Thu May 14 14:48:50 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: 163448 $")
00031 
00032 #include <stdio.h>
00033 #include <stdlib.h>
00034 #include <string.h>
00035 #include <sys/time.h>
00036 #include <signal.h>
00037 #include <errno.h>
00038 #include <unistd.h>
00039 
00040 #include "asterisk/pbx.h"
00041 #include "asterisk/frame.h"
00042 #include "asterisk/sched.h"
00043 #include "asterisk/options.h"
00044 #include "asterisk/channel.h"
00045 #include "asterisk/logger.h"
00046 #include "asterisk/file.h"
00047 #include "asterisk/translate.h"
00048 #include "asterisk/manager.h"
00049 #include "asterisk/chanvars.h"
00050 #include "asterisk/linkedlists.h"
00051 #include "asterisk/indications.h"
00052 #include "asterisk/lock.h"
00053 #include "asterisk/utils.h"
00054 
00055 #define MAX_AUTOMONS 1500
00056 
00057 struct asent {
00058    struct ast_channel *chan;
00059    /*! This gets incremented each time autoservice gets started on the same
00060     *  channel.  It will ensure that it doesn't actually get stopped until 
00061     *  it gets stopped for the last time. */
00062    unsigned int use_count;
00063    unsigned int orig_end_dtmf_flag:1;
00064    /*! Frames go on at the head of deferred_frames, so we have the frames
00065     *  from newest to oldest.  As we put them at the head of the readq, we'll
00066     *  end up with them in the right order for the channel's readq. */
00067    AST_LIST_HEAD_NOLOCK(, ast_frame) deferred_frames;
00068    AST_LIST_ENTRY(asent) list;
00069 };
00070 
00071 static AST_LIST_HEAD_STATIC(aslist, asent);
00072 static ast_cond_t as_cond;
00073 
00074 static pthread_t asthread = AST_PTHREADT_NULL;
00075 
00076 static int as_chan_list_state;
00077 
00078 static void *autoservice_run(void *ign)
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 (!as->chan->_softhangup) {
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          struct ast_frame hangup_frame = { 0, };
00125          /* No frame means the channel has been hung up.
00126           * A hangup frame needs to be queued here as ast_waitfor() may
00127           * never return again for the condition to be detected outside
00128           * of autoservice.  So, we'll leave a HANGUP queued up so the
00129           * thread in charge of this channel will know. */
00130 
00131          hangup_frame.frametype = AST_FRAME_CONTROL;
00132          hangup_frame.subclass = AST_CONTROL_HANGUP;
00133 
00134          defer_frame = &hangup_frame;
00135       } else {
00136 
00137          /* Do not add a default entry in this switch statement.  Each new
00138           * frame type should be addressed directly as to whether it should
00139           * be queued up or not. */
00140 
00141          switch (f->frametype) {
00142          /* Save these frames */
00143          case AST_FRAME_DTMF_END:
00144          case AST_FRAME_CONTROL:
00145          case AST_FRAME_TEXT:
00146          case AST_FRAME_IMAGE:
00147          case AST_FRAME_HTML:
00148             defer_frame = f;
00149             break;
00150 
00151          /* Throw these frames away */
00152          case AST_FRAME_DTMF_BEGIN:
00153          case AST_FRAME_VOICE:
00154          case AST_FRAME_VIDEO:
00155          case AST_FRAME_NULL:
00156          case AST_FRAME_IAX:
00157          case AST_FRAME_CNG:
00158          case AST_FRAME_MODEM:
00159             break;
00160          }
00161       }
00162 
00163       if (defer_frame) {
00164          for (i = 0; i < x; i++) {
00165             struct ast_frame *dup_f;
00166             
00167             if (mons[i] != chan) {
00168                continue;
00169             }
00170             
00171             if ((dup_f = ast_frdup(defer_frame))) {
00172                AST_LIST_INSERT_HEAD(&ents[i]->deferred_frames, dup_f, frame_list);
00173             }
00174             
00175             break;
00176          }
00177       }
00178 
00179       if (f) {
00180          ast_frfree(f);
00181       }
00182    }
00183 
00184    asthread = AST_PTHREADT_NULL;
00185 
00186    return NULL;
00187 }
00188 
00189 int ast_autoservice_start(struct ast_channel *chan)
00190 {
00191    int res = 0;
00192    struct asent *as;
00193 
00194    /* Check if the channel already has autoservice */
00195    AST_LIST_LOCK(&aslist);
00196    AST_LIST_TRAVERSE(&aslist, as, list) {
00197       if (as->chan == chan) {
00198          as->use_count++;
00199          break;
00200       }
00201    }
00202    AST_LIST_UNLOCK(&aslist);
00203 
00204    if (as) {
00205       /* Entry exists, autoservice is already handling this channel */
00206       return 0;
00207    }
00208 
00209    if (!(as = ast_calloc(1, sizeof(*as))))
00210       return -1;
00211    
00212    /* New entry created */
00213    as->chan = chan;
00214    as->use_count = 1;
00215 
00216    ast_channel_lock(chan);
00217    as->orig_end_dtmf_flag = ast_test_flag(chan, AST_FLAG_END_DTMF_ONLY) ? 1 : 0;
00218    if (!as->orig_end_dtmf_flag)
00219       ast_set_flag(chan, AST_FLAG_END_DTMF_ONLY);
00220    ast_channel_unlock(chan);
00221 
00222    AST_LIST_LOCK(&aslist);
00223 
00224    if (AST_LIST_EMPTY(&aslist) && asthread != AST_PTHREADT_NULL) {
00225       ast_cond_signal(&as_cond);
00226    }
00227 
00228    AST_LIST_INSERT_HEAD(&aslist, as, list);
00229 
00230    if (asthread == AST_PTHREADT_NULL) { /* need start the thread */
00231       if (ast_pthread_create_background(&asthread, NULL, autoservice_run, NULL)) {
00232          ast_log(LOG_WARNING, "Unable to create autoservice thread :(\n");
00233          /* There will only be a single member in the list at this point,
00234             the one we just added. */
00235          AST_LIST_REMOVE(&aslist, as, list);
00236          free(as);
00237          asthread = AST_PTHREADT_NULL;
00238          res = -1;
00239       } else {
00240          pthread_kill(asthread, SIGURG);
00241       }
00242    }
00243 
00244    AST_LIST_UNLOCK(&aslist);
00245 
00246    return res;
00247 }
00248 
00249 int ast_autoservice_stop(struct ast_channel *chan)
00250 {
00251    int res = -1;
00252    struct asent *as, *removed = NULL;
00253    struct ast_frame *f;
00254    int chan_list_state;
00255 
00256    AST_LIST_LOCK(&aslist);
00257 
00258    /* Save the autoservice channel list state.  We _must_ verify that the channel
00259     * list has been rebuilt before we return.  Because, after we return, the channel
00260     * could get destroyed and we don't want our poor autoservice thread to step on
00261     * it after its gone! */
00262    chan_list_state = as_chan_list_state;
00263 
00264    /* Find the entry, but do not free it because it still can be in the
00265       autoservice thread array */
00266    AST_LIST_TRAVERSE_SAFE_BEGIN(&aslist, as, list) {  
00267       if (as->chan == chan) {
00268          as->use_count--;
00269          if (as->use_count < 1) {
00270             AST_LIST_REMOVE_CURRENT(&aslist, list);
00271             removed = as;
00272          }
00273          break;
00274       }
00275    }
00276    AST_LIST_TRAVERSE_SAFE_END
00277 
00278    if (removed && asthread != AST_PTHREADT_NULL) {
00279       pthread_kill(asthread, SIGURG);
00280    }
00281 
00282    AST_LIST_UNLOCK(&aslist);
00283 
00284    if (!removed) {
00285       return 0;
00286    }
00287 
00288    /* Wait while autoservice thread rebuilds its list. */
00289    while (chan_list_state == as_chan_list_state) {
00290       usleep(1000);
00291    }
00292 
00293    /* Now autoservice thread should have no references to our entry
00294       and we can safely destroy it */
00295 
00296    if (!chan->_softhangup) {
00297       res = 0;
00298    }
00299 
00300    if (!as->orig_end_dtmf_flag) {
00301       ast_clear_flag(chan, AST_FLAG_END_DTMF_ONLY);
00302    }
00303 
00304    ast_channel_lock(chan);
00305    while ((f = AST_LIST_REMOVE_HEAD(&as->deferred_frames, frame_list))) {
00306       ast_queue_frame_head(chan, f);
00307       ast_frfree(f);
00308    }
00309    ast_channel_unlock(chan);
00310 
00311    free(as);
00312 
00313    return res;
00314 }
00315 
00316 void ast_autoservice_init(void)
00317 {
00318    ast_cond_init(&as_cond, NULL);
00319 }

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