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/** |
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* This file is part of the CernVM File System. |
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*/ |
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#ifndef CVMFS_BACKOFF_H_ |
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#define CVMFS_BACKOFF_H_ |
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#include <pthread.h> |
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#include "util/prng.h" |
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#include "util/single_copy.h" |
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/** |
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* When Throttle() is called in quick succession, the exponential backoff will |
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* start (sleep). The class forgets a call to Throttle() after reset_after_ms |
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* milliseconds. |
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*/ |
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class BackoffThrottle : public SingleCopy { |
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public: |
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static const unsigned kDefaultInitDelay = 32; /**< 32ms */ |
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static const unsigned kDefaultMaxDelay = 2000; /**< Maximum 2 seconds */ |
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/** |
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* Clear memory after 10s |
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*/ |
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static const unsigned kDefaultResetAfter = 10000; |
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BackoffThrottle() { |
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Init(kDefaultInitDelay, kDefaultMaxDelay, kDefaultResetAfter); |
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} |
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BackoffThrottle(const unsigned init_delay_ms, |
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const unsigned max_delay_ms, |
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const unsigned reset_after_ms) |
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{ |
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Init(init_delay_ms, max_delay_ms, reset_after_ms); |
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} |
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~BackoffThrottle(); |
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void Throttle(); |
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void Reset(); |
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private: |
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void Init(const unsigned init_delay_ms, |
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const unsigned max_delay_ms, |
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const unsigned reset_after_ms); |
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unsigned delay_range_; |
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unsigned init_delay_ms_; |
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unsigned max_delay_ms_; |
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unsigned reset_after_ms_; |
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time_t last_throttle_; |
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Prng prng_; |
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pthread_mutex_t *lock_; |
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}; |
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#endif // CVMFS_BACKOFF_H_ |
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