Adds a modified copy of talk/base to webrtc/base. It is the first step in migrating talk/base to webrtc/base.

BUG=N/A
R=andrew@webrtc.org, wu@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/12199004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6107 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/base/asyncinvoker.cc

@@ -0,0 +1,91 @@
+/*
+ *  Copyright 2014 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/base/asyncinvoker.h"
+
+namespace rtc {
+
+AsyncInvoker::AsyncInvoker() : destroying_(false) {}
+
+AsyncInvoker::~AsyncInvoker() {
+  destroying_ = true;
+  SignalInvokerDestroyed();
+  // Messages for this need to be cleared *before* our destructor is complete.
+  MessageQueueManager::Clear(this);
+}
+
+void AsyncInvoker::OnMessage(Message* msg) {
+  // Get the AsyncClosure shared ptr from this message's data.
+  ScopedRefMessageData<AsyncClosure>* data =
+      static_cast<ScopedRefMessageData<AsyncClosure>*>(msg->pdata);
+  scoped_refptr<AsyncClosure> closure = data->data();
+  delete msg->pdata;
+  msg->pdata = NULL;
+
+  // Execute the closure and trigger the return message if needed.
+  closure->Execute();
+}
+
+void AsyncInvoker::Flush(Thread* thread, uint32 id /*= MQID_ANY*/) {
+  if (destroying_) return;
+
+  // Run this on |thread| to reduce the number of context switches.
+  if (Thread::Current() != thread) {
+    thread->Invoke<void>(Bind(&AsyncInvoker::Flush, this, thread, id));
+    return;
+  }
+
+  MessageList removed;
+  thread->Clear(this, id, &removed);
+  for (MessageList::iterator it = removed.begin(); it != removed.end(); ++it) {
+    // This message was pending on this thread, so run it now.
+    thread->Send(it->phandler,
+                 it->message_id,
+                 it->pdata);
+  }
+}
+
+void AsyncInvoker::DoInvoke(Thread* thread, AsyncClosure* closure,
+                            uint32 id) {
+  if (destroying_) {
+    LOG(LS_WARNING) << "Tried to invoke while destroying the invoker.";
+    // Since this call transwers ownership of |closure|, we clean it up here.
+    delete closure;
+    return;
+  }
+  thread->Post(this, id, new ScopedRefMessageData<AsyncClosure>(closure));
+}
+
+NotifyingAsyncClosureBase::NotifyingAsyncClosureBase(AsyncInvoker* invoker,
+                                                     Thread* calling_thread)
+    : invoker_(invoker), calling_thread_(calling_thread) {
+  calling_thread->SignalQueueDestroyed.connect(
+      this, &NotifyingAsyncClosureBase::CancelCallback);
+  invoker->SignalInvokerDestroyed.connect(
+      this, &NotifyingAsyncClosureBase::CancelCallback);
+}
+
+void NotifyingAsyncClosureBase::TriggerCallback() {
+  CritScope cs(&crit_);
+  if (!CallbackCanceled() && !callback_.empty()) {
+    invoker_->AsyncInvoke<void>(calling_thread_, callback_);
+  }
+}
+
+void NotifyingAsyncClosureBase::CancelCallback() {
+  // If the callback is triggering when this is called, block the
+  // destructor of the dying object here by waiting until the callback
+  // is done triggering.
+  CritScope cs(&crit_);
+  // calling_thread_ == NULL means do not trigger the callback.
+  calling_thread_ = NULL;
+}
+
+}  // namespace rtc