Wed Oct 28 11:50:55 2009

Asterisk developer's documentation


autoservice.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2008, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  * Russell Bryant <russell@digium.com>
00008  *
00009  * See http://www.asterisk.org for more information about
00010  * the Asterisk project. Please do not directly contact
00011  * any of the maintainers of this project for assistance;
00012  * the project provides a web site, mailing lists and IRC
00013  * channels for your use.
00014  *
00015  * This program is free software, distributed under the terms of
00016  * the GNU General Public License Version 2. See the LICENSE file
00017  * at the top of the source tree.
00018  */
00019 
00020 /*! \file
00021  *
00022  * \brief Automatic channel service routines
00023  *
00024  * \author Mark Spencer <markster@digium.com> 
00025  * \author Russell Bryant <russell@digium.com>
00026  */
00027 
00028 #include "asterisk.h"
00029 
00030 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 223489 $")
00031 
00032 #include <sys/time.h>
00033 #include <signal.h>
00034 
00035 #include "asterisk/_private.h" /* prototype for ast_autoservice_init() */
00036 
00037 #include "asterisk/pbx.h"
00038 #include "asterisk/frame.h"
00039 #include "asterisk/sched.h"
00040 #include "asterisk/channel.h"
00041 #include "asterisk/file.h"
00042 #include "asterisk/translate.h"
00043 #include "asterisk/manager.h"
00044 #include "asterisk/chanvars.h"
00045 #include "asterisk/linkedlists.h"
00046 #include "asterisk/indications.h"
00047 #include "asterisk/lock.h"
00048 #include "asterisk/utils.h"
00049 
00050 #define MAX_AUTOMONS 1500
00051 
00052 struct asent {
00053    struct ast_channel *chan;
00054    /*! This gets incremented each time autoservice gets started on the same
00055     *  channel.  It will ensure that it doesn't actually get stopped until 
00056     *  it gets stopped for the last time. */
00057    unsigned int use_count;
00058    unsigned int orig_end_dtmf_flag:1;
00059    /*! Frames go on at the head of deferred_frames, so we have the frames
00060     *  from newest to oldest.  As we put them at the head of the readq, we'll
00061     *  end up with them in the right order for the channel's readq. */
00062    AST_LIST_HEAD_NOLOCK(, ast_frame) deferred_frames;
00063    AST_LIST_ENTRY(asent) list;
00064 };
00065 
00066 static AST_LIST_HEAD_STATIC(aslist, asent);
00067 static ast_cond_t as_cond;
00068 
00069 static pthread_t asthread = AST_PTHREADT_NULL;
00070 
00071 static int as_chan_list_state;
00072 
00073 static void *autoservice_run(void *ign)
00074 {
00075    struct ast_frame hangup_frame = {
00076       .frametype = AST_FRAME_CONTROL,
00077       .subclass = AST_CONTROL_HANGUP,
00078    };
00079 
00080    for (;;) {
00081       struct ast_channel *mons[MAX_AUTOMONS];
00082       struct asent *ents[MAX_AUTOMONS];
00083       struct ast_channel *chan;
00084       struct asent *as;
00085       int i, x = 0, ms = 50;
00086       struct ast_frame *f = NULL;
00087       struct ast_frame *defer_frame = NULL;
00088 
00089       AST_LIST_LOCK(&aslist);
00090 
00091       /* At this point, we know that no channels that have been removed are going
00092        * to get used again. */
00093       as_chan_list_state++;
00094 
00095       if (AST_LIST_EMPTY(&aslist)) {
00096          ast_cond_wait(&as_cond, &aslist.lock);
00097       }
00098 
00099       AST_LIST_TRAVERSE(&aslist, as, list) {
00100          if (!ast_check_hangup(as->chan)) {
00101             if (x < MAX_AUTOMONS) {
00102                ents[x] = as;
00103                mons[x++] = as->chan;
00104             } else {
00105                ast_log(LOG_WARNING, "Exceeded maximum number of automatic monitoring events.  Fix autoservice.c\n");
00106             }
00107          }
00108       }
00109 
00110       AST_LIST_UNLOCK(&aslist);
00111 
00112       if (!x) {
00113          continue;
00114       }
00115 
00116       chan = ast_waitfor_n(mons, x, &ms);
00117       if (!chan) {
00118          continue;
00119       }
00120 
00121       f = ast_read(chan);
00122 
00123       if (!f) {
00124          /* No frame means the channel has been hung up.
00125           * A hangup frame needs to be queued here as ast_waitfor() may
00126           * never return again for the condition to be detected outside
00127           * of autoservice.  So, we'll leave a HANGUP queued up so the
00128           * thread in charge of this channel will know. */
00129 
00130          defer_frame = &hangup_frame;
00131       } else {
00132 
00133          /* Do not add a default entry in this switch statement.  Each new
00134           * frame type should be addressed directly as to whether it should
00135           * be queued up or not. */
00136 
00137          switch (f->frametype) {
00138          /* Save these frames */
00139          case AST_FRAME_DTMF_END:
00140          case AST_FRAME_CONTROL:
00141          case AST_FRAME_TEXT:
00142          case AST_FRAME_IMAGE:
00143          case AST_FRAME_HTML:
00144             defer_frame = f;
00145             break;
00146 
00147          /* Throw these frames away */
00148          case AST_FRAME_DTMF_BEGIN:
00149          case AST_FRAME_VOICE:
00150          case AST_FRAME_VIDEO:
00151          case AST_FRAME_NULL:
00152          case AST_FRAME_IAX:
00153          case AST_FRAME_CNG:
00154          case AST_FRAME_MODEM:
00155             break;
00156          }
00157       }
00158 
00159       if (defer_frame) {
00160          for (i = 0; i < x; i++) {
00161             struct ast_frame *dup_f;
00162             
00163             if (mons[i] != chan) {
00164                continue;
00165             }
00166             
00167             if (defer_frame != f) {
00168                if ((dup_f = ast_frdup(defer_frame))) {
00169                   AST_LIST_INSERT_HEAD(&ents[i]->deferred_frames, dup_f, frame_list);
00170                }
00171             } else {
00172                if ((dup_f = ast_frisolate(defer_frame))) {
00173                   if (dup_f != defer_frame) {
00174                      ast_frfree(defer_frame);
00175                   }
00176                   AST_LIST_INSERT_HEAD(&ents[i]->deferred_frames, dup_f, frame_list);
00177                }
00178             }
00179             
00180             break;
00181          }
00182       } else if (f) {
00183          ast_frfree(f);
00184       }
00185    }
00186 
00187    asthread = AST_PTHREADT_NULL;
00188 
00189    return NULL;
00190 }
00191 
00192 int ast_autoservice_start(struct ast_channel *chan)
00193 {
00194    int res = 0;
00195    struct asent *as;
00196 
00197    AST_LIST_LOCK(&aslist);
00198    AST_LIST_TRAVERSE(&aslist, as, list) {
00199       if (as->chan == chan) {
00200          as->use_count++;
00201          break;
00202       }
00203    }
00204    AST_LIST_UNLOCK(&aslist);
00205 
00206    if (as) {
00207       /* Entry exists, autoservice is already handling this channel */
00208       return 0;
00209    }
00210 
00211    if (!(as = ast_calloc(1, sizeof(*as))))
00212       return -1;
00213    
00214    /* New entry created */
00215    as->chan = chan;
00216    as->use_count = 1;
00217 
00218    ast_channel_lock(chan);
00219    as->orig_end_dtmf_flag = ast_test_flag(chan, AST_FLAG_END_DTMF_ONLY) ? 1 : 0;
00220    if (!as->orig_end_dtmf_flag)
00221       ast_set_flag(chan, AST_FLAG_END_DTMF_ONLY);
00222    ast_channel_unlock(chan);
00223 
00224    AST_LIST_LOCK(&aslist);
00225 
00226    if (AST_LIST_EMPTY(&aslist) && asthread != AST_PTHREADT_NULL) {
00227       ast_cond_signal(&as_cond);
00228    }
00229 
00230    AST_LIST_INSERT_HEAD(&aslist, as, list);
00231 
00232    if (asthread == AST_PTHREADT_NULL) { /* need start the thread */
00233       if (ast_pthread_create_background(&asthread, NULL, autoservice_run, NULL)) {
00234          ast_log(LOG_WARNING, "Unable to create autoservice thread :(\n");
00235          /* There will only be a single member in the list at this point,
00236             the one we just added. */
00237          AST_LIST_REMOVE(&aslist, as, list);
00238          free(as);
00239          asthread = AST_PTHREADT_NULL;
00240          res = -1;
00241       } else {
00242          pthread_kill(asthread, SIGURG);
00243       }
00244    }
00245 
00246    AST_LIST_UNLOCK(&aslist);
00247 
00248    return res;
00249 }
00250 
00251 int ast_autoservice_stop(struct ast_channel *chan)
00252 {
00253    int res = -1;
00254    struct asent *as, *removed = NULL;
00255    struct ast_frame *f;
00256    int chan_list_state;
00257 
00258    AST_LIST_LOCK(&aslist);
00259 
00260    /* Save the autoservice channel list state.  We _must_ verify that the channel
00261     * list has been rebuilt before we return.  Because, after we return, the channel
00262     * could get destroyed and we don't want our poor autoservice thread to step on
00263     * it after its gone! */
00264    chan_list_state = as_chan_list_state;
00265 
00266    /* Find the entry, but do not free it because it still can be in the
00267       autoservice thread array */
00268    AST_LIST_TRAVERSE_SAFE_BEGIN(&aslist, as, list) {  
00269       if (as->chan == chan) {
00270          as->use_count--;
00271          if (as->use_count < 1) {
00272             AST_LIST_REMOVE_CURRENT(list);
00273             removed = as;
00274          }
00275          break;
00276       }
00277    }
00278    AST_LIST_TRAVERSE_SAFE_END;
00279 
00280    if (removed && asthread != AST_PTHREADT_NULL) {
00281       pthread_kill(asthread, SIGURG);
00282    }
00283 
00284    AST_LIST_UNLOCK(&aslist);
00285 
00286    if (!removed) {
00287       return 0;
00288    }
00289 
00290    /* Wait while autoservice thread rebuilds its list. */
00291    while (chan_list_state == as_chan_list_state) {
00292       usleep(1000);
00293    }
00294 
00295    /* Now autoservice thread should have no references to our entry
00296       and we can safely destroy it */
00297 
00298    if (!chan->_softhangup) {
00299       res = 0;
00300    }
00301 
00302    if (!as->orig_end_dtmf_flag) {
00303       ast_clear_flag(chan, AST_FLAG_END_DTMF_ONLY);
00304    }
00305 
00306    ast_channel_lock(chan);
00307    while ((f = AST_LIST_REMOVE_HEAD(&as->deferred_frames, frame_list))) {
00308       ast_queue_frame_head(chan, f);
00309       ast_frfree(f);
00310    }
00311    ast_channel_unlock(chan);
00312 
00313    free(as);
00314 
00315    return res;
00316 }
00317 
00318 void ast_autoservice_init(void)
00319 {
00320    ast_cond_init(&as_cond, NULL);
00321 }

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