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-rw-r--r--lib/isc/ratelimiter.c372
1 files changed, 372 insertions, 0 deletions
diff --git a/lib/isc/ratelimiter.c b/lib/isc/ratelimiter.c
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+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+/*! \file */
+
+#include <inttypes.h>
+#include <stdbool.h>
+
+#include <isc/mem.h>
+#include <isc/ratelimiter.h>
+#include <isc/refcount.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;
+ isc_refcount_t references;
+ isc_task_t *task;
+ isc_timer_t *timer;
+ isc_interval_t interval;
+ uint32_t pertic;
+ bool pushpop;
+ 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));
+ *rl = (isc_ratelimiter_t){
+ .mctx = mctx,
+ .task = task,
+ .pertic = 1,
+ .state = isc_ratelimiter_idle,
+ };
+
+ isc_refcount_init(&rl->references, 1);
+ isc_interval_set(&rl->interval, 0, 0);
+ ISC_LIST_INIT(rl->pending);
+
+ isc_mutex_init(&rl->lock);
+
+ 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.
+ */
+ isc_refcount_increment(&rl->references);
+
+ 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:
+ isc_refcount_decrementz(&rl->references);
+ isc_refcount_destroy(&rl->references);
+ isc_mutex_destroy(&rl->lock);
+ 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;
+
+ REQUIRE(rl != NULL);
+ REQUIRE(interval != NULL);
+
+ 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, false);
+ }
+ UNLOCK(&rl->lock);
+ return (result);
+}
+
+void
+isc_ratelimiter_setpertic(isc_ratelimiter_t *rl, uint32_t pertic) {
+ REQUIRE(rl != NULL);
+
+ if (pertic == 0) {
+ pertic = 1;
+ }
+ rl->pertic = pertic;
+}
+
+void
+isc_ratelimiter_setpushpop(isc_ratelimiter_t *rl, bool pushpop) {
+ REQUIRE(rl != NULL);
+
+ rl->pushpop = pushpop;
+}
+
+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(rl != NULL);
+ REQUIRE(task != NULL);
+ REQUIRE(eventp != NULL && *eventp != NULL);
+ ev = *eventp;
+ REQUIRE(ev->ev_sender == NULL);
+
+ LOCK(&rl->lock);
+ if (rl->state == isc_ratelimiter_ratelimited ||
+ rl->state == isc_ratelimiter_stalled)
+ {
+ ev->ev_sender = task;
+ *eventp = NULL;
+ if (rl->pushpop) {
+ ISC_LIST_PREPEND(rl->pending, ev, ev_ratelink);
+ } else {
+ ISC_LIST_APPEND(rl->pending, ev, ev_ratelink);
+ }
+ } else if (rl->state == isc_ratelimiter_idle) {
+ result = isc_timer_reset(rl->timer, isc_timertype_ticker, NULL,
+ &rl->interval, 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);
+}
+
+isc_result_t
+isc_ratelimiter_dequeue(isc_ratelimiter_t *rl, isc_event_t *event) {
+ isc_result_t result = ISC_R_SUCCESS;
+
+ REQUIRE(rl != NULL);
+ REQUIRE(event != NULL);
+
+ LOCK(&rl->lock);
+ if (ISC_LINK_LINKED(event, ev_ratelink)) {
+ ISC_LIST_UNLINK(rl->pending, event, ev_ratelink);
+ event->ev_sender = NULL;
+ } else {
+ result = ISC_R_NOTFOUND;
+ }
+ UNLOCK(&rl->lock);
+ return (result);
+}
+
+static void
+ratelimiter_tick(isc_task_t *task, isc_event_t *event) {
+ isc_ratelimiter_t *rl = (isc_ratelimiter_t *)event->ev_arg;
+ isc_event_t *p;
+ 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_ratelink);
+ } else {
+ /*
+ * No work left to do. Stop the timer so that we don't
+ * waste resources by having it fire periodically.
+ */
+ isc_result_t result = isc_timer_reset(
+ rl->timer, isc_timertype_inactive, NULL, NULL,
+ 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;
+ isc_result_t result;
+
+ REQUIRE(rl != NULL);
+
+ LOCK(&rl->lock);
+ rl->state = isc_ratelimiter_shuttingdown;
+ (void)isc_timer_reset(rl->timer, isc_timertype_inactive, NULL, NULL,
+ false);
+ while ((ev = ISC_LIST_HEAD(rl->pending)) != NULL) {
+ task = ev->ev_sender;
+ ISC_LIST_UNLINK(rl->pending, ev, ev_ratelink);
+ ev->ev_attributes |= ISC_EVENTATTR_CANCELED;
+ isc_task_send(task, &ev);
+ }
+ task = NULL;
+ isc_task_attach(rl->task, &task);
+
+ result = isc_timer_reset(rl->timer, isc_timertype_inactive, NULL, NULL,
+ false);
+ RUNTIME_CHECK(result == ISC_R_SUCCESS);
+ isc_timer_destroy(&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);
+ isc_task_detach(&task);
+}
+
+static void
+ratelimiter_free(isc_ratelimiter_t *rl) {
+ isc_refcount_destroy(&rl->references);
+ isc_mutex_destroy(&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);
+
+ isc_refcount_increment(&source->references);
+
+ *target = source;
+}
+
+void
+isc_ratelimiter_detach(isc_ratelimiter_t **rlp) {
+ isc_ratelimiter_t *rl;
+
+ REQUIRE(rlp != NULL && *rlp != NULL);
+
+ rl = *rlp;
+ *rlp = NULL;
+
+ if (isc_refcount_decrement(&rl->references) == 1) {
+ ratelimiter_free(rl);
+ }
+}
+
+isc_result_t
+isc_ratelimiter_stall(isc_ratelimiter_t *rl) {
+ isc_result_t result = ISC_R_SUCCESS;
+
+ REQUIRE(rl != NULL);
+
+ 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, false);
+ RUNTIME_CHECK(result == ISC_R_SUCCESS);
+ FALLTHROUGH;
+ 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;
+
+ REQUIRE(rl != NULL);
+
+ 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, 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);
+}