Crate gaea

A low-level library to build event driven applications. The core of the library is poll, which polls multiple event sources for readiness events. Based on these readiness events the application will continue, e.g. by running a Future.

A number of readiness event sources are provided:

• OsQueue: a readiness event queue backed by the OS (epoll or kqueue).
• Queue: a single threaded, user space queue.
• Timers: a single threaded, deadline based readiness queue.

Getting started

Using the crate starts by creating one or more event::Sources.

// `OsQueue` implements `event::Source` and is backed by epoll or kqueue.
let os_queue = OsQueue::new()?;
// `Queue` is a user space readiness event queue, which also implements
// `event::Source`.
let queue = Queue::new();

As the name suggest event::Sources are the sources of readiness events, these can be polled for readiness events (we’ll get back to this later). This crate provides three OsQueue, Queue and Timers. But as event::Source is a trait it can be implemented outside of this crate.

Next an event::Sink is required, this used to store the readiness events from the event sources.

// `Vec`tor implements `event::Sink`.
let events = Vec::new();

Just like event::Source, event::Sink is also a trait. When, for example, building some kind of runtime event::Source can be directly implemented on the scheduler type and instead of adding an Event to a collection it will schedule a process/Future/task to run. For convenience Vectors also implement event::Sink.

Both the event::Sources and event::Sink should only be created once and reused in each call to poll. After we created both we can start polling the event::Sources.

// Poll both `os_queue` and `queue` for readiness events, with a maximum
// timeout of 1 seconds. Here we use an `io::Error` as error, see `poll`
// docs for more information on handling errors from different event
// sources.
poll::<_, io::Error>(&mut [&mut os_queue, &mut queue], &mut events,
    Some(Duration::from_secs(1)))?;

After the event::Sources are polled our event::Sink will be filled with readiness events, if there are any. These can be used to continue processing. Stick all the above in a loop and you’ve got yourself an event loop, congratulations!

use std::io;
use std::time::Duration;

use gaea::{poll, OsQueue, Queue};

// Create our `event::Source`s.
let mut os_queue = OsQueue::new()?;
let mut queue = Queue::new();

// And our `event::Sink`.
let mut events = Vec::new();

// TODO: add events and such here...

// Our event loop.
loop {
    // Poll for readiness events.
    poll::<_, io::Error>(&mut [&mut os_queue, &mut queue], &mut events,
        Some(Duration::from_secs(1)))?;

    // And process each event.
    for event in events.drain(..) {
        println!("Got event: id={}, readiness={:?}", event.id(),
            event.readiness());
    }
}

Examples

More complete examples of how to use the crate can be found in the examples directory of the source code (on GitHub).

Re-exports

• pub use crate::event::Event;
• pub use crate::event::Ready;
• pub use crate::os::OsQueue;

Modules

• event
  Readiness event types.
• net
  Networking primitives.
• os
  Operating System backed readiness event queue.
• unix
  Unix only extensions.

Structs

• Queue
  User space readiness queue.
• Timers
  Timer readiness queue.

Functions

• poll
  Poll event sources for readiness events.