Tagged transaction queue integration (#893)

* Make the graph generic.

* Adapting pool API for the graph.

* Merge pool & graph.

* Restructure.

* Fix test of transaction pool.

* Get rid of node/transaction-pool.

* Compilation fixes.

* Test7

* Fix compilation of tests.

* Revert runtime changes.

* Add validate_transaction to test-runtime.

* Fix RPC tests.

* Add clearing of the old transactions.

* Trigger pool events.

* Use new queue API.

* Fix wasm build, re-export Hasher.

* No warning if validate transaction fails.

* Get rid of Into<u64> and use As

substrate/core/transaction-pool/graph/src/watcher.rs

@@ -0,0 +1,116 @@
+// Copyright 2018 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Extrinsics status updates.
+
+use futures::{
+	Stream,
+	sync::mpsc,
+};
+
+/// Possible extrinsic status events
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub enum Status<H, H2> {
+	/// Extrinsic is part of the future queue.
+	Future,
+	/// Extrinsic is part of the ready queue.
+	Ready,
+	/// Extrinsic has been finalised in block with given hash.
+	Finalised(H2),
+	/// Some state change (perhaps another extrinsic was included) rendered this extrinsic invalid.
+	Usurped(H),
+	/// The extrinsic has been broadcast to the given peers.
+	Broadcast(Vec<String>),
+	/// Extrinsic has been dropped from the pool because of the limit.
+	Dropped,
+}
+
+/// Extrinsic watcher.
+///
+/// Represents a stream of status updates for particular extrinsic.
+#[derive(Debug)]
+pub struct Watcher<H, H2> {
+	receiver: mpsc::UnboundedReceiver<Status<H, H2>>,
+}
+
+impl<H, H2> Watcher<H, H2> {
+	/// Pipe the notifications to given sink.
+	///
+	/// Make sure to drive the future to completion.
+	pub fn into_stream(self) -> impl Stream<Item=Status<H, H2>, Error=()> {
+		// we can safely ignore the error here, `UnboundedReceiver` never fails.
+		self.receiver.map_err(|_| ())
+	}
+}
+
+/// Sender part of the watcher. Exposed only for testing purposes.
+#[derive(Debug)]
+pub struct Sender<H, H2> {
+	receivers: Vec<mpsc::UnboundedSender<Status<H, H2>>>,
+	finalised: bool,
+}
+
+impl<H, H2> Default for Sender<H, H2> {
+	fn default() -> Self {
+		Sender {
+			receivers: Default::default(),
+			finalised: false,
+		}
+	}
+}
+
+impl<H: Clone, H2: Clone> Sender<H, H2> {
+	/// Add a new watcher to this sender object.
+	pub fn new_watcher(&mut self) -> Watcher<H, H2> {
+		let (tx, receiver) = mpsc::unbounded();
+		self.receivers.push(tx);
+		Watcher {
+			receiver,
+		}
+	}
+
+	/// Some state change (perhaps another extrinsic was included) rendered this extrinsic invalid.
+	pub fn usurped(&mut self, hash: H) {
+		self.send(Status::Usurped(hash))
+	}
+
+	/// Extrinsic has been finalised in block with given hash.
+	pub fn finalised(&mut self, hash: H2) {
+		self.send(Status::Finalised(hash));
+		self.finalised = true;
+	}
+
+	/// Transaction has been dropped from the pool because of the limit.
+	pub fn dropped(&mut self) {
+		self.send(Status::Dropped);
+	}
+
+	/// The extrinsic has been broadcast to the given peers.
+	pub fn broadcast(&mut self, peers: Vec<String>) {
+		self.send(Status::Broadcast(peers))
+	}
+
+
+	/// Returns true if the are no more listeners for this extrinsic or it was finalised.
+	pub fn is_done(&self) -> bool {
+		self.finalised || self.receivers.is_empty()
+	}
+
+	fn send(&mut self, status: Status<H, H2>) {
+		self.receivers.retain(|sender| sender.unbounded_send(status.clone()).is_ok())
+	}
+}