56 lines
1.8 KiB
Rust
56 lines
1.8 KiB
Rust
// xfail-pretty
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// 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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// Test performance of a task "spawn ladder", in which children task have many
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// many ancestor taskgroups, but with only a few such groups alive at a time.
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// Each child task has to enlist as a descendant in each of its ancestor
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// groups, but that shouldn't have to happen for already-dead groups.
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//
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// The filename is a song reference; google it in quotes.
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use core::cell::Cell;
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fn child_generation(gens_left: uint, c: comm::Chan<()>) {
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// This used to be O(n^2) in the number of generations that ever existed.
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// With this code, only as many generations are alive at a time as tasks
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// alive at a time,
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let c = Cell(c);
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do task::spawn_supervised {
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let c = c.take();
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if gens_left & 1 == 1 {
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task::yield(); // shake things up a bit
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}
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if gens_left > 0 {
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child_generation(gens_left - 1, c); // recurse
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} else {
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c.send(())
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}
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}
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}
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fn main() {
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let args = os::args();
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let args = if os::getenv(~"RUST_BENCH").is_some() {
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~[~"", ~"100000"]
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} else if args.len() <= 1 {
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~[~"", ~"100"]
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} else {
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copy args
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};
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let (p,c) = comm::stream();
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child_generation(uint::from_str(args[1]).get(), c);
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if p.try_recv().is_none() {
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fail!(~"it happened when we slumbered");
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}
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}
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