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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef MEDIA_BASE_SERIAL_RUNNER_H_
      6 #define MEDIA_BASE_SERIAL_RUNNER_H_
      7 
      8 #include <queue>
      9 
     10 #include "base/callback.h"
     11 #include "base/memory/ref_counted.h"
     12 #include "base/memory/scoped_ptr.h"
     13 #include "base/memory/weak_ptr.h"
     14 #include "media/base/pipeline_status.h"
     15 
     16 namespace base {
     17 class MessageLoopProxy;
     18 }
     19 
     20 namespace media {
     21 
     22 // Runs a series of bound functions accepting Closures or PipelineStatusCB.
     23 // SerialRunner doesn't use regular Closure/PipelineStatusCBs as it late binds
     24 // the completion callback as the series progresses.
     25 class SerialRunner {
     26  public:
     27   typedef base::Callback<void(const base::Closure&)> BoundClosure;
     28   typedef base::Callback<void(const PipelineStatusCB&)> BoundPipelineStatusCB;
     29 
     30   // Serial queue of bound functions to run.
     31   class Queue {
     32    public:
     33     Queue();
     34     ~Queue();
     35 
     36     void Push(const BoundClosure& bound_fn);
     37     void Push(const BoundPipelineStatusCB& bound_fn);
     38 
     39    private:
     40     friend class SerialRunner;
     41 
     42     BoundPipelineStatusCB Pop();
     43     bool empty();
     44 
     45     std::queue<BoundPipelineStatusCB> bound_fns_;
     46   };
     47 
     48   // Executes the bound functions in series, executing |done_cb| when finished.
     49   //
     50   // All bound functions are executed on the thread that Run() is called on,
     51   // including |done_cb|.
     52   //
     53   // Deleting the object will prevent execution of any unstarted bound
     54   // functions, including |done_cb|.
     55   static scoped_ptr<SerialRunner> Run(
     56       const Queue& bound_fns, const PipelineStatusCB& done_cb);
     57 
     58  private:
     59   friend struct base::DefaultDeleter<SerialRunner>;
     60 
     61   SerialRunner(const Queue& bound_fns, const PipelineStatusCB& done_cb);
     62   ~SerialRunner();
     63 
     64   void RunNextInSeries(PipelineStatus last_status);
     65 
     66   base::WeakPtrFactory<SerialRunner> weak_this_;
     67   scoped_refptr<base::MessageLoopProxy> message_loop_;
     68   Queue bound_fns_;
     69   PipelineStatusCB done_cb_;
     70 
     71   DISALLOW_COPY_AND_ASSIGN(SerialRunner);
     72 };
     73 
     74 }  // namespace media
     75 
     76 #endif  // MEDIA_BASE_SERIAL_RUNNER_H_
     77