56 lines
1.8 KiB
Rust
56 lines
1.8 KiB
Rust
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#![feature(question_mark)]
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extern crate syscall;
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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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syscall::fevent(fd, syscall::EVENT_READ).map_err(|x| Error::from_sys(x))?;
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self.callbacks.insert(fd, Box::new(callback));
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Ok(())
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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 = syscall::Event::default();
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self.file.read(&mut event)?;
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if let Some(callback) = self.callbacks.get_mut(&event.id) {
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if let Some(ret) = callback(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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