Code cleanup in the sync module (#11552)

* Code cleanup

`flush_queue()` is mostly used by tests
remove some unused params
avoid clones in a few places

* Consistent params naming
Consistent use of log calls

* Fix todo

It'a actually not trivial to find out the size of these collections, likely we keep blocks from all kinds of forks in the `self.blocks`/`self.parents` collections and there's no good way to anticipate how many blocks we're going to drain. Most of the time we end up draining 0 blocks and then we drain a whole bunch of them, up to 30 000.

* Revert making flush_queue() test-only
Address review grumbles

* More review grumbles

* fix build

ethcore/client-traits/src/lib.rs

@@ -197,8 +197,8 @@ pub trait IoClient: Sync + Send {
 	/// Queue transactions for importing.
 	fn queue_transactions(&self, transactions: Vec<Bytes>, peer_id: usize);
 
-	/// Queue block import with transaction receipts. Does no sealing and transaction validation.
+	/// Queue block import with transaction receipts. Does no sealing or transaction validation.
-	fn queue_ancient_block(&self, block_bytes: Unverified, receipts_bytes: Bytes) -> EthcoreResult<H256>;
+	fn queue_ancient_block(&self, unverified: Unverified, receipts_bytes: Bytes) -> EthcoreResult<H256>;
 
 	/// Queue consensus engine message.
 	fn queue_consensus_message(&self, message: Bytes);

ethcore/src/client/client.rs

@@ -178,7 +178,7 @@ struct Importer {
 }
 
 /// Blockchain database client backed by a persistent database. Owns and manages a blockchain and a block queue.
-/// Call `import_block()` to import a block asynchronously; `flush_queue()` flushes the queue.
+/// Call `import_block()` to import a block asynchronously.
 pub struct Client {
 	/// Flag used to disable the client forever. Not to be confused with `liveness`.
 	///
@@ -870,7 +870,7 @@ impl Client {
 		*self.on_user_defaults_change.lock() = Some(Box::new(f));
 	}
 
-	/// Flush the block import queue.
+	/// Flush the block import queue. Used mostly for tests.
 	pub fn flush_queue(&self) {
 		self.importer.block_queue.flush();
 		while !self.importer.block_queue.is_empty() {
@@ -1444,6 +1444,7 @@ impl ImportBlock for Client {
 			return Err(EthcoreError::Block(BlockError::UnknownParent(unverified.parent_hash())));
 		}
 
+		// If the queue is empty we propagate the block in a `PriorityTask`.
 		let raw = if self.importer.block_queue.is_empty() {
 			Some((unverified.bytes.clone(), *unverified.header.difficulty()))
 		} else {
@@ -2729,6 +2730,7 @@ impl ImportExportBlocks for Client {
 			}
 		};
 		self.flush_queue();
+
 		Ok(())
 	}
 }

ethcore/sync/src/block_sync.rs

@@ -407,9 +407,9 @@ impl BlockDownloader {
 					trace_sync!(self, "Error decoding block receipts RLP: {:?}", e);
 					BlockDownloaderImportError::Invalid
 				})?;
-				receipts.push(receipt.as_raw().to_vec());
+				receipts.push(receipt.as_raw());
 			}
-			let hashes = self.blocks.insert_receipts(receipts);
+			let hashes = self.blocks.insert_receipts(&receipts);
 			if hashes.len() != item_count {
 				trace_sync!(self, "Deactivating peer for giving invalid block receipts");
 				return Err(BlockDownloaderImportError::Invalid);
@@ -501,7 +501,7 @@ impl BlockDownloader {
 					MAX_BODIES_TO_REQUEST_SMALL
 				};
 
-				let needed_bodies = self.blocks.needed_bodies(number_of_bodies_to_request, false);
+				let needed_bodies = self.blocks.needed_bodies(number_of_bodies_to_request);
 				if !needed_bodies.is_empty() {
 					return Some(BlockRequest::Bodies {
 						hashes: needed_bodies,
@@ -509,7 +509,7 @@ impl BlockDownloader {
 				}
 
 				if self.download_receipts {
-					let needed_receipts = self.blocks.needed_receipts(MAX_RECEPITS_TO_REQUEST, false);
+					let needed_receipts = self.blocks.needed_receipts(MAX_RECEPITS_TO_REQUEST);
 					if !needed_receipts.is_empty() {
 						return Some(BlockRequest::Receipts {
 							hashes: needed_receipts,
@@ -518,7 +518,7 @@ impl BlockDownloader {
 				}
 
 				// find subchain to download
-				if let Some((h, count)) = self.blocks.needed_headers(MAX_HEADERS_TO_REQUEST, false) {
+				if let Some((h, count)) = self.blocks.needed_headers(MAX_HEADERS_TO_REQUEST) {
 					return Some(BlockRequest::Headers {
 						start: h,
 						count: count as u64,

ethcore/sync/src/blocks.rs

@@ -19,7 +19,7 @@ use std::collections::{HashSet, HashMap, hash_map};
 use bytes::Bytes;
 use ethereum_types::H256;
 use keccak_hash::{keccak, KECCAK_NULL_RLP, KECCAK_EMPTY_LIST_RLP};
-use log::{trace, warn};
+use log::{debug, trace, warn};
 use parity_util_mem::MallocSizeOf;
 use rlp::{Rlp, RlpStream, DecoderError};
 use triehash_ethereum::ordered_trie_root;
@@ -103,7 +103,7 @@ fn unverified_from_sync(header: SyncHeader, body: Option<SyncBody>) -> Unverifie
 		header: header.header,
 		transactions: body.transactions,
 		uncles: body.uncles,
-		bytes: stream.out().to_vec(),
+		bytes: stream.out(),
 	}
 }
 
@@ -196,11 +196,11 @@ impl BlockCollection {
 	}
 
 	/// Insert a collection of block receipts for previously downloaded headers.
-	pub fn insert_receipts(&mut self, receipts: Vec<Bytes>) -> Vec<Vec<H256>> {
+	pub fn insert_receipts(&mut self, receipts: &[&[u8]]) -> Vec<Vec<H256>> {
 		if !self.need_receipts {
 			return Vec::new();
 		}
-		receipts.into_iter()
+		receipts.iter()
 			.filter_map(|r| {
 				self.insert_receipt(r)
 					.map_err(|e| trace!(target: "sync", "Ignored invalid receipt: {:?}", e))
@@ -210,15 +210,15 @@ impl BlockCollection {
 	}
 
 	/// Returns a set of block hashes that require a body download. The returned set is marked as being downloaded.
-	pub fn needed_bodies(&mut self, count: usize, _ignore_downloading: bool) -> Vec<H256> {
+	pub fn needed_bodies(&mut self, count: usize) -> Vec<H256> {
 		if self.head.is_none() {
 			return Vec::new();
 		}
-		let mut needed_bodies: Vec<H256> = Vec::new();
+		let mut needed_bodies: Vec<H256> = Vec::with_capacity(count);
 		let mut head = self.head;
-		while head.is_some() && needed_bodies.len() < count {
+		while needed_bodies.len() < count {
-			head = self.parents.get(&head.unwrap()).cloned();
+			head = match head {
-			if let Some(head) = head {
+				Some(head) => {
 					match self.blocks.get(&head) {
 						Some(block) if block.body.is_none() && !self.downloading_bodies.contains(&head) => {
 							self.downloading_bodies.insert(head.clone());
@@ -226,8 +226,12 @@ impl BlockCollection {
 						}
 						_ => (),
 					}
+					self.parents.get(&head).copied()
+				},
+				None => break
+			};
 		}
-		}
+
 		for h in self.header_ids.values() {
 			if needed_bodies.len() >= count {
 				break;
@@ -241,25 +245,28 @@ impl BlockCollection {
 	}
 
 	/// Returns a set of block hashes that require a receipt download. The returned set is marked as being downloaded.
-	pub fn needed_receipts(&mut self, count: usize, _ignore_downloading: bool) -> Vec<H256> {
+	pub fn needed_receipts(&mut self, count: usize) -> Vec<H256> {
 		if self.head.is_none() || !self.need_receipts {
 			return Vec::new();
 		}
-		let mut needed_receipts: Vec<H256> = Vec::new();
+		let mut needed_receipts: Vec<H256> = Vec::with_capacity(count);
 		let mut head = self.head;
-		while head.is_some() && needed_receipts.len() < count {
+		while needed_receipts.len() < count {
-			head = self.parents.get(&head.unwrap()).cloned();
+			head = match head {
-			if let Some(head) = head {
+				Some(head) => {
 					match self.blocks.get(&head) {
 						Some(block) => {
 							if block.receipts.is_none() && !self.downloading_receipts.contains(&block.receipts_root) {
 								self.downloading_receipts.insert(block.receipts_root);
-							needed_receipts.push(head.clone());
+								needed_receipts.push(head);
 							}
 						}
 						_ => (),
 					}
-			}
+					self.parents.get(&head).copied()
+				},
+				None => break
+			};
 		}
 		// If there are multiple blocks per receipt, only request one of them.
 		for (root, h) in self.receipt_ids.iter().map(|(root, hashes)| (root, hashes[0])) {
@@ -275,12 +282,12 @@ impl BlockCollection {
 	}
 
 	/// Returns a set of block hashes that require a header download. The returned set is marked as being downloaded.
-	pub fn needed_headers(&mut self, count: usize, ignore_downloading: bool) -> Option<(H256, usize)> {
+	pub fn needed_headers(&mut self, count: usize) -> Option<(H256, usize)> {
 		// find subchain to download
 		let mut download = None;
 		{
 			for h in &self.heads {
-				if ignore_downloading || !self.downloading_headers.contains(h) {
+				if !self.downloading_headers.contains(h) {
 					self.downloading_headers.insert(h.clone());
 					download = Some(h.clone());
 					break;
@@ -317,13 +324,11 @@ impl BlockCollection {
 			return Vec::new();
 		}
 
-		let mut drained = Vec::new();
 		let mut hashes = Vec::new();
-		{
 		let mut blocks = Vec::new();
 		let mut head = self.head;
 		while let Some(h) = head {
-				head = self.parents.get(&h).cloned();
+			head = self.parents.get(&h).copied();
 			if let Some(head) = head {
 				match self.blocks.remove(&head) {
 					Some(block) => {
@@ -343,16 +348,16 @@ impl BlockCollection {
 			}
 		}
 
-			for block in blocks.into_iter() {
+		let mut drained = Vec::with_capacity(blocks.len());
+		for block in blocks {
 			let unverified = unverified_from_sync(block.header, block.body);
 			drained.push(BlockAndReceipts {
 				block: unverified,
-					receipts: block.receipts.clone(),
+				receipts: block.receipts,
 			});
 		}
-		}
 
-		trace!(target: "sync", "Drained {} blocks, new head :{:?}", drained.len(), self.head);
+		debug!(target: "sync", "Drained {} blocks, new head :{:?}", drained.len(), self.head);
 		drained
 	}
 
@@ -409,7 +414,7 @@ impl BlockCollection {
 		}
 	}
 
-	fn insert_receipt(&mut self, r: Bytes) -> Result<Vec<H256>, network::Error> {
+	fn insert_receipt(&mut self, r: &[u8]) -> Result<Vec<H256>, network::Error> {
 		let receipt_root = {
 			let receipts = Rlp::new(&r);
 			ordered_trie_root(receipts.iter().map(|r| r.as_raw()))
@@ -422,7 +427,7 @@ impl BlockCollection {
 					match self.blocks.get_mut(&h) {
 						Some(ref mut block) => {
 							trace!(target: "sync", "Got receipt {}", h);
-							block.receipts = Some(r.clone());
+							block.receipts = Some(r.to_vec());
 						},
 						None => {
 							warn!("Got receipt with no header {}", h);
@@ -581,11 +586,11 @@ mod test {
 		bc.reset_to(heads);
 		assert!(!bc.is_empty());
 		assert_eq!(hashes[0], bc.heads[0]);
-		assert!(bc.needed_bodies(1, false).is_empty());
+		assert!(bc.needed_bodies(1).is_empty());
 		assert!(!bc.contains(&hashes[0]));
 		assert!(!bc.is_downloading(&hashes[0]));
 
-		let (h, n) = bc.needed_headers(6, false).unwrap();
+		let (h, n) = bc.needed_headers(6).unwrap();
 		assert!(bc.is_downloading(&hashes[0]));
 		assert_eq!(hashes[0], h);
 		assert_eq!(n, 6);
@@ -608,9 +613,9 @@ mod test {
 		assert!(!bc.contains(&hashes[0]));
 		assert_eq!(hashes[5], bc.head.unwrap());
 
-		let (h, _) = bc.needed_headers(6, false).unwrap();
+		let (h, _) = bc.needed_headers(6).unwrap();
 		assert_eq!(hashes[5], h);
-		let (h, _) = bc.needed_headers(6, false).unwrap();
+		let (h, _) = bc.needed_headers(6).unwrap();
 		assert_eq!(hashes[20], h);
 		bc.insert_headers(headers[10..16].into_iter().map(Clone::clone).collect());
 		assert!(bc.drain().is_empty());