Limit for logs filter. (#2180)

* Limit for logs filter.

* Moving limit inside the filter object

* Fixing tests

ethcore/src/client/client.rs

@@ -957,7 +957,7 @@ impl BlockChainClient for Client {
 		}
 	}
 
-	fn logs(&self, filter: Filter, limit: Option<usize>) -> Vec<LocalizedLogEntry> {
+	fn logs(&self, filter: Filter) -> Vec<LocalizedLogEntry> {
 		let blocks = filter.bloom_possibilities().iter()
 			.filter_map(|bloom| self.blocks_with_bloom(bloom, filter.from_block.clone(), filter.to_block.clone()))
 			.flat_map(|m| m)
@@ -966,7 +966,7 @@ impl BlockChainClient for Client {
 			.into_iter()
 			.collect::<Vec<u64>>();
 
-		self.chain.read().logs(blocks, |entry| filter.matches(entry), limit)
+		self.chain.read().logs(blocks, |entry| filter.matches(entry), filter.limit)
 	}
 
 	fn filter_traces(&self, filter: TraceFilter) -> Option<Vec<LocalizedTrace>> {

ethcore/src/client/test_client.rs

@@ -67,6 +67,8 @@ pub struct TestBlockChainClient {
 	pub execution_result: RwLock<Option<Result<Executed, CallError>>>,
 	/// Transaction receipts.
 	pub receipts: RwLock<HashMap<TransactionID, LocalizedReceipt>>,
+	/// Logs
+	pub logs: RwLock<Vec<LocalizedLogEntry>>,
 	/// Block queue size.
 	pub queue_size: AtomicUsize,
 	/// Miner
@@ -114,6 +116,7 @@ impl TestBlockChainClient {
 			code: RwLock::new(HashMap::new()),
 			execution_result: RwLock::new(None),
 			receipts: RwLock::new(HashMap::new()),
+			logs: RwLock::new(Vec::new()),
 			queue_size: AtomicUsize::new(0),
 			miner: Arc::new(Miner::with_spec(&spec)),
 			spec: spec,
@@ -165,6 +168,11 @@ impl TestBlockChainClient {
 		*self.latest_block_timestamp.write() = ts;
 	}
 
+	/// Set logs to return for each logs call.
+	pub fn set_logs(&self, logs: Vec<LocalizedLogEntry>) {
+		*self.logs.write() = logs;
+	}
+
 	/// Add blocks to test client.
 	pub fn add_blocks(&self, count: usize, with: EachBlockWith) {
 		let len = self.numbers.read().len();
@@ -390,8 +398,13 @@ impl BlockChainClient for TestBlockChainClient {
 		unimplemented!();
 	}
 
-	fn logs(&self, _filter: Filter, _limit: Option<usize>) -> Vec<LocalizedLogEntry> {
-		Vec::new()
+	fn logs(&self, filter: Filter) -> Vec<LocalizedLogEntry> {
+		let mut logs = self.logs.read().clone();
+		let len = logs.len();
+		match filter.limit {
+			Some(limit) if limit <= len => logs.split_off(len - limit),
+			_ => logs,
+		}
 	}
 
 	fn last_hashes(&self) -> LastHashes {

ethcore/src/client/traits.rs

@@ -156,7 +156,7 @@ pub trait BlockChainClient : Sync + Send {
 	fn blocks_with_bloom(&self, bloom: &H2048, from_block: BlockID, to_block: BlockID) -> Option<Vec<BlockNumber>>;
 
 	/// Returns logs matching given filter.
-	fn logs(&self, filter: Filter, limit: Option<usize>) -> Vec<LocalizedLogEntry>;
+	fn logs(&self, filter: Filter) -> Vec<LocalizedLogEntry>;
 
 	/// Makes a non-persistent transaction call.
 	fn call(&self, t: &SignedTransaction, block: BlockID, analytics: CallAnalytics) -> Result<Executed, CallError>;

ethcore/src/tests/client.rs

@@ -142,7 +142,8 @@ fn returns_logs() {
 		to_block: BlockID::Latest,
 		address: None,
 		topics: vec![],
-	}, None);
+		limit: None,
+	});
 	assert_eq!(logs.len(), 0);
 }
 
@@ -156,7 +157,8 @@ fn returns_logs_with_limit() {
 		to_block: BlockID::Latest,
 		address: None,
 		topics: vec![],
-	}, Some(2));
+		limit: Some(2),
+	});
 	assert_eq!(logs.len(), 0);
 }
 

ethcore/src/types/filter.rs

@@ -41,6 +41,12 @@ pub struct Filter {
 	/// If None, match all.
 	/// If specified, log must contain one of these topics.
 	pub topics: Vec<Option<Vec<H256>>>,
+
+	/// Logs limit
+	///
+	/// If None, return all logs
+	/// If specified, should only return *last* `n` logs.
+	pub limit: Option<usize>,
 }
 
 impl Clone for Filter {
@@ -59,7 +65,8 @@ impl Clone for Filter {
 			from_block: self.from_block.clone(),
 			to_block: self.to_block.clone(),
 			address: self.address.clone(),
-			topics: topics[..].to_vec()
+			topics: topics[..].to_vec(),
+			limit: self.limit,
 		}
 	}
 }
@@ -117,6 +124,7 @@ mod tests {
 			to_block: BlockID::Latest,
 			address: None,
 			topics: vec![None, None, None, None],
+			limit: None,
 		};
 
 		let possibilities = none_filter.bloom_possibilities();
@@ -136,7 +144,8 @@ mod tests {
 				None,
 				None,
 				None,
-			]
+			],
+			limit: None,
 		};
 
 		let possibilities = filter.bloom_possibilities();
@@ -154,7 +163,8 @@ mod tests {
 				Some(vec!["ff74e91598aed6ae5d2fdcf8b24cd2c7be49a0808112a305069355b7160f23f9".into()]),
 				None,
 				None,
-			]
+			],
+			limit: None,
 		};
 
 		let possibilities = filter.bloom_possibilities();
@@ -181,7 +191,8 @@ mod tests {
 				]),
 				Some(vec!["ff74e91598aed6ae5d2fdcf8b24cd2c7be49a0808112a305069355b7160f23f9".into()]),
 				None
-			]
+			],
+			limit: None,
 		};
 
 		// number of possibilites should be equal 2 * 2 * 2 * 1 = 8
@@ -201,7 +212,8 @@ mod tests {
 				Some(vec!["ff74e91598aed6ae5d2fdcf8b24cd2c7be49a0808112a305069355b7160f23fa".into()]),
 				None,
 				None,
-			]
+			],
+			limit: None,
 		};
 
 		let entry0 = LogEntry {