error>
 where
 	T: WalletBackend<K>,
 	K: Keychain,
 {
 	let root_key_id = wallet.keychain().root_key_id();
-	let derivation = wallet.next_child(root_key_id.clone());
+	let derivation = wallet.next_child(root_key_id.clone())?;
-	let key_id = wallet.keychain().derive_key_id(derivation).unwrap();
+	let key_id = wallet.keychain().derive_key_id(derivation)?;
-	(key_id, derivation)
+	Ok((key_id, derivation))
 }
 
 /// Retrieve an existing key from a wallet
-pub fn retrieve_existing_key<T, K>(wallet: &T, key_id: Identifier) -> (Identifier, u32)
+pub fn retrieve_existing_key<T, K>(
+	wallet: &T,
+	key_id: Identifier,
+) -> Result<(Identifier, u32), Error>
 where
 	T: WalletBackend<K>,
 	K: Keychain,
 {
-	if let Some(existing) = wallet.get_output(&key_id) {
+	let existing = wallet.get(&key_id)?;
 	let key_id = existing.key_id.clone();
 	let derivation = existing.n_child;
-		(key_id, derivation)
+	Ok((key_id, derivation))
-	} else {
-		panic!("should never happen");
-	}
 }

wallet/src/libwallet/internal/restore.rs

@@ -235,9 +235,7 @@ where
 	K: Keychain,
 {
 	// Don't proceed if wallet.dat has anything in it
-	let is_empty = wallet
+	let is_empty = wallet.iter().next().is_none();
-		.read_wallet(|wallet_data| Ok(wallet_data.outputs().len() == 0))
-		.context(ErrorKind::FileWallet("could not read wallet"))?;
 	if !is_empty {
 		error!(
 			LOGGER,
@@ -265,17 +263,12 @@ where
 			output_listing.highest_index
 		);
 
-		let _ = wallet.with_wallet(|wallet_data| {
+		let root_key_id = wallet.keychain().root_key_id();
-			let keychain = wallet_data.keychain().clone();
+		let result_vec =
-			let result_vec = find_outputs_with_key(
+			find_outputs_with_key(wallet, output_listing.outputs.clone(), &mut found_key_index);
-				wallet_data,
+		let mut batch = wallet.batch()?;
-				output_listing.outputs.clone(),
+		for output in result_vec {
-				&mut found_key_index,
+			batch.save(OutputData {
-			);
-			if result_vec.len() > 0 {
-				for output in result_vec.clone() {
-					let root_key_id = keychain.root_key_id();
-					wallet_data.add_output(OutputData {
 				root_key_id: root_key_id.clone(),
 				key_id: output.1.clone(),
 				n_child: output.2,
@@ -288,8 +281,8 @@ where
 				merkle_proof: output.7,
 			});
 		}
-			}
+		batch.commit()?;
-		});
+
 		if output_listing.highest_index == output_listing.last_retrieved_index {
 			break;
 		}

wallet/src/libwallet/internal/selection.rs

@@ -86,22 +86,23 @@ where
 	let lock_inputs = context.get_inputs().clone();
 	let _lock_outputs = context.get_outputs().clone();
 
+	let root_key_id = keychain.root_key_id();
+
 	// Return a closure to acquire wallet lock and lock the coins being spent
 	// so we avoid accidental double spend attempt.
 	let update_sender_wallet_fn = move |wallet: &mut T| {
-		wallet.with_wallet(|wallet_data| {
+		let mut batch = wallet.batch()?;
-			// Lock the inputs we've selected
 		for id in lock_inputs {
-				let coin = wallet_data.get_output(&id).unwrap().clone();
+			let mut coin = batch.get(&id).unwrap();
-				wallet_data.lock_output(&coin);
+			batch.lock_output(&mut coin);
 		}
+		// write the output representing our change
 		if let Some(d) = change_derivation {
-				// Add our change output to the wallet
-				let root_key_id = keychain.root_key_id();
 			let change_id = keychain.derive_key_id(change_derivation.unwrap()).unwrap();
-				wallet_data.add_output(OutputData {
+
-					root_key_id: root_key_id.clone(),
+			batch.save(OutputData {
-					key_id: change_id,
+				root_key_id: root_key_id,
+				key_id: change_id.clone(),
 				n_child: d,
 				value: change as u64,
 				status: OutputStatus::Unconfirmed,
@@ -112,7 +113,8 @@ where
 				merkle_proof: None,
 			});
 		}
-		})
+		batch.commit()?;
+		Ok(())
 	};
 
 	Ok((slate, context, update_sender_wallet_fn))
@@ -138,7 +140,7 @@ where
 	K: Keychain,
 {
 	// Create a potential output for this transaction
-	let (key_id, derivation) = keys::new_output_key(wallet)?;
+	let (key_id, derivation) = keys::next_available_key(wallet).unwrap();
 
 	let keychain = wallet.keychain().clone();
 	let root_key_id = keychain.root_key_id();
@@ -162,8 +164,8 @@ where
 	// Create closure that adds the output to recipient's wallet
 	// (up to the caller to decide when to do)
 	let wallet_add_fn = move |wallet: &mut T| {
-		wallet.with_wallet(|wallet_data| {
+		let mut batch = wallet.batch()?;
-			wallet_data.add_output(OutputData {
+		batch.save(OutputData {
 			root_key_id: root_key_id,
 			key_id: key_id_inner,
 			n_child: derivation,
@@ -175,7 +177,8 @@ where
 			block: None,
 			merkle_proof: None,
 		});
-		})
+		batch.commit()?;
+		Ok(())
 	};
 	Ok((key_id, context, wallet_add_fn))
 }
@@ -209,29 +212,25 @@ where
 	let key_id = wallet.keychain().root_key_id();
 
 	// select some spendable coins from the wallet
-	let mut coins = wallet.read_wallet(|wallet_data| {
+	let mut coins = wallet.select_coins(
-		Ok(wallet_data.select_coins(
 		key_id.clone(),
 		amount,
 		current_height,
 		minimum_confirmations,
 		max_outputs,
 		selection_strategy_is_use_all,
-		))
+	);
-	})?;
 
 	// Get the maximum number of outputs in the wallet
 	let max_outputs = wallet
-		.read_wallet(|wallet_data| {
+		.select_coins(
-			Ok(wallet_data.select_coins(
 			key_id.clone(),
 			amount,
 			current_height,
 			minimum_confirmations,
 			max_outputs,
 			true,
-			))
+		)
-		})?
 		.len();
 
 	// sender is responsible for setting the fee on the partial tx
@@ -267,16 +266,14 @@ where
 			}
 
 			// select some spendable coins from the wallet
-			coins = wallet.read_wallet(|wallet_data| {
+			coins = wallet.select_coins(
-				Ok(wallet_data.select_coins(
 				key_id.clone(),
 				amount_with_fee,
 				current_height,
 				minimum_confirmations,
 				max_outputs,
 				selection_strategy_is_use_all,
-				))
+			);
-			})?;
 			fee = tx_fee(coins.len(), 2, coins_proof_count(&coins), None);
 			total = coins.iter().map(|c| c.value).sum();
 			amount_with_fee = amount + fee;
@@ -284,8 +281,7 @@ where
 	}
 
 	// build transaction skeleton with inputs and change
-	let (mut parts, change, change_derivation) =
+	let (mut parts, change, change_derivation) = inputs_and_change(&coins, wallet, amount, fee)?;
-		inputs_and_change(&coins, wallet, current_height, amount, fee)?;
 
 	// This is more proof of concept than anything but here we set lock_height
 	// on tx being sent (based on current chain height via api).
@@ -303,7 +299,6 @@ pub fn coins_proof_count(coins: &Vec<OutputData>) -> usize {
 pub fn inputs_and_change<T, K>(
 	coins: &Vec<OutputData>,
 	wallet: &mut T,
-	height: u64,
 	amount: u64,
 	fee: u64,
 ) -> Result<(Vec<Box<build::Append<K>>>, u64, Option<u32>), Error>
@@ -341,20 +336,14 @@ where
 			parts.push(build::input(coin.value, key_id));
 		}
 	}
-	let change_key;
 	let mut change_derivation = None;
 	if change != 0 {
-		// track the output representing our change
+		let keychain = wallet.keychain().clone();
-		change_key = wallet.with_wallet(|wallet_data| {
-			let keychain = wallet_data.keychain().clone();
 		let root_key_id = keychain.root_key_id();
-			let cd = wallet_data.next_child(root_key_id.clone());
+		change_derivation = Some(wallet.next_child(root_key_id.clone()).unwrap());
-			let change_key = keychain.derive_key_id(cd).unwrap();
+		let change_k = keychain.derive_key_id(change_derivation.unwrap()).unwrap();
-			change_derivation = Some(cd);
-			Some(change_key)
-		})?;
 
-		parts.push(build::output(change, change_key.clone().unwrap()));
+		parts.push(build::output(change, change_k.clone()));
 	}
 
 	Ok((parts, change, change_derivation))

wallet/src/libwallet/internal/tx.rs

@@ -151,22 +151,20 @@ where
 	let key_id = keychain.root_key_id();
 
 	// select some spendable coins from the wallet
-	let coins = wallet.read_wallet(|wallet_data| {
+	let coins = wallet.select_coins(
-		Ok(wallet_data.select_coins(
 		key_id.clone(),
 		amount,
 		current_height,
 		minimum_confirmations,
 		max_outputs,
 		false,
-		))
+	);
-	})?;
 
 	debug!(LOGGER, "selected some coins - {}", coins.len());
 
 	let fee = tx_fee(coins.len(), 2, selection::coins_proof_count(&coins), None);
 	let (mut parts, _, _) =
-		selection::inputs_and_change(&coins, wallet, current_height, amount, fee)?;
+		selection::inputs_and_change(&coins, wallet, amount, fee)?;
 
 	//TODO: If we end up using this, create change output here
 

wallet/src/libwallet/internal/updater.rs

@@ -40,13 +40,9 @@ where
 {
 	let root_key_id = wallet.keychain().clone().root_key_id();
 
-	let mut outputs = vec![];
-
 	// just read the wallet here, no need for a write lock
-	let _ = wallet.read_wallet(|wallet_data| {
+	let mut outputs = wallet
-		outputs = wallet_data
+		.iter()
-			.outputs()
-			.values()
 		.filter(|out| out.root_key_id == root_key_id)
 		.filter(|out| {
 			if show_spent {
@@ -55,13 +51,8 @@ where
 				out.status != OutputStatus::Spent
 			}
 		})
-			.collect::<Vec<_>>()
+		.collect::<Vec<_>>();
-			.iter()
-			.map(|&o| o.clone())
-			.collect();
 	outputs.sort_by_key(|out| out.n_child);
-		Ok(())
-	});
 	Ok(outputs)
 }
 
@@ -109,21 +100,21 @@ where
 	// the corresponding api output (if it exists)
 	// and refresh it in-place in the wallet.
 	// Note: minimizing the time we spend holding the wallet lock.
-	wallet.with_wallet(|wallet_data| {
+	let mut batch = wallet.batch()?;
-		for commit in wallet_outputs.keys() {
+	for (commit, id) in wallet_outputs.iter() {
-			let id = wallet_outputs.get(&commit).unwrap();
+		if let Some((height, bid)) = api_blocks.get(&commit) {
-			if let Entry::Occupied(mut output) = wallet_data.outputs().entry(id.to_hex()) {
+			if let Ok(mut output) = batch.get(id) {
-				if let Some(b) = api_blocks.get(&commit) {
+				output.height = *height;
-					let output = output.get_mut();
+				output.block = Some(bid.clone());
-					output.height = b.0;
-					output.block = Some(b.1.clone());
 				if let Some(merkle_proof) = api_merkle_proofs.get(&commit) {
 					output.merkle_proof = Some(merkle_proof.clone());
 				}
+				batch.save(output);
 			}
 		}
 	}
-	})
+	batch.commit()?;
+	Ok(())
 }
 
 /// build a local map of wallet outputs keyed by commit
@@ -136,19 +127,15 @@ where
 	K: Keychain,
 {
 	let mut wallet_outputs: HashMap<pedersen::Commitment, Identifier> = HashMap::new();
-	let _ = wallet.read_wallet(|wallet_data| {
+	let keychain = wallet.keychain().clone();
-		let keychain = wallet_data.keychain().clone();
 	let root_key_id = keychain.root_key_id().clone();
-		let unspents = wallet_data
+	let unspents = wallet
-			.outputs()
+		.iter()
-			.values()
 		.filter(|x| x.root_key_id == root_key_id && x.status != OutputStatus::Spent);
 	for out in unspents {
 		let commit = keychain.commit_with_key_index(out.value, out.n_child)?;
 		wallet_outputs.insert(commit, out.key_id.clone());
 	}
-		Ok(())
-	});
 	Ok(wallet_outputs)
 }
 
@@ -162,9 +149,8 @@ where
 	K: Keychain,
 {
 	let mut wallet_outputs: HashMap<pedersen::Commitment, Identifier> = HashMap::new();
-	let _ = wallet.read_wallet(|wallet_data| {
+	let keychain = wallet.keychain().clone();
-		let keychain = wallet_data.keychain().clone();
+	let unspents = wallet.iter().filter(|x| {
-		let unspents = wallet_data.outputs().values().filter(|x| {
 		x.root_key_id == keychain.root_key_id() && x.block.is_none()
 			&& x.status == OutputStatus::Unspent
 	});
@@ -172,8 +158,6 @@ where
 		let commit = keychain.commit_with_key_index(out.value, out.n_child)?;
 		wallet_outputs.insert(commit, out.key_id.clone());
 	}
-		Ok(())
-	});
 	Ok(wallet_outputs)
 }
 
@@ -191,19 +175,21 @@ where
 	// now for each commit, find the output in the wallet and the corresponding
 	// api output (if it exists) and refresh it in-place in the wallet.
 	// Note: minimizing the time we spend holding the wallet lock.
-	wallet.with_wallet(|wallet_data| {
+	{
-		for commit in wallet_outputs.keys() {
+		let mut batch = wallet.batch()?;
-			let id = wallet_outputs.get(&commit).unwrap();
+		for (commit, id) in wallet_outputs.iter() {
-			if let Entry::Occupied(mut output) = wallet_data.outputs().entry(id.to_hex()) {
+			if let Ok(mut output) = batch.get(id) {
 				match api_outputs.get(&commit) {
-					Some(_) => output.get_mut().mark_unspent(),
+					Some(_) => output.mark_unspent(),
-					None => output.get_mut().mark_spent(),
+					None => output.mark_spent(),
 				};
+				batch.save(output);
 			}
 		}
-		let details = wallet_data.details();
+		batch.commit()?;
+	}
+	let details = wallet.details();
 	details.last_confirmed_height = height;
-	})?;
 	Ok(())
 }
 
@@ -236,12 +222,18 @@ where
 	if height < 500 {
 		return Ok(());
 	}
-	wallet.with_wallet(|wallet_data| {
+	let mut ids_to_del = vec![];
-		wallet_data.outputs().retain(|_, ref mut out| {
+	for out in wallet.iter() {
-			!(out.status == OutputStatus::Unconfirmed && out.height > 0
+		if out.status == OutputStatus::Unconfirmed && out.height > 0 && out.height < height - 500 {
-				&& out.height < height - 500)
+			ids_to_del.push(out.key_id.clone())
-		});
+		}
-	})
+	}
+	let mut batch = wallet.batch()?;
+	for id in ids_to_del {
+		batch.delete(&id);
+	}
+	batch.commit()?;
+	Ok(())
 }
 
 /// Retrieve summary info about the wallet
@@ -251,18 +243,17 @@ where
 	T: WalletBackend<K> + WalletClient,
 	K: Keychain,
 {
-	let ret_val = wallet.read_wallet(|wallet_data| {
+	let current_height = wallet.details().last_confirmed_height;
-		let current_height = wallet_data.details().last_confirmed_height;
+	let keychain = wallet.keychain().clone();
+	let outputs = wallet
+		.iter()
+		.filter(|out| out.root_key_id == keychain.root_key_id());
+
 	let mut unspent_total = 0;
 	let mut immature_total = 0;
 	let mut unconfirmed_total = 0;
 	let mut locked_total = 0;
-		for out in wallet_data
+	for out in outputs {
-			.outputs()
-			.clone()
-			.values()
-			.filter(|out| out.root_key_id == wallet_data.keychain().root_key_id())
-		{
 		if out.status == OutputStatus::Unspent && out.lock_height <= current_height {
 			unspent_total += out.value;
 		}
@@ -278,15 +269,13 @@ where
 	}
 
 	Ok(WalletInfo {
-			last_confirmed_height: wallet_data.details().last_confirmed_height,
+		last_confirmed_height: current_height,
 		total: unspent_total + unconfirmed_total + immature_total,
 		amount_awaiting_confirmation: unconfirmed_total,
 		amount_immature: immature_total,
 		amount_locked: locked_total,
 		amount_currently_spendable: unspent_total,
 	})
-	});
-	ret_val
 }
 
 /// Build a coinbase output and insert into wallet
@@ -327,17 +316,17 @@ where
 
 	let height = block_fees.height;
 	let lock_height = height + global::coinbase_maturity();
-
-	// Now acquire the wallet lock and write the new output.
-	let (key_id, derivation) = wallet.with_wallet(|wallet_data| {
 	let key_id = block_fees.key_id();
+
 	let (key_id, derivation) = match key_id {
-			Some(key_id) => keys::retrieve_existing_key(wallet_data, key_id),
+		Some(key_id) => keys::retrieve_existing_key(wallet, key_id)?,
-			None => keys::next_available_key(wallet_data),
+		None => keys::next_available_key(wallet)?,
 	};
 
-		// track the new output and return the stuff needed for reward
+	{
-		wallet_data.add_output(OutputData {
+		// Now acquire the wallet lock and write the new output.
+		let mut batch = wallet.batch()?;
+		batch.save(OutputData {
 			root_key_id: root_key_id.clone(),
 			key_id: key_id.clone(),
 			n_child: derivation,
@@ -349,9 +338,8 @@ where
 			block: None,
 			merkle_proof: None,
 		});
-
+		batch.commit()?;
-		(key_id, derivation)
+	}
-	})?;
 
 	debug!(
 		LOGGER,

wallet/src/libwallet/types.rs

@@ -19,11 +19,13 @@ use std::collections::HashMap;
 use std::fmt;
 
 use serde;
+use serde_json;
 
 use failure::ResultExt;
 
 use core::core::hash::Hash;
 use core::core::merkle_proof::MerkleProof;
+use core::ser;
 
 use keychain::{Identifier, Keychain};
 
@@ -49,36 +51,17 @@ where
 	/// Return the keychain being used
 	fn keychain(&mut self) -> &mut K;
 
-	/// Return the outputs directly
+	/// Iterate over all output data stored by the backend
-	fn outputs(&mut self) -> &mut HashMap<String, OutputData>;
+	fn iter<'a>(&'a self) -> Box<Iterator<Item = OutputData> + 'a>;
 
-	/// Allows for reading wallet data (read-only)
+	/// Get output data by id
-	fn read_wallet<T, F>(&mut self, f: F) -> Result<T, Error>
+	fn get(&self, id: &Identifier) -> Result<OutputData, Error>;
-	where
-		F: FnOnce(&mut Self) -> Result<T, Error>;
 
-	/// Get all outputs from a wallet impl (probably with some sort
+	/// Create a new write batch to update or remove output data
-	/// of query param), read+write. Implementor should save
+	fn batch<'a>(&'a mut self) -> Result<Box<WalletOutputBatch + 'a>, Error>;
-	/// any changes to its data and perform any locking needed
-	fn with_wallet<T, F>(&mut self, f: F) -> Result<T, Error>
-	where
-		F: FnOnce(&mut Self) -> T;
-
-	/// Add an output
-	fn add_output(&mut self, out: OutputData);
-
-	/// Delete an output
-	fn delete_output(&mut self, id: &Identifier);
-
-	/// Lock an output
-	fn lock_output(&mut self, out: &OutputData);
-
-	/// get a single output
-	fn get_output(&self, key_id: &Identifier) -> Option<&OutputData>;
 
 	/// Next child ID when we want to create a new output
-	/// Should also increment index
+	fn next_child<'a>(&mut self, root_key_id: Identifier) -> Result<u32, Error>;
-	fn next_child(&mut self, root_key_id: Identifier) -> u32;
 
 	/// Return current details
 	fn details(&mut self) -> &mut WalletDetails;
@@ -98,6 +81,26 @@ where
 	fn restore(&mut self) -> Result<(), Error>;
 }
 
+/// Batch trait to update the output data backend atomically. Trying to use a
+/// batch after commit MAY result in a panic. Due to this being a trait, the
+/// commit method can't take ownership.
+pub trait WalletOutputBatch {
+	/// Add or update data about an output to the backend
+	fn save(&mut self, out: OutputData) -> Result<(), Error>;
+
+	/// Gets output data by id
+	fn get(&self, id: &Identifier) -> Result<OutputData, Error>;
+
+	/// Delete data about an output to the backend
+	fn delete(&mut self, id: &Identifier) -> Result<(), Error>;
+
+	/// Save an output as locked in the backend
+	fn lock_output(&mut self, out: &mut OutputData) -> Result<(), Error>;
+
+	/// Write the wallet data to backend file
+	fn commit(&self) -> Result<(), Error>;
+}
+
 /// Encapsulate all communication functions. No functions within libwallet
 /// should care about communication details
 pub trait WalletClient {
@@ -148,8 +151,8 @@ pub trait WalletClient {
 }
 
 /// Information about an output that's being tracked by the wallet. Must be
-/// enough to reconstruct the commitment associated with the output when the
+/// enough to reconstruct the commitment associated with the ouput when the
-/// root private key is known.*/
+/// root private key is known.
 
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, PartialOrd, Eq, Ord)]
 pub struct OutputData {
@@ -175,6 +178,19 @@ pub struct OutputData {
 	pub merkle_proof: Option<MerkleProofWrapper>,
 }
 
+impl ser::Writeable for OutputData {
+	fn write<W: ser::Writer>(&self, writer: &mut W) -> Result<(), ser::Error> {
+		writer.write_bytes(&serde_json::to_vec(self).map_err(|_| ser::Error::CorruptedData)?)
+	}
+}
+
+impl ser::Readable for OutputData {
+	fn read(reader: &mut ser::Reader) -> Result<OutputData, ser::Error> {
+		let data = reader.read_vec()?;
+		serde_json::from_slice(&data[..]).map_err(|_| ser::Error::CorruptedData)
+	}
+}
+
 impl OutputData {
 	/// Lock a given output to avoid conflicting use
 	pub fn lock(&mut self) {

wallet/src/lmdb_wallet.rs

@@ -0,0 +1,255 @@
+// Copyright 2018 The Grin Developers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::cell::RefCell;
+use std::collections::HashMap;
+use std::collections::hash_map::Values;
+use std::ops::Deref;
+use std::sync::Arc;
+use std::{fs, path};
+
+use failure::{Context, ResultExt};
+
+use keychain::{Identifier, Keychain};
+use store::{self, option_to_not_found, to_key, u64_to_key};
+
+use client;
+use libtx::slate::Slate;
+use libwallet::types::*;
+use libwallet::{internal, Error, ErrorKind};
+use types::{WalletConfig, WalletSeed};
+use util::secp::pedersen;
+
+pub const DB_DIR: &'static str = "wallet";
+
+const OUTPUT_PREFIX: u8 = 'o' as u8;
+const DERIV_PREFIX: u8 = 'd' as u8;
+
+impl From<store::Error> for Error {
+	fn from(error: store::Error) -> Error {
+		Error::from((ErrorKind::Backend(format!("{:?}", error))))
+	}
+}
+
+pub struct LMDBBackend<K> {
+	db: store::Store,
+	config: WalletConfig,
+	/// passphrase: TODO better ways of dealing with this other than storing
+	passphrase: String,
+
+	/// Keychain
+	keychain: Option<K>,
+}
+
+impl<K> LMDBBackend<K> {
+	pub fn new(config: WalletConfig, passphrase: &str) -> Result<Self, Error> {
+		let db_path = path::Path::new(&config.data_file_dir).join(DB_DIR);
+		fs::create_dir_all(&db_path).expect("Couldn't create wallet backend directory!");
+
+		let lmdb_env = Arc::new(store::new_env(db_path.to_str().unwrap().to_string()));
+		let db = store::Store::open(lmdb_env, DB_DIR);
+		Ok(LMDBBackend {
+			db,
+			config: config.clone(),
+			passphrase: String::from(passphrase),
+			keychain: None,
+		})
+	}
+}
+
+impl<K> WalletBackend<K> for LMDBBackend<K>
+where
+	K: Keychain,
+{
+	/// Initialise with whatever stored credentials we have
+	fn open_with_credentials(&mut self) -> Result<(), Error> {
+		let wallet_seed = WalletSeed::from_file(&self.config)
+			.context(ErrorKind::CallbackImpl("Error opening wallet"))?;
+		let keychain = wallet_seed.derive_keychain(&self.passphrase);
+		self.keychain = Some(keychain.context(ErrorKind::CallbackImpl("Error deriving keychain"))?);
+		// Just blow up password for now after it's been used
+		self.passphrase = String::from("");
+		Ok(())
+	}
+
+	/// Close wallet and remove any stored credentials (TBD)
+	fn close(&mut self) -> Result<(), Error> {
+		self.keychain = None;
+		Ok(())
+	}
+
+	/// Return the keychain being used
+	fn keychain(&mut self) -> &mut K {
+		self.keychain.as_mut().unwrap()
+	}
+
+	fn get(&self, id: &Identifier) -> Result<OutputData, Error> {
+		let key = to_key(OUTPUT_PREFIX, &mut id.to_bytes().to_vec());
+		option_to_not_found(self.db.get_ser(&key)).map_err(|e| e.into())
+	}
+
+	fn iter<'a>(&'a self) -> Box<Iterator<Item = OutputData> + 'a> {
+		Box::new(self.db.iter(&[OUTPUT_PREFIX]).unwrap())
+	}
+
+	fn batch<'a>(&'a mut self) -> Result<Box<WalletOutputBatch + 'a>, Error> {
+		Ok(Box::new(Batch {
+			store: self,
+			db: RefCell::new(Some(self.db.batch()?)),
+		}))
+	}
+
+	fn next_child<'a>(&mut self, root_key_id: Identifier) -> Result<u32, Error> {
+		let batch = self.db.batch()?;
+		// a simple counter, only one batch per db guarantees atomicity
+		let deriv_key = to_key(DERIV_PREFIX, &mut root_key_id.to_bytes().to_vec());
+		let deriv_idx = match batch.get_ser(&deriv_key)? {
+			Some(idx) => idx,
+			None => 0,
+		};
+		batch.put_ser(&deriv_key, &(deriv_idx + 1))?;
+		batch.commit()?;
+		Ok(deriv_idx + 1)
+	}
+
+	fn select_coins(
+		&self,
+		root_key_id: Identifier,
+		amount: u64,
+		current_height: u64,
+		minimum_confirmations: u64,
+		max_outputs: usize,
+		select_all: bool,
+	) -> Vec<OutputData> {
+		unimplemented!()
+	}
+
+	fn details(&mut self) -> &mut WalletDetails {
+		unimplemented!()
+	}
+
+	fn restore(&mut self) -> Result<(), Error> {
+		internal::restore::restore(self).context(ErrorKind::Restore)?;
+		Ok(())
+	}
+}
+
+/// An atomic batch in which all changes can be committed all at once or
+/// discarded on error.
+pub struct Batch<'a, K: 'a> {
+	store: &'a LMDBBackend<K>,
+	db: RefCell<Option<store::Batch<'a>>>,
+}
+
+#[allow(missing_docs)]
+impl<'a, K> WalletOutputBatch for Batch<'a, K> {
+	fn save(&mut self, out: OutputData) -> Result<(), Error> {
+		let key = to_key(OUTPUT_PREFIX, &mut out.key_id.to_bytes().to_vec());
+		self.db.borrow().as_ref().unwrap().put_ser(&key, &out)?;
+		Ok(())
+	}
+
+	fn get(&self, id: &Identifier) -> Result<OutputData, Error> {
+		let key = to_key(OUTPUT_PREFIX, &mut id.to_bytes().to_vec());
+		option_to_not_found(self.db.borrow().as_ref().unwrap().get_ser(&key)).map_err(|e| e.into())
+	}
+
+	fn delete(&mut self, id: &Identifier) -> Result<(), Error> {
+		let key = to_key(OUTPUT_PREFIX, &mut id.to_bytes().to_vec());
+		self.db.borrow().as_ref().unwrap().delete(&key)?;
+		Ok(())
+	}
+
+	fn lock_output(&mut self, out: &mut OutputData) -> Result<(), Error> {
+		out.lock();
+		self.save(out.clone())
+	}
+
+	fn commit(&self) -> Result<(), Error> {
+		let db = self.db.replace(None);
+		db.unwrap().commit()?;
+		Ok(())
+	}
+}
+
+impl<K> WalletClient for LMDBBackend<K> {
+	/// Return URL for check node
+	fn node_url(&self) -> &str {
+		&self.config.check_node_api_http_addr
+	}
+
+	/// Call the wallet API to create a coinbase transaction
+	fn create_coinbase(&self, dest: &str, block_fees: &BlockFees) -> Result<CbData, Error> {
+		let res = client::create_coinbase(dest, block_fees)
+			.context(ErrorKind::WalletComms(format!("Creating Coinbase")))?;
+		Ok(res)
+	}
+
+	/// Send a transaction slate to another listening wallet and return result
+	fn send_tx_slate(&self, dest: &str, slate: &Slate) -> Result<Slate, Error> {
+		let res = client::send_tx_slate(dest, slate)
+			.context(ErrorKind::WalletComms(format!("Sending transaction")))?;
+		Ok(res)
+	}
+
+	/// Posts a tranaction to a grin node
+	fn post_tx(&self, dest: &str, tx: &TxWrapper, fluff: bool) -> Result<(), Error> {
+		let res = client::post_tx(dest, tx, fluff).context(ErrorKind::Node)?;
+		Ok(res)
+	}
+
+	/// retrieves the current tip from the specified grin node
+	fn get_chain_height(&self, addr: &str) -> Result<u64, Error> {
+		let res = client::get_chain_height(addr).context(ErrorKind::Node)?;
+		Ok(res)
+	}
+
+	/// retrieve a list of outputs from the specified grin node
+	/// need "by_height" and "by_id" variants
+	fn get_outputs_from_node(
+		&self,
+		addr: &str,
+		wallet_outputs: Vec<pedersen::Commitment>,
+	) -> Result<HashMap<pedersen::Commitment, String>, Error> {
+		let res = client::get_outputs_from_node(addr, wallet_outputs).context(ErrorKind::Node)?;
+		Ok(res)
+	}
+
+	/// Get any missing block hashes from node
+	fn get_missing_block_hashes_from_node(
+		&self,
+		addr: &str,
+		height: u64,
+		wallet_outputs: Vec<pedersen::Commitment>,
+	) -> Result<
+		(
+			HashMap<pedersen::Commitment, (u64, BlockIdentifier)>,
+			HashMap<pedersen::Commitment, MerkleProofWrapper>,
+		),
+		Error,
+	> {
+		let res = client::get_missing_block_hashes_from_node(addr, height, wallet_outputs)
+			.context(ErrorKind::Node)?;
+		Ok(res)
+	}
+
+	/// retrieve merkle proof for a commit from a node
+	fn get_merkle_proof_for_commit(
+		&self,
+		addr: &str,
+		commit: &str,
+	) -> Result<MerkleProofWrapper, Error> {
+		Err(ErrorKind::GenericError("Not Implemented"))?
+	}
+}

wallet/src/types.rs

@@ -0,0 +1,150 @@
+// Copyright 2018 The Grin Developers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::cmp::min;
+use std::fs::{self, File};
+use std::io::{Read, Write};
+use std::path::MAIN_SEPARATOR;
+use std::path::Path;
+
+use blake2;
+use rand::{thread_rng, Rng};
+
+use error::{Error, ErrorKind};
+use failure::ResultExt;
+use keychain::Keychain;
+use util;
+use util::LOGGER;
+
+pub const SEED_FILE: &'static str = "wallet.seed";
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct WalletConfig {
+	// Right now the decision to run or not a wallet is based on the command.
+	// This may change in the near-future.
+	// pub enable_wallet: bool,
+
+	// The api interface/ip_address that this api server (i.e. this wallet) will run
+	// by default this is 127.0.0.1 (and will not accept connections from external clients)
+	pub api_listen_interface: String,
+	// The port this wallet will run on
+	pub api_listen_port: u16,
+	// The api address of a running server node against which transaction inputs
+	// will be checked during send
+	pub check_node_api_http_addr: String,
+	// The directory in which wallet files are stored
+	pub data_file_dir: String,
+}
+
+impl Default for WalletConfig {
+	fn default() -> WalletConfig {
+		WalletConfig {
+			// enable_wallet: false,
+			api_listen_interface: "127.0.0.1".to_string(),
+			api_listen_port: 13415,
+			check_node_api_http_addr: "http://127.0.0.1:13413".to_string(),
+			data_file_dir: ".".to_string(),
+		}
+	}
+}
+
+impl WalletConfig {
+	pub fn api_listen_addr(&self) -> String {
+		format!("{}:{}", self.api_listen_interface, self.api_listen_port)
+	}
+}
+
+#[derive(Clone, PartialEq)]
+pub struct WalletSeed([u8; 32]);
+
+impl WalletSeed {
+	pub fn from_bytes(bytes: &[u8]) -> WalletSeed {
+		let mut seed = [0; 32];
+		for i in 0..min(32, bytes.len()) {
+			seed[i] = bytes[i];
+		}
+		WalletSeed(seed)
+	}
+
+	fn from_hex(hex: &str) -> Result<WalletSeed, Error> {
+		let bytes =
+			util::from_hex(hex.to_string()).context(ErrorKind::GenericError("Invalid hex"))?;
+		Ok(WalletSeed::from_bytes(&bytes))
+	}
+
+	pub fn to_hex(&self) -> String {
+		util::to_hex(self.0.to_vec())
+	}
+
+	pub fn derive_keychain<K: Keychain>(&self, password: &str) -> Result<K, Error> {
+		let seed = blake2::blake2b::blake2b(64, &password.as_bytes(), &self.0);
+		let result = K::from_seed(seed.as_bytes())?;
+		Ok(result)
+	}
+
+	pub fn init_new() -> WalletSeed {
+		let seed: [u8; 32] = thread_rng().gen();
+		WalletSeed(seed)
+	}
+
+	pub fn init_file(wallet_config: &WalletConfig) -> Result<WalletSeed, Error> {
+		// create directory if it doesn't exist
+		fs::create_dir_all(&wallet_config.data_file_dir).context(ErrorKind::IO)?;
+
+		let seed_file_path = &format!(
+			"{}{}{}",
+			wallet_config.data_file_dir, MAIN_SEPARATOR, SEED_FILE,
+		);
+
+		debug!(LOGGER, "Generating wallet seed file at: {}", seed_file_path);
+
+		if Path::new(seed_file_path).exists() {
+			Err(ErrorKind::WalletSeedExists)?
+		} else {
+			let seed = WalletSeed::init_new();
+			let mut file = File::create(seed_file_path).context(ErrorKind::IO)?;
+			file.write_all(&seed.to_hex().as_bytes())
+				.context(ErrorKind::IO)?;
+			Ok(seed)
+		}
+	}
+
+	pub fn from_file(wallet_config: &WalletConfig) -> Result<WalletSeed, Error> {
+		// create directory if it doesn't exist
+		fs::create_dir_all(&wallet_config.data_file_dir).context(ErrorKind::IO)?;
+
+		let seed_file_path = &format!(
+			"{}{}{}",
+			wallet_config.data_file_dir, MAIN_SEPARATOR, SEED_FILE,
+		);
+
+		debug!(LOGGER, "Using wallet seed file at: {}", seed_file_path,);
+
+		if Path::new(seed_file_path).exists() {
+			let mut file = File::open(seed_file_path).context(ErrorKind::IO)?;
+			let mut buffer = String::new();
+			file.read_to_string(&mut buffer).context(ErrorKind::IO)?;
+			let wallet_seed = WalletSeed::from_hex(&buffer)?;
+			Ok(wallet_seed)
+		} else {
+			error!(
+				LOGGER,
+				"wallet seed file {} could not be opened (grin wallet init). \
+				 Run \"grin wallet init\" to initialize a new wallet.",
+				seed_file_path
+			);
+			Err(ErrorKind::WalletSeedDoesntExist)?
+		}
+	}
+}

wallet/tests/transaction.rs

@@ -15,6 +15,7 @@
 extern crate grin_chain as chain;
 extern crate grin_core as core;
 extern crate grin_keychain as keychain;
+extern crate grin_store as store;
 extern crate grin_util as util;
 extern crate grin_wallet as wallet;
 extern crate rand;
@@ -46,8 +47,10 @@ fn setup(test_dir: &str, chain_dir: &str) -> Chain {
 	global::set_mining_mode(ChainTypes::AutomatedTesting);
 	let genesis_block = pow::mine_genesis_block().unwrap();
 	let dir_name = format!("{}/{}", test_dir, chain_dir);
+	let db_env = Arc::new(store::new_env(dir_name.to_string()));
 	chain::Chain::init(
 		dir_name.to_string(),
+		db_env,
 		Arc::new(NoopAdapter {}),
 		genesis_block,
 		pow::verify_size,