Archipelago » blktap-utils

/*

 * Copyright (c) 2011, XenSource 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:

 *     * Redistributions of source code must retain the above copyright

 *       notice, this list of conditions and the following disclaimer.

 *     * 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.

 *     * Neither the name of XenSource Inc. 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;

}