scaproust 0.3.2

Nanomsg scalability protocols implementation in rust. Various messaging patterns over pluggable transports
Documentation 
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// Copyright (c) 2015-2017 Contributors as noted in the AUTHORS file.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0>
// or the MIT license <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
// This file may not be copied, modified, or distributed except according to those terms.

use std::cell::RefCell;
use std::io::Result;
use std::collections::VecDeque;

use mio::{Registration, SetReadiness, Evented, Poll, Token, Ready, PollOpt};

use io_error::*;

pub struct EventLoopBus<T> {
    queue: VecDeque<T>,
    registration: RefCell<Option<Registration>>,
    readiness: RefCell<Option<SetReadiness>>
}

impl<T> EventLoopBus<T> {
    pub fn new() -> EventLoopBus<T> {
        EventLoopBus {
            queue: VecDeque::new(),
            registration: RefCell::new(None),
            readiness: RefCell::new(None)
        }
    }

    pub fn send(&mut self, t: T) {
        if self.queue.is_empty() {
            self.set_readiness(Ready::readable());
        }

        self.queue.push_back(t)
    }

    pub fn recv(&mut self) -> Option<T> {
        if self.queue.len() == 1 {
            self.set_readiness(Ready::empty());
        }

        self.queue.pop_front()
    }

    fn set_readiness(&mut self, events: Ready) {
        if let Some(ref readiness) = *self.readiness.borrow_mut() {
            let _ = readiness.set_readiness(events);
        }
    }
}

impl<T> Evented for EventLoopBus<T> {
    fn register(&self, poll: &Poll, token: Token, interest: Ready, opts: PollOpt) -> Result<()> {
        if self.registration.borrow().is_some() {
            return Err(other_io_error("bus already registered"));
        }

        let (registration, readiness) = Registration::new2();

        try!(poll.register(&registration, token, interest, opts));

        if self.queue.is_empty() == false {
            let _ = readiness.set_readiness(Ready::readable());
        }

        *self.registration.borrow_mut() = Some(registration);
        *self.readiness.borrow_mut() = Some(readiness);

        Ok(())
    }

    fn reregister(&self, poll: &Poll, token: Token, interest: Ready, opts: PollOpt) -> Result<()> {
        match *self.registration.borrow_mut() {
            Some(ref registration) => Evented::reregister(registration, poll, token, interest, opts),
            None => Err(other_io_error("bus not registered")),
        }
    }

    fn deregister(&self, poll: &Poll) -> Result<()> {
        match *self.registration.borrow_mut() {
            Some(ref registration) => Evented::deregister(registration, poll),
            None => Err(other_io_error("bus not registered")),
        }
    }

}