Make mio optional in ethcore-io (#8537)

* Make mio optional in ethcore-io

* Add some annotations, plus a check for features

* Increase timer for test

util/io/src/service_non_mio.rs

@@ -0,0 +1,334 @@
+// Copyright 2015-2017 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity 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.
+
+// Parity 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 Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+use std::sync::{Arc, Weak};
+use std::thread;
+use crossbeam::sync::chase_lev;
+use slab::Slab;
+use fnv::FnvHashMap;
+use {IoError, IoHandler};
+use parking_lot::{RwLock, Mutex};
+use num_cpus;
+use std::time::Duration;
+use timer::{Timer, Guard as TimerGuard};
+use time::Duration as TimeDuration;
+
+/// Timer ID
+pub type TimerToken = usize;
+/// IO Handler ID
+pub type HandlerId = usize;
+
+/// Maximum number of tokens a handler can use
+pub const TOKENS_PER_HANDLER: usize = 16384;
+const MAX_HANDLERS: usize = 8;
+
+/// IO access point. This is passed to all IO handlers and provides an interface to the IO subsystem.
+pub struct IoContext<Message> where Message: Send + Sync + 'static {
+	handler: HandlerId,
+	shared: Arc<Shared<Message>>,
+}
+
+impl<Message> IoContext<Message> where Message: Send + Sync + 'static {
+	/// Register a new recurring IO timer. 'IoHandler::timeout' will be called with the token.
+	pub fn register_timer(&self, token: TimerToken, delay: Duration) -> Result<(), IoError> {
+		let channel = self.channel();
+
+		let msg = WorkTask::TimerTrigger {
+			handler_id: self.handler,
+			token: token,
+		};
+
+		let delay = TimeDuration::from_std(delay)
+			.map_err(|e| ::std::io::Error::new(::std::io::ErrorKind::Other, e))?;
+		let guard = self.shared.timer.lock().schedule_repeating(delay, move || {
+			channel.send_raw(msg.clone());
+		});
+
+		self.shared.timers.lock().insert(token, guard);
+
+		Ok(())
+	}
+
+	/// Register a new IO timer once. 'IoHandler::timeout' will be called with the token.
+	pub fn register_timer_once(&self, token: TimerToken, delay: Duration) -> Result<(), IoError> {
+		let channel = self.channel();
+
+		let msg = WorkTask::TimerTrigger {
+			handler_id: self.handler,
+			token: token,
+		};
+
+		let delay = TimeDuration::from_std(delay)
+			.map_err(|e| ::std::io::Error::new(::std::io::ErrorKind::Other, e))?;
+		let guard = self.shared.timer.lock().schedule_with_delay(delay, move || {
+			channel.send_raw(msg.clone());
+		});
+
+		self.shared.timers.lock().insert(token, guard);
+
+		Ok(())
+	}
+
+	/// Delete a timer.
+	pub fn clear_timer(&self, token: TimerToken) -> Result<(), IoError> {
+		self.shared.timers.lock().remove(&token);
+		Ok(())
+	}
+
+	/// Broadcast a message to other IO clients
+	pub fn message(&self, message: Message) -> Result<(), IoError> {
+		if let Some(ref channel) = *self.shared.channel.lock() {
+			channel.push(WorkTask::UserMessage(Arc::new(message)));
+		}
+		for thread in self.shared.threads.read().iter() {
+			thread.unpark();
+		}
+
+		Ok(())
+	}
+
+	/// Get message channel
+	pub fn channel(&self) -> IoChannel<Message> {
+		IoChannel { shared: Arc::downgrade(&self.shared) }
+	}
+
+	/// Unregister current IO handler.
+	pub fn unregister_handler(&self) -> Result<(), IoError> {
+		self.shared.handlers.write().remove(self.handler);
+		Ok(())
+	}
+}
+
+/// Allows sending messages into the event loop. All the IO handlers will get the message
+/// in the `message` callback.
+pub struct IoChannel<Message> where Message: Send + Sync + 'static {
+	shared: Weak<Shared<Message>>,
+}
+
+impl<Message> Clone for IoChannel<Message> where Message: Send + Sync + 'static {
+	fn clone(&self) -> IoChannel<Message> {
+		IoChannel {
+			shared: self.shared.clone(),
+		}
+	}
+}
+
+impl<Message> IoChannel<Message> where Message: Send + Sync + 'static {
+	/// Send a message through the channel
+	pub fn send(&self, message: Message) -> Result<(), IoError> {
+		if let Some(shared) = self.shared.upgrade() {
+			match *shared.channel.lock() {
+				Some(ref channel) => channel.push(WorkTask::UserMessage(Arc::new(message))),
+				None => self.send_sync(message)?
+			};
+
+			for thread in shared.threads.read().iter() {
+				thread.unpark();
+			}
+		}
+
+		Ok(())
+	}
+
+	/// Send a message through the channel and handle it synchronously
+	pub fn send_sync(&self, message: Message) -> Result<(), IoError> {
+		if let Some(shared) = self.shared.upgrade() {
+			for id in 0 .. MAX_HANDLERS {
+				if let Some(h) = shared.handlers.read().get(id) {
+					let handler = h.clone();
+					let ctxt = IoContext { handler: id, shared: shared.clone() };
+					handler.message(&ctxt, &message);
+				}
+			}
+		}
+
+		Ok(())
+	}
+
+	// Send low level io message
+	fn send_raw(&self, message: WorkTask<Message>) {
+		if let Some(shared) = self.shared.upgrade() {
+			if let Some(ref channel) = *shared.channel.lock() {
+				channel.push(message);
+			}
+
+			for thread in shared.threads.read().iter() {
+				thread.unpark();
+			}
+		}
+	}
+
+	/// Create a new channel disconnected from an event loop.
+	pub fn disconnected() -> IoChannel<Message> {
+		IoChannel {
+			shared: Weak::default(),
+		}
+	}
+}
+
+/// General IO Service. Starts an event loop and dispatches IO requests.
+/// 'Message' is a notification message type
+pub struct IoService<Message> where Message: Send + Sync + 'static {
+	thread_joins: Mutex<Vec<thread::JoinHandle<()>>>,
+	shared: Arc<Shared<Message>>,
+}
+
+// Struct shared throughout the whole implementation.
+struct Shared<Message> where Message: Send + Sync + 'static {
+	// All the I/O handlers that have been registered.
+	handlers: RwLock<Slab<Arc<IoHandler<Message>>>>,
+	// All the background threads, so that we can unpark them.
+	threads: RwLock<Vec<thread::Thread>>,
+	// Used to create timeouts.
+	timer: Mutex<Timer>,
+	// List of created timers. We need to keep them in a data struct so that we can cancel them if
+	// necessary.
+	timers: Mutex<FnvHashMap<TimerToken, TimerGuard>>,
+	// Channel used to send work to the worker threads.
+	channel: Mutex<Option<chase_lev::Worker<WorkTask<Message>>>>,
+}
+
+// Messages used to communicate with the event loop from other threads.
+enum WorkTask<Message> where Message: Send + Sized {
+	Shutdown,
+	TimerTrigger {
+		handler_id: HandlerId,
+		token: TimerToken,
+	},
+	UserMessage(Arc<Message>)
+}
+
+impl<Message> Clone for WorkTask<Message> where Message: Send + Sized {
+	fn clone(&self) -> WorkTask<Message> {
+		match *self {
+			WorkTask::Shutdown => WorkTask::Shutdown,
+			WorkTask::TimerTrigger { handler_id, token } => WorkTask::TimerTrigger { handler_id, token },
+			WorkTask::UserMessage(ref msg) => WorkTask::UserMessage(msg.clone()),
+		}
+	}
+}
+
+impl<Message> IoService<Message> where Message: Send + Sync + 'static {
+	/// Starts IO event loop
+	pub fn start() -> Result<IoService<Message>, IoError> {
+		let (tx, rx) = chase_lev::deque();
+
+		let shared = Arc::new(Shared {
+			handlers: RwLock::new(Slab::with_capacity(MAX_HANDLERS)),
+			threads: RwLock::new(Vec::new()),
+			timer: Mutex::new(Timer::new()),
+			timers: Mutex::new(FnvHashMap::default()),
+			channel: Mutex::new(Some(tx)),
+		});
+
+		let thread_joins = (0 .. num_cpus::get()).map(|_| {
+			let rx = rx.clone();
+			let shared = shared.clone();
+			thread::spawn(move || {
+				do_work(&shared, rx)
+			})
+		}).collect::<Vec<_>>();
+
+		*shared.threads.write() = thread_joins.iter().map(|t| t.thread().clone()).collect();
+
+		Ok(IoService {
+			thread_joins: Mutex::new(thread_joins),
+			shared,
+		})
+	}
+
+	/// Stops the IO service.
+	pub fn stop(&self) {
+		trace!(target: "shutdown", "[IoService] Closing...");
+		// Clear handlers so that shared pointers are not stuck on stack
+		// in Channel::send_sync
+		self.shared.handlers.write().clear();
+		let channel = self.shared.channel.lock().take();
+		let mut thread_joins = self.thread_joins.lock();
+		if let Some(channel) = channel {
+			for _ in 0 .. thread_joins.len() {
+				channel.push(WorkTask::Shutdown);
+			}
+		}
+		for thread in thread_joins.drain(..) {
+			thread.thread().unpark();
+			thread.join().unwrap_or_else(|e| {
+				debug!(target: "shutdown", "Error joining IO service worker thread: {:?}", e);
+			});
+		}
+		trace!(target: "shutdown", "[IoService] Closed.");
+	}
+
+	/// Register an IO handler with the event loop.
+	pub fn register_handler(&self, handler: Arc<IoHandler<Message>+Send>) -> Result<(), IoError> {
+		let id = self.shared.handlers.write().insert(handler.clone());
+		assert!(id <= MAX_HANDLERS, "Too many handlers registered");
+		let ctxt = IoContext { handler: id, shared: self.shared.clone() };
+		handler.initialize(&ctxt);
+		Ok(())
+	}
+
+	/// Send a message over the network. Normaly `HostIo::send` should be used. This can be used from non-io threads.
+	pub fn send_message(&self, message: Message) -> Result<(), IoError> {
+		if let Some(ref channel) = *self.shared.channel.lock() {
+			channel.push(WorkTask::UserMessage(Arc::new(message)));
+		}
+		for thread in self.shared.threads.read().iter() {
+			thread.unpark();
+		}
+		Ok(())
+	}
+
+	/// Create a new message channel
+	#[inline]
+	pub fn channel(&self) -> IoChannel<Message> {
+		IoChannel {
+			shared: Arc::downgrade(&self.shared)
+		}
+	}
+}
+
+impl<Message> Drop for IoService<Message> where Message: Send + Sync {
+	fn drop(&mut self) {
+		self.stop()
+	}
+}
+
+fn do_work<Message>(shared: &Arc<Shared<Message>>, rx: chase_lev::Stealer<WorkTask<Message>>)
+	where Message: Send + Sync + 'static 
+{
+	loop {
+		match rx.steal() {
+			chase_lev::Steal::Abort => continue,
+			chase_lev::Steal::Empty => thread::park(),
+			chase_lev::Steal::Data(WorkTask::Shutdown) => break,
+			chase_lev::Steal::Data(WorkTask::UserMessage(message)) => {
+				for id in 0 .. MAX_HANDLERS {
+					if let Some(handler) = shared.handlers.read().get(id) {
+						let ctxt = IoContext { handler: id, shared: shared.clone() };
+						handler.message(&ctxt, &message);
+					}
+				}
+			},
+			chase_lev::Steal::Data(WorkTask::TimerTrigger { handler_id, token }) => {
+				if let Some(handler) = shared.handlers.read().get(handler_id) {
+					let ctxt = IoContext { handler: handler_id, shared: shared.clone() };
+					handler.timeout(&ctxt, token);
+				}
+			},
+		}
+	}
+}