src/lib/log-throttle.c

/* Copyright (c) 2016-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "ioloop.h"
#include "time-util.h"
#include "log-throttle.h"

struct log_throttle {
    struct log_throttle_settings set;
    log_throttle_callback_t *callback;
    void *context;

    struct timeval last_time;
    unsigned int last_count;

    struct timeout *to_throttled;
};

#undef log_throttle_init
struct log_throttle *
log_throttle_init(const struct log_throttle_settings *set,
          log_throttle_callback_t *callback, void *context)
{
    struct log_throttle *throttle;

    i_assert(set->throttle_at_max_per_interval > 0);
    i_assert(set->unthrottle_at_max_per_interval > 0);

    throttle = i_new(struct log_throttle, 1);
    throttle->set = *set;
    if (throttle->set.interval_msecs == 0)
        throttle->set.interval_msecs = 1000;
    throttle->callback = callback;
    throttle->context = context;
    return throttle;
}

void log_throttle_deinit(struct log_throttle **_throttle)
{
    struct log_throttle *throttle = *_throttle;

    *_throttle = NULL;
    timeout_remove(&throttle->to_throttled);
    i_free(throttle);
}

static void log_throttle_callback(struct log_throttle *throttle)
{
    if (throttle->last_count > 0)
        throttle->callback(throttle->last_count, throttle->context);
    if (throttle->last_count < throttle->set.unthrottle_at_max_per_interval)
        timeout_remove(&throttle->to_throttled);
    throttle->last_count = 0;
}

bool log_throttle_accept(struct log_throttle *throttle)
{
    if (throttle->to_throttled != NULL) {
        /* unthrottling and last_count resets are done only by
           the callback */
        throttle->last_count++;
        return FALSE;
    } else if (timeval_diff_msecs(&ioloop_timeval, &throttle->last_time) >=
                (int)throttle->set.interval_msecs) {
        throttle->last_time = ioloop_timeval;
        throttle->last_count = 1;
        return TRUE;
    } else if (++throttle->last_count <= throttle->set.throttle_at_max_per_interval) {
        return TRUE;
    } else {
        throttle->last_count = 1;
        throttle->to_throttled =
            timeout_add(throttle->set.interval_msecs,
                    log_throttle_callback, throttle);
        return FALSE;
    }
}