contrib/bind-9.5.2/lib/isc/ratelimiter.c

   1 /*
   2  * Copyright (C) 2004, 2005, 2007  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1999-2002  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and/or distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  10  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  11  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  13  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  14  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  15  * PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* $Id: ratelimiter.c,v 1.25 2007/06/19 23:47:17 tbox Exp $ */
  19
  20 /*! \file */
  21
  22 #include <config.h>
  23
  24 #include <isc/mem.h>
  25 #include <isc/ratelimiter.h>
  26 #include <isc/task.h>
  27 #include <isc/time.h>
  28 #include <isc/timer.h>
  29 #include <isc/util.h>
  30
  31 typedef enum {
  32         isc_ratelimiter_stalled = 0,
  33         isc_ratelimiter_ratelimited = 1,
  34         isc_ratelimiter_idle = 2,
  35         isc_ratelimiter_shuttingdown = 3
  36 } isc_ratelimiter_state_t;
  37
  38 struct isc_ratelimiter {
  39         isc_mem_t *             mctx;
  40         isc_mutex_t             lock;
  41         int                     refs;
  42         isc_task_t *            task;
  43         isc_timer_t *           timer;
  44         isc_interval_t          interval;
  45         isc_uint32_t            pertic;
  46         isc_ratelimiter_state_t state;
  47         isc_event_t             shutdownevent;
  48         ISC_LIST(isc_event_t)   pending;
  49 };
  50
  51 #define ISC_RATELIMITEREVENT_SHUTDOWN (ISC_EVENTCLASS_RATELIMITER + 1)
  52
  53 static void
  54 ratelimiter_tick(isc_task_t *task, isc_event_t *event);
  55
  56 static void
  57 ratelimiter_shutdowncomplete(isc_task_t *task, isc_event_t *event);
  58
  59 isc_result_t
  60 isc_ratelimiter_create(isc_mem_t *mctx, isc_timermgr_t *timermgr,
  61                        isc_task_t *task, isc_ratelimiter_t **ratelimiterp)
  62 {
  63         isc_result_t result;
  64         isc_ratelimiter_t *rl;
  65         INSIST(ratelimiterp != NULL && *ratelimiterp == NULL);
  66
  67         rl = isc_mem_get(mctx, sizeof(*rl));
  68         if (rl == NULL)
  69                 return ISC_R_NOMEMORY;
  70         rl->mctx = mctx;
  71         rl->refs = 1;
  72         rl->task = task;
  73         isc_interval_set(&rl->interval, 0, 0);
  74         rl->timer = NULL;
  75         rl->pertic = 1;
  76         rl->state = isc_ratelimiter_idle;
  77         ISC_LIST_INIT(rl->pending);
  78
  79         result = isc_mutex_init(&rl->lock);
  80         if (result != ISC_R_SUCCESS)
  81                 goto free_mem;
  82         result = isc_timer_create(timermgr, isc_timertype_inactive,
  83                                   NULL, NULL, rl->task, ratelimiter_tick,
  84                                   rl, &rl->timer);
  85         if (result != ISC_R_SUCCESS)
  86                 goto free_mutex;
  87
  88         /*
  89          * Increment the reference count to indicate that we may
  90          * (soon) have events outstanding.
  91          */
  92         rl->refs++;
  93
  94         ISC_EVENT_INIT(&rl->shutdownevent,
  95                        sizeof(isc_event_t),
  96                        0, NULL, ISC_RATELIMITEREVENT_SHUTDOWN,
  97                        ratelimiter_shutdowncomplete, rl, rl, NULL, NULL);
  98
  99         *ratelimiterp = rl;
 100         return (ISC_R_SUCCESS);
 101
 102 free_mutex:
 103         DESTROYLOCK(&rl->lock);
 104 free_mem:
 105         isc_mem_put(mctx, rl, sizeof(*rl));
 106         return (result);
 107 }
 108
 109 isc_result_t
 110 isc_ratelimiter_setinterval(isc_ratelimiter_t *rl, isc_interval_t *interval) {
 111         isc_result_t result = ISC_R_SUCCESS;
 112         LOCK(&rl->lock);
 113         rl->interval = *interval;
 114         /*
 115          * If the timer is currently running, change its rate.
 116          */
 117         if (rl->state == isc_ratelimiter_ratelimited) {
 118                 result = isc_timer_reset(rl->timer, isc_timertype_ticker, NULL,
 119                                          &rl->interval, ISC_FALSE);
 120         }
 121         UNLOCK(&rl->lock);
 122         return (result);
 123 }
 124
 125 void
 126 isc_ratelimiter_setpertic(isc_ratelimiter_t *rl, isc_uint32_t pertic) {
 127         if (pertic == 0)
 128                 pertic = 1;
 129         rl->pertic = pertic;
 130 }
 131
 132 isc_result_t
 133 isc_ratelimiter_enqueue(isc_ratelimiter_t *rl, isc_task_t *task,
 134                         isc_event_t **eventp)
 135 {
 136         isc_result_t result = ISC_R_SUCCESS;
 137         isc_event_t *ev;
 138
 139         REQUIRE(eventp != NULL && *eventp != NULL);
 140         REQUIRE(task != NULL);
 141         ev = *eventp;
 142         REQUIRE(ev->ev_sender == NULL);
 143
 144         LOCK(&rl->lock);
 145         if (rl->state == isc_ratelimiter_ratelimited ||
 146             rl->state == isc_ratelimiter_stalled) {
 147                 isc_event_t *ev = *eventp;
 148                 ev->ev_sender = task;
 149                 ISC_LIST_APPEND(rl->pending, ev, ev_link);
 150                 *eventp = NULL;
 151         } else if (rl->state == isc_ratelimiter_idle) {
 152                 result = isc_timer_reset(rl->timer, isc_timertype_ticker, NULL,
 153                                          &rl->interval, ISC_FALSE);
 154                 if (result == ISC_R_SUCCESS) {
 155                         ev->ev_sender = task;
 156                         rl->state = isc_ratelimiter_ratelimited;
 157                 }
 158         } else {
 159                 INSIST(rl->state == isc_ratelimiter_shuttingdown);
 160                 result = ISC_R_SHUTTINGDOWN;
 161         }
 162         UNLOCK(&rl->lock);
 163         if (*eventp != NULL && result == ISC_R_SUCCESS)
 164                 isc_task_send(task, eventp);
 165         return (result);
 166 }
 167
 168 static void
 169 ratelimiter_tick(isc_task_t *task, isc_event_t *event) {
 170         isc_result_t result = ISC_R_SUCCESS;
 171         isc_ratelimiter_t *rl = (isc_ratelimiter_t *)event->ev_arg;
 172         isc_event_t *p;
 173         isc_uint32_t pertic;
 174
 175         UNUSED(task);
 176
 177         isc_event_free(&event);
 178
 179         pertic = rl->pertic;
 180         while (pertic != 0) {
 181                 pertic--;
 182                 LOCK(&rl->lock);
 183                 p = ISC_LIST_HEAD(rl->pending);
 184                 if (p != NULL) {
 185                         /*
 186                          * There is work to do.  Let's do it after unlocking.
 187                          */
 188                         ISC_LIST_UNLINK(rl->pending, p, ev_link);
 189                 } else {
 190                         /*
 191                          * No work left to do.  Stop the timer so that we don't
 192                          * waste resources by having it fire periodically.
 193                          */
 194                         result = isc_timer_reset(rl->timer,
 195                                                  isc_timertype_inactive,
 196                                                  NULL, NULL, ISC_FALSE);
 197                         RUNTIME_CHECK(result == ISC_R_SUCCESS);
 198                         rl->state = isc_ratelimiter_idle;
 199                         pertic = 0;     /* Force the loop to exit. */
 200                 }
 201                 UNLOCK(&rl->lock);
 202                 if (p != NULL) {
 203                         isc_task_t *evtask = p->ev_sender;
 204                         isc_task_send(evtask, &p);
 205                 }
 206                 INSIST(p == NULL);
 207         }
 208 }
 209
 210 void
 211 isc_ratelimiter_shutdown(isc_ratelimiter_t *rl) {
 212         isc_event_t *ev;
 213         isc_task_t *task;
 214         LOCK(&rl->lock);
 215         rl->state = isc_ratelimiter_shuttingdown;
 216         (void)isc_timer_reset(rl->timer, isc_timertype_inactive,
 217                               NULL, NULL, ISC_FALSE);
 218         while ((ev = ISC_LIST_HEAD(rl->pending)) != NULL) {
 219                 ISC_LIST_UNLINK(rl->pending, ev, ev_link);
 220                 ev->ev_attributes |= ISC_EVENTATTR_CANCELED;
 221                 task = ev->ev_sender;
 222                 isc_task_send(task, &ev);
 223         }
 224         isc_timer_detach(&rl->timer);
 225         /*
 226          * Send an event to our task.  The delivery of this event
 227          * indicates that no more timer events will be delivered.
 228          */
 229         ev = &rl->shutdownevent;
 230         isc_task_send(rl->task, &ev);
 231
 232         UNLOCK(&rl->lock);
 233 }
 234
 235 static void
 236 ratelimiter_shutdowncomplete(isc_task_t *task, isc_event_t *event) {
 237         isc_ratelimiter_t *rl = (isc_ratelimiter_t *)event->ev_arg;
 238
 239         UNUSED(task);
 240
 241         isc_ratelimiter_detach(&rl);
 242 }
 243
 244 static void
 245 ratelimiter_free(isc_ratelimiter_t *rl) {
 246         DESTROYLOCK(&rl->lock);
 247         isc_mem_put(rl->mctx, rl, sizeof(*rl));
 248 }
 249
 250 void
 251 isc_ratelimiter_attach(isc_ratelimiter_t *source, isc_ratelimiter_t **target) {
 252         REQUIRE(source != NULL);
 253         REQUIRE(target != NULL && *target == NULL);
 254
 255         LOCK(&source->lock);
 256         REQUIRE(source->refs > 0);
 257         source->refs++;
 258         INSIST(source->refs > 0);
 259         UNLOCK(&source->lock);
 260         *target = source;
 261 }
 262
 263 void
 264 isc_ratelimiter_detach(isc_ratelimiter_t **rlp) {
 265         isc_ratelimiter_t *rl = *rlp;
 266         isc_boolean_t free_now = ISC_FALSE;
 267
 268         LOCK(&rl->lock);
 269         REQUIRE(rl->refs > 0);
 270         rl->refs--;
 271         if (rl->refs == 0)
 272                 free_now = ISC_TRUE;
 273         UNLOCK(&rl->lock);
 274
 275         if (free_now)
 276                 ratelimiter_free(rl);
 277
 278         *rlp = NULL;
 279 }
 280
 281 isc_result_t
 282 isc_ratelimiter_stall(isc_ratelimiter_t *rl) {
 283         isc_result_t result = ISC_R_SUCCESS;
 284
 285         LOCK(&rl->lock);
 286         switch (rl->state) {
 287         case isc_ratelimiter_shuttingdown:
 288                 result = ISC_R_SHUTTINGDOWN;
 289                 break;
 290         case isc_ratelimiter_ratelimited:
 291                 result = isc_timer_reset(rl->timer, isc_timertype_inactive,
 292                                          NULL, NULL, ISC_FALSE);
 293                 RUNTIME_CHECK(result == ISC_R_SUCCESS);
 294         case isc_ratelimiter_idle:
 295         case isc_ratelimiter_stalled:
 296                 rl->state = isc_ratelimiter_stalled;
 297                 break;
 298         }
 299         UNLOCK(&rl->lock);
 300         return (result);
 301 }
 302
 303 isc_result_t
 304 isc_ratelimiter_release(isc_ratelimiter_t *rl) {
 305         isc_result_t result = ISC_R_SUCCESS;
 306
 307         LOCK(&rl->lock);
 308         switch (rl->state) {
 309         case isc_ratelimiter_shuttingdown:
 310                 result = ISC_R_SHUTTINGDOWN;
 311                 break;
 312         case isc_ratelimiter_stalled:
 313                 if (!ISC_LIST_EMPTY(rl->pending)) {
 314                         result = isc_timer_reset(rl->timer,
 315                                                  isc_timertype_ticker, NULL,
 316                                                  &rl->interval, ISC_FALSE);
 317                         if (result == ISC_R_SUCCESS)
 318                                 rl->state = isc_ratelimiter_ratelimited;
 319                 } else
 320                         rl->state = isc_ratelimiter_idle;
 321                 break;
 322         case isc_ratelimiter_ratelimited:
 323         case isc_ratelimiter_idle:
 324                 break;
 325         }
 326         UNLOCK(&rl->lock);
 327         return (result);
 328 }