687 lines
21 KiB
Rust
687 lines
21 KiB
Rust
// NB: transitionary, de-mode-ing.
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// tjc: Re-forbid deprecated modes once a snapshot fixes the
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// function problem
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#[forbid(deprecated_pattern)];
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#[doc(hidden)];
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use task::TaskBuilder;
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use task::atomically;
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extern mod rustrt {
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#[legacy_exports];
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fn rust_task_weaken(ch: rust_port_id);
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fn rust_task_unweaken(ch: rust_port_id);
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#[rust_stack]
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fn rust_compare_and_swap_ptr(address: &mut libc::uintptr_t,
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oldval: libc::uintptr_t,
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newval: libc::uintptr_t) -> bool;
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fn rust_create_little_lock() -> rust_little_lock;
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fn rust_destroy_little_lock(lock: rust_little_lock);
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fn rust_lock_little_lock(lock: rust_little_lock);
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fn rust_unlock_little_lock(lock: rust_little_lock);
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}
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#[abi = "rust-intrinsic"]
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extern mod rusti {
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#[cfg(stage1)] #[cfg(stage2)] #[cfg(stage3)]
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fn atomic_cxchg(dst: &mut int, old: int, src: int) -> int;
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fn atomic_xadd(dst: &mut int, src: int) -> int;
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fn atomic_xsub(dst: &mut int, src: int) -> int;
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}
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#[allow(non_camel_case_types)] // runtime type
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type rust_port_id = uint;
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type GlobalPtr = *libc::uintptr_t;
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// FIXME #3527: Remove once snapshots have atomic_cxchg
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#[cfg(stage0)]
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fn compare_and_swap(address: &mut libc::uintptr_t,
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oldval: libc::uintptr_t,
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newval: libc::uintptr_t) -> bool {
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rustrt::rust_compare_and_swap_ptr(address, oldval, newval)
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}
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#[cfg(stage1)]
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#[cfg(stage2)]
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#[cfg(stage3)]
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fn compare_and_swap(address: &mut int, oldval: int, newval: int) -> bool {
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let old = rusti::atomic_cxchg(address, oldval, newval);
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old == oldval
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}
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/**
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* Atomically gets a channel from a pointer to a pointer-sized memory location
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* or, if no channel exists creates and installs a new channel and sets up a
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* new task to receive from it.
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*/
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pub unsafe fn chan_from_global_ptr<T: Send>(
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global: GlobalPtr,
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task_fn: fn() -> task::TaskBuilder,
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f: fn~(comm::Port<T>)
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) -> comm::Chan<T> {
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enum Msg {
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Proceed,
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Abort
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}
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log(debug,~"ENTERING chan_from_global_ptr, before is_prob_zero check");
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let is_probably_zero = *global == 0u;
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log(debug,~"after is_prob_zero check");
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if is_probably_zero {
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log(debug,~"is probably zero...");
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// There's no global channel. We must make it
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let (setup_po, setup_ch) = do task_fn().spawn_conversation
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|move f, setup_po, setup_ch| {
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let po = comm::Port::<T>();
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let ch = comm::Chan(&po);
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comm::send(setup_ch, ch);
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// Wait to hear if we are the official instance of
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// this global task
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match comm::recv::<Msg>(setup_po) {
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Proceed => f(move po),
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Abort => ()
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}
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};
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log(debug,~"before setup recv..");
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// This is the proposed global channel
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let ch = comm::recv(setup_po);
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// 0 is our sentinal value. It is not a valid channel
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assert *ch != 0;
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// Install the channel
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log(debug,~"BEFORE COMPARE AND SWAP");
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let swapped = compare_and_swap(
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cast::reinterpret_cast(&global),
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0, cast::reinterpret_cast(&ch));
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log(debug,fmt!("AFTER .. swapped? %?", swapped));
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if swapped {
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// Success!
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comm::send(setup_ch, Proceed);
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ch
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} else {
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// Somebody else got in before we did
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comm::send(setup_ch, Abort);
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cast::reinterpret_cast(&*global)
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}
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} else {
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log(debug, ~"global != 0");
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cast::reinterpret_cast(&*global)
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}
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}
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#[test]
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pub fn test_from_global_chan1() {
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// This is unreadable, right?
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// The global channel
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let globchan = 0;
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let globchanp = ptr::addr_of(&globchan);
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// Create the global channel, attached to a new task
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let ch = unsafe {
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do chan_from_global_ptr(globchanp, task::task) |po| {
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let ch = comm::recv(po);
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comm::send(ch, true);
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let ch = comm::recv(po);
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comm::send(ch, true);
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}
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};
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// Talk to it
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let po = comm::Port();
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comm::send(ch, comm::Chan(&po));
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assert comm::recv(po) == true;
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// This one just reuses the previous channel
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let ch = unsafe {
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do chan_from_global_ptr(globchanp, task::task) |po| {
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let ch = comm::recv(po);
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comm::send(ch, false);
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}
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};
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// Talk to the original global task
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let po = comm::Port();
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comm::send(ch, comm::Chan(&po));
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assert comm::recv(po) == true;
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}
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#[test]
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pub fn test_from_global_chan2() {
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for iter::repeat(100) {
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// The global channel
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let globchan = 0;
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let globchanp = ptr::addr_of(&globchan);
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let resultpo = comm::Port();
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let resultch = comm::Chan(&resultpo);
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// Spawn a bunch of tasks that all want to compete to
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// create the global channel
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for uint::range(0, 10) |i| {
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do task::spawn {
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let ch = unsafe {
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do chan_from_global_ptr(
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globchanp, task::task) |po| {
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for uint::range(0, 10) |_j| {
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let ch = comm::recv(po);
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comm::send(ch, {i});
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}
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}
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};
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let po = comm::Port();
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comm::send(ch, comm::Chan(&po));
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// We are The winner if our version of the
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// task was installed
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let winner = comm::recv(po);
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comm::send(resultch, winner == i);
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}
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}
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// There should be only one winner
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let mut winners = 0u;
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for uint::range(0u, 10u) |_i| {
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let res = comm::recv(resultpo);
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if res { winners += 1u };
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}
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assert winners == 1u;
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}
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}
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/**
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* Convert the current task to a 'weak' task temporarily
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*
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* As a weak task it will not be counted towards the runtime's set
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* of live tasks. When there are no more outstanding live (non-weak) tasks
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* the runtime will send an exit message on the provided channel.
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*
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* This function is super-unsafe. Do not use.
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*
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* # Safety notes
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*
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* * Weak tasks must either die on their own or exit upon receipt of
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* the exit message. Failure to do so will cause the runtime to never
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* exit
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* * Tasks must not call `weaken_task` multiple times. This will
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* break the kernel's accounting of live tasks.
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* * Weak tasks must not be supervised. A supervised task keeps
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* a reference to its parent, so the parent will not die.
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*/
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pub unsafe fn weaken_task(f: fn(comm::Port<()>)) {
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let po = comm::Port();
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let ch = comm::Chan(&po);
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unsafe {
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rustrt::rust_task_weaken(cast::reinterpret_cast(&ch));
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}
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let _unweaken = Unweaken(ch);
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f(po);
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struct Unweaken {
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ch: comm::Chan<()>,
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drop unsafe {
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rustrt::rust_task_unweaken(cast::reinterpret_cast(&self.ch));
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}
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}
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fn Unweaken(ch: comm::Chan<()>) -> Unweaken {
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Unweaken {
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ch: ch
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}
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}
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}
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#[test]
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pub fn test_weaken_task_then_unweaken() {
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do task::try {
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unsafe {
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do weaken_task |_po| {
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}
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}
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};
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}
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#[test]
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pub fn test_weaken_task_wait() {
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do task::spawn_unlinked {
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unsafe {
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do weaken_task |po| {
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comm::recv(po);
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}
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}
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}
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}
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#[test]
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pub fn test_weaken_task_stress() {
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// Create a bunch of weak tasks
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for iter::repeat(100u) {
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do task::spawn {
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unsafe {
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do weaken_task |_po| {
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}
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}
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}
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do task::spawn_unlinked {
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unsafe {
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do weaken_task |po| {
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// Wait for it to tell us to die
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comm::recv(po);
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}
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}
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}
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}
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}
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#[test]
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#[ignore(cfg(windows))]
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pub fn test_weaken_task_fail() {
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let res = do task::try {
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unsafe {
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do weaken_task |_po| {
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fail;
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}
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}
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};
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assert result::is_err(&res);
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}
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/****************************************************************************
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* Shared state & exclusive ARC
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****************************************************************************/
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// An unwrapper uses this protocol to communicate with the "other" task that
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// drops the last refcount on an arc. Unfortunately this can't be a proper
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// pipe protocol because the unwrapper has to access both stages at once.
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type UnwrapProto = ~mut Option<(pipes::ChanOne<()>, pipes::PortOne<bool>)>;
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struct ArcData<T> {
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mut count: libc::intptr_t,
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mut unwrapper: libc::uintptr_t, // either a UnwrapProto or 0
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// FIXME(#3224) should be able to make this non-option to save memory, and
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// in unwrap() use "let ~ArcData { data: result, _ } = thing" to unwrap it
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mut data: Option<T>,
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}
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struct ArcDestruct<T> {
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mut data: *libc::c_void,
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drop unsafe {
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if self.data.is_null() {
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return; // Happens when destructing an unwrapper's handle.
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}
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do task::unkillable {
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let data: ~ArcData<T> = cast::reinterpret_cast(&self.data);
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let new_count = rusti::atomic_xsub(&mut data.count, 1) - 1;
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assert new_count >= 0;
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if new_count == 0 {
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// Were we really last, or should we hand off to an unwrapper?
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// It's safe to not xchg because the unwrapper will set the
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// unwrap lock *before* dropping his/her reference. In effect,
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// being here means we're the only *awake* task with the data.
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if data.unwrapper != 0 {
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let p: UnwrapProto =
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cast::reinterpret_cast(&data.unwrapper);
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let (message, response) = option::swap_unwrap(p);
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// Send 'ready' and wait for a response.
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pipes::send_one(move message, ());
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// Unkillable wait. Message guaranteed to come.
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if pipes::recv_one(move response) {
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// Other task got the data.
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cast::forget(move data);
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} else {
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// Other task was killed. drop glue takes over.
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}
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} else {
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// drop glue takes over.
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}
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} else {
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cast::forget(move data);
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}
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}
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}
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}
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fn ArcDestruct<T>(data: *libc::c_void) -> ArcDestruct<T> {
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ArcDestruct {
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data: data
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}
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}
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pub unsafe fn unwrap_shared_mutable_state<T: Send>(rc: SharedMutableState<T>)
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-> T {
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struct DeathThroes<T> {
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mut ptr: Option<~ArcData<T>>,
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mut response: Option<pipes::ChanOne<bool>>,
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drop unsafe {
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let response = option::swap_unwrap(&mut self.response);
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// In case we get killed early, we need to tell the person who
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// tried to wake us whether they should hand-off the data to us.
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if task::failing() {
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pipes::send_one(move response, false);
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// Either this swap_unwrap or the one below (at "Got here")
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// ought to run.
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cast::forget(option::swap_unwrap(&mut self.ptr));
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} else {
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assert self.ptr.is_none();
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pipes::send_one(move response, true);
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}
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}
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}
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do task::unkillable {
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let ptr: ~ArcData<T> = cast::reinterpret_cast(&rc.data);
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let (c1,p1) = pipes::oneshot(); // ()
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let (c2,p2) = pipes::oneshot(); // bool
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let server: UnwrapProto = ~mut Some((move c1,move p2));
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let serverp: libc::uintptr_t = cast::transmute(move server);
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// Try to put our server end in the unwrapper slot.
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if rustrt::rust_compare_and_swap_ptr(&mut ptr.unwrapper, 0, serverp) {
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// Got in. Step 0: Tell destructor not to run. We are now it.
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rc.data = ptr::null();
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// Step 1 - drop our own reference.
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let new_count = rusti::atomic_xsub(&mut ptr.count, 1) - 1;
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//assert new_count >= 0;
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if new_count == 0 {
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// We were the last owner. Can unwrap immediately.
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// Also we have to free the server endpoints.
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let _server: UnwrapProto = cast::transmute(move serverp);
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option::swap_unwrap(&mut ptr.data)
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// drop glue takes over.
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} else {
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// The *next* person who sees the refcount hit 0 will wake us.
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let end_result =
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DeathThroes { ptr: Some(move ptr),
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response: Some(move c2) };
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let mut p1 = Some(move p1); // argh
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do task::rekillable {
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pipes::recv_one(option::swap_unwrap(&mut p1));
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}
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// Got here. Back in the 'unkillable' without getting killed.
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// Recover ownership of ptr, then take the data out.
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let ptr = option::swap_unwrap(&mut end_result.ptr);
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option::swap_unwrap(&mut ptr.data)
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// drop glue takes over.
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}
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} else {
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// Somebody else was trying to unwrap. Avoid guaranteed deadlock.
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cast::forget(move ptr);
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// Also we have to free the (rejected) server endpoints.
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let _server: UnwrapProto = cast::transmute(move serverp);
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fail ~"Another task is already unwrapping this ARC!";
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}
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}
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}
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/**
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* COMPLETELY UNSAFE. Used as a primitive for the safe versions in std::arc.
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*
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* Data races between tasks can result in crashes and, with sufficient
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* cleverness, arbitrary type coercion.
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*/
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pub type SharedMutableState<T: Send> = ArcDestruct<T>;
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pub unsafe fn shared_mutable_state<T: Send>(data: T) ->
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SharedMutableState<T> {
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let data = ~ArcData { count: 1, unwrapper: 0, data: Some(move data) };
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unsafe {
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let ptr = cast::transmute(move data);
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ArcDestruct(ptr)
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}
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}
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#[inline(always)]
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pub unsafe fn get_shared_mutable_state<T: Send>(rc: &a/SharedMutableState<T>)
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-> &a/mut T {
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unsafe {
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let ptr: ~ArcData<T> = cast::reinterpret_cast(&(*rc).data);
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assert ptr.count > 0;
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// Cast us back into the correct region
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let r = cast::transmute_region(option::get_ref(&ptr.data));
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cast::forget(move ptr);
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return cast::transmute_mut(r);
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}
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}
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#[inline(always)]
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pub unsafe fn get_shared_immutable_state<T: Send>(
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rc: &a/SharedMutableState<T>) -> &a/T {
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unsafe {
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let ptr: ~ArcData<T> = cast::reinterpret_cast(&(*rc).data);
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assert ptr.count > 0;
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// Cast us back into the correct region
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let r = cast::transmute_region(option::get_ref(&ptr.data));
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cast::forget(move ptr);
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return r;
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}
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}
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pub unsafe fn clone_shared_mutable_state<T: Send>(rc: &SharedMutableState<T>)
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-> SharedMutableState<T> {
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unsafe {
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let ptr: ~ArcData<T> = cast::reinterpret_cast(&(*rc).data);
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let new_count = rusti::atomic_xadd(&mut ptr.count, 1) + 1;
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assert new_count >= 2;
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cast::forget(move ptr);
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}
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ArcDestruct((*rc).data)
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}
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/****************************************************************************/
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#[allow(non_camel_case_types)] // runtime type
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type rust_little_lock = *libc::c_void;
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struct LittleLock {
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l: rust_little_lock,
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drop { rustrt::rust_destroy_little_lock(self.l); }
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}
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fn LittleLock() -> LittleLock {
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LittleLock {
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l: rustrt::rust_create_little_lock()
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}
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}
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impl LittleLock {
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#[inline(always)]
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unsafe fn lock<T>(f: fn() -> T) -> T {
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struct Unlock {
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l: rust_little_lock,
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drop { rustrt::rust_unlock_little_lock(self.l); }
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}
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fn Unlock(l: rust_little_lock) -> Unlock {
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Unlock {
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l: l
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}
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}
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do atomically {
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rustrt::rust_lock_little_lock(self.l);
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let _r = Unlock(self.l);
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f()
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}
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}
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}
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struct ExData<T: Send> { lock: LittleLock, mut failed: bool, mut data: T, }
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/**
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* An arc over mutable data that is protected by a lock. For library use only.
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*/
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pub struct Exclusive<T: Send> { x: SharedMutableState<ExData<T>> }
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pub fn exclusive<T:Send >(user_data: T) -> Exclusive<T> {
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let data = ExData {
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lock: LittleLock(), mut failed: false, mut data: move user_data
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};
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Exclusive { x: unsafe { shared_mutable_state(move data) } }
|
|
}
|
|
|
|
impl<T: Send> Exclusive<T> {
|
|
// Duplicate an exclusive ARC, as std::arc::clone.
|
|
fn clone() -> Exclusive<T> {
|
|
Exclusive { x: unsafe { clone_shared_mutable_state(&self.x) } }
|
|
}
|
|
|
|
// Exactly like std::arc::mutex_arc,access(), but with the little_lock
|
|
// instead of a proper mutex. Same reason for being unsafe.
|
|
//
|
|
// Currently, scheduling operations (i.e., yielding, receiving on a pipe,
|
|
// accessing the provided condition variable) are prohibited while inside
|
|
// the exclusive. Supporting that is a work in progress.
|
|
#[inline(always)]
|
|
unsafe fn with<U>(f: fn(x: &mut T) -> U) -> U {
|
|
let rec = unsafe { get_shared_mutable_state(&self.x) };
|
|
do rec.lock.lock {
|
|
if rec.failed {
|
|
fail ~"Poisoned exclusive - another task failed inside!";
|
|
}
|
|
rec.failed = true;
|
|
let result = f(&mut rec.data);
|
|
rec.failed = false;
|
|
move result
|
|
}
|
|
}
|
|
|
|
#[inline(always)]
|
|
unsafe fn with_imm<U>(f: fn(x: &T) -> U) -> U {
|
|
do self.with |x| {
|
|
f(cast::transmute_immut(x))
|
|
}
|
|
}
|
|
}
|
|
|
|
// FIXME(#3724) make this a by-move method on the exclusive
|
|
pub fn unwrap_exclusive<T: Send>(arc: Exclusive<T>) -> T {
|
|
let Exclusive { x: x } = move arc;
|
|
let inner = unsafe { unwrap_shared_mutable_state(move x) };
|
|
let ExData { data: data, _ } = move inner;
|
|
move data
|
|
}
|
|
|
|
#[cfg(test)]
|
|
pub mod tests {
|
|
#[test]
|
|
pub fn exclusive_arc() {
|
|
let mut futures = ~[];
|
|
|
|
let num_tasks = 10;
|
|
let count = 10;
|
|
|
|
let total = exclusive(~mut 0);
|
|
|
|
for uint::range(0, num_tasks) |_i| {
|
|
let total = total.clone();
|
|
let (chan, port) = pipes::stream();
|
|
futures.push(move port);
|
|
|
|
do task::spawn |move total, move chan| {
|
|
for uint::range(0, count) |_i| {
|
|
do total.with |count| {
|
|
**count += 1;
|
|
}
|
|
}
|
|
chan.send(());
|
|
}
|
|
};
|
|
|
|
for futures.each |f| { f.recv() }
|
|
|
|
do total.with |total| {
|
|
assert **total == num_tasks * count
|
|
};
|
|
}
|
|
|
|
#[test] #[should_fail] #[ignore(cfg(windows))]
|
|
pub fn exclusive_poison() {
|
|
// Tests that if one task fails inside of an exclusive, subsequent
|
|
// accesses will also fail.
|
|
let x = exclusive(1);
|
|
let x2 = x.clone();
|
|
do task::try |move x2| {
|
|
do x2.with |one| {
|
|
assert *one == 2;
|
|
}
|
|
};
|
|
do x.with |one| {
|
|
assert *one == 1;
|
|
}
|
|
}
|
|
|
|
#[test]
|
|
pub fn exclusive_unwrap_basic() {
|
|
let x = exclusive(~~"hello");
|
|
assert unwrap_exclusive(move x) == ~~"hello";
|
|
}
|
|
|
|
#[test]
|
|
pub fn exclusive_unwrap_contended() {
|
|
let x = exclusive(~~"hello");
|
|
let x2 = ~mut Some(x.clone());
|
|
do task::spawn |move x2| {
|
|
let x2 = option::swap_unwrap(x2);
|
|
do x2.with |_hello| { }
|
|
task::yield();
|
|
}
|
|
assert unwrap_exclusive(move x) == ~~"hello";
|
|
|
|
// Now try the same thing, but with the child task blocking.
|
|
let x = exclusive(~~"hello");
|
|
let x2 = ~mut Some(x.clone());
|
|
let mut res = None;
|
|
do task::task().future_result(|+r| res = Some(move r)).spawn
|
|
|move x2| {
|
|
let x2 = option::swap_unwrap(x2);
|
|
assert unwrap_exclusive(move x2) == ~~"hello";
|
|
}
|
|
// Have to get rid of our reference before blocking.
|
|
{ let _x = move x; } // FIXME(#3161) util::ignore doesn't work here
|
|
let res = option::swap_unwrap(&mut res);
|
|
res.recv();
|
|
}
|
|
|
|
#[test] #[should_fail] #[ignore(cfg(windows))]
|
|
pub fn exclusive_unwrap_conflict() {
|
|
let x = exclusive(~~"hello");
|
|
let x2 = ~mut Some(x.clone());
|
|
let mut res = None;
|
|
do task::task().future_result(|+r| res = Some(move r)).spawn
|
|
|move x2| {
|
|
let x2 = option::swap_unwrap(x2);
|
|
assert unwrap_exclusive(move x2) == ~~"hello";
|
|
}
|
|
assert unwrap_exclusive(move x) == ~~"hello";
|
|
let res = option::swap_unwrap(&mut res);
|
|
res.recv();
|
|
}
|
|
|
|
#[test] #[ignore(cfg(windows))]
|
|
pub fn exclusive_unwrap_deadlock() {
|
|
// This is not guaranteed to get to the deadlock before being killed,
|
|
// but it will show up sometimes, and if the deadlock were not there,
|
|
// the test would nondeterministically fail.
|
|
let result = do task::try {
|
|
// a task that has two references to the same exclusive will
|
|
// deadlock when it unwraps. nothing to be done about that.
|
|
let x = exclusive(~~"hello");
|
|
let x2 = x.clone();
|
|
do task::spawn {
|
|
for 10.times { task::yield(); } // try to let the unwrapper go
|
|
fail; // punt it awake from its deadlock
|
|
}
|
|
let _z = unwrap_exclusive(move x);
|
|
do x2.with |_hello| { }
|
|
};
|
|
assert result.is_err();
|
|
}
|
|
}
|