Automatically trigger compaction every 2000 blocks (#1054)

Does so in a separate thread as it can take some time. Also
remove validation pre-compaction as it's hopefully unecessary
now.

chain/src/chain.rs

@@ -636,12 +636,8 @@ impl Chain {
 	/// Meanwhile, the chain will not be able to accept new blocks. It should
 	/// therefore be called judiciously.
 	pub fn compact(&self) -> Result<(), Error> {
-		// First check we can successfully validate the full chain state.
+		debug!(LOGGER, "Starting blockchain compaction.");
-		// If we cannot then do not attempt to compact.
+		// Compact the txhashset via the extension.
-		// This should not be required long term - but doing this for debug purposes.
-		self.validate(true)?;
-
-		// Now compact the txhashset via the extension.
 		{
 			let mut txhashes = self.txhashset.write().unwrap();
 			txhashes.compact()?;
@@ -654,7 +650,8 @@ impl Chain {
 		}
 
 		// Now check we can still successfully validate the chain state after
-		// compacting.
+		// compacting, shouldn't be necessary once all of this is well-oiled
+		debug!(LOGGER, "Validating state after compaction.");
 		self.validate(true)?;
 
 		// we need to be careful here in testing as 20 blocks is not that long
@@ -666,10 +663,17 @@ impl Chain {
 			return Ok(());
 		}
 
+		debug!(
+			LOGGER,
+			"Compaction remove blocks older than {}.",
+			head.height - horizon
+		);
+		let mut count = 0;
 		let mut current = self.store.get_header_by_height(head.height - horizon - 1)?;
 		loop {
 			match self.store.get_block(&current.hash()) {
 				Ok(b) => {
+					count += 1;
 					self.store.delete_block(&b.hash())?;
 					self.store.delete_block_marker(&b.hash())?;
 					self.store.delete_block_sums(&b.hash())?;
@@ -688,6 +692,7 @@ impl Chain {
 				Err(e) => return Err(From::from(e)),
 			}
 		}
+		debug!(LOGGER, "Compaction removed {} blocks, done.", count);
 		Ok(())
 	}
 

servers/src/common/adapters.rs

@@ -20,11 +20,12 @@ use std::net::SocketAddr;
 use std::ops::Deref;
 use std::sync::{Arc, RwLock, Weak};
 use std::sync::atomic::{AtomicBool, Ordering};
+use std::thread;
 use std::time::Instant;
 use rand;
 use rand::Rng;
 
-use chain::{self, ChainAdapter, Options};
+use chain::{self, ChainAdapter, Options, Tip};
 use core::core;
 use core::core::block::BlockHeader;
 use core::core::hash::{Hash, Hashed};
@@ -53,6 +54,7 @@ fn wo<T>(weak_one: &OneTime<Weak<T>>) -> Arc<T> {
 /// implementations.
 pub struct NetToChainAdapter {
 	currently_syncing: Arc<AtomicBool>,
+	archive_mode: bool,
 	chain: Weak<chain::Chain>,
 	tx_pool: Arc<RwLock<pool::TransactionPool<PoolToChainAdapter>>>,
 	peers: OneTime<Weak<p2p::Peers>>,
@@ -354,16 +356,18 @@ impl NetToChainAdapter {
 	/// Construct a new NetToChainAdapter instance
 	pub fn new(
 		currently_syncing: Arc<AtomicBool>,
+		archive_mode: bool,
 		chain_ref: Weak<chain::Chain>,
 		tx_pool: Arc<RwLock<pool::TransactionPool<PoolToChainAdapter>>>,
 		config: ServerConfig,
 	) -> NetToChainAdapter {
 		NetToChainAdapter {
-			currently_syncing: currently_syncing,
+			currently_syncing,
+			archive_mode,
 			chain: chain_ref,
-			tx_pool: tx_pool,
+			tx_pool,
 			peers: OneTime::new(),
-			config: config,
+			config,
 		}
 	}
 
@@ -415,8 +419,9 @@ impl NetToChainAdapter {
 		let bhash = b.hash();
 		let chain = w(&self.chain);
 		match chain.process_block(b, self.chain_opts()) {
-			Ok(_) => {
+			Ok((tip, _)) => {
 				self.validate_chain(bhash);
+				self.check_compact(tip);
 				true
 			}
 			Err(chain::Error::Orphan) => {
@@ -480,6 +485,28 @@ impl NetToChainAdapter {
 		}
 	}
 
+	fn check_compact(&self, tip_res: Option<Tip>) {
+		// no compaction during sync or if we're in historical mode
+		if self.archive_mode || self.currently_syncing.load(Ordering::Relaxed) {
+			return;
+		}
+
+		if let Some(tip) = tip_res {
+			// trigger compaction every 2000 blocks, uses a different thread to avoid
+			// blocking the caller thread (likely a peer)
+			if tip.height % 2000 == 0 {
+				let chain = w(&self.chain);
+				let _ = thread::Builder::new()
+					.name("compactor".to_string())
+					.spawn(move || {
+						if let Err(e) = chain.compact() {
+							error!(LOGGER, "Could not compact chain: {:?}", e);
+						}
+					});
+			}
+		}
+	}
+
 	// After receiving a compact block if we cannot successfully hydrate
 	// it into a full block then fallback to requesting the full block
 	// from the same peer that gave us the compact block

servers/src/grin/server.rs

@@ -146,6 +146,7 @@ impl Server {
 
 		let net_adapter = Arc::new(NetToChainAdapter::new(
 			currently_syncing.clone(),
+			archive_mode,
 			Arc::downgrade(&shared_chain),
 			tx_pool.clone(),
 			config.clone(),