Jeremy Soller
82 lines
2.7 KiB
Rust
82 lines
2.7 KiB
Rust
use std::collections::BTreeMap;
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use std::fs::File;
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use std::io::{Read, Error, Result};
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use std::os::unix::io::RawFd;
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pub struct EventQueue<R> {
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/// The file to read events from
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file: File,
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/// A map of registered file descriptors to their handler callbacks
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callbacks: BTreeMap<RawFd, Box<FnMut(usize) -> Result<Option<R>>>>
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}
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impl<R> EventQueue<R> {
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/// Create a new event queue
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pub fn new() -> Result<EventQueue<R>> {
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Ok(EventQueue {
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file: File::open("event:")?,
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callbacks: BTreeMap::new()
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})
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}
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/// Add a file to the event queue, calling a callback when an event occurs
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///
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/// The callback is given a mutable reference to the file and the event data
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/// (typically the length of data available for read)
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///
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/// The callback returns Ok(None) if it wishes to continue the event loop,
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/// or Ok(Some(R)) to break the event loop and return the value.
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/// Err can be used to allow the callback to return an I/O error, and break the
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/// event loop
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pub fn add<F: FnMut(usize) -> Result<Option<R>> + 'static>(&mut self, fd: RawFd, callback: F) -> Result<()> {
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::fevent(fd, ::EVENT_READ).map_err(|x| Error::from_raw_os_error(x.errno))?;
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self.callbacks.insert(fd, Box::new(callback));
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Ok(())
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}
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/// Remove a file from the event queue, returning its callback if found
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pub fn remove(&mut self, fd: RawFd) -> Result<Option<Box<FnMut(usize) -> Result<Option<R>>>>> {
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if let Some(callback) = self.callbacks.remove(&fd) {
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::fevent(fd, 0).map_err(|x| Error::from_raw_os_error(x.errno))?;
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Ok(Some(callback))
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} else {
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Ok(None)
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}
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}
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/// Send an event to a descriptor callback
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pub fn trigger(&mut self, fd: RawFd, count: usize) -> Result<Option<R>> {
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if let Some(callback) = self.callbacks.get_mut(&fd) {
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callback(count)
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} else {
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Ok(None)
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}
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}
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/// Send an event to all descriptor callbacks, useful for cleaning out buffers after init
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pub fn trigger_all(&mut self, count: usize) -> Result<Vec<R>> {
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let mut rets = Vec::new();
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for (_fd, callback) in self.callbacks.iter_mut() {
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if let Some(ret) = callback(count)? {
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rets.push(ret);
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}
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}
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Ok(rets)
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}
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/// Process the event queue until a callback returns Some(R)
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pub fn run(&mut self) -> Result<R> {
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loop {
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let mut event = ::Event::default();
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if self.file.read(&mut event)? > 0 {
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if let Some(ret) = self.trigger(event.id, event.data)? {
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return Ok(ret);
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}
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}
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}
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}
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}
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