granicus.if.org Git - libevent/blob - bufferevent_ratelim.c

   1 /*
   2  * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
   3  * Copyright (c) 2002-2006 Niels Provos <provos@citi.umich.edu>
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. The name of the author may not be used to endorse or promote products
  15  *    derived from this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28 #include "evconfig-private.h"
  29
  30 #include <sys/types.h>
  31 #include <limits.h>
  32 #include <string.h>
  33 #include <stdlib.h>
  34
  35 #include "event2/event.h"
  36 #include "event2/event_struct.h"
  37 #include "event2/util.h"
  38 #include "event2/bufferevent.h"
  39 #include "event2/bufferevent_struct.h"
  40 #include "event2/buffer.h"
  41
  42 #include "ratelim-internal.h"
  43
  44 #include "bufferevent-internal.h"
  45 #include "mm-internal.h"
  46 #include "util-internal.h"
  47 #include "event-internal.h"
  48
  49 int
  50 ev_token_bucket_init_(struct ev_token_bucket *bucket,
  51     const struct ev_token_bucket_cfg *cfg,
  52     ev_uint32_t current_tick,
  53     int reinitialize)
  54 {
  55         if (reinitialize) {
  56                 /* on reinitialization, we only clip downwards, since we've
  57                    already used who-knows-how-much bandwidth this tick.  We
  58                    leave "last_updated" as it is; the next update will add the
  59                    appropriate amount of bandwidth to the bucket.
  60                 */
  61                 if (bucket->read_limit > (ev_int64_t) cfg->read_maximum)
  62                         bucket->read_limit = cfg->read_maximum;
  63                 if (bucket->write_limit > (ev_int64_t) cfg->write_maximum)
  64                         bucket->write_limit = cfg->write_maximum;
  65         } else {
  66                 bucket->read_limit = cfg->read_rate;
  67                 bucket->write_limit = cfg->write_rate;
  68                 bucket->last_updated = current_tick;
  69         }
  70         return 0;
  71 }
  72
  73 int
  74 ev_token_bucket_update_(struct ev_token_bucket *bucket,
  75     const struct ev_token_bucket_cfg *cfg,
  76     ev_uint32_t current_tick)
  77 {
  78         /* It's okay if the tick number overflows, since we'll just
  79          * wrap around when we do the unsigned subtraction. */
  80         unsigned n_ticks = current_tick - bucket->last_updated;
  81
  82         /* Make sure some ticks actually happened, and that time didn't
  83          * roll back. */
  84         if (n_ticks == 0 || n_ticks > INT_MAX)
  85                 return 0;
  86
  87         /* Naively, we would say
  88                 bucket->limit += n_ticks * cfg->rate;
  89
  90                 if (bucket->limit > cfg->maximum)
  91                         bucket->limit = cfg->maximum;
  92
  93            But we're worried about overflow, so we do it like this:
  94         */
  95
  96         if ((cfg->read_maximum - bucket->read_limit) / n_ticks < cfg->read_rate)
  97                 bucket->read_limit = cfg->read_maximum;
  98         else
  99                 bucket->read_limit += n_ticks * cfg->read_rate;
 100
 101
 102         if ((cfg->write_maximum - bucket->write_limit) / n_ticks < cfg->write_rate)
 103                 bucket->write_limit = cfg->write_maximum;
 104         else
 105                 bucket->write_limit += n_ticks * cfg->write_rate;
 106
 107
 108         bucket->last_updated = current_tick;
 109
 110         return 1;
 111 }
 112
 113 static inline void
 114 bufferevent_update_buckets(struct bufferevent_private *bev)
 115 {
 116         /* Must hold lock on bev. */
 117         struct timeval now;
 118         unsigned tick;
 119         event_base_gettimeofday_cached(bev->bev.ev_base, &now);
 120         tick = ev_token_bucket_get_tick_(&now, bev->rate_limiting->cfg);
 121         if (tick != bev->rate_limiting->limit.last_updated)
 122                 ev_token_bucket_update_(&bev->rate_limiting->limit,
 123                     bev->rate_limiting->cfg, tick);
 124 }
 125
 126 ev_uint32_t
 127 ev_token_bucket_get_tick_(const struct timeval *tv,
 128     const struct ev_token_bucket_cfg *cfg)
 129 {
 130         /* This computation uses two multiplies and a divide.  We could do
 131          * fewer if we knew that the tick length was an integer number of
 132          * seconds, or if we knew it divided evenly into a second.  We should
 133          * investigate that more.
 134          */
 135
 136         /* We cast to an ev_uint64_t first, since we don't want to overflow
 137          * before we do the final divide. */
 138         ev_uint64_t msec = (ev_uint64_t)tv->tv_sec * 1000 + tv->tv_usec / 1000;
 139         return (unsigned)(msec / cfg->msec_per_tick);
 140 }
 141
 142 struct ev_token_bucket_cfg *
 143 ev_token_bucket_cfg_new(size_t read_rate, size_t read_burst,
 144     size_t write_rate, size_t write_burst,
 145     const struct timeval *tick_len)
 146 {
 147         struct ev_token_bucket_cfg *r;
 148         struct timeval g;
 149         if (! tick_len) {
 150                 g.tv_sec = 1;
 151                 g.tv_usec = 0;
 152                 tick_len = &g;
 153         }
 154         if (read_rate > read_burst || write_rate > write_burst ||
 155             read_rate < 1 || write_rate < 1)
 156                 return NULL;
 157         if (read_rate > EV_RATE_LIMIT_MAX ||
 158             write_rate > EV_RATE_LIMIT_MAX ||
 159             read_burst > EV_RATE_LIMIT_MAX ||
 160             write_burst > EV_RATE_LIMIT_MAX)
 161                 return NULL;
 162         r = mm_calloc(1, sizeof(struct ev_token_bucket_cfg));
 163         if (!r)
 164                 return NULL;
 165         r->read_rate = read_rate;
 166         r->write_rate = write_rate;
 167         r->read_maximum = read_burst;
 168         r->write_maximum = write_burst;
 169         memcpy(&r->tick_timeout, tick_len, sizeof(struct timeval));
 170         r->msec_per_tick = (tick_len->tv_sec * 1000) +
 171             (tick_len->tv_usec & COMMON_TIMEOUT_MICROSECONDS_MASK)/1000;
 172         return r;
 173 }
 174
 175 void
 176 ev_token_bucket_cfg_free(struct ev_token_bucket_cfg *cfg)
 177 {
 178         mm_free(cfg);
 179 }
 180
 181 /* Default values for max_single_read & max_single_write variables. */
 182 #define MAX_SINGLE_READ_DEFAULT 16384
 183 #define MAX_SINGLE_WRITE_DEFAULT 16384
 184
 185 #define LOCK_GROUP(g) EVLOCK_LOCK((g)->lock, 0)
 186 #define UNLOCK_GROUP(g) EVLOCK_UNLOCK((g)->lock, 0)
 187
 188 static int bev_group_suspend_reading_(struct bufferevent_rate_limit_group *g);
 189 static int bev_group_suspend_writing_(struct bufferevent_rate_limit_group *g);
 190 static void bev_group_unsuspend_reading_(struct bufferevent_rate_limit_group *g);
 191 static void bev_group_unsuspend_writing_(struct bufferevent_rate_limit_group *g);
 192
 193 /** Helper: figure out the maximum amount we should write if is_write, or
 194     the maximum amount we should read if is_read.  Return that maximum, or
 195     0 if our bucket is wholly exhausted.
 196  */
 197 static inline ev_ssize_t
 198 bufferevent_get_rlim_max_(struct bufferevent_private *bev, int is_write)
 199 {
 200         /* needs lock on bev. */
 201         ev_ssize_t max_so_far = is_write?bev->max_single_write:bev->max_single_read;
 202
 203 #define LIM(x)                                          \
 204         (is_write ? (x).write_limit : (x).read_limit)
 205
 206 #define GROUP_SUSPENDED(g)                      \
 207         (is_write ? (g)->write_suspended : (g)->read_suspended)
 208
 209         /* Sets max_so_far to MIN(x, max_so_far) */
 210 #define CLAMPTO(x)                              \
 211         do {                                    \
 212                 if (max_so_far > (x))           \
 213                         max_so_far = (x);       \
 214         } while (0);
 215
 216         if (!bev->rate_limiting)
 217                 return max_so_far;
 218
 219         /* If rate-limiting is enabled at all, update the appropriate
 220            bucket, and take the smaller of our rate limit and the group
 221            rate limit.
 222          */
 223
 224         if (bev->rate_limiting->cfg) {
 225                 bufferevent_update_buckets(bev);
 226                 max_so_far = LIM(bev->rate_limiting->limit);
 227         }
 228         if (bev->rate_limiting->group) {
 229                 struct bufferevent_rate_limit_group *g =
 230                     bev->rate_limiting->group;
 231                 ev_ssize_t share;
 232                 LOCK_GROUP(g);
 233                 if (GROUP_SUSPENDED(g)) {
 234                         /* We can get here if we failed to lock this
 235                          * particular bufferevent while suspending the whole
 236                          * group. */
 237                         if (is_write)
 238                                 bufferevent_suspend_write_(&bev->bev,
 239                                     BEV_SUSPEND_BW_GROUP);
 240                         else
 241                                 bufferevent_suspend_read_(&bev->bev,
 242                                     BEV_SUSPEND_BW_GROUP);
 243                         share = 0;
 244                 } else {
 245                         /* XXXX probably we should divide among the active
 246                          * members, not the total members. */
 247                         share = LIM(g->rate_limit) / g->n_members;
 248                         if (share < g->min_share)
 249                                 share = g->min_share;
 250                 }
 251                 UNLOCK_GROUP(g);
 252                 CLAMPTO(share);
 253         }
 254
 255         if (max_so_far < 0)
 256                 max_so_far = 0;
 257         return max_so_far;
 258 }
 259
 260 ev_ssize_t
 261 bufferevent_get_read_max_(struct bufferevent_private *bev)
 262 {
 263         return bufferevent_get_rlim_max_(bev, 0);
 264 }
 265
 266 ev_ssize_t
 267 bufferevent_get_write_max_(struct bufferevent_private *bev)
 268 {
 269         return bufferevent_get_rlim_max_(bev, 1);
 270 }
 271
 272 int
 273 bufferevent_decrement_read_buckets_(struct bufferevent_private *bev, ev_ssize_t bytes)
 274 {
 275         /* XXXXX Make sure all users of this function check its return value */
 276         int r = 0;
 277         /* need to hold lock on bev */
 278         if (!bev->rate_limiting)
 279                 return 0;
 280
 281         if (bev->rate_limiting->cfg) {
 282                 bev->rate_limiting->limit.read_limit -= bytes;
 283                 if (bev->rate_limiting->limit.read_limit <= 0) {
 284                         bufferevent_suspend_read_(&bev->bev, BEV_SUSPEND_BW);
 285                         if (event_add(&bev->rate_limiting->refill_bucket_event,
 286                                 &bev->rate_limiting->cfg->tick_timeout) < 0)
 287                                 r = -1;
 288                 } else if (bev->read_suspended & BEV_SUSPEND_BW) {
 289                         if (!(bev->write_suspended & BEV_SUSPEND_BW))
 290                                 event_del(&bev->rate_limiting->refill_bucket_event);
 291                         bufferevent_unsuspend_read_(&bev->bev, BEV_SUSPEND_BW);
 292                 }
 293         }
 294
 295         if (bev->rate_limiting->group) {
 296                 LOCK_GROUP(bev->rate_limiting->group);
 297                 bev->rate_limiting->group->rate_limit.read_limit -= bytes;
 298                 bev->rate_limiting->group->total_read += bytes;
 299                 if (bev->rate_limiting->group->rate_limit.read_limit <= 0) {
 300                         bev_group_suspend_reading_(bev->rate_limiting->group);
 301                 } else if (bev->rate_limiting->group->read_suspended) {
 302                         bev_group_unsuspend_reading_(bev->rate_limiting->group);
 303                 }
 304                 UNLOCK_GROUP(bev->rate_limiting->group);
 305         }
 306
 307         return r;
 308 }
 309
 310 int
 311 bufferevent_decrement_write_buckets_(struct bufferevent_private *bev, ev_ssize_t bytes)
 312 {
 313         /* XXXXX Make sure all users of this function check its return value */
 314         int r = 0;
 315         /* need to hold lock */
 316         if (!bev->rate_limiting)
 317                 return 0;
 318
 319         if (bev->rate_limiting->cfg) {
 320                 bev->rate_limiting->limit.write_limit -= bytes;
 321                 if (bev->rate_limiting->limit.write_limit <= 0) {
 322                         bufferevent_suspend_write_(&bev->bev, BEV_SUSPEND_BW);
 323                         if (event_add(&bev->rate_limiting->refill_bucket_event,
 324                                 &bev->rate_limiting->cfg->tick_timeout) < 0)
 325                                 r = -1;
 326                 } else if (bev->write_suspended & BEV_SUSPEND_BW) {
 327                         if (!(bev->read_suspended & BEV_SUSPEND_BW))
 328                                 event_del(&bev->rate_limiting->refill_bucket_event);
 329                         bufferevent_unsuspend_write_(&bev->bev, BEV_SUSPEND_BW);
 330                 }
 331         }
 332
 333         if (bev->rate_limiting->group) {
 334                 LOCK_GROUP(bev->rate_limiting->group);
 335                 bev->rate_limiting->group->rate_limit.write_limit -= bytes;
 336                 bev->rate_limiting->group->total_written += bytes;
 337                 if (bev->rate_limiting->group->rate_limit.write_limit <= 0) {
 338                         bev_group_suspend_writing_(bev->rate_limiting->group);
 339                 } else if (bev->rate_limiting->group->write_suspended) {
 340                         bev_group_unsuspend_writing_(bev->rate_limiting->group);
 341                 }
 342                 UNLOCK_GROUP(bev->rate_limiting->group);
 343         }
 344
 345         return r;
 346 }
 347
 348 /** Stop reading on every bufferevent in <b>g</b> */
 349 static int
 350 bev_group_suspend_reading_(struct bufferevent_rate_limit_group *g)
 351 {
 352         /* Needs group lock */
 353         struct bufferevent_private *bev;
 354         g->read_suspended = 1;
 355         g->pending_unsuspend_read = 0;
 356
 357         /* Note that in this loop we call EVLOCK_TRY_LOCK_ instead of BEV_LOCK,
 358            to prevent a deadlock.  (Ordinarily, the group lock nests inside
 359            the bufferevent locks.  If we are unable to lock any individual
 360            bufferevent, it will find out later when it looks at its limit
 361            and sees that its group is suspended.)
 362         */
 363         LIST_FOREACH(bev, &g->members, rate_limiting->next_in_group) {
 364                 if (EVLOCK_TRY_LOCK_(bev->lock)) {
 365                         bufferevent_suspend_read_(&bev->bev,
 366                             BEV_SUSPEND_BW_GROUP);
 367                         EVLOCK_UNLOCK(bev->lock, 0);
 368                 }
 369         }
 370         return 0;
 371 }
 372
 373 /** Stop writing on every bufferevent in <b>g</b> */
 374 static int
 375 bev_group_suspend_writing_(struct bufferevent_rate_limit_group *g)
 376 {
 377         /* Needs group lock */
 378         struct bufferevent_private *bev;
 379         g->write_suspended = 1;
 380         g->pending_unsuspend_write = 0;
 381         LIST_FOREACH(bev, &g->members, rate_limiting->next_in_group) {
 382                 if (EVLOCK_TRY_LOCK_(bev->lock)) {
 383                         bufferevent_suspend_write_(&bev->bev,
 384                             BEV_SUSPEND_BW_GROUP);
 385                         EVLOCK_UNLOCK(bev->lock, 0);
 386                 }
 387         }
 388         return 0;
 389 }
 390
 391 /** Timer callback invoked on a single bufferevent with one or more exhausted
 392     buckets when they are ready to refill. */
 393 static void
 394 bev_refill_callback_(evutil_socket_t fd, short what, void *arg)
 395 {
 396         unsigned tick;
 397         struct timeval now;
 398         struct bufferevent_private *bev = arg;
 399         int again = 0;
 400         BEV_LOCK(&bev->bev);
 401         if (!bev->rate_limiting || !bev->rate_limiting->cfg) {
 402                 BEV_UNLOCK(&bev->bev);
 403                 return;
 404         }
 405
 406         /* First, update the bucket */
 407         event_base_gettimeofday_cached(bev->bev.ev_base, &now);
 408         tick = ev_token_bucket_get_tick_(&now,
 409             bev->rate_limiting->cfg);
 410         ev_token_bucket_update_(&bev->rate_limiting->limit,
 411             bev->rate_limiting->cfg,
 412             tick);
 413
 414         /* Now unsuspend any read/write operations as appropriate. */
 415         if ((bev->read_suspended & BEV_SUSPEND_BW)) {
 416                 if (bev->rate_limiting->limit.read_limit > 0)
 417                         bufferevent_unsuspend_read_(&bev->bev, BEV_SUSPEND_BW);
 418                 else
 419                         again = 1;
 420         }
 421         if ((bev->write_suspended & BEV_SUSPEND_BW)) {
 422                 if (bev->rate_limiting->limit.write_limit > 0)
 423                         bufferevent_unsuspend_write_(&bev->bev, BEV_SUSPEND_BW);
 424                 else
 425                         again = 1;
 426         }
 427         if (again) {
 428                 /* One or more of the buckets may need another refill if they
 429                    started negative.
 430
 431                    XXXX if we need to be quiet for more ticks, we should
 432                    maybe figure out what timeout we really want.
 433                 */
 434                 /* XXXX Handle event_add failure somehow */
 435                 event_add(&bev->rate_limiting->refill_bucket_event,
 436                     &bev->rate_limiting->cfg->tick_timeout);
 437         }
 438         BEV_UNLOCK(&bev->bev);
 439 }
 440
 441 /** Helper: grab a random element from a bufferevent group.
 442  *
 443  * Requires that we hold the lock on the group.
 444  */
 445 static struct bufferevent_private *
 446 bev_group_random_element_(struct bufferevent_rate_limit_group *group)
 447 {
 448         int which;
 449         struct bufferevent_private *bev;
 450
 451         /* requires group lock */
 452
 453         if (!group->n_members)
 454                 return NULL;
 455
 456         EVUTIL_ASSERT(! LIST_EMPTY(&group->members));
 457
 458         which = evutil_weakrand_range_(&group->weakrand_seed, group->n_members);
 459
 460         bev = LIST_FIRST(&group->members);
 461         while (which--)
 462                 bev = LIST_NEXT(bev, rate_limiting->next_in_group);
 463
 464         return bev;
 465 }
 466
 467 /** Iterate over the elements of a rate-limiting group 'g' with a random
 468     starting point, assigning each to the variable 'bev', and executing the
 469     block 'block'.
 470
 471     We do this in a half-baked effort to get fairness among group members.
 472     XXX Round-robin or some kind of priority queue would be even more fair.
 473  */
 474 #define FOREACH_RANDOM_ORDER(block)                     \
 475         do {                                            \
 476                 first = bev_group_random_element_(g);   \
 477                 for (bev = first; bev != LIST_END(&g->members); \
 478                     bev = LIST_NEXT(bev, rate_limiting->next_in_group)) { \
 479                         block ;                                  \
 480                 }                                                \
 481                 for (bev = LIST_FIRST(&g->members); bev && bev != first; \
 482                     bev = LIST_NEXT(bev, rate_limiting->next_in_group)) { \
 483                         block ;                                         \
 484                 }                                                       \
 485         } while (0)
 486
 487 static void
 488 bev_group_unsuspend_reading_(struct bufferevent_rate_limit_group *g)
 489 {
 490         int again = 0;
 491         struct bufferevent_private *bev, *first;
 492
 493         g->read_suspended = 0;
 494         FOREACH_RANDOM_ORDER({
 495                 if (EVLOCK_TRY_LOCK_(bev->lock)) {
 496                         bufferevent_unsuspend_read_(&bev->bev,
 497                             BEV_SUSPEND_BW_GROUP);
 498                         EVLOCK_UNLOCK(bev->lock, 0);
 499                 } else {
 500                         again = 1;
 501                 }
 502         });
 503         g->pending_unsuspend_read = again;
 504 }
 505
 506 static void
 507 bev_group_unsuspend_writing_(struct bufferevent_rate_limit_group *g)
 508 {
 509         int again = 0;
 510         struct bufferevent_private *bev, *first;
 511         g->write_suspended = 0;
 512
 513         FOREACH_RANDOM_ORDER({
 514                 if (EVLOCK_TRY_LOCK_(bev->lock)) {
 515                         bufferevent_unsuspend_write_(&bev->bev,
 516                             BEV_SUSPEND_BW_GROUP);
 517                         EVLOCK_UNLOCK(bev->lock, 0);
 518                 } else {
 519                         again = 1;
 520                 }
 521         });
 522         g->pending_unsuspend_write = again;
 523 }
 524
 525 /** Callback invoked every tick to add more elements to the group bucket
 526     and unsuspend group members as needed.
 527  */
 528 static void
 529 bev_group_refill_callback_(evutil_socket_t fd, short what, void *arg)
 530 {
 531         struct bufferevent_rate_limit_group *g = arg;
 532         unsigned tick;
 533         struct timeval now;
 534
 535         event_base_gettimeofday_cached(event_get_base(&g->master_refill_event), &now);
 536
 537         LOCK_GROUP(g);
 538
 539         tick = ev_token_bucket_get_tick_(&now, &g->rate_limit_cfg);
 540         ev_token_bucket_update_(&g->rate_limit, &g->rate_limit_cfg, tick);
 541
 542         if (g->pending_unsuspend_read ||
 543             (g->read_suspended && (g->rate_limit.read_limit >= g->min_share))) {
 544                 bev_group_unsuspend_reading_(g);
 545         }
 546         if (g->pending_unsuspend_write ||
 547             (g->write_suspended && (g->rate_limit.write_limit >= g->min_share))){
 548                 bev_group_unsuspend_writing_(g);
 549         }
 550
 551         /* XXXX Rather than waiting to the next tick to unsuspend stuff
 552          * with pending_unsuspend_write/read, we should do it on the
 553          * next iteration of the mainloop.
 554          */
 555
 556         UNLOCK_GROUP(g);
 557 }
 558
 559 int
 560 bufferevent_set_rate_limit(struct bufferevent *bev,
 561     struct ev_token_bucket_cfg *cfg)
 562 {
 563         struct bufferevent_private *bevp = BEV_UPCAST(bev);
 564         int r = -1;
 565         struct bufferevent_rate_limit *rlim;
 566         struct timeval now;
 567         ev_uint32_t tick;
 568         int reinit = 0, suspended = 0;
 569         /* XXX reference-count cfg */
 570
 571         BEV_LOCK(bev);
 572
 573         if (cfg == NULL) {
 574                 if (bevp->rate_limiting) {
 575                         rlim = bevp->rate_limiting;
 576                         rlim->cfg = NULL;
 577                         bufferevent_unsuspend_read_(bev, BEV_SUSPEND_BW);
 578                         bufferevent_unsuspend_write_(bev, BEV_SUSPEND_BW);
 579                         if (event_initialized(&rlim->refill_bucket_event))
 580                                 event_del(&rlim->refill_bucket_event);
 581                 }
 582                 r = 0;
 583                 goto done;
 584         }
 585
 586         event_base_gettimeofday_cached(bev->ev_base, &now);
 587         tick = ev_token_bucket_get_tick_(&now, cfg);
 588
 589         if (bevp->rate_limiting && bevp->rate_limiting->cfg == cfg) {
 590                 /* no-op */
 591                 r = 0;
 592                 goto done;
 593         }
 594         if (bevp->rate_limiting == NULL) {
 595                 rlim = mm_calloc(1, sizeof(struct bufferevent_rate_limit));
 596                 if (!rlim)
 597                         goto done;
 598                 bevp->rate_limiting = rlim;
 599         } else {
 600                 rlim = bevp->rate_limiting;
 601         }
 602         reinit = rlim->cfg != NULL;
 603
 604         rlim->cfg = cfg;
 605         ev_token_bucket_init_(&rlim->limit, cfg, tick, reinit);
 606
 607         if (reinit) {
 608                 EVUTIL_ASSERT(event_initialized(&rlim->refill_bucket_event));
 609                 event_del(&rlim->refill_bucket_event);
 610         }
 611         event_assign(&rlim->refill_bucket_event, bev->ev_base,
 612             -1, EV_FINALIZE, bev_refill_callback_, bevp);
 613
 614         if (rlim->limit.read_limit > 0) {
 615                 bufferevent_unsuspend_read_(bev, BEV_SUSPEND_BW);
 616         } else {
 617                 bufferevent_suspend_read_(bev, BEV_SUSPEND_BW);
 618                 suspended=1;
 619         }
 620         if (rlim->limit.write_limit > 0) {
 621                 bufferevent_unsuspend_write_(bev, BEV_SUSPEND_BW);
 622         } else {
 623                 bufferevent_suspend_write_(bev, BEV_SUSPEND_BW);
 624                 suspended = 1;
 625         }
 626
 627         if (suspended)
 628                 event_add(&rlim->refill_bucket_event, &cfg->tick_timeout);
 629
 630         r = 0;
 631
 632 done:
 633         BEV_UNLOCK(bev);
 634         return r;
 635 }
 636
 637 struct bufferevent_rate_limit_group *
 638 bufferevent_rate_limit_group_new(struct event_base *base,
 639     const struct ev_token_bucket_cfg *cfg)
 640 {
 641         struct bufferevent_rate_limit_group *g;
 642         struct timeval now;
 643         ev_uint32_t tick;
 644
 645         event_base_gettimeofday_cached(base, &now);
 646         tick = ev_token_bucket_get_tick_(&now, cfg);
 647
 648         g = mm_calloc(1, sizeof(struct bufferevent_rate_limit_group));
 649         if (!g)
 650                 return NULL;
 651         memcpy(&g->rate_limit_cfg, cfg, sizeof(g->rate_limit_cfg));
 652         LIST_INIT(&g->members);
 653
 654         ev_token_bucket_init_(&g->rate_limit, cfg, tick, 0);
 655
 656         event_assign(&g->master_refill_event, base, -1, EV_PERSIST|EV_FINALIZE,
 657             bev_group_refill_callback_, g);
 658         /*XXXX handle event_add failure */
 659         event_add(&g->master_refill_event, &cfg->tick_timeout);
 660
 661         EVTHREAD_ALLOC_LOCK(g->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
 662
 663         bufferevent_rate_limit_group_set_min_share(g, 64);
 664
 665         evutil_weakrand_seed_(&g->weakrand_seed,
 666             (ev_uint32_t) ((now.tv_sec + now.tv_usec) + (ev_intptr_t)g));
 667
 668         return g;
 669 }
 670
 671 int
 672 bufferevent_rate_limit_group_set_cfg(
 673         struct bufferevent_rate_limit_group *g,
 674         const struct ev_token_bucket_cfg *cfg)
 675 {
 676         int same_tick;
 677         if (!g || !cfg)
 678                 return -1;
 679
 680         LOCK_GROUP(g);
 681         same_tick = evutil_timercmp(
 682                 &g->rate_limit_cfg.tick_timeout, &cfg->tick_timeout, ==);
 683         memcpy(&g->rate_limit_cfg, cfg, sizeof(g->rate_limit_cfg));
 684
 685         if (g->rate_limit.read_limit > (ev_ssize_t)cfg->read_maximum)
 686                 g->rate_limit.read_limit = cfg->read_maximum;
 687         if (g->rate_limit.write_limit > (ev_ssize_t)cfg->write_maximum)
 688                 g->rate_limit.write_limit = cfg->write_maximum;
 689
 690         if (!same_tick) {
 691                 /* This can cause a hiccup in the schedule */
 692                 event_add(&g->master_refill_event, &cfg->tick_timeout);
 693         }
 694
 695         /* The new limits might force us to adjust min_share differently. */
 696         bufferevent_rate_limit_group_set_min_share(g, g->configured_min_share);
 697
 698         UNLOCK_GROUP(g);
 699         return 0;
 700 }
 701
 702 int
 703 bufferevent_rate_limit_group_set_min_share(
 704         struct bufferevent_rate_limit_group *g,
 705         size_t share)
 706 {
 707         if (share > EV_SSIZE_MAX)
 708                 return -1;
 709
 710         g->configured_min_share = share;
 711
 712         /* Can't set share to less than the one-tick maximum.  IOW, at steady
 713          * state, at least one connection can go per tick. */
 714         if (share > g->rate_limit_cfg.read_rate)
 715                 share = g->rate_limit_cfg.read_rate;
 716         if (share > g->rate_limit_cfg.write_rate)
 717                 share = g->rate_limit_cfg.write_rate;
 718
 719         g->min_share = share;
 720         return 0;
 721 }
 722
 723 void
 724 bufferevent_rate_limit_group_free(struct bufferevent_rate_limit_group *g)
 725 {
 726         LOCK_GROUP(g);
 727         EVUTIL_ASSERT(0 == g->n_members);
 728         event_del(&g->master_refill_event);
 729         UNLOCK_GROUP(g);
 730         EVTHREAD_FREE_LOCK(g->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
 731         mm_free(g);
 732 }
 733
 734 int
 735 bufferevent_add_to_rate_limit_group(struct bufferevent *bev,
 736     struct bufferevent_rate_limit_group *g)
 737 {
 738         int wsuspend, rsuspend;
 739         struct bufferevent_private *bevp = BEV_UPCAST(bev);
 740         BEV_LOCK(bev);
 741
 742         if (!bevp->rate_limiting) {
 743                 struct bufferevent_rate_limit *rlim;
 744                 rlim = mm_calloc(1, sizeof(struct bufferevent_rate_limit));
 745                 if (!rlim) {
 746                         BEV_UNLOCK(bev);
 747                         return -1;
 748                 }
 749                 event_assign(&rlim->refill_bucket_event, bev->ev_base,
 750                     -1, EV_FINALIZE, bev_refill_callback_, bevp);
 751                 bevp->rate_limiting = rlim;
 752         }
 753
 754         if (bevp->rate_limiting->group == g) {
 755                 BEV_UNLOCK(bev);
 756                 return 0;
 757         }
 758         if (bevp->rate_limiting->group)
 759                 bufferevent_remove_from_rate_limit_group(bev);
 760
 761         LOCK_GROUP(g);
 762         bevp->rate_limiting->group = g;
 763         ++g->n_members;
 764         LIST_INSERT_HEAD(&g->members, bevp, rate_limiting->next_in_group);
 765
 766         rsuspend = g->read_suspended;
 767         wsuspend = g->write_suspended;
 768
 769         UNLOCK_GROUP(g);
 770
 771         if (rsuspend)
 772                 bufferevent_suspend_read_(bev, BEV_SUSPEND_BW_GROUP);
 773         if (wsuspend)
 774                 bufferevent_suspend_write_(bev, BEV_SUSPEND_BW_GROUP);
 775
 776         BEV_UNLOCK(bev);
 777         return 0;
 778 }
 779
 780 int
 781 bufferevent_remove_from_rate_limit_group(struct bufferevent *bev)
 782 {
 783         return bufferevent_remove_from_rate_limit_group_internal_(bev, 1);
 784 }
 785
 786 int
 787 bufferevent_remove_from_rate_limit_group_internal_(struct bufferevent *bev,
 788     int unsuspend)
 789 {
 790         struct bufferevent_private *bevp = BEV_UPCAST(bev);
 791         BEV_LOCK(bev);
 792         if (bevp->rate_limiting && bevp->rate_limiting->group) {
 793                 struct bufferevent_rate_limit_group *g =
 794                     bevp->rate_limiting->group;
 795                 LOCK_GROUP(g);
 796                 bevp->rate_limiting->group = NULL;
 797                 --g->n_members;
 798                 LIST_REMOVE(bevp, rate_limiting->next_in_group);
 799                 UNLOCK_GROUP(g);
 800         }
 801         if (unsuspend) {
 802                 bufferevent_unsuspend_read_(bev, BEV_SUSPEND_BW_GROUP);
 803                 bufferevent_unsuspend_write_(bev, BEV_SUSPEND_BW_GROUP);
 804         }
 805         BEV_UNLOCK(bev);
 806         return 0;
 807 }
 808
 809 /* ===
 810  * API functions to expose rate limits.
 811  *
 812  * Don't use these from inside Libevent; they're meant to be for use by
 813  * the program.
 814  * === */
 815
 816 /* Mostly you don't want to use this function from inside libevent;
 817  * bufferevent_get_read_max_() is more likely what you want*/
 818 ev_ssize_t
 819 bufferevent_get_read_limit(struct bufferevent *bev)
 820 {
 821         ev_ssize_t r;
 822         struct bufferevent_private *bevp;
 823         BEV_LOCK(bev);
 824         bevp = BEV_UPCAST(bev);
 825         if (bevp->rate_limiting && bevp->rate_limiting->cfg) {
 826                 bufferevent_update_buckets(bevp);
 827                 r = bevp->rate_limiting->limit.read_limit;
 828         } else {
 829                 r = EV_SSIZE_MAX;
 830         }
 831         BEV_UNLOCK(bev);
 832         return r;
 833 }
 834
 835 /* Mostly you don't want to use this function from inside libevent;
 836  * bufferevent_get_write_max_() is more likely what you want*/
 837 ev_ssize_t
 838 bufferevent_get_write_limit(struct bufferevent *bev)
 839 {
 840         ev_ssize_t r;
 841         struct bufferevent_private *bevp;
 842         BEV_LOCK(bev);
 843         bevp = BEV_UPCAST(bev);
 844         if (bevp->rate_limiting && bevp->rate_limiting->cfg) {
 845                 bufferevent_update_buckets(bevp);
 846                 r = bevp->rate_limiting->limit.write_limit;
 847         } else {
 848                 r = EV_SSIZE_MAX;
 849         }
 850         BEV_UNLOCK(bev);
 851         return r;
 852 }
 853
 854 int
 855 bufferevent_set_max_single_read(struct bufferevent *bev, size_t size)
 856 {
 857         struct bufferevent_private *bevp;
 858         int ret = 0;
 859         BEV_LOCK(bev);
 860         bevp = BEV_UPCAST(bev);
 861         if (size == 0 || size > EV_SSIZE_MAX)
 862                 bevp->max_single_read = MAX_SINGLE_READ_DEFAULT;
 863         else
 864                 bevp->max_single_read = size;
 865         ret = evbuffer_set_max_read(bev->input, bevp->max_single_read);
 866         BEV_UNLOCK(bev);
 867         return ret;
 868 }
 869
 870 int
 871 bufferevent_set_max_single_write(struct bufferevent *bev, size_t size)
 872 {
 873         struct bufferevent_private *bevp;
 874         BEV_LOCK(bev);
 875         bevp = BEV_UPCAST(bev);
 876         if (size == 0 || size > EV_SSIZE_MAX)
 877                 bevp->max_single_write = MAX_SINGLE_WRITE_DEFAULT;
 878         else
 879                 bevp->max_single_write = size;
 880         BEV_UNLOCK(bev);
 881         return 0;
 882 }
 883
 884 ev_ssize_t
 885 bufferevent_get_max_single_read(struct bufferevent *bev)
 886 {
 887         ev_ssize_t r;
 888
 889         BEV_LOCK(bev);
 890         r = BEV_UPCAST(bev)->max_single_read;
 891         BEV_UNLOCK(bev);
 892         return r;
 893 }
 894
 895 ev_ssize_t
 896 bufferevent_get_max_single_write(struct bufferevent *bev)
 897 {
 898         ev_ssize_t r;
 899
 900         BEV_LOCK(bev);
 901         r = BEV_UPCAST(bev)->max_single_write;
 902         BEV_UNLOCK(bev);
 903         return r;
 904 }
 905
 906 ev_ssize_t
 907 bufferevent_get_max_to_read(struct bufferevent *bev)
 908 {
 909         ev_ssize_t r;
 910         BEV_LOCK(bev);
 911         r = bufferevent_get_read_max_(BEV_UPCAST(bev));
 912         BEV_UNLOCK(bev);
 913         return r;
 914 }
 915
 916 ev_ssize_t
 917 bufferevent_get_max_to_write(struct bufferevent *bev)
 918 {
 919         ev_ssize_t r;
 920         BEV_LOCK(bev);
 921         r = bufferevent_get_write_max_(BEV_UPCAST(bev));
 922         BEV_UNLOCK(bev);
 923         return r;
 924 }
 925
 926 const struct ev_token_bucket_cfg *
 927 bufferevent_get_token_bucket_cfg(const struct bufferevent *bev) {
 928         struct bufferevent_private *bufev_private = BEV_UPCAST(bev);
 929         struct ev_token_bucket_cfg *cfg;
 930
 931         BEV_LOCK(bev);
 932
 933         if (bufev_private->rate_limiting) {
 934                 cfg = bufev_private->rate_limiting->cfg;
 935         } else {
 936                 cfg = NULL;
 937         }
 938
 939         BEV_UNLOCK(bev);
 940
 941         return cfg;
 942 }
 943
 944 /* Mostly you don't want to use this function from inside libevent;
 945  * bufferevent_get_read_max_() is more likely what you want*/
 946 ev_ssize_t
 947 bufferevent_rate_limit_group_get_read_limit(
 948         struct bufferevent_rate_limit_group *grp)
 949 {
 950         ev_ssize_t r;
 951         LOCK_GROUP(grp);
 952         r = grp->rate_limit.read_limit;
 953         UNLOCK_GROUP(grp);
 954         return r;
 955 }
 956
 957 /* Mostly you don't want to use this function from inside libevent;
 958  * bufferevent_get_write_max_() is more likely what you want. */
 959 ev_ssize_t
 960 bufferevent_rate_limit_group_get_write_limit(
 961         struct bufferevent_rate_limit_group *grp)
 962 {
 963         ev_ssize_t r;
 964         LOCK_GROUP(grp);
 965         r = grp->rate_limit.write_limit;
 966         UNLOCK_GROUP(grp);
 967         return r;
 968 }
 969
 970 int
 971 bufferevent_decrement_read_limit(struct bufferevent *bev, ev_ssize_t decr)
 972 {
 973         int r = 0;
 974         ev_ssize_t old_limit, new_limit;
 975         struct bufferevent_private *bevp;
 976         BEV_LOCK(bev);
 977         bevp = BEV_UPCAST(bev);
 978         EVUTIL_ASSERT(bevp->rate_limiting && bevp->rate_limiting->cfg);
 979         old_limit = bevp->rate_limiting->limit.read_limit;
 980
 981         new_limit = (bevp->rate_limiting->limit.read_limit -= decr);
 982         if (old_limit > 0 && new_limit <= 0) {
 983                 bufferevent_suspend_read_(bev, BEV_SUSPEND_BW);
 984                 if (event_add(&bevp->rate_limiting->refill_bucket_event,
 985                         &bevp->rate_limiting->cfg->tick_timeout) < 0)
 986                         r = -1;
 987         } else if (old_limit <= 0 && new_limit > 0) {
 988                 if (!(bevp->write_suspended & BEV_SUSPEND_BW))
 989                         event_del(&bevp->rate_limiting->refill_bucket_event);
 990                 bufferevent_unsuspend_read_(bev, BEV_SUSPEND_BW);
 991         }
 992
 993         BEV_UNLOCK(bev);
 994         return r;
 995 }
 996
 997 int
 998 bufferevent_decrement_write_limit(struct bufferevent *bev, ev_ssize_t decr)
 999 {
1000         /* XXXX this is mostly copy-and-paste from
1001          * bufferevent_decrement_read_limit */
1002         int r = 0;
1003         ev_ssize_t old_limit, new_limit;
1004         struct bufferevent_private *bevp;
1005         BEV_LOCK(bev);
1006         bevp = BEV_UPCAST(bev);
1007         EVUTIL_ASSERT(bevp->rate_limiting && bevp->rate_limiting->cfg);
1008         old_limit = bevp->rate_limiting->limit.write_limit;
1009
1010         new_limit = (bevp->rate_limiting->limit.write_limit -= decr);
1011         if (old_limit > 0 && new_limit <= 0) {
1012                 bufferevent_suspend_write_(bev, BEV_SUSPEND_BW);
1013                 if (event_add(&bevp->rate_limiting->refill_bucket_event,
1014                         &bevp->rate_limiting->cfg->tick_timeout) < 0)
1015                         r = -1;
1016         } else if (old_limit <= 0 && new_limit > 0) {
1017                 if (!(bevp->read_suspended & BEV_SUSPEND_BW))
1018                         event_del(&bevp->rate_limiting->refill_bucket_event);
1019                 bufferevent_unsuspend_write_(bev, BEV_SUSPEND_BW);
1020         }
1021
1022         BEV_UNLOCK(bev);
1023         return r;
1024 }
1025
1026 int
1027 bufferevent_rate_limit_group_decrement_read(
1028         struct bufferevent_rate_limit_group *grp, ev_ssize_t decr)
1029 {
1030         int r = 0;
1031         ev_ssize_t old_limit, new_limit;
1032         LOCK_GROUP(grp);
1033         old_limit = grp->rate_limit.read_limit;
1034         new_limit = (grp->rate_limit.read_limit -= decr);
1035
1036         if (old_limit > 0 && new_limit <= 0) {
1037                 bev_group_suspend_reading_(grp);
1038         } else if (old_limit <= 0 && new_limit > 0) {
1039                 bev_group_unsuspend_reading_(grp);
1040         }
1041
1042         UNLOCK_GROUP(grp);
1043         return r;
1044 }
1045
1046 int
1047 bufferevent_rate_limit_group_decrement_write(
1048         struct bufferevent_rate_limit_group *grp, ev_ssize_t decr)
1049 {
1050         int r = 0;
1051         ev_ssize_t old_limit, new_limit;
1052         LOCK_GROUP(grp);
1053         old_limit = grp->rate_limit.write_limit;
1054         new_limit = (grp->rate_limit.write_limit -= decr);
1055
1056         if (old_limit > 0 && new_limit <= 0) {
1057                 bev_group_suspend_writing_(grp);
1058         } else if (old_limit <= 0 && new_limit > 0) {
1059                 bev_group_unsuspend_writing_(grp);
1060         }
1061
1062         UNLOCK_GROUP(grp);
1063         return r;
1064 }
1065
1066 void
1067 bufferevent_rate_limit_group_get_totals(struct bufferevent_rate_limit_group *grp,
1068     ev_uint64_t *total_read_out, ev_uint64_t *total_written_out)
1069 {
1070         EVUTIL_ASSERT(grp != NULL);
1071         if (total_read_out)
1072                 *total_read_out = grp->total_read;
1073         if (total_written_out)
1074                 *total_written_out = grp->total_written;
1075 }
1076
1077 void
1078 bufferevent_rate_limit_group_reset_totals(struct bufferevent_rate_limit_group *grp)
1079 {
1080         grp->total_read = grp->total_written = 0;
1081 }
1082
1083 int
1084 bufferevent_ratelim_init_(struct bufferevent_private *bev)
1085 {
1086         bev->rate_limiting = NULL;
1087         bev->max_single_read = MAX_SINGLE_READ_DEFAULT;
1088         bev->max_single_write = MAX_SINGLE_WRITE_DEFAULT;
1089
1090         if (evbuffer_set_max_read(bev->bev.input, bev->max_single_read))
1091                 return -1;
1092
1093         return 0;
1094 }