/**

 * This file is part of the CernVM File System.

 */

#ifndef CVMFS_BACKOFF_H_

#define CVMFS_BACKOFF_H_

#include <pthread.h>

#include "prng.h"

#include "util/single_copy.h"

/**

 * When Throttle() is called in quick succession, the exponential backoff will

 * start (sleep).  The class forgets a call to Throttle() after reset_after_ms

 * milliseconds.

 */

class BackoffThrottle : public SingleCopy {

 public:

  static const unsigned kDefaultInitDelay = 32;  /**< 32ms */

  static const unsigned kDefaultMaxDelay = 2000; /**< Maximum 2 seconds */

  /**

   * Clear memory after 10s

   */

  static const unsigned kDefaultResetAfter = 10000;

                  const unsigned max_delay_ms,

                  const unsigned reset_after_ms)

  ~BackoffThrottle();

  void Throttle();

  void Reset();

 private:

  void Init(const unsigned init_delay_ms,

            const unsigned max_delay_ms,

            const unsigned reset_after_ms);

  unsigned delay_range_;

  unsigned init_delay_ms_;

  unsigned max_delay_ms_;

  unsigned reset_after_ms_;

  time_t last_throttle_;

  Prng prng_;

  pthread_mutex_t *lock_;

};

#endif  // CVMFS_BACKOFF_H_