Limit the number of transactions in pending set (#8777)

* Unordered iterator.

* Use unordered and limited set if full not required.

* Split timeout work into smaller timers.

* Avoid collecting all pending transactions when mining

* Remove println.

* Use priority ordering in eth-filter.

* Fix ethcore-miner tests and tx propagation.

* Review grumbles addressed.

* Add test for unordered not populating the cache.

* Fix ethcore tests.

* Fix light tests.

* Fix ethcore-sync tests.

* Fix RPC tests.

ethcore/light/src/net/mod.rs

@@ -72,6 +72,9 @@ const PROPAGATE_TIMEOUT_INTERVAL: Duration = Duration::from_secs(5);
 const RECALCULATE_COSTS_TIMEOUT: TimerToken = 3;
 const RECALCULATE_COSTS_INTERVAL: Duration = Duration::from_secs(60 * 60);
 
+/// Max number of transactions in a single packet.
+const MAX_TRANSACTIONS_TO_PROPAGATE: usize = 64;
+
 // minimum interval between updates.
 const UPDATE_INTERVAL: Duration = Duration::from_millis(5000);
 
@@ -647,7 +650,7 @@ impl LightProtocol {
 	fn propagate_transactions(&self, io: &IoContext) {
 		if self.capabilities.read().tx_relay { return }
 
-		let ready_transactions = self.provider.ready_transactions();
+		let ready_transactions = self.provider.ready_transactions(MAX_TRANSACTIONS_TO_PROPAGATE);
 		if ready_transactions.is_empty() { return }
 
 		trace!(target: "pip", "propagate transactions: {} ready", ready_transactions.len());

ethcore/light/src/net/tests/mod.rs

@@ -173,8 +173,8 @@ impl Provider for TestProvider {
 		})
 	}
 
-	fn ready_transactions(&self) -> Vec<PendingTransaction> {
-		self.0.client.ready_transactions()
+	fn ready_transactions(&self, max_len: usize) -> Vec<PendingTransaction> {
+		self.0.client.ready_transactions(max_len)
 	}
 }