queued_expensive_operation_controller.h

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// Copyright 2015 Google Inc.

#ifndef PAGESPEED_CONTROLLER_QUEUED_EXPENSIVE_OPERATION_CONTROLLER_H_
#define PAGESPEED_CONTROLLER_QUEUED_EXPENSIVE_OPERATION_CONTROLLER_H_

#include <queue>

#include "pagespeed/controller/expensive_operation_controller.h"
#include "pagespeed/kernel/base/abstract_mutex.h"
#include "pagespeed/kernel/base/basictypes.h"
#include "pagespeed/kernel/base/function.h"
#include "pagespeed/kernel/base/scoped_ptr.h"
#include "pagespeed/kernel/base/statistics.h"
#include "pagespeed/kernel/base/thread_annotations.h"
#include "pagespeed/kernel/base/thread_system.h"

namespace net_instaweb {

class QueuedExpensiveOperationController
    : public ExpensiveOperationController {
 public:
  static const char kActiveExpensiveOperations[];
  static const char kQueuedExpensiveOperations[];
  static const char kPermittedExpensiveOperations[];

  QueuedExpensiveOperationController(int max_expensive_operations,
                                     ThreadSystem* thread_system,
                                     Statistics* stats);
  virtual ~QueuedExpensiveOperationController();

  virtual void ScheduleExpensiveOperation(Function* callback);
  virtual void NotifyExpensiveOperationComplete();

  static void InitStats(Statistics* stats);

 private:
  void IncrementInProgress() EXCLUSIVE_LOCKS_REQUIRED(mutex_);
  void DecrementInProgress() EXCLUSIVE_LOCKS_REQUIRED(mutex_);

  void Enqueue(Function* function) EXCLUSIVE_LOCKS_REQUIRED(mutex_);
  Function* Dequeue() EXCLUSIVE_LOCKS_REQUIRED(mutex_);

  const int max_in_progress_;
  std::queue<Function*> queue_ GUARDED_BY(mutex_);
  int num_in_progress_ GUARDED_BY(mutex_);
  scoped_ptr<AbstractMutex> mutex_;
  UpDownCounter* active_operations_counter_;
  UpDownCounter* queued_operations_counter_;
  TimedVariable* permitted_operations_counter_;

  
};

}  

#endif