102 lines
2.8 KiB
Rust
102 lines
2.8 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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//! Abstraction of a task pool for basic parallelism.
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use core::prelude::*;
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use task;
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use task::spawn;
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use vec::Vec;
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use comm::{channel, Sender};
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enum Msg<T> {
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Execute(proc(&T):Send),
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Quit
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}
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/// A task pool used to execute functions in parallel.
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pub struct TaskPool<T> {
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channels: Vec<Sender<Msg<T>>>,
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next_index: uint,
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}
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#[unsafe_destructor]
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impl<T> Drop for TaskPool<T> {
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fn drop(&mut self) {
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for channel in self.channels.iter_mut() {
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channel.send(Quit);
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}
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}
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}
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impl<T> TaskPool<T> {
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/// Spawns a new task pool with `n_tasks` tasks. The provided
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/// `init_fn_factory` returns a function which, given the index of the
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/// task, should return local data to be kept around in that task.
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///
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/// # Failure
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///
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/// This function will fail if `n_tasks` is less than 1.
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pub fn new(n_tasks: uint,
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init_fn_factory: || -> proc(uint):Send -> T)
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-> TaskPool<T> {
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assert!(n_tasks >= 1);
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let channels = Vec::from_fn(n_tasks, |i| {
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let (tx, rx) = channel::<Msg<T>>();
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let init_fn = init_fn_factory();
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let task_body = proc() {
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let local_data = init_fn(i);
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loop {
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match rx.recv() {
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Execute(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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// Run on this scheduler.
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task::spawn(task_body);
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tx
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});
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return TaskPool {
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channels: channels,
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next_index: 0,
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};
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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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pub fn execute(&mut self, f: proc(&T):Send) {
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self.channels[self.next_index].send(Execute(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: || -> proc(uint):Send -> uint = || { proc(i) i };
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let mut pool = TaskPool::new(4, f);
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for _ in range(0u, 8) {
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pool.execute(proc(i) println!("Hello from thread {}!", *i));
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}
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}
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#[test]
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#[should_fail]
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fn test_zero_tasks_failure() {
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let f: || -> proc(uint):Send -> uint = || { proc(i) i };
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TaskPool::new(0, f);
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}
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