146 lines
4.2 KiB
Rust
146 lines
4.2 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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use core::prelude::*;
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use core::cast;
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use core::ptr;
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use core::sys;
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use core::uint;
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use core::vec;
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use future_spawn = future::spawn;
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/**
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* The maximum number of tasks this module will spawn for a single
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* operation.
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*/
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static max_tasks : uint = 32u;
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/// The minimum number of elements each task will process.
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static min_granularity : uint = 1024u;
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/**
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* An internal helper to map a function over a large vector and
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* return the intermediate results.
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*
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* This is used to build most of the other parallel vector functions,
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* like map or alli.
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*/
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fn map_slices<A:Copy + Send,B:Copy + Send>(
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xs: &[A],
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f: &fn() -> ~fn(uint, v: &[A]) -> B)
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-> ~[B] {
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let len = xs.len();
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if len < min_granularity {
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info!("small slice");
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// This is a small vector, fall back on the normal map.
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~[f()(0u, xs)]
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}
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else {
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let num_tasks = uint::min(max_tasks, len / min_granularity);
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let items_per_task = len / num_tasks;
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let mut futures = ~[];
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let mut base = 0u;
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info!("spawning tasks");
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while base < len {
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let end = uint::min(len, base + items_per_task);
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do vec::as_imm_buf(xs) |p, _len| {
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let f = f();
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let base = base;
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let f = do future_spawn() || {
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unsafe {
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let len = end - base;
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let slice = (ptr::offset(p, base),
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len * sys::size_of::<A>());
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info!("pre-slice: %?", (base, slice));
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let slice : &[A] =
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cast::transmute(slice);
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info!("slice: %?", (base, slice.len(), end - base));
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assert_eq!(slice.len(), end - base);
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f(base, slice)
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}
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};
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futures.push(f);
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};
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base += items_per_task;
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}
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info!("tasks spawned");
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info!("num_tasks: %?", (num_tasks, futures.len()));
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assert_eq!(num_tasks, futures.len());
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let r = do vec::map_consume(futures) |ys| {
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let mut ys = ys;
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ys.get()
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};
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r
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}
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}
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/// A parallel version of map.
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pub fn map<A:Copy + Send,B:Copy + Send>(
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xs: &[A], fn_factory: &fn() -> ~fn(&A) -> B) -> ~[B] {
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vec::concat(map_slices(xs, || {
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let f = fn_factory();
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let result: ~fn(uint, &[A]) -> ~[B] =
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|_, slice| vec::map(slice, |x| f(x));
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result
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}))
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}
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/// A parallel version of mapi.
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pub fn mapi<A:Copy + Send,B:Copy + Send>(
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xs: &[A],
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fn_factory: &fn() -> ~fn(uint, &A) -> B) -> ~[B] {
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let slices = map_slices(xs, || {
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let f = fn_factory();
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let result: ~fn(uint, &[A]) -> ~[B] = |base, slice| {
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vec::mapi(slice, |i, x| {
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f(i + base, x)
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})
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};
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result
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});
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let r = vec::concat(slices);
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info!("%?", (r.len(), xs.len()));
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assert_eq!(r.len(), xs.len());
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r
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}
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/// Returns true if the function holds for all elements in the vector.
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pub fn alli<A:Copy + Send>(
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xs: &[A],
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fn_factory: &fn() -> ~fn(uint, &A) -> bool) -> bool
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{
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let mapped = map_slices(xs, || {
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let f = fn_factory();
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let result: ~fn(uint, &[A]) -> bool = |base, slice| {
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slice.iter().enumerate().all(|(i, x)| f(i + base, x))
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};
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result
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});
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mapped.iter().all(|&x| x)
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}
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/// Returns true if the function holds for any elements in the vector.
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pub fn any<A:Copy + Send>(
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xs: &[A],
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fn_factory: &fn() -> ~fn(&A) -> bool) -> bool {
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let mapped = map_slices(xs, || {
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let f = fn_factory();
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let result: ~fn(uint, &[A]) -> bool = |_, slice| slice.iter().any_(f);
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result
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});
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mapped.iter().any_(|&x| x)
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}
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