38bd694df1
As per #3637.
96 lines
3.0 KiB
Rust
96 lines
3.0 KiB
Rust
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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/// A task pool abstraction. Useful for achieving predictable CPU
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/// parallelism.
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use pipes::{Chan, Port};
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use task::{SchedMode, SingleThreaded};
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enum Msg<T> {
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Execute(~fn(&T)),
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Quit
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}
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pub struct TaskPool<T> {
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channels: ~[Chan<Msg<T>>],
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mut next_index: uint,
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drop {
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for self.channels.each |channel| {
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channel.send(Quit);
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}
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}
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}
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pub impl<T> TaskPool<T> {
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/// Spawns a new task pool with `n_tasks` tasks. If the `sched_mode`
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/// is None, the tasks run on this scheduler; otherwise, they run on a
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/// new scheduler with the given mode. The provided `init_fn_factory`
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/// returns a function which, given the index of the task, should return
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/// local data to be kept around in that task.
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static fn new(n_tasks: uint,
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opt_sched_mode: Option<SchedMode>,
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init_fn_factory: ~fn() -> ~fn(uint) -> T) -> TaskPool<T> {
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assert n_tasks >= 1;
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let channels = do vec::from_fn(n_tasks) |i| {
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let (port, chan) = pipes::stream::<Msg<T>>();
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let init_fn = init_fn_factory();
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let task_body: ~fn() = |move port, move init_fn| {
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let local_data = init_fn(i);
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loop {
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match port.recv() {
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Execute(move f) => f(&local_data),
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Quit => break
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}
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}
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};
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// Start the task.
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match opt_sched_mode {
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None => {
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// Run on this scheduler.
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task::spawn(move task_body);
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}
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Some(sched_mode) => {
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task::task().sched_mode(sched_mode).spawn(move task_body);
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}
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}
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move chan
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};
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return TaskPool { channels: move channels, next_index: 0 };
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}
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/// Executes the function `f` on a task in the pool. The function
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/// receives a reference to the local data returned by the `init_fn`.
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fn execute(&self, f: ~fn(&T)) {
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self.channels[self.next_index].send(Execute(move f));
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self.next_index += 1;
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if self.next_index == self.channels.len() { self.next_index = 0; }
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}
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}
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#[test]
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fn test_task_pool() {
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let f: ~fn() -> ~fn(uint) -> uint = || {
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let g: ~fn(uint) -> uint = |i| i;
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move g
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};
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let pool = TaskPool::new(4, Some(SingleThreaded), move f);
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for 8.times {
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pool.execute(|i| io::println(fmt!("Hello from thread %u!", *i)));
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}
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}
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