text: /*
   * Copyright (c) 2016, Citrix Systems, Inc.
   *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   * 
   *  1. Redistributions of source code must retain the above copyright
   *     notice, this list of conditions and the following disclaimer.
   *  2. Redistributions in binary form must reproduce the above copyright
   *     notice, this list of conditions and the following disclaimer in the
   *     documentation and/or other materials provided with the distribution.
   *  3. Neither the name of the copyright holder nor the names of its 
   *     contributors may be used to endorse or promote products derived from 
   *     this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  /*
   * Simple log rate limiting. Allow for bursts, then drop messages
   * until some interval expired.
   */
  
  #ifdef HAVE_CONFIG_H
  #include "config.h"
  #endif
  
  #include "tapdisk-loglimit.h"
  #include "compiler.h"
  #include "list.h"
  
  void
  tapdisk_loglimit_init(td_loglimit_t *rl, int burst, int interval)
  {
  	rl->burst    = burst;
  	rl->interval = interval;
  
  	rl->count    = 0;
  	rl->dropped  = 0;
  
  	gettimeofday(&rl->ts, NULL);
  }
  
  static void
  timeradd_ms(struct timeval *tv, long ms)
  {
  	tv->tv_usec += ms * 1000;
  	if (tv->tv_usec > 1000000) {
  		tv->tv_sec  += tv->tv_usec / 1000000;
  		tv->tv_usec %= 1000000;
  	}
  }
  
  static void
  tapdisk_loglimit_update(td_loglimit_t *rl, struct timeval *now)
  {
  	struct timeval next = rl->ts;
  
  	timeradd_ms(&next, rl->interval);
  
  	if (timercmp(&next, now, <)) {
  		rl->count = 0;
  		rl->ts    = *now;
  	}
  }
  
  static void
  tapdisk_loglimit_update_now(td_loglimit_t *rl)
  {
  	struct timeval now;
  
  	gettimeofday(&now, NULL);
  
  	tapdisk_loglimit_update(rl, &now);
  }
  
  int
  tapdisk_loglimit_pass(td_loglimit_t *rl)
  {
  	if (!rl->interval)
  		return 1; /* unlimited */
  
  	if (unlikely(rl->count >= rl->burst)) {
  
  		tapdisk_loglimit_update_now(rl);
  
  		if (rl->count >= rl->burst) {
  			rl->dropped++;
  			return 0;
  		}
  	}
  
  	rl->count++;
  	return 1;
  }
  