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