From b16ef312cb28582a1d324d20e4328afeef2c7538 Mon Sep 17 00:00:00 2001
From: "darin@google.com"
 <darin@google.com@0039d316-1c4b-4281-b951-d872f2087c98>
Date: Tue, 19 Aug 2008 18:36:23 +0000
Subject: Define MessagePumpDefault and use it to implement MessageLoop on
 non-Windows platforms.  This is actually just a first-step toward the real
 fix which is to use MessagePumpDefault on all platforms on non-UI and non-IO
 threads.

This CL also fixes some GCC compilation errors.  I renamed MessageLoopOwnable
to TaskBase, which seems more appropriate since a MessageLoopOwnable has a
next Task pointer and clearly is only meaningful in the context of Task.  (I
wonder why it is even a separate class, but that is another issue.)  I had to
make the next_task / set_next_task methods public since they are used by an
inner class of MessageLoop.  Perhaps those inner classes should be made into
top-level classes, but that seemed like too much to change at this time.

R=jar,mmentovai

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@1045 0039d316-1c4b-4281-b951-d872f2087c98
---
 base/message_pump_default.cc | 100 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 base/message_pump_default.cc

(limited to 'base/message_pump_default.cc')

diff --git a/base/message_pump_default.cc b/base/message_pump_default.cc
new file mode 100644
index 0000000..916d035
--- /dev/null
+++ b/base/message_pump_default.cc
@@ -0,0 +1,100 @@
+// 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/message_pump_default.h"
+
+#include "base/logging.h"
+#include "base/time.h"
+
+namespace base {
+
+MessagePumpDefault::MessagePumpDefault()
+    : keep_running_(true),
+      event_(false, false) {
+}
+
+void MessagePumpDefault::Run(Delegate* delegate) {
+  DCHECK(keep_running_) << "Quit must have been called outside of Run!";
+
+  for (;;) {
+    bool did_work = delegate->DoWork();
+    if (!keep_running_)
+      break;
+    if (did_work)
+      continue;
+
+    // TODO(darin): Delayed work will be starved if DoWork continues to return
+    // true.  We should devise a better strategy.
+
+    TimeDelta delay;
+    did_work = delegate->DoDelayedWork(&delay);
+    if (!keep_running_)
+      break;
+    if (did_work)
+      continue;
+
+    did_work = delegate->DoIdleWork();
+    if (!keep_running_)
+      break;
+    if (did_work)
+      continue;
+    // When DoIdleWork does not work, we also assume that it ran very quickly
+    // such that |delay| still properly indicates how long we are to sleep.
+
+    if (delay < TimeDelta::FromMilliseconds(0)) {
+      event_.Wait();
+    } else {
+      event_.TimedWait(delay);
+    }
+    // Since event_ is auto-reset, we don't need to do anything special here
+    // other than service each delegate method.
+  }
+
+  keep_running_ = true;
+}
+
+void MessagePumpDefault::Quit() {
+  keep_running_ = false;
+}
+
+void MessagePumpDefault::ScheduleWork() {
+  // Since this can be called on any thread, we need to ensure that our Run
+  // loop wakes up.
+  event_.Signal();
+}
+
+void MessagePumpDefault::ScheduleDelayedWork(const TimeDelta& delay) {
+  // We know that we can't be blocked on Wait right now since this method can
+  // only be called on the same thread as Run, but to ensure that when we do
+  // sleep, we sleep for the right time, we signal the event to cause the Run
+  // loop to do one more iteration.
+  event_.Signal();
+}
+
+}  // namespace base
-- 
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