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// -*- rust -*-
// xfail-pretty
/*
A parallel version of fibonacci numbers.
This version is meant mostly as a way of stressing and benchmarking
the task system. It supports a lot of command-line arguments to
control how it runs.
*/
#[legacy_modes];
extern mod std;
use std::{time, getopts};
use io::WriterUtil;
use int::range;
use pipes::Port;
use pipes::Chan;
use pipes::send;
use pipes::recv;
use core::result;
use result::{Ok, Err};
fn fib(n: int) -> int {
fn pfib(c: Chan<int>, n: int) {
if n == 0 {
c.send(0);
} else if n <= 2 {
c.send(1);
} else {
let p = pipes::PortSet();
let ch = p.chan();
task::spawn(|| pfib(ch, n - 1) );
let ch = p.chan();
task::spawn(|| pfib(ch, n - 2) );
c.send(p.recv() + p.recv());
}
}
let (ch, p) = pipes::stream();
let t = task::spawn(|| pfib(ch, n) );
p.recv()
}
type config = {stress: bool};
fn parse_opts(argv: ~[~str]) -> config {
let opts = ~[getopts::optflag(~"stress")];
let opt_args = vec::slice(argv, 1u, vec::len(argv));
match getopts::getopts(opt_args, opts) {
Ok(m) => { return {stress: getopts::opt_present(m, ~"stress")} }
Err(_) => { fail; }
}
}
fn stress_task(&&id: int) {
let mut i = 0;
loop {
let n = 15;
assert (fib(n) == fib(n));
i += 1;
error!("%d: Completed %d iterations", id, i);
}
}
fn stress(num_tasks: int) {
let mut results = ~[];
for range(0, num_tasks) |i| {
do task::task().future_result(|+r| {
results.push(r);
}).spawn {
stress_task(i);
}
}
for results.each |r| { future::get(r); }
}
fn main() {
let args = os::args();
let args = if os::getenv(~"RUST_BENCH").is_some() {
~[~"", ~"20"]
} else if args.len() <= 1u {
~[~"", ~"8"]
} else {
args
};
let opts = parse_opts(args);
if opts.stress {
stress(2);
} else {
let max = uint::parse_bytes(str::to_bytes(args[1]),
10u).get() as int;
let num_trials = 10;
let out = io::stdout();
for range(1, max + 1) |n| {
for range(0, num_trials) |i| {
let start = time::precise_time_ns();
let fibn = fib(n);
let stop = time::precise_time_ns();
let elapsed = stop - start;
out.write_line(fmt!("%d\t%d\t%s", n, fibn,
u64::str(elapsed)));
}
}
}
}
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