Handle failure conditions correctly in pipes.

Author: eholk

src/libcore/pipes.rs

@@ -47,7 +47,7 @@ extern mod rustrt {
     #[rust_stack]
     fn task_clear_event_reject(task: *rust_task);
 
-    fn task_wait_event(this: *rust_task) -> *libc::c_void;
+    fn task_wait_event(this: *rust_task, killed: &mut bool) -> *libc::c_void;
     fn task_signal_event(target: *rust_task, event: *libc::c_void);
 }
 
@@ -57,6 +57,16 @@ unsafe fn uniquify<T>(x: *T) -> ~T {
     unsafe { unsafe::reinterpret_cast(x) }
 }
 
+fn wait_event(this: *rust_task) -> *libc::c_void {
+    let mut killed = false;
+
+    let res = rustrt::task_wait_event(this, &mut killed);
+    if killed && !task::failing() {
+        fail "killed"
+    }
+    res
+}
+
 fn swap_state_acq(&dst: state, src: state) -> state {
     unsafe {
         reinterpret_cast(rusti::atomic_xchng_acq(
@@ -113,23 +123,23 @@ fn recv<T: send>(-p: recv_packet<T>) -> option<T> {
     let this = rustrt::rust_get_task();
     rustrt::task_clear_event_reject(this);
     p.header.blocked_task = some(this);
+    let mut first = true;
     loop {
+        rustrt::task_clear_event_reject(this);
         let old_state = swap_state_acq(p.header.state,
                                        blocked);
         #debug("%?", old_state);
         alt old_state {
           empty {
             #debug("no data available on %?, going to sleep.", p_);
-            rustrt::task_wait_event(this);
+            wait_event(this);
             #debug("woke up, p.state = %?", p.header.state);
-            if p.header.state == full {
-                let mut payload = none;
-                payload <-> (*p).payload;
-                p.header.state = terminated;
-                ret some(option::unwrap(payload))
+          }
+          blocked {
+            if first {
+                fail "blocking on already blocked packet"
             }
           }
-          blocked { fail "blocking on already blocked packet" }
           full {
             let mut payload = none;
             payload <-> (*p).payload;
@@ -141,11 +151,12 @@ fn recv<T: send>(-p: recv_packet<T>) -> option<T> {
             ret none;
           }
         }
+        first = false;
     }
 }
 
 /// Returns true if messages are available.
-fn peek<T: send>(p: recv_packet<T>) -> bool {
+pure fn peek<T: send>(p: recv_packet<T>) -> bool {
     alt p.header().state {
       empty { false }
       blocked { fail "peeking on blocked packet" }
@@ -236,7 +247,7 @@ fn wait_many(pkts: ~[&a.packet_header]) -> uint {
 
     while !data_avail {
         #debug("sleeping on %? packets", pkts.len());
-        let event = rustrt::task_wait_event(this) as *packet_header;
+        let event = wait_event(this) as *packet_header;
         let pos = vec::position(pkts, |p| ptr::addr_of(*p) == event);
 
         alt pos {
@@ -356,7 +367,7 @@ class recv_packet<T: send> {
         option::unwrap(p)
     }
 
-    fn header() -> &self.packet_header {
+    pure fn header() -> &self.packet_header {
         alt self.p {
           some(packet) {
             unsafe {

src/libcore/task.rs

@@ -46,6 +46,7 @@ export future_result;
 export future_task;
 export unsupervise;
 export run_listener;
+export run_with;
 
 export spawn;
 export spawn_with;

src/rt/rust_builtin.cpp

@@ -930,11 +930,11 @@ task_clear_event_reject(rust_task *task) {
 // Waits on an event, returning the pointer to the event that unblocked this
 // task.
 extern "C" void *
-task_wait_event(rust_task *task) {
+task_wait_event(rust_task *task, bool *killed) {
     // TODO: we should assert that the passed in task is the currently running
     // task. We wouldn't want to wait some other task.
 
-    return task->wait_event();
+    return task->wait_event(killed);
 }
 
 extern "C" void

src/rt/rust_task.cpp

@@ -713,16 +713,14 @@ rust_task::allow_kill() {
 }
 
 void *
-rust_task::wait_event() {
+rust_task::wait_event(bool *killed) {
     scoped_lock with(state_lock);
 
     if(!event_reject) {
         block_locked(&event_cond, "waiting on event");
-        bool killed = false;
         state_lock.unlock();
-        yield(&killed);
+        yield(killed);
         state_lock.lock();
-        // TODO: what is the right thing to do if we are killed?
     }
 
     event_reject = false;

src/rt/rust_task.h

@@ -316,7 +316,7 @@ rust_task : public kernel_owned<rust_task>, rust_cond
         this->event_reject = false;
     }
 
-    void *wait_event();
+    void *wait_event(bool *killed);
     void signal_event(void *event);
 
     void cleanup_after_turn();

src/test/run-pass/pipe-detect-term.rs

@@ -26,5 +26,24 @@ fn main() {
         }
     });
 
-    sleep(iotask, 1000);
+    sleep(iotask, 100);
+
+    let b = task::builder();
+    task::unsupervise(b);
+    task::run(b, failtest);
+}
+
+// Make sure the right thing happens during failure.
+fn failtest() {
+    let iotask = uv::global_loop::get();
+    
+    let (c, p) = oneshot::init();
+
+    do task::spawn_with(c) |_c| { 
+        fail;
+    }
+
+    #error("%?", recv(p));
+    // make sure we get killed if we missed it in the receive.
+    loop { task::yield() }
 }