ratelimiter.c revision e0f1d72aa5d22752f2e7b18ece70d4c890cc4c19
/*
* Copyright (C) 1999, 2000 Internet Software Consortium.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
* SOFTWARE.
*/
#include <config.h>
#include <isc/assertions.h>
#include <isc/boolean.h>
#include <isc/error.h>
#include <isc/ratelimiter.h>
#include <isc/time.h>
#include <isc/util.h>
struct isc_ratelimiter {
isc_mem_t * mctx;
isc_mutex_t lock;
isc_task_t * task;
isc_timer_t * timer;
isc_interval_t interval;
isc_ratelimiter_state_t state;
ISC_LIST(isc_event_t) pending;
};
static void ratelimiter_tick(isc_task_t *task, isc_event_t *event);
isc_result_t
isc_ratelimiter_create(isc_mem_t *mctx, isc_timermgr_t *timermgr,
isc_task_t *task, isc_ratelimiter_t **ratelimiterp)
{
isc_result_t result;
isc_ratelimiter_t *rl;
INSIST(ratelimiterp != NULL && *ratelimiterp == NULL);
rl = isc_mem_get(mctx, sizeof(*rl));
if (rl == NULL)
return ISC_R_NOMEMORY;
rl->mctx = mctx;
rl->task = task;
isc_interval_set(&rl->interval, 0, 0);
rl->timer = NULL;
rl->state = isc_ratelimiter_worklimited;
ISC_LIST_INIT(rl->pending);
result = isc_mutex_init(&rl->lock);
if (result != ISC_R_SUCCESS)
goto free_mem;
result = isc_timer_create(timermgr, isc_timertype_inactive,
NULL, NULL, rl->task, ratelimiter_tick,
rl, &rl->timer);
if (result != ISC_R_SUCCESS)
goto free_mutex;
*ratelimiterp = rl;
return (ISC_R_SUCCESS);
free_mutex:
isc_mutex_destroy(&rl->lock);
free_mem:
isc_mem_put(mctx, rl, sizeof(*rl));
return (result);
}
isc_result_t
isc_ratelimiter_setinterval(isc_ratelimiter_t *rl, isc_interval_t *interval) {
isc_result_t result = ISC_R_SUCCESS;
LOCK(&rl->lock);
rl->interval = *interval;
/*
* If the timer is currently running, change its rate.
*/
if (rl->state == isc_ratelimiter_ratelimited) {
result = isc_timer_reset(rl->timer, isc_timertype_ticker, NULL,
&rl->interval, ISC_FALSE);
}
UNLOCK(&rl->lock);
return (result);
}
isc_result_t
isc_ratelimiter_enqueue(isc_ratelimiter_t *rl, isc_event_t **eventp) {
isc_result_t result = ISC_R_SUCCESS;
INSIST(eventp != NULL && *eventp != NULL);
LOCK(&rl->lock);
if (rl->state == isc_ratelimiter_ratelimited) {
isc_event_t *ev = *eventp;
ISC_LIST_APPEND(rl->pending, ev, ev_link);
*eventp = NULL;
} else {
result = isc_timer_reset(rl->timer, isc_timertype_ticker, NULL,
&rl->interval, ISC_FALSE);
if (result == ISC_R_SUCCESS)
rl->state = isc_ratelimiter_ratelimited;
}
UNLOCK(&rl->lock);
if (*eventp != NULL)
isc_task_send(rl->task, eventp);
ENSURE(*eventp == NULL);
return (result);
}
static void
ratelimiter_tick(isc_task_t *task, isc_event_t *event) {
isc_result_t result = ISC_R_SUCCESS;
isc_ratelimiter_t *rl = (isc_ratelimiter_t *)event->ev_arg;
isc_event_t *p;
(void) task; /* Unused */
LOCK(&rl->lock);
p = ISC_LIST_HEAD(rl->pending);
if (p != NULL) {
/*
* There is work to do. Let's do it after unlocking.
*/
ISC_LIST_UNLINK(rl->pending, p, ev_link);
} else {
/*
* No work left to do. Stop the timer so that we don't
* waste resources by having it fire periodically.
*/
result = isc_timer_reset(rl->timer, isc_timertype_inactive,
NULL, NULL, ISC_FALSE);
RUNTIME_CHECK(result == ISC_R_SUCCESS);
rl->state = isc_ratelimiter_worklimited;
}
UNLOCK(&rl->lock);
isc_event_free(&event);
/*
* If we have an event, dispatch it.
* There is potential for optimization here since
* we are already executing in the context of "task".
*/
if (p != NULL)
isc_task_send(rl->task, &p);
INSIST(p == NULL);
}
void
isc_ratelimiter_destroy(isc_ratelimiter_t **ratelimiterp) {
isc_ratelimiter_t *rl = *ratelimiterp;
isc_event_t *p;
(void) isc_timer_reset(rl->timer, isc_timertype_inactive,
NULL, NULL, ISC_FALSE);
isc_timer_detach(&rl->timer);
while ((p = ISC_LIST_HEAD(rl->pending)) != NULL) {
ISC_LIST_UNLINK(rl->pending, p, ev_link);
isc_event_free(&p);
}
isc_mutex_destroy(&rl->lock);
isc_mem_put(rl->mctx, rl, sizeof(*rl));
*ratelimiterp = NULL;
}