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

7 files changed, 201 insertions, 13 deletions

diff --git a/base/SConscript b/base/SConscript
index b8d9da9..a23672d 100644
--- a/base/SConscript
+++ b/base/SConscript
@@ -137,6 +137,7 @@ if env['PLATFORM'] in ('darwin', 'linux2'):
       'lock_impl_posix.cc',
       'thread_posix.cc',
       'thread_local_storage_posix.cc',
+      'waitable_event_generic.cc',
   ])
 
 env.ChromeStaticLibrary('base', input_files)
@@ -249,6 +250,7 @@ test_files = [
     'time_unittest.cc',
     'timer_unittest.cc',
     'values_unittest.cc',
+    'waitable_event_unittest.cc',
     'win_util_unittest.cc',
     'word_iterator_unittest.cc',
     'wmi_util_unittest.cc',
diff --git a/base/build/base_unittests.vcproj b/base/build/base_unittests.vcproj
index 9c56e25..648cd17 100644
--- a/base/build/base_unittests.vcproj
+++ b/base/build/base_unittests.vcproj
@@ -328,6 +328,10 @@
 				>
 			</File>
 			<File
+				RelativePath="..\waitable_event_unittest.cc"
+				>
+			</File>
+			<File
 				RelativePath="..\watchdog_test.cc"
 				>
 			</File>
diff --git a/base/thread.cc b/base/thread.cc
index 0a19a16..ab79a9a 100644
--- a/base/thread.cc
+++ b/base/thread.cc
@@ -36,6 +36,7 @@
 #include "base/object_watcher.h"
 #include "base/ref_counted.h"
 #include "base/string_util.h"
+#include "base/waitable_event.h"
 #include "base/win_util.h"
 
 namespace {
@@ -46,15 +47,9 @@ namespace {
 class ThreadStartInfo : public base::RefCountedThreadSafe<ThreadStartInfo> {
  public:
   Thread* self;
-  HANDLE start_event;
+  base::WaitableEvent start_event;
 
-  explicit ThreadStartInfo(Thread* t)
-      : self(t),
-        start_event(CreateEvent(NULL, FALSE, FALSE, NULL)) {
-  }
-
-  ~ThreadStartInfo() {
-    CloseHandle(start_event);
+  explicit ThreadStartInfo(Thread* t) : self(t), start_event(false, false) {
   }
 };
 
@@ -170,7 +165,7 @@ bool Thread::StartWithStackSize(size_t stack_size) {
   }
 
   // Wait for the thread to start and initialize message_loop_
-  WaitForSingleObject(info->start_event, INFINITE);
+  info->start_event.Wait();
   return true;
 }
 
@@ -232,7 +227,7 @@ unsigned __stdcall Thread::ThreadFunc(void* param) {
     self->message_loop_ = &message_loop;
     SetThreadName(self->thread_name().c_str(), GetCurrentThreadId());
     message_loop.SetThreadName(self->thread_name());
-    SetEvent(info->start_event);
+    info->start_event.Signal();
   }
 
   // Let the thread do extra initialization.
diff --git a/base/waitable_event.h b/base/waitable_event.h
index 778dabf..be0cd68 100644
--- a/base/waitable_event.h
+++ b/base/waitable_event.h
@@ -30,12 +30,17 @@
 #ifndef BASE_WAITABLE_EVENT_H_
 #define BASE_WAITABLE_EVENT_H_
 
-#include "base/time.h"
+#include "base/basictypes.h"
 
 #if defined(OS_WIN)
 typedef void* HANDLE;
+#else
+#include "base/condition_variable.h"
+#include "base/lock.h"
 #endif
 
+class TimeDelta;
+
 namespace base {
 
 // A WaitableEvent can be a useful thread synchronization tool when you want to
@@ -71,7 +76,8 @@ class WaitableEvent {
   // to be woken up.
   void Signal();
 
-  // Returns true if the event is in the signaled state, else false.
+  // Returns true if the event is in the signaled state, else false.  If this
+  // is not a manual reset event, then this test will cause a reset.
   bool IsSignaled();
 
   // Wait indefinitely for the event to be signaled.  Returns true if the event
@@ -86,7 +92,14 @@ class WaitableEvent {
  private:
 #if defined(OS_WIN)
   HANDLE event_;
+#else
+  Lock lock_;  // Needs to be listed first so it will be constructed first.
+  ConditionVariable cvar_;
+  bool signaled_;
+  bool manual_reset_;
 #endif
+
+  DISALLOW_COPY_AND_ASSIGN(WaitableEvent);
 };
 
 }  // namespace base
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
diff --git a/base/waitable_event_unittest.cc b/base/waitable_event_unittest.cc
new file mode 100644
index 0000000..c35bd2eb
--- /dev/null
+++ b/base/waitable_event_unittest.cc
@@ -0,0 +1,77 @@
+// 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/time.h"
+#include "base/waitable_event.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using base::WaitableEvent;
+
+namespace {
+typedef testing::Test WaitableEventTest;
+}
+
+TEST(WaitableEventTest, ManualBasics) {
+  WaitableEvent event(true, false);
+
+  EXPECT_FALSE(event.IsSignaled());
+
+  event.Signal();
+  EXPECT_TRUE(event.IsSignaled());
+  EXPECT_TRUE(event.IsSignaled());
+
+  event.Reset();
+  EXPECT_FALSE(event.IsSignaled());
+  EXPECT_FALSE(event.TimedWait(TimeDelta::FromMilliseconds(10)));
+
+  event.Signal();
+  EXPECT_TRUE(event.Wait());
+  EXPECT_TRUE(event.TimedWait(TimeDelta::FromMilliseconds(10)));
+}
+
+TEST(WaitableEventTest, AutoBasics) {
+  WaitableEvent event(false, false);
+
+  EXPECT_FALSE(event.IsSignaled());
+
+  event.Signal();
+  EXPECT_TRUE(event.IsSignaled());
+  EXPECT_FALSE(event.IsSignaled());
+
+  event.Reset();
+  EXPECT_FALSE(event.IsSignaled());
+  EXPECT_FALSE(event.TimedWait(TimeDelta::FromMilliseconds(10)));
+
+  event.Signal();
+  EXPECT_TRUE(event.Wait());
+  EXPECT_FALSE(event.TimedWait(TimeDelta::FromMilliseconds(10)));
+
+  event.Signal();
+  EXPECT_TRUE(event.TimedWait(TimeDelta::FromMilliseconds(10)));
+}
diff --git a/base/waitable_event_win.cc b/base/waitable_event_win.cc
index 58fbfde..da2d2d8 100644
--- a/base/waitable_event_win.cc
+++ b/base/waitable_event_win.cc
@@ -30,7 +30,9 @@
 #include "base/waitable_event.h"
 
 #include <windows.h>
+
 #include "base/logging.h"
+#include "base/time.h"
 
 namespace base {
 
@@ -78,7 +80,6 @@ bool WaitableEvent::TimedWait(const TimeDelta& max_time) {
   // about it if it should ever fail.
   NOTREACHED() << "WaitForSingleObject failed";
   return false;
-
 }
 
 }  // namespace base