bridges/bridge_multiplexed.c

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 2008, Digium, Inc.
   5  *
   6  * Joshua Colp <jcolp@digium.com>
   7  *
   8  * See http://www.asterisk.org for more information about
   9  * the Asterisk project. Please do not directly contact
  10  * any of the maintainers of this project for assistance;
  11  * the project provides a web site, mailing lists and IRC
  12  * channels for your use.
  13  *
  14  * This program is free software, distributed under the terms of
  15  * the GNU General Public License Version 2. See the LICENSE file
  16  * at the top of the source tree.
  17  */
  18
  19 /*! \file
  20  *
  21  * \brief Two channel bridging module which groups bridges into batches of threads
  22  *
  23  * \author Joshua Colp <jcolp@digium.com>
  24  *
  25  * \ingroup bridges
  26  */
  27
  28 #include "asterisk.h"
  29
  30 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  31
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35 #include <sys/types.h>
  36 #include <sys/stat.h>
  37 #include <fcntl.h>
  38
  39 #include "asterisk/module.h"
  40 #include "asterisk/channel.h"
  41 #include "asterisk/bridging.h"
  42 #include "asterisk/bridging_technology.h"
  43 #include "asterisk/frame.h"
  44 #include "asterisk/astobj2.h"
  45
  46 /*! \brief Number of buckets our multiplexed thread container can have */
  47 #define MULTIPLEXED_BUCKETS 53
  48
  49 /*! \brief Number of channels we handle in a single thread */
  50 #define MULTIPLEXED_MAX_CHANNELS 8
  51
  52 /*! \brief Structure which represents a single thread handling multiple 2 channel bridges */
  53 struct multiplexed_thread {
  54         /*! Thread itself */
  55         pthread_t thread;
  56         /*! Pipe used to wake up the multiplexed thread */
  57         int pipe[2];
  58         /*! Channels in this thread */
  59         struct ast_channel *chans[MULTIPLEXED_MAX_CHANNELS];
  60         /*! Number of channels in this thread */
  61         unsigned int count;
  62         /*! Bit used to indicate that the thread is waiting on channels */
  63         unsigned int waiting:1;
  64         /*! Number of channels actually being serviced by this thread */
  65         unsigned int service_count;
  66 };
  67
  68 /*! \brief Container of all operating multiplexed threads */
  69 static struct ao2_container *multiplexed_threads;
  70
  71 /*! \brief Callback function for finding a free multiplexed thread */
  72 static int find_multiplexed_thread(void *obj, void *arg, int flags)
  73 {
  74         struct multiplexed_thread *multiplexed_thread = obj;
  75         return (multiplexed_thread->count <= (MULTIPLEXED_MAX_CHANNELS - 2)) ? CMP_MATCH | CMP_STOP : 0;
  76 }
  77
  78 /*! \brief Destroy callback for a multiplexed thread structure */
  79 static void destroy_multiplexed_thread(void *obj)
  80 {
  81         struct multiplexed_thread *multiplexed_thread = obj;
  82
  83         if (multiplexed_thread->pipe[0] > -1) {
  84                 close(multiplexed_thread->pipe[0]);
  85         }
  86         if (multiplexed_thread->pipe[1] > -1) {
  87                 close(multiplexed_thread->pipe[1]);
  88         }
  89
  90         return;
  91 }
  92
  93 /*! \brief Create function which finds/reserves/references a multiplexed thread structure */
  94 static int multiplexed_bridge_create(struct ast_bridge *bridge)
  95 {
  96         struct multiplexed_thread *multiplexed_thread;
  97
  98         ao2_lock(multiplexed_threads);
  99
 100         /* Try to find an existing thread to handle our additional channels */
 101         if (!(multiplexed_thread = ao2_callback(multiplexed_threads, 0, find_multiplexed_thread, NULL))) {
 102                 int flags;
 103
 104                 /* If we failed we will have to create a new one from scratch */
 105                 if (!(multiplexed_thread = ao2_alloc(sizeof(*multiplexed_thread), destroy_multiplexed_thread))) {
 106                         ast_debug(1, "Failed to find or create a new multiplexed thread for bridge '%p'\n", bridge);
 107                         ao2_unlock(multiplexed_threads);
 108                         return -1;
 109                 }
 110
 111                 multiplexed_thread->pipe[0] = multiplexed_thread->pipe[1] = -1;
 112                 /* Setup a pipe so we can poke the thread itself when needed */
 113                 if (pipe(multiplexed_thread->pipe)) {
 114                         ast_debug(1, "Failed to create a pipe for poking a multiplexed thread for bridge '%p'\n", bridge);
 115                         ao2_ref(multiplexed_thread, -1);
 116                         ao2_unlock(multiplexed_threads);
 117                         return -1;
 118                 }
 119
 120                 /* Setup each pipe for non-blocking operation */
 121                 flags = fcntl(multiplexed_thread->pipe[0], F_GETFL);
 122                 if (fcntl(multiplexed_thread->pipe[0], F_SETFL, flags | O_NONBLOCK) < 0) {
 123                         ast_log(LOG_WARNING, "Failed to setup first nudge pipe for non-blocking operation on %p (%d: %s)\n", bridge, errno, strerror(errno));
 124                         ao2_ref(multiplexed_thread, -1);
 125                         ao2_unlock(multiplexed_threads);
 126                         return -1;
 127                 }
 128                 flags = fcntl(multiplexed_thread->pipe[1], F_GETFL);
 129                 if (fcntl(multiplexed_thread->pipe[1], F_SETFL, flags | O_NONBLOCK) < 0) {
 130                         ast_log(LOG_WARNING, "Failed to setup second nudge pipe for non-blocking operation on %p (%d: %s)\n", bridge, errno, strerror(errno));
 131                         ao2_ref(multiplexed_thread, -1);
 132                         ao2_unlock(multiplexed_threads);
 133                         return -1;
 134                 }
 135
 136                 /* Set up default parameters */
 137                 multiplexed_thread->thread = AST_PTHREADT_NULL;
 138
 139                 /* Finally link us into the container so others may find us */
 140                 ao2_link(multiplexed_threads, multiplexed_thread);
 141                 ast_debug(1, "Created multiplexed thread '%p' for bridge '%p'\n", multiplexed_thread, bridge);
 142         } else {
 143                 ast_debug(1, "Found multiplexed thread '%p' for bridge '%p'\n", multiplexed_thread, bridge);
 144         }
 145
 146         /* Bump the count of the thread structure up by two since the channels for this bridge will be joining shortly */
 147         multiplexed_thread->count += 2;
 148
 149         ao2_unlock(multiplexed_threads);
 150
 151         bridge->bridge_pvt = multiplexed_thread;
 152
 153         return 0;
 154 }
 155
 156 /*! \brief Internal function which nudges the thread */
 157 static void multiplexed_nudge(struct multiplexed_thread *multiplexed_thread)
 158 {
 159         int nudge = 0;
 160
 161         if (multiplexed_thread->thread == AST_PTHREADT_NULL) {
 162                 return;
 163         }
 164
 165         if (write(multiplexed_thread->pipe[1], &nudge, sizeof(nudge)) != sizeof(nudge)) {
 166                 ast_log(LOG_ERROR, "We couldn't poke multiplexed thread '%p'... something is VERY wrong\n", multiplexed_thread);
 167         }
 168
 169         while (multiplexed_thread->waiting) {
 170                 sched_yield();
 171         }
 172
 173         return;
 174 }
 175
 176 /*! \brief Destroy function which unreserves/unreferences/removes a multiplexed thread structure */
 177 static int multiplexed_bridge_destroy(struct ast_bridge *bridge)
 178 {
 179         struct multiplexed_thread *multiplexed_thread = bridge->bridge_pvt;
 180
 181         ao2_lock(multiplexed_threads);
 182
 183         multiplexed_thread->count -= 2;
 184
 185         if (!multiplexed_thread->count) {
 186                 ast_debug(1, "Unlinking multiplexed thread '%p' since nobody is using it anymore\n", multiplexed_thread);
 187                 ao2_unlink(multiplexed_threads, multiplexed_thread);
 188         }
 189
 190         multiplexed_nudge(multiplexed_thread);
 191
 192         ao2_unlock(multiplexed_threads);
 193
 194         ao2_ref(multiplexed_thread, -1);
 195
 196         return 0;
 197 }
 198
 199 /*! \brief Thread function that executes for multiplexed threads */
 200 static void *multiplexed_thread_function(void *data)
 201 {
 202         struct multiplexed_thread *multiplexed_thread = data;
 203         int fds = multiplexed_thread->pipe[0];
 204
 205         ao2_lock(multiplexed_thread);
 206
 207         ast_debug(1, "Starting actual thread for multiplexed thread '%p'\n", multiplexed_thread);
 208
 209         while (multiplexed_thread->thread != AST_PTHREADT_STOP) {
 210                 struct ast_channel *winner = NULL, *first = multiplexed_thread->chans[0];
 211                 int to = -1, outfd = -1;
 212
 213                 /* Move channels around so not just the first one gets priority */
 214                 memmove(multiplexed_thread->chans, multiplexed_thread->chans + 1, sizeof(struct ast_channel *) * (multiplexed_thread->service_count - 1));
 215                 multiplexed_thread->chans[multiplexed_thread->service_count - 1] = first;
 216
 217                 multiplexed_thread->waiting = 1;
 218                 ao2_unlock(multiplexed_thread);
 219                 winner = ast_waitfor_nandfds(multiplexed_thread->chans, multiplexed_thread->service_count, &fds, 1, NULL, &outfd, &to);
 220                 multiplexed_thread->waiting = 0;
 221                 ao2_lock(multiplexed_thread);
 222                 if (multiplexed_thread->thread == AST_PTHREADT_STOP) {
 223                         break;
 224                 }
 225
 226                 if (outfd > -1) {
 227                         int nudge;
 228
 229                         if (read(multiplexed_thread->pipe[0], &nudge, sizeof(nudge)) < 0) {
 230                                 if (errno != EINTR && errno != EAGAIN) {
 231                                         ast_log(LOG_WARNING, "read() failed for pipe on multiplexed thread '%p': %s\n", multiplexed_thread, strerror(errno));
 232                                 }
 233                         }
 234                 }
 235                 if (winner && winner->bridge) {
 236                         struct ast_bridge *bridge = winner->bridge;
 237                         int stop = 0;
 238                         ao2_unlock(multiplexed_thread);
 239                         while ((bridge = winner->bridge) && ao2_trylock(bridge)) {
 240                                 sched_yield();
 241                                 if (multiplexed_thread->thread == AST_PTHREADT_STOP) {
 242                                         stop = 1;
 243                                         break;
 244                                 }
 245                         }
 246                         if (!stop && bridge) {
 247                                 ast_bridge_handle_trip(bridge, NULL, winner, -1);
 248                                 ao2_unlock(bridge);
 249                         }
 250                         ao2_lock(multiplexed_thread);
 251                 }
 252         }
 253
 254         multiplexed_thread->thread = AST_PTHREADT_NULL;
 255
 256         ast_debug(1, "Stopping actual thread for multiplexed thread '%p'\n", multiplexed_thread);
 257
 258         ao2_unlock(multiplexed_thread);
 259         ao2_ref(multiplexed_thread, -1);
 260
 261         return NULL;
 262 }
 263
 264 /*! \brief Helper function which adds or removes a channel and nudges the thread */
 265 static void multiplexed_add_or_remove(struct multiplexed_thread *multiplexed_thread, struct ast_channel *chan, int add)
 266 {
 267         int i, removed = 0;
 268         pthread_t thread = AST_PTHREADT_NULL;
 269
 270         ao2_lock(multiplexed_thread);
 271
 272         multiplexed_nudge(multiplexed_thread);
 273
 274         for (i = 0; i < MULTIPLEXED_MAX_CHANNELS; i++) {
 275                 if (multiplexed_thread->chans[i] == chan) {
 276                         if (!add) {
 277                                 multiplexed_thread->chans[i] = NULL;
 278                                 multiplexed_thread->service_count--;
 279                                 removed = 1;
 280                         }
 281                         break;
 282                 } else if (!multiplexed_thread->chans[i] && add) {
 283                         multiplexed_thread->chans[i] = chan;
 284                         multiplexed_thread->service_count++;
 285                         break;
 286                 }
 287         }
 288
 289         if (multiplexed_thread->service_count && multiplexed_thread->thread == AST_PTHREADT_NULL) {
 290                 ao2_ref(multiplexed_thread, +1);
 291                 if (ast_pthread_create(&multiplexed_thread->thread, NULL, multiplexed_thread_function, multiplexed_thread)) {
 292                         ao2_ref(multiplexed_thread, -1);
 293                         ast_debug(1, "Failed to create an actual thread for multiplexed thread '%p', trying next time\n", multiplexed_thread);
 294                 }
 295         } else if (!multiplexed_thread->service_count && multiplexed_thread->thread != AST_PTHREADT_NULL) {
 296                 thread = multiplexed_thread->thread;
 297                 multiplexed_thread->thread = AST_PTHREADT_STOP;
 298         } else if (!add && removed) {
 299                 memmove(multiplexed_thread->chans + i, multiplexed_thread->chans + i + 1, sizeof(struct ast_channel *) * (MULTIPLEXED_MAX_CHANNELS - (i + 1)));
 300         }
 301
 302         ao2_unlock(multiplexed_thread);
 303
 304         if (thread != AST_PTHREADT_NULL) {
 305                 pthread_join(thread, NULL);
 306         }
 307
 308         return;
 309 }
 310
 311 /*! \brief Join function which actually adds the channel into the array to be monitored */
 312 static int multiplexed_bridge_join(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 313 {
 314         struct ast_channel *c0 = AST_LIST_FIRST(&bridge->channels)->chan, *c1 = AST_LIST_LAST(&bridge->channels)->chan;
 315         struct multiplexed_thread *multiplexed_thread = bridge->bridge_pvt;
 316
 317         ast_debug(1, "Adding channel '%s' to multiplexed thread '%p' for monitoring\n", bridge_channel->chan->name, multiplexed_thread);
 318
 319         multiplexed_add_or_remove(multiplexed_thread, bridge_channel->chan, 1);
 320
 321         /* If the second channel has not yet joined do not make things compatible */
 322         if (c0 == c1) {
 323                 return 0;
 324         }
 325
 326         if ((ast_format_cmp(&c0->writeformat, &c1->readformat) == AST_FORMAT_CMP_EQUAL) &&
 327                 (ast_format_cmp(&c0->readformat, &c1->writeformat) == AST_FORMAT_CMP_EQUAL) &&
 328                 (ast_format_cap_identical(c0->nativeformats, c1->nativeformats))) {
 329                 return 0;
 330         }
 331
 332         return ast_channel_make_compatible(c0, c1);
 333 }
 334
 335 /*! \brief Leave function which actually removes the channel from the array */
 336 static int multiplexed_bridge_leave(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 337 {
 338         struct multiplexed_thread *multiplexed_thread = bridge->bridge_pvt;
 339
 340         ast_debug(1, "Removing channel '%s' from multiplexed thread '%p'\n", bridge_channel->chan->name, multiplexed_thread);
 341
 342         multiplexed_add_or_remove(multiplexed_thread, bridge_channel->chan, 0);
 343
 344         return 0;
 345 }
 346
 347 /*! \brief Suspend function which means control of the channel is going elsewhere */
 348 static void multiplexed_bridge_suspend(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 349 {
 350         struct multiplexed_thread *multiplexed_thread = bridge->bridge_pvt;
 351
 352         ast_debug(1, "Suspending channel '%s' from multiplexed thread '%p'\n", bridge_channel->chan->name, multiplexed_thread);
 353
 354         multiplexed_add_or_remove(multiplexed_thread, bridge_channel->chan, 0);
 355
 356         return;
 357 }
 358
 359 /*! \brief Unsuspend function which means control of the channel is coming back to us */
 360 static void multiplexed_bridge_unsuspend(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 361 {
 362         struct multiplexed_thread *multiplexed_thread = bridge->bridge_pvt;
 363
 364         ast_debug(1, "Unsuspending channel '%s' from multiplexed thread '%p'\n", bridge_channel->chan->name, multiplexed_thread);
 365
 366         multiplexed_add_or_remove(multiplexed_thread, bridge_channel->chan, 1);
 367
 368         return;
 369 }
 370
 371 /*! \brief Write function for writing frames into the bridge */
 372 static enum ast_bridge_write_result multiplexed_bridge_write(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
 373 {
 374         struct ast_bridge_channel *other;
 375
 376         if (AST_LIST_FIRST(&bridge->channels) == AST_LIST_LAST(&bridge->channels)) {
 377                 return AST_BRIDGE_WRITE_FAILED;
 378         }
 379
 380         if (!(other = (AST_LIST_FIRST(&bridge->channels) == bridge_channel ? AST_LIST_LAST(&bridge->channels) : AST_LIST_FIRST(&bridge->channels)))) {
 381                 return AST_BRIDGE_WRITE_FAILED;
 382         }
 383
 384         if (other->state == AST_BRIDGE_CHANNEL_STATE_WAIT) {
 385                 ast_write(other->chan, frame);
 386         }
 387
 388         return AST_BRIDGE_WRITE_SUCCESS;
 389 }
 390
 391 static struct ast_bridge_technology multiplexed_bridge = {
 392         .name = "multiplexed_bridge",
 393         .capabilities = AST_BRIDGE_CAPABILITY_1TO1MIX,
 394         .preference = AST_BRIDGE_PREFERENCE_HIGH,
 395         .create = multiplexed_bridge_create,
 396         .destroy = multiplexed_bridge_destroy,
 397         .join = multiplexed_bridge_join,
 398         .leave = multiplexed_bridge_leave,
 399         .suspend = multiplexed_bridge_suspend,
 400         .unsuspend = multiplexed_bridge_unsuspend,
 401         .write = multiplexed_bridge_write,
 402 };
 403
 404 static int unload_module(void)
 405 {
 406         int res = ast_bridge_technology_unregister(&multiplexed_bridge);
 407
 408         ao2_ref(multiplexed_threads, -1);
 409         multiplexed_bridge.format_capabilities = ast_format_cap_destroy(multiplexed_bridge.format_capabilities);
 410
 411         return res;
 412 }
 413
 414 static int load_module(void)
 415 {
 416         if (!(multiplexed_threads = ao2_container_alloc(MULTIPLEXED_BUCKETS, NULL, NULL))) {
 417                 return AST_MODULE_LOAD_DECLINE;
 418         }
 419         if (!(multiplexed_bridge.format_capabilities = ast_format_cap_alloc())) {
 420                 return AST_MODULE_LOAD_DECLINE;
 421         }
 422         ast_format_cap_add_all_by_type(multiplexed_bridge.format_capabilities, AST_FORMAT_TYPE_AUDIO);
 423         ast_format_cap_add_all_by_type(multiplexed_bridge.format_capabilities, AST_FORMAT_TYPE_VIDEO);
 424         ast_format_cap_add_all_by_type(multiplexed_bridge.format_capabilities, AST_FORMAT_TYPE_TEXT);
 425         return ast_bridge_technology_register(&multiplexed_bridge);
 426 }
 427
 428 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Multiplexed two channel bridging module");