Fri Jun 19 12:09:31 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: 163515 $")
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    for (;;) {
00076       struct ast_channel *mons[MAX_AUTOMONS];
00077       struct asent *ents[MAX_AUTOMONS];
00078       struct ast_channel *chan;
00079       struct asent *as;
00080       int i, x = 0, ms = 50;
00081       struct ast_frame *f = NULL;
00082       struct ast_frame *defer_frame = NULL;
00083 
00084       AST_LIST_LOCK(&aslist);
00085 
00086       /* At this point, we know that no channels that have been removed are going
00087        * to get used again. */
00088       as_chan_list_state++;
00089 
00090       if (AST_LIST_EMPTY(&aslist)) {
00091          ast_cond_wait(&as_cond, &aslist.lock);
00092       }
00093 
00094       AST_LIST_TRAVERSE(&aslist, as, list) {
00095          if (!ast_check_hangup(as->chan)) {
00096             if (x < MAX_AUTOMONS) {
00097                ents[x] = as;
00098                mons[x++] = as->chan;
00099             } else {
00100                ast_log(LOG_WARNING, "Exceeded maximum number of automatic monitoring events.  Fix autoservice.c\n");
00101             }
00102          }
00103       }
00104 
00105       AST_LIST_UNLOCK(&aslist);
00106 
00107       if (!x) {
00108          continue;
00109       }
00110 
00111       chan = ast_waitfor_n(mons, x, &ms);
00112       if (!chan) {
00113          continue;
00114       }
00115 
00116       f = ast_read(chan);
00117    
00118       if (!f) {
00119          struct ast_frame hangup_frame = { 0, };
00120          /* No frame means the channel has been hung up.
00121           * A hangup frame needs to be queued here as ast_waitfor() may
00122           * never return again for the condition to be detected outside
00123           * of autoservice.  So, we'll leave a HANGUP queued up so the
00124           * thread in charge of this channel will know. */
00125 
00126          hangup_frame.frametype = AST_FRAME_CONTROL;
00127          hangup_frame.subclass = AST_CONTROL_HANGUP;
00128 
00129          defer_frame = &hangup_frame;
00130       } else {
00131 
00132          /* Do not add a default entry in this switch statement.  Each new
00133           * frame type should be addressed directly as to whether it should
00134           * be queued up or not. */
00135 
00136          switch (f->frametype) {
00137          /* Save these frames */
00138          case AST_FRAME_DTMF_END:
00139          case AST_FRAME_CONTROL:
00140          case AST_FRAME_TEXT:
00141          case AST_FRAME_IMAGE:
00142          case AST_FRAME_HTML:
00143             defer_frame = f;
00144             break;
00145 
00146          /* Throw these frames away */
00147          case AST_FRAME_DTMF_BEGIN:
00148          case AST_FRAME_VOICE:
00149          case AST_FRAME_VIDEO:
00150          case AST_FRAME_NULL:
00151          case AST_FRAME_IAX:
00152          case AST_FRAME_CNG:
00153          case AST_FRAME_MODEM:
00154             break;
00155          }
00156       }
00157 
00158       if (defer_frame) {
00159          for (i = 0; i < x; i++) {
00160             struct ast_frame *dup_f;
00161             
00162             if (mons[i] != chan) {
00163                continue;
00164             }
00165             
00166             if ((dup_f = ast_frdup(defer_frame))) {
00167                AST_LIST_INSERT_HEAD(&ents[i]->deferred_frames, dup_f, frame_list);
00168             }
00169             
00170             break;
00171          }
00172       }
00173 
00174       if (f) {
00175          ast_frfree(f);
00176       }
00177    }
00178 
00179    asthread = AST_PTHREADT_NULL;
00180 
00181    return NULL;
00182 }
00183 
00184 int ast_autoservice_start(struct ast_channel *chan)
00185 {
00186    int res = 0;
00187    struct asent *as;
00188 
00189    AST_LIST_LOCK(&aslist);
00190    AST_LIST_TRAVERSE(&aslist, as, list) {
00191       if (as->chan == chan) {
00192          as->use_count++;
00193          break;
00194       }
00195    }
00196    AST_LIST_UNLOCK(&aslist);
00197 
00198    if (as) {
00199       /* Entry exists, autoservice is already handling this channel */
00200       return 0;
00201    }
00202 
00203    if (!(as = ast_calloc(1, sizeof(*as))))
00204       return -1;
00205    
00206    /* New entry created */
00207    as->chan = chan;
00208    as->use_count = 1;
00209 
00210    ast_channel_lock(chan);
00211    as->orig_end_dtmf_flag = ast_test_flag(chan, AST_FLAG_END_DTMF_ONLY) ? 1 : 0;
00212    if (!as->orig_end_dtmf_flag)
00213       ast_set_flag(chan, AST_FLAG_END_DTMF_ONLY);
00214    ast_channel_unlock(chan);
00215 
00216    AST_LIST_LOCK(&aslist);
00217 
00218    if (AST_LIST_EMPTY(&aslist) && asthread != AST_PTHREADT_NULL) {
00219       ast_cond_signal(&as_cond);
00220    }
00221 
00222    AST_LIST_INSERT_HEAD(&aslist, as, list);
00223 
00224    if (asthread == AST_PTHREADT_NULL) { /* need start the thread */
00225       if (ast_pthread_create_background(&asthread, NULL, autoservice_run, NULL)) {
00226          ast_log(LOG_WARNING, "Unable to create autoservice thread :(\n");
00227          /* There will only be a single member in the list at this point,
00228             the one we just added. */
00229          AST_LIST_REMOVE(&aslist, as, list);
00230          free(as);
00231          asthread = AST_PTHREADT_NULL;
00232          res = -1;
00233       } else {
00234          pthread_kill(asthread, SIGURG);
00235       }
00236    }
00237 
00238    AST_LIST_UNLOCK(&aslist);
00239 
00240    return res;
00241 }
00242 
00243 int ast_autoservice_stop(struct ast_channel *chan)
00244 {
00245    int res = -1;
00246    struct asent *as, *removed = NULL;
00247    struct ast_frame *f;
00248    int chan_list_state;
00249 
00250    AST_LIST_LOCK(&aslist);
00251 
00252    /* Save the autoservice channel list state.  We _must_ verify that the channel
00253     * list has been rebuilt before we return.  Because, after we return, the channel
00254     * could get destroyed and we don't want our poor autoservice thread to step on
00255     * it after its gone! */
00256    chan_list_state = as_chan_list_state;
00257 
00258    /* Find the entry, but do not free it because it still can be in the
00259       autoservice thread array */
00260    AST_LIST_TRAVERSE_SAFE_BEGIN(&aslist, as, list) {  
00261       if (as->chan == chan) {
00262          as->use_count--;
00263          if (as->use_count < 1) {
00264             AST_LIST_REMOVE_CURRENT(list);
00265             removed = as;
00266          }
00267          break;
00268       }
00269    }
00270    AST_LIST_TRAVERSE_SAFE_END;
00271 
00272    if (removed && asthread != AST_PTHREADT_NULL) {
00273       pthread_kill(asthread, SIGURG);
00274    }
00275 
00276    AST_LIST_UNLOCK(&aslist);
00277 
00278    if (!removed) {
00279       return 0;
00280    }
00281 
00282    /* Wait while autoservice thread rebuilds its list. */
00283    while (chan_list_state == as_chan_list_state) {
00284       usleep(1000);
00285    }
00286 
00287    /* Now autoservice thread should have no references to our entry
00288       and we can safely destroy it */
00289 
00290    if (!chan->_softhangup) {
00291       res = 0;
00292    }
00293 
00294    if (!as->orig_end_dtmf_flag) {
00295       ast_clear_flag(chan, AST_FLAG_END_DTMF_ONLY);
00296    }
00297 
00298    ast_channel_lock(chan);
00299    while ((f = AST_LIST_REMOVE_HEAD(&as->deferred_frames, frame_list))) {
00300       ast_queue_frame_head(chan, f);
00301       ast_frfree(f);
00302    }
00303    ast_channel_unlock(chan);
00304 
00305    free(as);
00306 
00307    return res;
00308 }
00309 
00310 void ast_autoservice_init(void)
00311 {
00312    ast_cond_init(&as_cond, NULL);
00313 }

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