1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
|
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#[allow(missing_doc)];
/// A task pool abstraction. Useful for achieving predictable CPU
/// parallelism.
use std::task;
use std::vec;
enum Msg<T> {
Execute(proc(&T)),
Quit
}
pub struct TaskPool<T> {
priv channels: ~[Chan<Msg<T>>],
priv next_index: uint,
}
#[unsafe_destructor]
impl<T> Drop for TaskPool<T> {
fn drop(&mut self) {
for channel in self.channels.mut_iter() {
channel.send(Quit);
}
}
}
impl<T> TaskPool<T> {
/// Spawns a new task pool with `n_tasks` tasks. If the `sched_mode`
/// is None, the tasks run on this scheduler; otherwise, they run on a
/// new scheduler with the given mode. The provided `init_fn_factory`
/// returns a function which, given the index of the task, should return
/// local data to be kept around in that task.
pub fn new(n_tasks: uint,
init_fn_factory: || -> proc(uint) -> T)
-> TaskPool<T> {
assert!(n_tasks >= 1);
let channels = vec::from_fn(n_tasks, |i| {
let (port, chan) = Chan::<Msg<T>>::new();
let init_fn = init_fn_factory();
let task_body: proc() = proc() {
let local_data = init_fn(i);
loop {
match port.recv() {
Execute(f) => f(&local_data),
Quit => break
}
}
};
// Run on this scheduler.
task::spawn(task_body);
chan
});
return TaskPool { channels: channels, next_index: 0 };
}
/// Executes the function `f` on a task in the pool. The function
/// receives a reference to the local data returned by the `init_fn`.
pub fn execute(&mut self, f: proc(&T)) {
self.channels[self.next_index].send(Execute(f));
self.next_index += 1;
if self.next_index == self.channels.len() { self.next_index = 0; }
}
}
#[test]
fn test_task_pool() {
let f: || -> proc(uint) -> uint = || {
let g: proc(uint) -> uint = proc(i) i;
g
};
let mut pool = TaskPool::new(4, f);
for _ in range(0, 8) {
pool.execute(proc(i) println!("Hello from thread {}!", *i));
}
}
|
