get rid of default implementation of Hashed trait for writable things (#2573)

chain/src/txhashset/utxo_view.rs

@@ -14,7 +14,7 @@
 
 //! Lightweight readonly view into output MMR for convenience.
 
-use crate::core::core::hash::Hash;
+use crate::core::core::hash::{Hash, Hashed};
 use crate::core::core::pmmr::{self, ReadonlyPMMR};
 use crate::core::core::{Block, BlockHeader, Input, Output, Transaction};
 use crate::core::global;

chain/src/types.rs

@@ -73,10 +73,11 @@ impl Tip {
 			total_difficulty: header.total_difficulty(),
 		}
 	}
+}
 
-	/// *Really* easy to accidentally call hash() on a tip (thinking its a header).
+impl Hashed for Tip {
-	/// So lets make hash() do the right thing here.
+	/// The hash of the underlying block.
-	pub fn hash(&self) -> Hash {
+	fn hash(&self) -> Hash {
 		self.last_block_h
 	}
 }

core/src/core/block.rs

@@ -25,7 +25,7 @@ use std::sync::Arc;
 use crate::consensus::{reward, REWARD};
 use crate::core::committed::{self, Committed};
 use crate::core::compact_block::{CompactBlock, CompactBlockBody};
-use crate::core::hash::{Hash, Hashed, ZERO_HASH};
+use crate::core::hash::{DefaultHashable, Hash, Hashed, ZERO_HASH};
 use crate::core::verifier_cache::VerifierCache;
 use crate::core::{
 	transaction, Commitment, Input, Output, Transaction, TransactionBody, TxKernel, Weighting,
@@ -160,9 +160,9 @@ impl FixedLength for HeaderEntry {
 	const LEN: usize = Hash::LEN + 8 + Difficulty::LEN + 4 + 1;
 }
 
-impl HeaderEntry {
+impl Hashed for HeaderEntry {
 	/// The hash of the underlying block.
-	pub fn hash(&self) -> Hash {
+	fn hash(&self) -> Hash {
 		self.hash
 	}
 }
@@ -197,6 +197,7 @@ pub struct BlockHeader {
 	/// Proof of work and related
 	pub pow: ProofOfWork,
 }
+impl DefaultHashable for BlockHeader {}
 
 impl Default for BlockHeader {
 	fn default() -> BlockHeader {
@@ -353,6 +354,13 @@ pub struct Block {
 	body: TransactionBody,
 }
 
+impl Hashed for Block {
+	/// The hash of the underlying block.
+	fn hash(&self) -> Hash {
+		self.header.hash()
+	}
+}
+
 /// Implementation of Writeable for a block, defines how to write the block to a
 /// binary writer. Differentiates between writing the block for the purpose of
 /// full serialization and the one of just extracting a hash.
@@ -570,11 +578,6 @@ impl Block {
 		&mut self.body.kernels
 	}
 
-	/// Blockhash, computed using only the POW
-	pub fn hash(&self) -> Hash {
-		self.header.hash()
-	}
-
 	/// Sum of all fees (inputs less outputs) in the block
 	pub fn total_fees(&self) -> u64 {
 		self.body

core/src/core/compact_block.rs

@@ -17,7 +17,7 @@
 use rand::{thread_rng, Rng};
 
 use crate::core::block::{Block, BlockHeader, Error};
-use crate::core::hash::Hashed;
+use crate::core::hash::{DefaultHashable, Hashed};
 use crate::core::id::ShortIdentifiable;
 use crate::core::{Output, ShortId, TxKernel};
 use crate::ser::{self, read_multi, Readable, Reader, VerifySortedAndUnique, Writeable, Writer};
@@ -137,6 +137,8 @@ pub struct CompactBlock {
 	body: CompactBlockBody,
 }
 
+impl DefaultHashable for CompactBlock {}
+
 impl CompactBlock {
 	/// "Lightweight" validation.
 	fn validate_read(&self) -> Result<(), Error> {

core/src/core/hash.rs

@@ -36,6 +36,19 @@ pub const ZERO_HASH: Hash = Hash([0; 32]);
 #[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord, Hash, Serialize, Deserialize)]
 pub struct Hash([u8; 32]);
 
+impl DefaultHashable for Hash {}
+
+impl Hash {
+	fn hash_with<T: Writeable>(&self, other: T) -> Hash {
+		let mut hasher = HashWriter::default();
+		ser::Writeable::write(self, &mut hasher).unwrap();
+		ser::Writeable::write(&other, &mut hasher).unwrap();
+		let mut ret = [0; 32];
+		hasher.finalize(&mut ret);
+		Hash(ret)
+	}
+}
+
 impl fmt::Debug for Hash {
 	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 		let hash_hex = self.to_hex();
@@ -212,25 +225,26 @@ impl ser::Writer for HashWriter {
 pub trait Hashed {
 	/// Obtain the hash of the object
 	fn hash(&self) -> Hash;
-	/// Hash the object together with another writeable object
-	fn hash_with<T: Writeable>(&self, other: T) -> Hash;
 }
 
-impl<W: ser::Writeable> Hashed for W {
+/// Implementing this trait enables the default
+/// hash implementation
+pub trait DefaultHashable: Writeable {}
+impl<D: DefaultHashable> Hashed for D {
 	fn hash(&self) -> Hash {
 		let mut hasher = HashWriter::default();
-		ser::Writeable::write(self, &mut hasher).unwrap();
+		Writeable::write(self, &mut hasher).unwrap();
-		let mut ret = [0; 32];
-		hasher.finalize(&mut ret);
-		Hash(ret)
-	}
-
-	fn hash_with<T: Writeable>(&self, other: T) -> Hash {
-		let mut hasher = HashWriter::default();
-		ser::Writeable::write(self, &mut hasher).unwrap();
-		ser::Writeable::write(&other, &mut hasher).unwrap();
 		let mut ret = [0; 32];
 		hasher.finalize(&mut ret);
 		Hash(ret)
 	}
 }
+
+impl<D: DefaultHashable> DefaultHashable for &D {}
+impl<D: DefaultHashable, E: DefaultHashable> DefaultHashable for (D, E) {}
+impl<D: DefaultHashable, E: DefaultHashable, F: DefaultHashable> DefaultHashable for (D, E, F) {}
+
+/// Implement Hashed trait for external types here
+impl DefaultHashable for crate::util::secp::pedersen::RangeProof {}
+impl DefaultHashable for Vec<u8> {}
+impl DefaultHashable for u64 {}

core/src/core/id.rs

@@ -20,7 +20,7 @@ use std::cmp::Ordering;
 use byteorder::{ByteOrder, LittleEndian};
 use siphasher::sip::SipHasher24;
 
-use crate::core::hash::{Hash, Hashed};
+use crate::core::hash::{DefaultHashable, Hash, Hashed};
 use crate::ser::{self, Readable, Reader, Writeable, Writer};
 use crate::util;
 
@@ -73,6 +73,7 @@ impl<H: Hashed> ShortIdentifiable for H {
 #[derive(Clone, Serialize, Deserialize, Hash)]
 pub struct ShortId([u8; 6]);
 
+impl DefaultHashable for ShortId {}
 /// We want to sort short_ids in a canonical and consistent manner so we can
 /// verify sort order in the same way we do for full inputs|outputs|kernels
 /// themselves.
@@ -168,6 +169,8 @@ mod test {
 			}
 		}
 
+		impl DefaultHashable for Foo {}
+
 		let foo = Foo(0);
 
 		let expected_hash =

core/src/core/transaction.rs

@@ -14,7 +14,7 @@
 
 //! Transactions
 
-use crate::core::hash::Hashed;
+use crate::core::hash::{DefaultHashable, Hashed};
 use crate::core::verifier_cache::VerifierCache;
 use crate::core::{committed, Committed};
 use crate::keychain::{self, BlindingFactor};
@@ -50,6 +50,8 @@ enum_from_primitive! {
 	}
 }
 
+impl DefaultHashable for KernelFeatures {}
+
 impl Writeable for KernelFeatures {
 	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ser::Error> {
 		writer.write_u8(*self as u8)?;
@@ -170,6 +172,7 @@ pub struct TxKernel {
 	pub excess_sig: secp::Signature,
 }
 
+impl DefaultHashable for TxKernel {}
 hashable_ord!(TxKernel);
 
 impl ::std::hash::Hash for TxKernel {
@@ -753,6 +756,8 @@ pub struct Transaction {
 	body: TransactionBody,
 }
 
+impl DefaultHashable for Transaction {}
+
 /// PartialEq
 impl PartialEq for Transaction {
 	fn eq(&self, tx: &Transaction) -> bool {
@@ -1113,6 +1118,7 @@ pub struct Input {
 	pub commit: Commitment,
 }
 
+impl DefaultHashable for Input {}
 hashable_ord!(Input);
 
 impl ::std::hash::Hash for Input {
@@ -1218,6 +1224,7 @@ pub struct Output {
 	pub proof: RangeProof,
 }
 
+impl DefaultHashable for Output {}
 hashable_ord!(Output);
 
 impl ::std::hash::Hash for Output {
@@ -1330,6 +1337,8 @@ pub struct OutputIdentifier {
 	pub commit: Commitment,
 }
 
+impl DefaultHashable for OutputIdentifier {}
+
 impl OutputIdentifier {
 	/// Build a new output_identifier.
 	pub fn new(features: OutputFeatures, commit: &Commitment) -> OutputIdentifier {

core/src/pow/types.rs

@@ -22,7 +22,7 @@ use rand::{thread_rng, Rng};
 use serde::{de, Deserialize, Deserializer, Serialize, Serializer};
 
 use crate::consensus::{graph_weight, MIN_DIFFICULTY, SECOND_POW_EDGE_BITS};
-use crate::core::hash::Hashed;
+use crate::core::hash::{DefaultHashable, Hashed};
 use crate::global;
 use crate::ser::{self, FixedLength, Readable, Reader, Writeable, Writer};
 
@@ -324,6 +324,8 @@ pub struct Proof {
 	pub nonces: Vec<u64>,
 }
 
+impl DefaultHashable for Proof {}
+
 impl fmt::Debug for Proof {
 	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 		write!(f, "Cuckoo{}(", self.edge_bits)?;

core/src/ser.rs

@@ -19,7 +19,7 @@
 //! To use it simply implement `Writeable` or `Readable` and then use the
 //! `serialize` or `deserialize` functions on them as appropriate.
 
-use crate::core::hash::{Hash, Hashed};
+use crate::core::hash::{DefaultHashable, Hash, Hashed};
 use crate::keychain::{BlindingFactor, Identifier, IDENTIFIER_SIZE};
 use crate::util::read_write::read_exact;
 use crate::util::secp::constants::{
@@ -615,7 +615,7 @@ where
 			match elem {
 				Ok(e) => buf.push(e),
 				Err(Error::IOErr(ref _d, ref kind)) if *kind == io::ErrorKind::UnexpectedEof => {
-					break
+					break;
 				}
 				Err(e) => return Err(e),
 			}
@@ -706,7 +706,7 @@ pub trait FixedLength {
 }
 
 /// Trait for types that can be added to a PMMR.
-pub trait PMMRable: Writeable + Clone + Debug {
+pub trait PMMRable: Writeable + Clone + Debug + DefaultHashable {
 	/// The type of element actually stored in the MMR data file.
 	/// This allows us to store Hash elements in the header MMR for variable size BlockHeaders.
 	type E: FixedLength + Readable + Writeable;
@@ -721,7 +721,7 @@ pub trait PMMRIndexHashable {
 	fn hash_with_index(&self, index: u64) -> Hash;
 }
 
-impl<T: Writeable> PMMRIndexHashable for T {
+impl<T: DefaultHashable> PMMRIndexHashable for T {
 	fn hash_with_index(&self, index: u64) -> Hash {
 		(index, self).hash()
 	}

core/tests/vec_backend.rs

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use self::core::core::hash::Hash;
+use self::core::core::hash::{DefaultHashable, Hash};
 use self::core::core::pmmr::{self, Backend};
 use self::core::core::BlockHeader;
 use self::core::ser;
@@ -25,6 +25,8 @@ use std::path::Path;
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub struct TestElem(pub [u32; 4]);
 
+impl DefaultHashable for TestElem {}
+
 impl FixedLength for TestElem {
 	const LEN: usize = 16;
 }

servers/src/mining/stratumserver.rs

@@ -29,6 +29,7 @@ use std::{cmp, thread};
 use crate::chain;
 use crate::common::stats::{StratumStats, WorkerStats};
 use crate::common::types::{StratumServerConfig, SyncState};
+use crate::core::core::hash::Hashed;
 use crate::core::core::verifier_cache::VerifierCache;
 use crate::core::core::Block;
 use crate::core::{pow, ser};

store/tests/pmmr.rs

@@ -21,6 +21,7 @@ use std::fs;
 use chrono::prelude::Utc;
 use croaring::Bitmap;
 
+use crate::core::core::hash::DefaultHashable;
 use crate::core::core::pmmr::{Backend, PMMR};
 use crate::core::ser::{
 	Error, FixedLength, PMMRIndexHashable, PMMRable, Readable, Reader, Writeable, Writer,
@@ -903,6 +904,8 @@ fn load(pos: u64, elems: &[TestElem], backend: &mut store::pmmr::PMMRBackend<Tes
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 struct TestElem(u32);
 
+impl DefaultHashable for TestElem {}
+
 impl FixedLength for TestElem {
 	const LEN: usize = 4;
 }