rust/src/libstd/uv_iotask.rs

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// Copyright 2012 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.
/*!
* A task-based interface to the uv loop
*
* The I/O task runs in its own single-threaded scheduler. By using the
* `interact` function you can execute code in a uv callback.
*/
#[forbid(deprecated_mode)];
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use ll = uv_ll;
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use core::libc::c_void;
use core::libc;
use core::pipes::{stream, Port, Chan, SharedChan};
use core::prelude::*;
use core::ptr::addr_of;
use core::task::TaskBuilder;
use core::task;
/// Used to abstract-away direct interaction with a libuv loop.
pub enum IoTask {
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IoTask_({
async_handle: *ll::uv_async_t,
op_chan: SharedChan<IoTaskMsg>
})
}
impl IoTask: Clone {
fn clone(&self) -> IoTask {
IoTask_({
async_handle: self.async_handle,
op_chan: self.op_chan.clone()
})
}
}
pub fn spawn_iotask(task: task::TaskBuilder) -> IoTask {
let (iotask_port, iotask_chan) = stream();
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do task.sched_mode(task::SingleThreaded).spawn {
debug!("entering libuv task");
run_loop(&iotask_chan);
debug!("libuv task exiting");
};
iotask_port.recv()
}
/**
* Provide a callback to be processed by `iotask`
*
* The primary way to do operations again a running `iotask` that
* doesn't involve creating a uv handle via `safe_handle`
*
* # Warning
*
* This function is the only safe way to interact with _any_ `iotask`.
* Using functions in the `uv::ll` module outside of the `cb` passed into
* this function is _very dangerous_.
*
* # Arguments
*
* * iotask - a uv I/O task that you want to do operations against
* * cb - a function callback to be processed on the running loop's
* thread. The only parameter passed in is an opaque pointer representing the
* running `uv_loop_t*`. In the context of this callback, it is safe to use
* this pointer to do various uv_* API calls contained within the `uv::ll`
* module. It is not safe to send the `loop_ptr` param to this callback out
* via ports/chans.
*/
pub unsafe fn interact(iotask: &IoTask,
cb: fn~(*c_void)) {
send_msg(iotask, Interaction(move cb));
}
/**
* Shut down the I/O task
*
* Is used to signal to the loop that it should close the internally-held
* async handle and do a sanity check to make sure that all other handles are
* closed, causing a failure otherwise.
*/
pub fn exit(iotask: &IoTask) {
unsafe {
send_msg(iotask, TeardownLoop);
}
}
// INTERNAL API
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enum IoTaskMsg {
Interaction (fn~(*libc::c_void)),
TeardownLoop
}
/// Run the loop and begin handling messages
fn run_loop(iotask_ch: &Chan<IoTask>) {
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unsafe {
debug!("creating loop");
let loop_ptr = ll::loop_new();
// set up the special async handle we'll use to allow multi-task
// communication with this loop
let async = ll::async_t();
let async_handle = addr_of(&async);
// associate the async handle with the loop
ll::async_init(loop_ptr, async_handle, wake_up_cb);
let (msg_po, msg_ch) = stream::<IoTaskMsg>();
// initialize our loop data and store it in the loop
let data: IoTaskLoopData = IoTaskLoopData {
async_handle: async_handle,
msg_po: msg_po
};
ll::set_data_for_uv_handle(async_handle, addr_of(&data));
// Send out a handle through which folks can talk to us
// while we dwell in the I/O loop
let iotask = IoTask_({
async_handle: async_handle,
op_chan: SharedChan(msg_ch)
});
iotask_ch.send(iotask);
log(debug, ~"about to run uv loop");
// enter the loop... this blocks until the loop is done..
ll::run(loop_ptr);
log(debug, ~"uv loop ended");
ll::loop_delete(loop_ptr);
}
}
// data that lives for the lifetime of the high-evel oo
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struct IoTaskLoopData {
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async_handle: *ll::uv_async_t,
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msg_po: Port<IoTaskMsg>,
}
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fn send_msg(iotask: &IoTask,
msg: IoTaskMsg) {
iotask.op_chan.send(move msg);
unsafe {
ll::async_send(iotask.async_handle);
}
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}
/// Dispatch all pending messages
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extern fn wake_up_cb(async_handle: *ll::uv_async_t,
status: int) {
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log(debug, fmt!("wake_up_cb extern.. handle: %? status: %?",
async_handle, status));
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unsafe {
let loop_ptr = ll::get_loop_for_uv_handle(async_handle);
let data =
ll::get_data_for_uv_handle(async_handle) as *IoTaskLoopData;
let msg_po = &(*data).msg_po;
while msg_po.peek() {
match msg_po.recv() {
Interaction(ref cb) => (*cb)(loop_ptr),
TeardownLoop => begin_teardown(data)
}
}
}
}
fn begin_teardown(data: *IoTaskLoopData) {
unsafe {
log(debug, ~"iotask begin_teardown() called, close async_handle");
let async_handle = (*data).async_handle;
ll::close(async_handle as *c_void, tear_down_close_cb);
}
}
extern fn tear_down_close_cb(handle: *ll::uv_async_t) {
unsafe {
let loop_ptr = ll::get_loop_for_uv_handle(handle);
let loop_refs = ll::loop_refcount(loop_ptr);
log(debug,
fmt!("tear_down_close_cb called, closing handle at %? refs %?",
handle, loop_refs));
assert loop_refs == 1i32;
}
}
#[cfg(test)]
mod test {
use core::prelude::*;
use uv::ll;
use uv_iotask::*;
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use core::iter;
use core::libc;
use core::oldcomm;
use core::ptr;
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use core::task;
extern fn async_close_cb(handle: *ll::uv_async_t) {
unsafe {
log(debug, fmt!("async_close_cb handle %?", handle));
let exit_ch = (*(ll::get_data_for_uv_handle(handle)
as *AhData)).exit_ch;
oldcomm::send(exit_ch, ());
}
}
extern fn async_handle_cb(handle: *ll::uv_async_t, status: libc::c_int) {
unsafe {
log(debug,
fmt!("async_handle_cb handle %? status %?",handle,status));
ll::close(handle, async_close_cb);
}
}
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struct AhData {
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iotask: IoTask,
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exit_ch: oldcomm::Chan<()>
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}
fn impl_uv_iotask_async(iotask: &IoTask) {
unsafe {
let async_handle = ll::async_t();
let ah_ptr = ptr::addr_of(&async_handle);
let exit_po = oldcomm::Port::<()>();
let exit_ch = oldcomm::Chan(&exit_po);
let ah_data = AhData {
iotask: iotask.clone(),
exit_ch: exit_ch
};
let ah_data_ptr: *AhData = unsafe {
ptr::to_unsafe_ptr(&ah_data)
};
debug!("about to interact");
do interact(iotask) |loop_ptr| {
unsafe {
debug!("interacting");
ll::async_init(loop_ptr, ah_ptr, async_handle_cb);
ll::set_data_for_uv_handle(
ah_ptr, ah_data_ptr as *libc::c_void);
ll::async_send(ah_ptr);
}
};
debug!("waiting for async close");
oldcomm::recv(exit_po);
}
}
// this fn documents the bear minimum neccesary to roll your own
// high_level_loop
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unsafe fn spawn_test_loop(exit_ch: oldcomm::Chan<()>) -> IoTask {
let (iotask_port, iotask_ch) = stream::<IoTask>();
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do task::spawn_sched(task::ManualThreads(1u)) {
debug!("about to run a test loop");
run_loop(&iotask_ch);
exit_ch.send(());
};
return iotask_port.recv();
}
extern fn lifetime_handle_close(handle: *libc::c_void) {
unsafe {
log(debug, fmt!("lifetime_handle_close ptr %?", handle));
}
}
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extern fn lifetime_async_callback(handle: *libc::c_void,
status: libc::c_int) {
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log(debug, fmt!("lifetime_handle_close ptr %? status %?",
handle, status));
}
#[test]
fn test_uv_iotask_async() {
unsafe {
let exit_po = oldcomm::Port::<()>();
let exit_ch = oldcomm::Chan(&exit_po);
let iotask = &spawn_test_loop(exit_ch);
debug!("spawned iotask");
// using this handle to manage the lifetime of the
// high_level_loop, as it will exit the first time one of
// the impl_uv_hl_async() is cleaned up with no one ref'd
// handles on the loop (Which can happen under
// race-condition type situations.. this ensures that the
// loop lives until, at least, all of the
// impl_uv_hl_async() runs have been called, at least.
let work_exit_po = oldcomm::Port::<()>();
let work_exit_ch = oldcomm::Chan(&work_exit_po);
for iter::repeat(7u) {
let iotask_clone = iotask.clone();
do task::spawn_sched(task::ManualThreads(1u)) {
debug!("async");
impl_uv_iotask_async(&iotask_clone);
debug!("done async");
oldcomm::send(work_exit_ch, ());
};
};
for iter::repeat(7u) {
debug!("waiting");
oldcomm::recv(work_exit_po);
};
log(debug, ~"sending teardown_loop msg..");
exit(iotask);
oldcomm::recv(exit_po);
log(debug, ~"after recv on exit_po.. exiting..");
}
}
}