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// Copyright 2013 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.
/*!
Weak tasks
Weak tasks are a runtime feature for building global services that
do not keep the runtime alive. Normally the runtime exits when all
tasks exits, but if a task is weak then the runtime may exit while
it is running, sending a notification to the task that the runtime
is trying to shut down.
*/
use cell::Cell;
use comm::{GenericSmartChan, stream};
use comm::{Port, Chan, SharedChan, GenericChan, GenericPort};
use hashmap::linear::LinearMap;
use option::{Some, None};
use unstable::at_exit::at_exit;
use unstable::finally::Finally;
use unstable::global::global_data_clone_create;
use task::rt::{task_id, get_task_id};
use task::task;
#[cfg(test)] use task::spawn;
type ShutdownMsg = ();
// FIXME #4729: This could be a PortOne but I've experienced bugginess
// with oneshot pipes and try_send
pub unsafe fn weaken_task(f: &fn(Port<ShutdownMsg>)) {
let service = global_data_clone_create(global_data_key,
create_global_service);
let (shutdown_port, shutdown_chan) = stream::<ShutdownMsg>();
let shutdown_port = Cell(shutdown_port);
let task = get_task_id();
// Expect the weak task service to be alive
assert!(service.try_send(RegisterWeakTask(task, shutdown_chan)));
unsafe { rust_dec_kernel_live_count(); }
do (|| {
f(shutdown_port.take())
}).finally || {
unsafe { rust_inc_kernel_live_count(); }
// Service my have already exited
service.send(UnregisterWeakTask(task));
}
}
type WeakTaskService = SharedChan<ServiceMsg>;
type TaskHandle = task_id;
fn global_data_key(_v: WeakTaskService) { }
enum ServiceMsg {
RegisterWeakTask(TaskHandle, Chan<ShutdownMsg>),
UnregisterWeakTask(TaskHandle),
Shutdown
}
fn create_global_service() -> ~WeakTaskService {
debug!("creating global weak task service");
let (port, chan) = stream::<ServiceMsg>();
let port = Cell(port);
let chan = SharedChan(chan);
let chan_clone = chan.clone();
do task().unlinked().spawn {
debug!("running global weak task service");
let port = Cell(port.take());
do (|| {
let port = port.take();
// The weak task service is itself a weak task
debug!("weakening the weak service task");
unsafe { rust_dec_kernel_live_count(); }
run_weak_task_service(port);
}).finally {
debug!("unweakening the weak service task");
unsafe { rust_inc_kernel_live_count(); }
}
}
do at_exit {
debug!("shutting down weak task service");
chan.send(Shutdown);
}
return ~chan_clone;
}
fn run_weak_task_service(port: Port<ServiceMsg>) {
let mut shutdown_map = LinearMap::new();
loop {
match port.recv() {
RegisterWeakTask(task, shutdown_chan) => {
let previously_unregistered =
shutdown_map.insert(task, shutdown_chan);
assert!(previously_unregistered);
}
UnregisterWeakTask(task) => {
match shutdown_map.pop(&task) {
Some(shutdown_chan) => {
// Oneshot pipes must send, even though
// nobody will receive this
shutdown_chan.send(());
}
None => fail!()
}
}
Shutdown => break
}
}
do shutdown_map.consume |_, shutdown_chan| {
// Weak task may have already exited
shutdown_chan.send(());
}
}
extern {
unsafe fn rust_inc_kernel_live_count();
unsafe fn rust_dec_kernel_live_count();
}
#[test]
fn test_simple() {
let (port, chan) = stream();
do spawn {
unsafe {
do weaken_task |_signal| {
}
}
chan.send(());
}
port.recv();
}
#[test]
fn test_weak_weak() {
let (port, chan) = stream();
do spawn {
unsafe {
do weaken_task |_signal| {
}
do weaken_task |_signal| {
}
}
chan.send(());
}
port.recv();
}
#[test]
fn test_wait_for_signal() {
do spawn {
unsafe {
do weaken_task |signal| {
signal.recv();
}
}
}
}
#[test]
fn test_wait_for_signal_many() {
use uint;
for uint::range(0, 100) |_| {
do spawn {
unsafe {
do weaken_task |signal| {
signal.recv();
}
}
}
}
}
#[test]
fn test_select_stream_and_oneshot() {
use comm::select2i;
use either::{Left, Right};
let (port, chan) = stream();
let (waitport, waitchan) = stream();
do spawn {
unsafe {
do weaken_task |signal| {
match select2i(&port, &signal) {
Left(*) => (),
Right(*) => fail!()
}
}
}
waitchan.send(());
}
chan.send(());
waitport.recv();
}
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