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      1 /*
      2  *  Copyright 2014 The WebRTC Project Authors. All rights reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #ifndef WEBRTC_BASE_ASYNCINVOKER_INL_H_
     12 #define WEBRTC_BASE_ASYNCINVOKER_INL_H_
     13 
     14 #include "webrtc/base/bind.h"
     15 #include "webrtc/base/callback.h"
     16 #include "webrtc/base/criticalsection.h"
     17 #include "webrtc/base/messagehandler.h"
     18 #include "webrtc/base/refcount.h"
     19 #include "webrtc/base/scoped_ref_ptr.h"
     20 #include "webrtc/base/sigslot.h"
     21 #include "webrtc/base/thread.h"
     22 
     23 namespace rtc {
     24 
     25 class AsyncInvoker;
     26 
     27 // Helper class for AsyncInvoker. Runs a task and triggers a callback
     28 // on the calling thread if necessary. Instances are ref-counted so their
     29 // lifetime can be independent of AsyncInvoker.
     30 class AsyncClosure : public RefCountInterface {
     31  public:
     32   // Runs the asynchronous task, and triggers a callback to the calling
     33   // thread if needed. Should be called from the target thread.
     34   virtual void Execute() = 0;
     35  protected:
     36   ~AsyncClosure() override {}
     37 };
     38 
     39 // Simple closure that doesn't trigger a callback for the calling thread.
     40 template <class FunctorT>
     41 class FireAndForgetAsyncClosure : public AsyncClosure {
     42  public:
     43   explicit FireAndForgetAsyncClosure(const FunctorT& functor)
     44       : functor_(functor) {}
     45   virtual void Execute() {
     46     functor_();
     47   }
     48  private:
     49   FunctorT functor_;
     50 };
     51 
     52 // Base class for closures that may trigger a callback for the calling thread.
     53 // Listens for the "destroyed" signals from the calling thread and the invoker,
     54 // and cancels the callback to the calling thread if either is destroyed.
     55 class NotifyingAsyncClosureBase : public AsyncClosure,
     56                                   public sigslot::has_slots<> {
     57  public:
     58   ~NotifyingAsyncClosureBase() override;
     59 
     60  protected:
     61   NotifyingAsyncClosureBase(AsyncInvoker* invoker, Thread* calling_thread);
     62   void TriggerCallback();
     63   void SetCallback(const Callback0<void>& callback) {
     64     CritScope cs(&crit_);
     65     callback_ = callback;
     66   }
     67   bool CallbackCanceled() const { return calling_thread_ == NULL; }
     68 
     69  private:
     70   Callback0<void> callback_;
     71   CriticalSection crit_;
     72   AsyncInvoker* invoker_;
     73   Thread* calling_thread_;
     74 
     75   void CancelCallback();
     76 };
     77 
     78 // Closures that have a non-void return value and require a callback.
     79 template <class ReturnT, class FunctorT, class HostT>
     80 class NotifyingAsyncClosure : public NotifyingAsyncClosureBase {
     81  public:
     82   NotifyingAsyncClosure(AsyncInvoker* invoker,
     83                         Thread* calling_thread,
     84                         const FunctorT& functor,
     85                         void (HostT::*callback)(ReturnT),
     86                         HostT* callback_host)
     87       :  NotifyingAsyncClosureBase(invoker, calling_thread),
     88          functor_(functor),
     89          callback_(callback),
     90          callback_host_(callback_host) {}
     91   virtual void Execute() {
     92     ReturnT result = functor_();
     93     if (!CallbackCanceled()) {
     94       SetCallback(Callback0<void>(Bind(callback_, callback_host_, result)));
     95       TriggerCallback();
     96     }
     97   }
     98 
     99  private:
    100   FunctorT functor_;
    101   void (HostT::*callback_)(ReturnT);
    102   HostT* callback_host_;
    103 };
    104 
    105 // Closures that have a void return value and require a callback.
    106 template <class FunctorT, class HostT>
    107 class NotifyingAsyncClosure<void, FunctorT, HostT>
    108     : public NotifyingAsyncClosureBase {
    109  public:
    110   NotifyingAsyncClosure(AsyncInvoker* invoker,
    111                         Thread* calling_thread,
    112                         const FunctorT& functor,
    113                         void (HostT::*callback)(),
    114                         HostT* callback_host)
    115       : NotifyingAsyncClosureBase(invoker, calling_thread),
    116         functor_(functor) {
    117     SetCallback(Callback0<void>(Bind(callback, callback_host)));
    118   }
    119   virtual void Execute() {
    120     functor_();
    121     TriggerCallback();
    122   }
    123 
    124  private:
    125   FunctorT functor_;
    126 };
    127 
    128 }  // namespace rtc
    129 
    130 #endif  // WEBRTC_BASE_ASYNCINVOKER_INL_H_
    131