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/*
* Copyright (C) 2004, 2005 Internet Systems Consortium, Inc. ("ISC")
* Copyright (C) 1999-2002 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 ISC DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL ISC 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.
*/
/* $Id: ratelimiter.c,v 1.21.18.2 2005/04/29 00:16:49 marka Exp $ */
/*! \file */
#include <config.h>
#include <isc/mem.h>
#include <isc/ratelimiter.h>
#include <isc/task.h>
#include <isc/time.h>
#include <isc/timer.h>
#include <isc/util.h>
typedef enum {
isc_ratelimiter_stalled = 0,
isc_ratelimiter_ratelimited = 1,
isc_ratelimiter_idle = 2,
isc_ratelimiter_shuttingdown = 3
} isc_ratelimiter_state_t;
struct isc_ratelimiter {
isc_mem_t * mctx;
isc_mutex_t lock;
int refs;
isc_task_t * task;
isc_timer_t * timer;
isc_interval_t interval;
isc_uint32_t pertic;
isc_ratelimiter_state_t state;
isc_event_t shutdownevent;
ISC_LIST(isc_event_t) pending;
};
#define ISC_RATELIMITEREVENT_SHUTDOWN (ISC_EVENTCLASS_RATELIMITER + 1)
static void
ratelimiter_tick(isc_task_t *task, isc_event_t *event);
static void
ratelimiter_shutdowncomplete(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->refs = 1;
rl->task = task;
isc_interval_set(&rl->interval, 0, 0);
rl->timer = NULL;
rl->pertic = 1;
rl->state = isc_ratelimiter_idle;
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;
/*
* Increment the reference count to indicate that we may
* (soon) have events outstanding.
*/
rl->refs++;
ISC_EVENT_INIT(&rl->shutdownevent,
sizeof(isc_event_t),
0, NULL, ISC_RATELIMITEREVENT_SHUTDOWN,
ratelimiter_shutdowncomplete, rl, rl, NULL, NULL);
*ratelimiterp = rl;
return (ISC_R_SUCCESS);
free_mutex:
DESTROYLOCK(&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);
}
void
isc_ratelimiter_setpertic(isc_ratelimiter_t *rl, isc_uint32_t pertic) {
if (pertic == 0)
pertic = 1;
rl->pertic = pertic;
}
isc_result_t
isc_ratelimiter_enqueue(isc_ratelimiter_t *rl, isc_task_t *task,
isc_event_t **eventp)
{
isc_result_t result = ISC_R_SUCCESS;
isc_event_t *ev;
REQUIRE(eventp != NULL && *eventp != NULL);
REQUIRE(task != NULL);
ev = *eventp;
REQUIRE(ev->ev_sender == NULL);
LOCK(&rl->lock);
if (rl->state == isc_ratelimiter_ratelimited ||
rl->state == isc_ratelimiter_stalled) {
isc_event_t *ev = *eventp;
ev->ev_sender = task;
ISC_LIST_APPEND(rl->pending, ev, ev_link);
*eventp = NULL;
} else if (rl->state == isc_ratelimiter_idle) {
result = isc_timer_reset(rl->timer, isc_timertype_ticker, NULL,
&rl->interval, ISC_FALSE);
if (result == ISC_R_SUCCESS) {
ev->ev_sender = task;
rl->state = isc_ratelimiter_ratelimited;
}
} else {
INSIST(rl->state == isc_ratelimiter_shuttingdown);
result = ISC_R_SHUTTINGDOWN;
}
UNLOCK(&rl->lock);
if (*eventp != NULL && result == ISC_R_SUCCESS)
isc_task_send(task, eventp);
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;
isc_uint32_t pertic;
UNUSED(task);
isc_event_free(&event);
pertic = rl->pertic;
while (pertic != 0) {
pertic--;
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_idle;
pertic = 0; /* Force the loop to exit. */
}
UNLOCK(&rl->lock);
if (p != NULL) {
isc_task_t *evtask = p->ev_sender;
isc_task_send(evtask, &p);
}
INSIST(p == NULL);
}
}
void
isc_ratelimiter_shutdown(isc_ratelimiter_t *rl) {
isc_event_t *ev;
isc_task_t *task;
LOCK(&rl->lock);
rl->state = isc_ratelimiter_shuttingdown;
(void)isc_timer_reset(rl->timer, isc_timertype_inactive,
NULL, NULL, ISC_FALSE);
while ((ev = ISC_LIST_HEAD(rl->pending)) != NULL) {
ISC_LIST_UNLINK(rl->pending, ev, ev_link);
ev->ev_attributes |= ISC_EVENTATTR_CANCELED;
task = ev->ev_sender;
isc_task_send(task, &ev);
}
isc_timer_detach(&rl->timer);
/*
* Send an event to our task. The delivery of this event
* indicates that no more timer events will be delivered.
*/
ev = &rl->shutdownevent;
isc_task_send(rl->task, &ev);
UNLOCK(&rl->lock);
}
static void
ratelimiter_shutdowncomplete(isc_task_t *task, isc_event_t *event) {
isc_ratelimiter_t *rl = (isc_ratelimiter_t *)event->ev_arg;
UNUSED(task);
isc_ratelimiter_detach(&rl);
}
static void
ratelimiter_free(isc_ratelimiter_t *rl) {
DESTROYLOCK(&rl->lock);
isc_mem_put(rl->mctx, rl, sizeof(*rl));
}
void
isc_ratelimiter_attach(isc_ratelimiter_t *source, isc_ratelimiter_t **target) {
REQUIRE(source != NULL);
REQUIRE(target != NULL && *target == NULL);
LOCK(&source->lock);
REQUIRE(source->refs > 0);
source->refs++;
INSIST(source->refs > 0);
UNLOCK(&source->lock);
*target = source;
}
void
isc_ratelimiter_detach(isc_ratelimiter_t **rlp) {
isc_ratelimiter_t *rl = *rlp;
isc_boolean_t free_now = ISC_FALSE;
LOCK(&rl->lock);
REQUIRE(rl->refs > 0);
rl->refs--;
if (rl->refs == 0)
free_now = ISC_TRUE;
UNLOCK(&rl->lock);
if (free_now)
ratelimiter_free(rl);
*rlp = NULL;
}
isc_result_t
isc_ratelimiter_stall(isc_ratelimiter_t *rl) {
isc_result_t result = ISC_R_SUCCESS;
LOCK(&rl->lock);
switch (rl->state) {
case isc_ratelimiter_shuttingdown:
result = ISC_R_SHUTTINGDOWN;
break;
case isc_ratelimiter_ratelimited:
result = isc_timer_reset(rl->timer, isc_timertype_inactive,
NULL, NULL, ISC_FALSE);
RUNTIME_CHECK(result == ISC_R_SUCCESS);
case isc_ratelimiter_idle:
case isc_ratelimiter_stalled:
rl->state = isc_ratelimiter_stalled;
break;
}
UNLOCK(&rl->lock);
return (result);
}
isc_result_t
isc_ratelimiter_release(isc_ratelimiter_t *rl) {
isc_result_t result = ISC_R_SUCCESS;
LOCK(&rl->lock);
switch (rl->state) {
case isc_ratelimiter_shuttingdown:
result = ISC_R_SHUTTINGDOWN;
break;
case isc_ratelimiter_stalled:
if (!ISC_LIST_EMPTY(rl->pending)) {
result = isc_timer_reset(rl->timer,
isc_timertype_ticker, NULL,
&rl->interval, ISC_FALSE);
if (result == ISC_R_SUCCESS)
rl->state = isc_ratelimiter_ratelimited;
} else
rl->state = isc_ratelimiter_idle;
break;
case isc_ratelimiter_ratelimited:
case isc_ratelimiter_idle:
break;
}
UNLOCK(&rl->lock);
return (result);
}
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