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/*
Copyright 2014 Martin Pärtel <martin.partel@gmail.com>
This file is part of bindfs.
bindfs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
bindfs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with bindfs. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef INC_BINDFS_RATE_LIMITER_H
#define INC_BINDFS_RATE_LIMITER_H
#include <string.h>
#include <pthread.h>
/* When we are idle, we allow some time to be "credited" to the next writer.
* Otherwise, the short pause between requests would "go to waste", lowering
* the throughput when there is only one requester. */
extern const double rate_limiter_idle_credit;
typedef struct RateLimiter {
double rate; /* bytes / second */
double (*clock)(void);
double last_modified;
double accumulated_sleep_time;
pthread_mutex_t mutex;
} RateLimiter;
double gettimeofday_clock(void);
/* 0 on success, error number on error. */
void rate_limiter_init(RateLimiter* limiter, double rate, double (*clock)(void));
/* Blocks until the rate limiter clears `size` units. */
void rate_limiter_wait(RateLimiter* limiter, size_t size);
/* Updates the rate limiter like `rate_limiter_wait` but does not actually
* sleep. Returns the time that the caller is expected to sleep. */
double rate_limiter_wait_nosleep(RateLimiter* limiter, size_t size);
/* Destroys the rate limiter. No wait_for_permit calls may be active. */
void rate_limiter_destroy(RateLimiter* limiter);
#endif
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