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-inl.h

@@ -0,0 +1,129 @@
+/*
+ *  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.
+ */
+
+#ifndef WEBRTC_BASE_ASYNCINVOKER_INL_H_
+#define WEBRTC_BASE_ASYNCINVOKER_INL_H_
+
+#include "webrtc/base/bind.h"
+#include "webrtc/base/callback.h"
+#include "webrtc/base/criticalsection.h"
+#include "webrtc/base/messagehandler.h"
+#include "webrtc/base/refcount.h"
+#include "webrtc/base/scoped_ref_ptr.h"
+#include "webrtc/base/sigslot.h"
+#include "webrtc/base/thread.h"
+
+namespace rtc {
+
+class AsyncInvoker;
+
+// Helper class for AsyncInvoker. Runs a task and triggers a callback
+// on the calling thread if necessary. Instances are ref-counted so their
+// lifetime can be independent of AsyncInvoker.
+class AsyncClosure : public RefCountInterface {
+ public:
+  virtual ~AsyncClosure() {}
+  // Runs the asynchronous task, and triggers a callback to the calling
+  // thread if needed. Should be called from the target thread.
+  virtual void Execute() = 0;
+};
+
+// Simple closure that doesn't trigger a callback for the calling thread.
+template <class FunctorT>
+class FireAndForgetAsyncClosure : public AsyncClosure {
+ public:
+  explicit FireAndForgetAsyncClosure(const FunctorT& functor)
+      : functor_(functor) {}
+  virtual void Execute() {
+    functor_();
+  }
+ private:
+  FunctorT functor_;
+};
+
+// Base class for closures that may trigger a callback for the calling thread.
+// Listens for the "destroyed" signals from the calling thread and the invoker,
+// and cancels the callback to the calling thread if either is destroyed.
+class NotifyingAsyncClosureBase : public AsyncClosure,
+                                  public sigslot::has_slots<> {
+ public:
+  virtual ~NotifyingAsyncClosureBase() { disconnect_all(); }
+
+ protected:
+  NotifyingAsyncClosureBase(AsyncInvoker* invoker, Thread* calling_thread);
+  void TriggerCallback();
+  void SetCallback(const Callback0<void>& callback) {
+    CritScope cs(&crit_);
+    callback_ = callback;
+  }
+  bool CallbackCanceled() const { return calling_thread_ == NULL; }
+
+ private:
+  Callback0<void> callback_;
+  CriticalSection crit_;
+  AsyncInvoker* invoker_;
+  Thread* calling_thread_;
+
+  void CancelCallback();
+};
+
+// Closures that have a non-void return value and require a callback.
+template <class ReturnT, class FunctorT, class HostT>
+class NotifyingAsyncClosure : public NotifyingAsyncClosureBase {
+ public:
+  NotifyingAsyncClosure(AsyncInvoker* invoker,
+                        Thread* calling_thread,
+                        const FunctorT& functor,
+                        void (HostT::*callback)(ReturnT),
+                        HostT* callback_host)
+      :  NotifyingAsyncClosureBase(invoker, calling_thread),
+         functor_(functor),
+         callback_(callback),
+         callback_host_(callback_host) {}
+  virtual void Execute() {
+    ReturnT result = functor_();
+    if (!CallbackCanceled()) {
+      SetCallback(Callback0<void>(Bind(callback_, callback_host_, result)));
+      TriggerCallback();
+    }
+  }
+
+ private:
+  FunctorT functor_;
+  void (HostT::*callback_)(ReturnT);
+  HostT* callback_host_;
+};
+
+// Closures that have a void return value and require a callback.
+template <class FunctorT, class HostT>
+class NotifyingAsyncClosure<void, FunctorT, HostT>
+    : public NotifyingAsyncClosureBase {
+ public:
+  NotifyingAsyncClosure(AsyncInvoker* invoker,
+                        Thread* calling_thread,
+                        const FunctorT& functor,
+                        void (HostT::*callback)(),
+                        HostT* callback_host)
+      : NotifyingAsyncClosureBase(invoker, calling_thread),
+        functor_(functor) {
+    SetCallback(Callback0<void>(Bind(callback, callback_host)));
+  }
+  virtual void Execute() {
+    functor_();
+    TriggerCallback();
+  }
+
+ private:
+  FunctorT functor_;
+};
+
+}  // namespace rtc
+
+#endif  // WEBRTC_BASE_ASYNCINVOKER_INL_H_