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 /*** MODULEINFO
  29         <support_level>core</support_level>
  30  ***/
  31
  32 #include "asterisk.h"
  33
  34 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  35
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <sys/types.h>
  40 #include <sys/stat.h>
  41 #include <fcntl.h>
  42
  43 #include "asterisk/module.h"
  44 #include "asterisk/channel.h"
  45 #include "asterisk/bridging.h"
  46 #include "asterisk/bridging_technology.h"
  47 #include "asterisk/frame.h"
  48 #include "asterisk/astobj2.h"
  49
  50 /*! \brief Number of buckets our multiplexed thread container can have */
  51 #define MULTIPLEXED_BUCKETS 53
  52
  53 /*! \brief Number of channels we handle in a single thread */
  54 #define MULTIPLEXED_MAX_CHANNELS 8
  55
  56 /*! \brief Structure which represents a single thread handling multiple 2 channel bridges */
  57 struct multiplexed_thread {
  58         /*! Thread itself */
  59         pthread_t thread;
  60         /*! Pipe used to wake up the multiplexed thread */
  61         int pipe[2];
  62         /*! Channels in this thread */
  63         struct ast_channel *chans[MULTIPLEXED_MAX_CHANNELS];
  64         /*! Number of channels in this thread */
  65         unsigned int count;
  66         /*! Bit used to indicate that the thread is waiting on channels */
  67         unsigned int waiting:1;
  68         /*! Number of channels actually being serviced by this thread */
  69         unsigned int service_count;
  70 };
  71
  72 /*! \brief Container of all operating multiplexed threads */
  73 static struct ao2_container *multiplexed_threads;
  74
  75 /*! \brief Callback function for finding a free multiplexed thread */
  76 static int find_multiplexed_thread(void *obj, void *arg, int flags)
  77 {
  78         struct multiplexed_thread *multiplexed_thread = obj;
  79         return (multiplexed_thread->count <= (MULTIPLEXED_MAX_CHANNELS - 2)) ? CMP_MATCH | CMP_STOP : 0;
  80 }
  81
  82 /*! \brief Destroy callback for a multiplexed thread structure */
  83 static void destroy_multiplexed_thread(void *obj)
  84 {
  85         struct multiplexed_thread *multiplexed_thread = obj;
  86
  87         if (multiplexed_thread->pipe[0] > -1) {
  88                 close(multiplexed_thread->pipe[0]);
  89         }
  90         if (multiplexed_thread->pipe[1] > -1) {
  91                 close(multiplexed_thread->pipe[1]);
  92         }
  93 }
  94
  95 /*! \brief Create function which finds/reserves/references a multiplexed thread structure */
  96 static int multiplexed_bridge_create(struct ast_bridge *bridge)
  97 {
  98         struct multiplexed_thread *multiplexed_thread;
  99
 100         ao2_lock(multiplexed_threads);
 101
 102         /* Try to find an existing thread to handle our additional channels */
 103         if (!(multiplexed_thread = ao2_callback(multiplexed_threads, 0, find_multiplexed_thread, NULL))) {
 104                 int flags;
 105
 106                 /* If we failed we will have to create a new one from scratch */
 107                 if (!(multiplexed_thread = ao2_alloc(sizeof(*multiplexed_thread), destroy_multiplexed_thread))) {
 108                         ast_debug(1, "Failed to find or create a new multiplexed thread for bridge '%p'\n", bridge);
 109                         ao2_unlock(multiplexed_threads);
 110                         return -1;
 111                 }
 112
 113                 multiplexed_thread->pipe[0] = multiplexed_thread->pipe[1] = -1;
 114                 /* Setup a pipe so we can poke the thread itself when needed */
 115                 if (pipe(multiplexed_thread->pipe)) {
 116                         ast_debug(1, "Failed to create a pipe for poking a multiplexed thread for bridge '%p'\n", bridge);
 117                         ao2_ref(multiplexed_thread, -1);
 118                         ao2_unlock(multiplexed_threads);
 119                         return -1;
 120                 }
 121
 122                 /* Setup each pipe for non-blocking operation */
 123                 flags = fcntl(multiplexed_thread->pipe[0], F_GETFL);
 124                 if (fcntl(multiplexed_thread->pipe[0], F_SETFL, flags | O_NONBLOCK) < 0) {
 125                         ast_log(LOG_WARNING, "Failed to setup first nudge pipe for non-blocking operation on %p (%d: %s)\n", bridge, errno, strerror(errno));
 126                         ao2_ref(multiplexed_thread, -1);
 127                         ao2_unlock(multiplexed_threads);
 128                         return -1;
 129                 }
 130                 flags = fcntl(multiplexed_thread->pipe[1], F_GETFL);
 131                 if (fcntl(multiplexed_thread->pipe[1], F_SETFL, flags | O_NONBLOCK) < 0) {
 132                         ast_log(LOG_WARNING, "Failed to setup second nudge pipe for non-blocking operation on %p (%d: %s)\n", bridge, errno, strerror(errno));
 133                         ao2_ref(multiplexed_thread, -1);
 134                         ao2_unlock(multiplexed_threads);
 135                         return -1;
 136                 }
 137
 138                 /* Set up default parameters */
 139                 multiplexed_thread->thread = AST_PTHREADT_NULL;
 140
 141                 /* Finally link us into the container so others may find us */
 142                 ao2_link(multiplexed_threads, multiplexed_thread);
 143                 ast_debug(1, "Created multiplexed thread '%p' for bridge '%p'\n", multiplexed_thread, bridge);
 144         } else {
 145                 ast_debug(1, "Found multiplexed thread '%p' for bridge '%p'\n", multiplexed_thread, bridge);
 146         }
 147
 148         /* Bump the count of the thread structure up by two since the channels for this bridge will be joining shortly */
 149         multiplexed_thread->count += 2;
 150
 151         ao2_unlock(multiplexed_threads);
 152
 153         bridge->bridge_pvt = multiplexed_thread;
 154
 155         return 0;
 156 }
 157
 158 /*! \brief Internal function which nudges the thread */
 159 static void multiplexed_nudge(struct multiplexed_thread *multiplexed_thread)
 160 {
 161         int nudge = 0;
 162
 163         if (multiplexed_thread->thread == AST_PTHREADT_NULL) {
 164                 return;
 165         }
 166
 167         if (write(multiplexed_thread->pipe[1], &nudge, sizeof(nudge)) != sizeof(nudge)) {
 168                 ast_log(LOG_ERROR, "We couldn't poke multiplexed thread '%p'... something is VERY wrong\n", multiplexed_thread);
 169         }
 170
 171         while (multiplexed_thread->waiting) {
 172                 sched_yield();
 173         }
 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 && ast_channel_internal_bridge(winner)) {
 236                         struct ast_bridge *bridge = ast_channel_internal_bridge(winner);
 237                         int stop = 0;
 238                         ao2_unlock(multiplexed_thread);
 239                         while ((bridge = ast_channel_internal_bridge(winner)) && 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
 309 /*! \brief Join function which actually adds the channel into the array to be monitored */
 310 static int multiplexed_bridge_join(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 311 {
 312         struct ast_channel *c0 = AST_LIST_FIRST(&bridge->channels)->chan, *c1 = AST_LIST_LAST(&bridge->channels)->chan;
 313         struct multiplexed_thread *multiplexed_thread = bridge->bridge_pvt;
 314
 315         ast_debug(1, "Adding channel '%s' to multiplexed thread '%p' for monitoring\n", ast_channel_name(bridge_channel->chan), multiplexed_thread);
 316
 317         multiplexed_add_or_remove(multiplexed_thread, bridge_channel->chan, 1);
 318
 319         /* If the second channel has not yet joined do not make things compatible */
 320         if (c0 == c1) {
 321                 return 0;
 322         }
 323
 324         if ((ast_format_cmp(ast_channel_writeformat(c0), ast_channel_readformat(c1)) == AST_FORMAT_CMP_EQUAL) &&
 325                 (ast_format_cmp(ast_channel_readformat(c0), ast_channel_writeformat(c1)) == AST_FORMAT_CMP_EQUAL) &&
 326                 (ast_format_cap_identical(ast_channel_nativeformats(c0), ast_channel_nativeformats(c1)))) {
 327                 return 0;
 328         }
 329
 330         return ast_channel_make_compatible(c0, c1);
 331 }
 332
 333 /*! \brief Leave function which actually removes the channel from the array */
 334 static int multiplexed_bridge_leave(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 335 {
 336         struct multiplexed_thread *multiplexed_thread = bridge->bridge_pvt;
 337
 338         ast_debug(1, "Removing channel '%s' from multiplexed thread '%p'\n", ast_channel_name(bridge_channel->chan), multiplexed_thread);
 339
 340         multiplexed_add_or_remove(multiplexed_thread, bridge_channel->chan, 0);
 341
 342         return 0;
 343 }
 344
 345 /*! \brief Suspend function which means control of the channel is going elsewhere */
 346 static void multiplexed_bridge_suspend(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 347 {
 348         struct multiplexed_thread *multiplexed_thread = bridge->bridge_pvt;
 349
 350         ast_debug(1, "Suspending channel '%s' from multiplexed thread '%p'\n", ast_channel_name(bridge_channel->chan), multiplexed_thread);
 351
 352         multiplexed_add_or_remove(multiplexed_thread, bridge_channel->chan, 0);
 353 }
 354
 355 /*! \brief Unsuspend function which means control of the channel is coming back to us */
 356 static void multiplexed_bridge_unsuspend(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 357 {
 358         struct multiplexed_thread *multiplexed_thread = bridge->bridge_pvt;
 359
 360         ast_debug(1, "Unsuspending channel '%s' from multiplexed thread '%p'\n", ast_channel_name(bridge_channel->chan), multiplexed_thread);
 361
 362         multiplexed_add_or_remove(multiplexed_thread, bridge_channel->chan, 1);
 363 }
 364
 365 /*! \brief Write function for writing frames into the bridge */
 366 static enum ast_bridge_write_result multiplexed_bridge_write(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
 367 {
 368         struct ast_bridge_channel *other;
 369
 370         /* If this is the only channel in this bridge then immediately exit */
 371         if (AST_LIST_FIRST(&bridge->channels) == AST_LIST_LAST(&bridge->channels)) {
 372                 return AST_BRIDGE_WRITE_FAILED;
 373         }
 374
 375         /* Find the channel we actually want to write to */
 376         if (!(other = (AST_LIST_FIRST(&bridge->channels) == bridge_channel ? AST_LIST_LAST(&bridge->channels) : AST_LIST_FIRST(&bridge->channels)))) {
 377                 return AST_BRIDGE_WRITE_FAILED;
 378         }
 379
 380         /* Write the frame out if they are in the waiting state... don't worry about freeing it, the bridging core will take care of it */
 381         if (other->state == AST_BRIDGE_CHANNEL_STATE_WAIT) {
 382                 ast_write(other->chan, frame);
 383         }
 384
 385         return AST_BRIDGE_WRITE_SUCCESS;
 386 }
 387
 388 static struct ast_bridge_technology multiplexed_bridge = {
 389         .name = "multiplexed_bridge",
 390         .capabilities = AST_BRIDGE_CAPABILITY_1TO1MIX,
 391         .preference = AST_BRIDGE_PREFERENCE_HIGH,
 392         .create = multiplexed_bridge_create,
 393         .destroy = multiplexed_bridge_destroy,
 394         .join = multiplexed_bridge_join,
 395         .leave = multiplexed_bridge_leave,
 396         .suspend = multiplexed_bridge_suspend,
 397         .unsuspend = multiplexed_bridge_unsuspend,
 398         .write = multiplexed_bridge_write,
 399 };
 400
 401 static int unload_module(void)
 402 {
 403         int res = ast_bridge_technology_unregister(&multiplexed_bridge);
 404
 405         ao2_ref(multiplexed_threads, -1);
 406         multiplexed_bridge.format_capabilities = ast_format_cap_destroy(multiplexed_bridge.format_capabilities);
 407
 408         return res;
 409 }
 410
 411 static int load_module(void)
 412 {
 413         if (!(multiplexed_threads = ao2_container_alloc(MULTIPLEXED_BUCKETS, NULL, NULL))) {
 414                 return AST_MODULE_LOAD_DECLINE;
 415         }
 416         if (!(multiplexed_bridge.format_capabilities = ast_format_cap_alloc())) {
 417                 return AST_MODULE_LOAD_DECLINE;
 418         }
 419         ast_format_cap_add_all_by_type(multiplexed_bridge.format_capabilities, AST_FORMAT_TYPE_AUDIO);
 420         ast_format_cap_add_all_by_type(multiplexed_bridge.format_capabilities, AST_FORMAT_TYPE_VIDEO);
 421         ast_format_cap_add_all_by_type(multiplexed_bridge.format_capabilities, AST_FORMAT_TYPE_TEXT);
 422         return ast_bridge_technology_register(&multiplexed_bridge);
 423 }
 424
 425 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Multiplexed two channel bridging module");