Thu Oct 8 21:55:55 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: 119354 $")
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) deferred_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 *autoservice_run(void *ign)
00076 {
00077    for (;;) {
00078       struct ast_channel *mons[MAX_AUTOMONS];
00079       struct asent *ents[MAX_AUTOMONS];
00080       struct ast_channel *chan;
00081       struct asent *as;
00082       int i, x = 0, ms = 50;
00083       struct ast_frame *f = NULL;
00084       struct ast_frame *defer_frame = NULL;
00085 
00086       AST_LIST_LOCK(&aslist);
00087 
00088       /* At this point, we know that no channels that have been removed are going
00089        * to get used again. */
00090       as_chan_list_state++;
00091 
00092       if (AST_LIST_EMPTY(&aslist)) {
00093          ast_cond_wait(&as_cond, &aslist.lock);
00094       }
00095 
00096       AST_LIST_TRAVERSE(&aslist, as, list) {
00097          if (!as->chan->_softhangup) {
00098             if (x < MAX_AUTOMONS) {
00099                ents[x] = as;
00100                mons[x++] = as->chan;
00101             } else {
00102                ast_log(LOG_WARNING, "Exceeded maximum number of automatic monitoring events.  Fix autoservice.c\n");
00103             }
00104          }
00105       }
00106 
00107       AST_LIST_UNLOCK(&aslist);
00108 
00109       chan = ast_waitfor_n(mons, x, &ms);
00110       if (!chan) {
00111          continue;
00112       }
00113 
00114       f = ast_read(chan);
00115    
00116       if (!f) {
00117          struct ast_frame hangup_frame = { 0, };
00118          /* No frame means the channel has been hung up.
00119           * A hangup frame needs to be queued here as ast_waitfor() may
00120           * never return again for the condition to be detected outside
00121           * of autoservice.  So, we'll leave a HANGUP queued up so the
00122           * thread in charge of this channel will know. */
00123 
00124          hangup_frame.frametype = AST_FRAME_CONTROL;
00125          hangup_frame.subclass = AST_CONTROL_HANGUP;
00126 
00127          defer_frame = &hangup_frame;
00128       } else {
00129 
00130          /* Do not add a default entry in this switch statement.  Each new
00131           * frame type should be addressed directly as to whether it should
00132           * be queued up or not. */
00133 
00134          switch (f->frametype) {
00135          /* Save these frames */
00136          case AST_FRAME_DTMF_END:
00137          case AST_FRAME_CONTROL:
00138          case AST_FRAME_TEXT:
00139          case AST_FRAME_IMAGE:
00140          case AST_FRAME_HTML:
00141             defer_frame = f;
00142             break;
00143 
00144          /* Throw these frames away */
00145          case AST_FRAME_DTMF_BEGIN:
00146          case AST_FRAME_VOICE:
00147          case AST_FRAME_VIDEO:
00148          case AST_FRAME_NULL:
00149          case AST_FRAME_IAX:
00150          case AST_FRAME_CNG:
00151          case AST_FRAME_MODEM:
00152             break;
00153          }
00154       }
00155 
00156       if (!defer_frame) {
00157          if (f) {
00158             ast_frfree(f);
00159          }
00160          continue;
00161       }
00162 
00163       if (f) {
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(f))) {
00172                AST_LIST_INSERT_TAIL(&ents[i]->deferred_frames, dup_f, frame_list);
00173             }
00174             
00175             break;
00176          }
00177          ast_frfree(f);
00178       }
00179    }
00180 
00181    asthread = AST_PTHREADT_NULL;
00182 
00183    return NULL;
00184 }
00185 
00186 int ast_autoservice_start(struct ast_channel *chan)
00187 {
00188    int res = 0;
00189    struct asent *as;
00190 
00191    /* Check if the channel already has autoservice */
00192    AST_LIST_LOCK(&aslist);
00193    AST_LIST_TRAVERSE(&aslist, as, list) {
00194       if (as->chan == chan) {
00195          as->use_count++;
00196          break;
00197       }
00198    }
00199    AST_LIST_UNLOCK(&aslist);
00200 
00201    if (as) {
00202       /* Entry exists, autoservice is already handling this channel */
00203       return 0;
00204    }
00205 
00206    if (!(as = ast_calloc(1, sizeof(*as))))
00207       return -1;
00208    
00209    /* New entry created */
00210    as->chan = chan;
00211    as->use_count = 1;
00212 
00213    ast_channel_lock(chan);
00214    as->orig_end_dtmf_flag = ast_test_flag(chan, AST_FLAG_END_DTMF_ONLY) ? 1 : 0;
00215    if (!as->orig_end_dtmf_flag)
00216       ast_set_flag(chan, AST_FLAG_END_DTMF_ONLY);
00217    ast_channel_unlock(chan);
00218 
00219    AST_LIST_LOCK(&aslist);
00220 
00221    if (AST_LIST_EMPTY(&aslist) && asthread != AST_PTHREADT_NULL) {
00222       ast_cond_signal(&as_cond);
00223    }
00224 
00225    AST_LIST_INSERT_HEAD(&aslist, as, list);
00226 
00227    if (asthread == AST_PTHREADT_NULL) { /* need start the thread */
00228       if (ast_pthread_create_background(&asthread, NULL, autoservice_run, NULL)) {
00229          ast_log(LOG_WARNING, "Unable to create autoservice thread :(\n");
00230          /* There will only be a single member in the list at this point,
00231             the one we just added. */
00232          AST_LIST_REMOVE(&aslist, as, list);
00233          free(as);
00234          asthread = AST_PTHREADT_NULL;
00235          res = -1;
00236       } else {
00237          pthread_kill(asthread, SIGURG);
00238       }
00239    }
00240 
00241    AST_LIST_UNLOCK(&aslist);
00242 
00243    return res;
00244 }
00245 
00246 int ast_autoservice_stop(struct ast_channel *chan)
00247 {
00248    int res = -1;
00249    struct asent *as, *removed = NULL;
00250    struct ast_frame *f;
00251    int chan_list_state;
00252 
00253    AST_LIST_LOCK(&aslist);
00254 
00255    /* Save the autoservice channel list state.  We _must_ verify that the channel
00256     * list has been rebuilt before we return.  Because, after we return, the channel
00257     * could get destroyed and we don't want our poor autoservice thread to step on
00258     * it after its gone! */
00259    chan_list_state = as_chan_list_state;
00260 
00261    /* Find the entry, but do not free it because it still can be in the
00262       autoservice thread array */
00263    AST_LIST_TRAVERSE_SAFE_BEGIN(&aslist, as, list) {  
00264       if (as->chan == chan) {
00265          as->use_count--;
00266          if (as->use_count < 1) {
00267             AST_LIST_REMOVE_CURRENT(&aslist, list);
00268             removed = as;
00269          }
00270          break;
00271       }
00272    }
00273    AST_LIST_TRAVERSE_SAFE_END
00274 
00275    if (removed && asthread != AST_PTHREADT_NULL) {
00276       pthread_kill(asthread, SIGURG);
00277    }
00278 
00279    AST_LIST_UNLOCK(&aslist);
00280 
00281    if (!removed) {
00282       return 0;
00283    }
00284 
00285    /* Wait while autoservice thread rebuilds its list. */
00286    while (chan_list_state == as_chan_list_state) {
00287       usleep(1000);
00288    }
00289 
00290    /* Now autoservice thread should have no references to our entry
00291       and we can safely destroy it */
00292 
00293    if (!chan->_softhangup) {
00294       res = 0;
00295    }
00296 
00297    if (!as->orig_end_dtmf_flag) {
00298       ast_clear_flag(chan, AST_FLAG_END_DTMF_ONLY);
00299    }
00300 
00301    while ((f = AST_LIST_REMOVE_HEAD(&as->deferred_frames, frame_list))) {
00302       ast_queue_frame(chan, f);
00303       ast_frfree(f);
00304    }
00305 
00306    free(as);
00307 
00308    return res;
00309 }
00310 
00311 void ast_autoservice_init(void)
00312 {
00313    ast_cond_init(&as_cond, NULL);
00314 }

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