Fixed a problem with spurious wakeups.

runtime/vm/thread.h

Index: runtime/vm/thread.h
diff --git a/runtime/vm/thread.h b/runtime/vm/thread.h
index 1ef4f299aa240c6136c8026b666d52b87ded2f25..996da30ffb6e5015dac22bd5da5eb9dbc1a9987b 100644
--- a/runtime/vm/thread.h
+++ b/runtime/vm/thread.h
@@ -2,8 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-#ifndef VM_THREAD_H_
-#define VM_THREAD_H_
+#ifndef RUNTIME_VM_THREAD_H_
+#define RUNTIME_VM_THREAD_H_

[siva, 2011/10/21 21:18:33]

Why did you change this? If you look at all the other header files you will see
a uniform pattern and we need to stick to that.

[jrgfogh, 2011/10/24 09:20:42]

A presubmit script told me to do it when I tried to upload the CL. It was based
on some version of lint.

[Søren Gjesse, 2011/10/26 12:07:10]

That is annoying. When this error is the only one the presubmit script gives run
it wiht --bypass_hooks to upload anyway.

 
 #include "vm/assert.h"
 #include "vm/allocation.h"
@@ -70,6 +70,7 @@ class Monitor {
   void Exit();
 
   // Wait for notification or timeout.
+  // May return too early due to spurious wakeups. Callers should test for this.

[siva, 2011/10/21 21:18:33]

I think this comment is not necessary.

[jrgfogh, 2011/10/24 09:20:42]

I disagree, since it affects the semantics. I would normally expect a class
Monitor to have correct monitor semantics, which this one doesn't.

   WaitResult Wait(int64_t millis);
 
   // Notify waiting threads.
@@ -118,6 +119,7 @@ class MonitorLocker : public StackResource {
     // TODO(iposva): Consider decrementing the no GC scope here.
   }
 
+  // May return too early due to spurious wakeups. Callers should test for this.

[siva, 2011/10/21 21:18:33]

Ditto.

[jrgfogh, 2011/10/24 09:20:42]

Ditto.

   Monitor::WaitResult Wait(int64_t millis = Monitor::kNoTimeout) {
     return monitor_->Wait(millis);
   }
@@ -139,4 +141,4 @@ class MonitorLocker : public StackResource {
 }  // namespace dart
 
 
-#endif  // VM_THREAD_H_
+#endif  // RUNTIME_VM_THREAD_H_

[siva, 2011/10/21 21:18:33]

ditto.

[jrgfogh, 2011/10/24 09:20:42]

ditto.