148 lines
4.3 KiB
Rust
148 lines
4.3 KiB
Rust
import comm::port;
|
|
import comm::chan;
|
|
import comm::send;
|
|
import comm::recv;
|
|
import future_spawn = future::spawn;
|
|
import future::extensions;
|
|
import core::vec::extensions;
|
|
|
|
export map, mapi, alli, any, mapi_factory;
|
|
|
|
/**
|
|
* The maximum number of tasks this module will spawn for a single
|
|
* operation.
|
|
*/
|
|
const max_tasks : uint = 32u;
|
|
|
|
/// The minimum number of elements each task will process.
|
|
const min_granularity : uint = 1024u;
|
|
|
|
/**
|
|
* An internal helper to map a function over a large vector and
|
|
* return the intermediate results.
|
|
*
|
|
* This is used to build most of the other parallel vector functions,
|
|
* like map or alli.
|
|
*/
|
|
fn map_slices<A: copy send, B: copy send>(
|
|
xs: ~[A],
|
|
f: fn() -> fn~(uint, v: &[A]) -> B)
|
|
-> ~[B] {
|
|
|
|
let len = xs.len();
|
|
if len < min_granularity {
|
|
log(info, ~"small slice");
|
|
// This is a small vector, fall back on the normal map.
|
|
~[f()(0u, xs)]
|
|
}
|
|
else {
|
|
let num_tasks = uint::min(max_tasks, len / min_granularity);
|
|
|
|
let items_per_task = len / num_tasks;
|
|
|
|
let mut futures = ~[];
|
|
let mut base = 0u;
|
|
log(info, ~"spawning tasks");
|
|
while base < len {
|
|
let end = uint::min(len, base + items_per_task);
|
|
// FIXME: why is the ::<A, ()> annotation required here? (#2617)
|
|
do vec::as_buf::<A, ()>(xs) |p, _len| {
|
|
let f = f();
|
|
let f = do future_spawn() |copy base| {
|
|
unsafe {
|
|
let len = end - base;
|
|
let slice = (ptr::offset(p, base),
|
|
len * sys::size_of::<A>());
|
|
log(info, fmt!{"pre-slice: %?", (base, slice)});
|
|
let slice : &[A] =
|
|
unsafe::reinterpret_cast(slice);
|
|
log(info, fmt!{"slice: %?",
|
|
(base, vec::len(slice), end - base)});
|
|
assert(vec::len(slice) == end - base);
|
|
f(base, slice)
|
|
}
|
|
};
|
|
vec::push(futures, f);
|
|
};
|
|
base += items_per_task;
|
|
}
|
|
log(info, ~"tasks spawned");
|
|
|
|
log(info, fmt!{"num_tasks: %?", (num_tasks, futures.len())});
|
|
assert(num_tasks == futures.len());
|
|
|
|
let r = do futures.map() |ys| {
|
|
ys.get()
|
|
};
|
|
assert(r.len() == futures.len());
|
|
r
|
|
}
|
|
}
|
|
|
|
/// A parallel version of map.
|
|
fn map<A: copy send, B: copy send>(xs: ~[A], f: fn~(A) -> B) -> ~[B] {
|
|
vec::concat(map_slices(xs, || {
|
|
fn~(_base: uint, slice : &[A], copy f) -> ~[B] {
|
|
vec::map(slice, f)
|
|
}
|
|
}))
|
|
}
|
|
|
|
/// A parallel version of mapi.
|
|
fn mapi<A: copy send, B: copy send>(xs: ~[A],
|
|
f: fn~(uint, A) -> B) -> ~[B] {
|
|
let slices = map_slices(xs, || {
|
|
fn~(base: uint, slice : &[A], copy f) -> ~[B] {
|
|
vec::mapi(slice, |i, x| {
|
|
f(i + base, x)
|
|
})
|
|
}
|
|
});
|
|
let r = vec::concat(slices);
|
|
log(info, (r.len(), xs.len()));
|
|
assert(r.len() == xs.len());
|
|
r
|
|
}
|
|
|
|
/**
|
|
* A parallel version of mapi.
|
|
*
|
|
* In this case, f is a function that creates functions to run over the
|
|
* inner elements. This is to skirt the need for copy constructors.
|
|
*/
|
|
fn mapi_factory<A: copy send, B: copy send>(
|
|
xs: ~[A], f: fn() -> fn~(uint, A) -> B) -> ~[B] {
|
|
let slices = map_slices(xs, || {
|
|
let f = f();
|
|
fn~(base: uint, slice : &[A], move f) -> ~[B] {
|
|
vec::mapi(slice, |i, x| {
|
|
f(i + base, x)
|
|
})
|
|
}
|
|
});
|
|
let r = vec::concat(slices);
|
|
log(info, (r.len(), xs.len()));
|
|
assert(r.len() == xs.len());
|
|
r
|
|
}
|
|
|
|
/// Returns true if the function holds for all elements in the vector.
|
|
fn alli<A: copy send>(xs: ~[A], f: fn~(uint, A) -> bool) -> bool {
|
|
do vec::all(map_slices(xs, || {
|
|
fn~(base: uint, slice : &[A], copy f) -> bool {
|
|
vec::alli(slice, |i, x| {
|
|
f(i + base, x)
|
|
})
|
|
}
|
|
})) |x| { x }
|
|
}
|
|
|
|
/// Returns true if the function holds for any elements in the vector.
|
|
fn any<A: copy send>(xs: ~[A], f: fn~(A) -> bool) -> bool {
|
|
do vec::any(map_slices(xs, || {
|
|
fn~(_base : uint, slice: &[A], copy f) -> bool {
|
|
vec::any(slice, f)
|
|
}
|
|
})) |x| { x }
|
|
}
|