Provide cross-platform implementation of WaitableEvent for use on Mac and Linux.

I gave the file the suffix _generic since it is implemented entirely in terms of other APIs in base.

This CL also adds a simple unit test for WaitableEvent, and I switched some code in thread.cc over to using WaitableEvent.


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@648 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 96 insertions, 0 deletions

diff --git a/base/waitable_event_generic.cc b/base/waitable_event_generic.cc
new file mode 100644
index 0000000..f036f8d
--- /dev/null
+++ b/base/waitable_event_generic.cc
@@ -0,0 +1,96 @@
+// Copyright 2008, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//    * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//    * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//    * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "base/waitable_event.h"
+
+namespace base {
+
+WaitableEvent::WaitableEvent(bool manual_reset, bool signaled)
+    : lock_(),
+      cvar_(&lock_),
+      signaled_(signaled),
+      manual_reset_(manual_reset) {
+}
+
+WaitableEvent::~WaitableEvent() {
+  // Members are destroyed in the reverse of their initialization order, so we
+  // should not have to worry about lock_ being destroyed before cvar_.
+}
+
+void WaitableEvent::Reset() {
+  AutoLock locked(lock_);
+  signaled_ = false;
+}
+
+void WaitableEvent::Signal() {
+  AutoLock locked(lock_);
+  if (!signaled_) {
+    signaled_ = true;
+    if (manual_reset_) {
+      cvar_.Broadcast(); 
+    } else {
+      cvar_.Signal();
+    }
+  }
+}
+
+bool WaitableEvent::IsSignaled() {
+  return TimedWait(TimeDelta::FromMilliseconds(0));
+}
+
+bool WaitableEvent::Wait() {
+  AutoLock locked(lock_);
+  while (!signaled_)
+    cvar_.Wait();
+  if (!manual_reset_)
+    signaled_ = false;
+  return true;
+}
+
+bool WaitableEvent::TimedWait(const TimeDelta& max_time) {
+  AutoLock locked(lock_);
+  // In case of spurious wake-ups, we need to adjust the amount of time that we
+  // spend sleeping.
+  TimeDelta total_time;
+  for (;;) {
+    TimeTicks start = TimeTicks::Now();
+    cvar_.TimedWait(max_time - total_time);
+    if (signaled_)
+      break;
+    total_time += TimeTicks::Now() - start;
+    if (total_time >= max_time)
+      break;
+  }
+  bool result = signaled_;
+  if (!manual_reset_)
+    signaled_ = false;
+  return result;
+}
+
+}  // namespace base