Wed Aug 7 17:15:36 2019

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 /*** MODULEINFO
00029    <support_level>core</support_level>
00030  ***/
00031 
00032 #include "asterisk.h"
00033 
00034 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 415463 $")
00035 
00036 #include <sys/time.h>
00037 #include <signal.h>
00038 
00039 #include "asterisk/_private.h" /* prototype for ast_autoservice_init() */
00040 
00041 #include "asterisk/pbx.h"
00042 #include "asterisk/frame.h"
00043 #include "asterisk/sched.h"
00044 #include "asterisk/channel.h"
00045 #include "asterisk/file.h"
00046 #include "asterisk/translate.h"
00047 #include "asterisk/manager.h"
00048 #include "asterisk/chanvars.h"
00049 #include "asterisk/linkedlists.h"
00050 #include "asterisk/indications.h"
00051 #include "asterisk/lock.h"
00052 #include "asterisk/utils.h"
00053 
00054 #define MAX_AUTOMONS 1500
00055 
00056 struct asent {
00057    struct ast_channel *chan;
00058    /*! This gets incremented each time autoservice gets started on the same
00059     *  channel.  It will ensure that it doesn't actually get stopped until 
00060     *  it gets stopped for the last time. */
00061    unsigned int use_count;
00062    unsigned int orig_end_dtmf_flag:1;
00063    unsigned int ignore_frame_types;
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 static volatile int asexit = 0;
00076 
00077 static int as_chan_list_state;
00078 
00079 static void *autoservice_run(void *ign)
00080 {
00081    struct ast_frame hangup_frame = {
00082       .frametype = AST_FRAME_CONTROL,
00083       .subclass.integer = AST_CONTROL_HANGUP,
00084    };
00085 
00086    while (!asexit) {
00087       struct ast_channel *mons[MAX_AUTOMONS];
00088       struct asent *ents[MAX_AUTOMONS];
00089       struct ast_channel *chan;
00090       struct asent *as;
00091       int i, x = 0, ms = 50;
00092       struct ast_frame *f = NULL;
00093       struct ast_frame *defer_frame = NULL;
00094 
00095       AST_LIST_LOCK(&aslist);
00096 
00097       /* At this point, we know that no channels that have been removed are going
00098        * to get used again. */
00099       as_chan_list_state++;
00100 
00101       if (AST_LIST_EMPTY(&aslist)) {
00102          ast_cond_wait(&as_cond, &aslist.lock);
00103       }
00104 
00105       AST_LIST_TRAVERSE(&aslist, as, list) {
00106          if (!ast_check_hangup(as->chan)) {
00107             if (x < MAX_AUTOMONS) {
00108                ents[x] = as;
00109                mons[x++] = as->chan;
00110             } else {
00111                ast_log(LOG_WARNING, "Exceeded maximum number of automatic monitoring events.  Fix autoservice.c\n");
00112             }
00113          }
00114       }
00115 
00116       AST_LIST_UNLOCK(&aslist);
00117 
00118       if (!x) {
00119          /* If we don't sleep, this becomes a busy loop, which causes
00120           * problems when Asterisk runs at a different priority than other
00121           * user processes.  As long as we check for new channels at least
00122           * once every 10ms, we should be fine. */
00123          usleep(10000);
00124          continue;
00125       }
00126 
00127       chan = ast_waitfor_n(mons, x, &ms);
00128       if (!chan) {
00129          continue;
00130       }
00131 
00132       f = ast_read(chan);
00133 
00134       if (!f) {
00135          /* No frame means the channel has been hung up.
00136           * A hangup frame needs to be queued here as ast_waitfor() may
00137           * never return again for the condition to be detected outside
00138           * of autoservice.  So, we'll leave a HANGUP queued up so the
00139           * thread in charge of this channel will know. */
00140 
00141          defer_frame = &hangup_frame;
00142       } else if (ast_is_deferrable_frame(f)) {
00143          defer_frame = f;
00144       }
00145 
00146       if (defer_frame) {
00147          for (i = 0; i < x; i++) {
00148             struct ast_frame *dup_f;
00149             
00150             if (mons[i] != chan) {
00151                continue;
00152             }
00153             
00154             if (defer_frame != f) {
00155                if ((dup_f = ast_frdup(defer_frame))) {
00156                   AST_LIST_INSERT_HEAD(&ents[i]->deferred_frames, dup_f, frame_list);
00157                }
00158             } else {
00159                if ((dup_f = ast_frisolate(defer_frame))) {
00160                   if (dup_f != defer_frame) {
00161                      ast_frfree(defer_frame);
00162                   }
00163                   AST_LIST_INSERT_HEAD(&ents[i]->deferred_frames, dup_f, frame_list);
00164                }
00165             }
00166             
00167             break;
00168          }
00169       } else if (f) {
00170          ast_frfree(f);
00171       }
00172    }
00173 
00174    asthread = AST_PTHREADT_NULL;
00175 
00176    return NULL;
00177 }
00178 
00179 int ast_autoservice_start(struct ast_channel *chan)
00180 {
00181    int res = 0;
00182    struct asent *as;
00183 
00184    AST_LIST_LOCK(&aslist);
00185    AST_LIST_TRAVERSE(&aslist, as, list) {
00186       if (as->chan == chan) {
00187          as->use_count++;
00188          break;
00189       }
00190    }
00191    AST_LIST_UNLOCK(&aslist);
00192 
00193    if (as) {
00194       /* Entry exists, autoservice is already handling this channel */
00195       return 0;
00196    }
00197 
00198    if (!(as = ast_calloc(1, sizeof(*as))))
00199       return -1;
00200    
00201    /* New entry created */
00202    as->chan = chan;
00203    as->use_count = 1;
00204 
00205    ast_channel_lock(chan);
00206    as->orig_end_dtmf_flag = ast_test_flag(chan, AST_FLAG_END_DTMF_ONLY) ? 1 : 0;
00207    if (!as->orig_end_dtmf_flag)
00208       ast_set_flag(chan, AST_FLAG_END_DTMF_ONLY);
00209    ast_channel_unlock(chan);
00210 
00211    AST_LIST_LOCK(&aslist);
00212 
00213    if (AST_LIST_EMPTY(&aslist) && asthread != AST_PTHREADT_NULL) {
00214       ast_cond_signal(&as_cond);
00215    }
00216 
00217    AST_LIST_INSERT_HEAD(&aslist, as, list);
00218 
00219    if (asthread == AST_PTHREADT_NULL) { /* need start the thread */
00220       if (ast_pthread_create_background(&asthread, NULL, autoservice_run, NULL)) {
00221          ast_log(LOG_WARNING, "Unable to create autoservice thread :(\n");
00222          /* There will only be a single member in the list at this point,
00223             the one we just added. */
00224          AST_LIST_REMOVE(&aslist, as, list);
00225          free(as);
00226          asthread = AST_PTHREADT_NULL;
00227          res = -1;
00228       } else {
00229          pthread_kill(asthread, SIGURG);
00230       }
00231    }
00232 
00233    AST_LIST_UNLOCK(&aslist);
00234 
00235    return res;
00236 }
00237 
00238 int ast_autoservice_stop(struct ast_channel *chan)
00239 {
00240    int res = -1;
00241    struct asent *as, *removed = NULL;
00242    struct ast_frame *f;
00243    int chan_list_state;
00244 
00245    AST_LIST_LOCK(&aslist);
00246 
00247    /* Save the autoservice channel list state.  We _must_ verify that the channel
00248     * list has been rebuilt before we return.  Because, after we return, the channel
00249     * could get destroyed and we don't want our poor autoservice thread to step on
00250     * it after its gone! */
00251    chan_list_state = as_chan_list_state;
00252 
00253    /* Find the entry, but do not free it because it still can be in the
00254       autoservice thread array */
00255    AST_LIST_TRAVERSE_SAFE_BEGIN(&aslist, as, list) {  
00256       if (as->chan == chan) {
00257          as->use_count--;
00258          if (as->use_count < 1) {
00259             AST_LIST_REMOVE_CURRENT(list);
00260             removed = as;
00261          }
00262          break;
00263       }
00264    }
00265    AST_LIST_TRAVERSE_SAFE_END;
00266 
00267    if (removed && asthread != AST_PTHREADT_NULL) {
00268       pthread_kill(asthread, SIGURG);
00269    }
00270 
00271    AST_LIST_UNLOCK(&aslist);
00272 
00273    if (!removed) {
00274       return 0;
00275    }
00276 
00277    /* Wait while autoservice thread rebuilds its list. */
00278    while (chan_list_state == as_chan_list_state) {
00279       usleep(1000);
00280    }
00281 
00282    /* Now autoservice thread should have no references to our entry
00283       and we can safely destroy it */
00284 
00285    if (!chan->_softhangup) {
00286       res = 0;
00287    }
00288 
00289    if (!as->orig_end_dtmf_flag) {
00290       ast_clear_flag(chan, AST_FLAG_END_DTMF_ONLY);
00291    }
00292 
00293    ast_channel_lock(chan);
00294    while ((f = AST_LIST_REMOVE_HEAD(&as->deferred_frames, frame_list))) {
00295       if (!((1 << f->frametype) & as->ignore_frame_types)) {
00296          ast_queue_frame_head(chan, f);
00297       }
00298       ast_frfree(f);
00299    }
00300    ast_channel_unlock(chan);
00301 
00302    free(as);
00303 
00304    return res;
00305 }
00306 
00307 int ast_autoservice_ignore(struct ast_channel *chan, enum ast_frame_type ftype)
00308 {
00309    struct asent *as;
00310    int res = -1;
00311 
00312    AST_LIST_LOCK(&aslist);
00313    AST_LIST_TRAVERSE(&aslist, as, list) {
00314       if (as->chan == chan) {
00315          res = 0;
00316          as->ignore_frame_types |= (1 << ftype);
00317          break;
00318       }
00319    }
00320    AST_LIST_UNLOCK(&aslist);
00321    return res;
00322 }
00323 
00324 static void autoservice_shutdown(void)
00325 {
00326    pthread_t th = asthread;
00327    asexit = 1;
00328    if (th != AST_PTHREADT_NULL) {
00329       ast_cond_signal(&as_cond);
00330       pthread_kill(th, SIGURG);
00331       pthread_join(th, NULL);
00332    }
00333 }
00334 
00335 void ast_autoservice_init(void)
00336 {
00337    ast_register_cleanup(autoservice_shutdown);
00338    ast_cond_init(&as_cond, NULL);
00339 }

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