Mon Mar 31 07:37:57 2008

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__, "$Revision$")
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    AST_LIST_HEAD_NOLOCK(, ast_frame) dtmf_frames;
00065    AST_LIST_ENTRY(asent) list;
00066 };
00067 
00068 static AST_LIST_HEAD_STATIC(aslist, asent);
00069 static ast_cond_t as_cond;
00070 
00071 static pthread_t asthread = AST_PTHREADT_NULL;
00072 
00073 static int as_chan_list_state;
00074 
00075 static void defer_frame(struct ast_channel *chan, struct ast_frame *f)
00076 {
00077    struct ast_frame *dup_f;
00078    struct asent *as;
00079 
00080    AST_LIST_LOCK(&aslist);
00081    AST_LIST_TRAVERSE(&aslist, as, list) {
00082       if (as->chan != chan)
00083          continue;
00084       if ((dup_f = ast_frdup(f)))
00085          AST_LIST_INSERT_TAIL(&as->dtmf_frames, dup_f, frame_list);
00086    }
00087    AST_LIST_UNLOCK(&aslist);
00088 }
00089 
00090 static void *autoservice_run(void *ign)
00091 {
00092    for (;;) {
00093       struct ast_channel *mons[MAX_AUTOMONS];
00094       struct ast_channel *chan;
00095       struct asent *as;
00096       int x = 0, ms = 50;
00097 
00098       AST_LIST_LOCK(&aslist);
00099 
00100       /* At this point, we know that no channels that have been removed are going
00101        * to get used again. */
00102       as_chan_list_state++;
00103 
00104       if (AST_LIST_EMPTY(&aslist))
00105          ast_cond_wait(&as_cond, &aslist.lock);
00106 
00107       AST_LIST_TRAVERSE(&aslist, as, list) {
00108          if (!as->chan->_softhangup) {
00109             if (x < MAX_AUTOMONS)
00110                mons[x++] = as->chan;
00111             else
00112                ast_log(LOG_WARNING, "Exceeded maximum number of automatic monitoring events.  Fix autoservice.c\n");
00113          }
00114       }
00115 
00116       AST_LIST_UNLOCK(&aslist);
00117 
00118       chan = ast_waitfor_n(mons, x, &ms);
00119       if (chan) {
00120          struct ast_frame *f = ast_read(chan);
00121    
00122          if (!f) {
00123             struct ast_frame hangup_frame = { 0, };
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             hangup_frame.frametype = AST_FRAME_CONTROL;
00131             hangup_frame.subclass = AST_CONTROL_HANGUP;
00132 
00133             defer_frame(chan, &hangup_frame);
00134 
00135             continue;
00136          }
00137          
00138          /* Do not add a default entry in this switch statement.  Each new
00139           * frame type should be addressed directly as to whether it should
00140           * be queued up or not. */
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(chan, 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          if (f)
00163             ast_frfree(f);
00164       }
00165    }
00166    asthread = AST_PTHREADT_NULL;
00167    return NULL;
00168 }
00169 
00170 int ast_autoservice_start(struct ast_channel *chan)
00171 {
00172    int res = 0;
00173    struct asent *as;
00174 
00175    /* Check if the channel already has autoservice */
00176    AST_LIST_LOCK(&aslist);
00177    AST_LIST_TRAVERSE(&aslist, as, list) {
00178       if (as->chan == chan) {
00179          as->use_count++;
00180          break;
00181       }
00182    }
00183    AST_LIST_UNLOCK(&aslist);
00184 
00185    if (as) {
00186       /* Entry exists, autoservice is already handling this channel */
00187       return 0;
00188    }
00189 
00190    if (!(as = ast_calloc(1, sizeof(*as))))
00191       return -1;
00192    
00193    /* New entry created */
00194    as->chan = chan;
00195    as->use_count = 1;
00196 
00197    ast_channel_lock(chan);
00198    as->orig_end_dtmf_flag = ast_test_flag(chan, AST_FLAG_END_DTMF_ONLY) ? 1 : 0;
00199    if (!as->orig_end_dtmf_flag)
00200       ast_set_flag(chan, AST_FLAG_END_DTMF_ONLY);
00201    ast_channel_unlock(chan);
00202 
00203    AST_LIST_LOCK(&aslist);
00204    if (AST_LIST_EMPTY(&aslist))
00205       ast_cond_signal(&as_cond);
00206    AST_LIST_INSERT_HEAD(&aslist, as, list);
00207    AST_LIST_UNLOCK(&aslist);
00208 
00209    if (asthread == AST_PTHREADT_NULL) { /* need start the thread */
00210       if (ast_pthread_create_background(&asthread, NULL, autoservice_run, NULL)) {
00211          ast_log(LOG_WARNING, "Unable to create autoservice thread :(\n");
00212          /* There will only be a single member in the list at this point,
00213             the one we just added. */
00214          AST_LIST_LOCK(&aslist);
00215          AST_LIST_REMOVE(&aslist, as, list);
00216          AST_LIST_UNLOCK(&aslist);
00217          free(as);
00218          res = -1;
00219       } else
00220          pthread_kill(asthread, SIGURG);
00221    }
00222 
00223    return res;
00224 }
00225 
00226 int ast_autoservice_stop(struct ast_channel *chan)
00227 {
00228    int res = -1;
00229    struct asent *as;
00230    AST_LIST_HEAD_NOLOCK(, ast_frame) dtmf_frames;
00231    struct ast_frame *f;
00232    int removed = 0;
00233    int orig_end_dtmf_flag = 0;
00234    int chan_list_state;
00235 
00236    AST_LIST_HEAD_INIT_NOLOCK(&dtmf_frames);
00237 
00238    AST_LIST_LOCK(&aslist);
00239 
00240    /* Save the autoservice channel list state.  We _must_ verify that the channel
00241     * list has been rebuilt before we return.  Because, after we return, the channel
00242     * could get destroyed and we don't want our poor autoservice thread to step on
00243     * it after its gone! */
00244    chan_list_state = as_chan_list_state;
00245 
00246    AST_LIST_TRAVERSE_SAFE_BEGIN(&aslist, as, list) {  
00247       if (as->chan == chan) {
00248          as->use_count--;
00249          if (as->use_count)
00250             break;
00251          AST_LIST_REMOVE_CURRENT(&aslist, list);
00252          AST_LIST_APPEND_LIST(&dtmf_frames, &as->dtmf_frames, frame_list);
00253          orig_end_dtmf_flag = as->orig_end_dtmf_flag;
00254          free(as);
00255          removed = 1;
00256          if (!chan->_softhangup)
00257             res = 0;
00258          break;
00259       }
00260    }
00261    AST_LIST_TRAVERSE_SAFE_END
00262 
00263    if (removed && asthread != AST_PTHREADT_NULL) 
00264       pthread_kill(asthread, SIGURG);
00265 
00266    AST_LIST_UNLOCK(&aslist);
00267 
00268    if (!removed)
00269       return 0;
00270 
00271    if (!orig_end_dtmf_flag)
00272       ast_clear_flag(chan, AST_FLAG_END_DTMF_ONLY);
00273 
00274    /* Wait for it to un-block */
00275    while (ast_test_flag(chan, AST_FLAG_BLOCKING))
00276       usleep(1000);
00277 
00278    while ((f = AST_LIST_REMOVE_HEAD(&dtmf_frames, frame_list))) {
00279       ast_queue_frame(chan, f);
00280       ast_frfree(f);
00281    }
00282 
00283    while (chan_list_state == as_chan_list_state)
00284       usleep(1000);
00285 
00286    return res;
00287 }
00288 
00289 void ast_autoservice_init(void)
00290 {
00291    ast_cond_init(&as_cond, NULL);
00292 }

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