autoservice.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2008, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 * Russell Bryant <russell@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */
 
/*! \file
 *
 * \brief Automatic channel service routines
 *
 * \author Mark Spencer <markster@digium.com>
 * \author Russell Bryant <russell@digium.com>
 */
 
/*** MODULEINFO
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#include <sys/time.h>
#include <signal.h>
 
#include "asterisk/_private.h" /* prototype for ast_autoservice_init() */
 
#include "asterisk/pbx.h"
#include "asterisk/frame.h"
#include "asterisk/sched.h"
#include "asterisk/channel.h"
#include "asterisk/file.h"
#include "asterisk/translate.h"
#include "asterisk/manager.h"
#include "asterisk/chanvars.h"
#include "asterisk/linkedlists.h"
#include "asterisk/indications.h"
#include "asterisk/lock.h"
#include "asterisk/utils.h"
 
#define MAX_AUTOMONS 1500
 
struct asent {
    struct ast_channel *chan;
    /*! This gets incremented each time autoservice gets started on the same
     *  channel.  It will ensure that it doesn't actually get stopped until
     *  it gets stopped for the last time. */
    unsigned int use_count;
    unsigned int orig_end_dtmf_flag:1;
    unsigned int video_update:1;
    unsigned int ignore_frame_types;
    /*! Frames go on at the head of deferred_frames, so we have the frames
     *  from newest to oldest.  As we put them at the head of the readq, we'll
     *  end up with them in the right order for the channel's readq. */
    AST_LIST_HEAD_NOLOCK(, ast_frame) deferred_frames;
    AST_LIST_ENTRY(asent) list;
};
 
static AST_LIST_HEAD_STATIC(aslist, asent);
static ast_cond_t as_cond;
 
static pthread_t asthread = AST_PTHREADT_NULL;
static volatile int asexit = 0;
 
static int as_chan_list_state;
 
static void *autoservice_run(void *ign)
{
    ast_callid callid = 0;
    struct ast_frame hangup_frame = {
        .frametype = AST_FRAME_CONTROL,
        .subclass.integer = AST_CONTROL_HANGUP,
    };
 
    while (!asexit) {
        struct ast_channel *mons[MAX_AUTOMONS];
        struct asent *ents[MAX_AUTOMONS];
        struct ast_channel *chan;
        struct asent *as;
        int i, x = 0, ms = 50;
        struct ast_frame *f = NULL;
        struct ast_frame *defer_frame = NULL;
 
        AST_LIST_LOCK(&aslist);
 
        /* At this point, we know that no channels that have been removed are going
         * to get used again. */
        as_chan_list_state++;
 
        if (AST_LIST_EMPTY(&aslist)) {
            ast_cond_wait(&as_cond, &aslist.lock);
        }
 
        AST_LIST_TRAVERSE(&aslist, as, list) {
            if (!ast_check_hangup(as->chan)) {
                if (x < MAX_AUTOMONS) {
                    ents[x] = as;
                    mons[x++] = as->chan;
                } else {
                    ast_log(LOG_WARNING, "Exceeded maximum number of automatic monitoring events.  Fix autoservice.c\n");
                }
            }
        }
 
        AST_LIST_UNLOCK(&aslist);
 
        if (!x) {
            /* If we don't sleep, this becomes a busy loop, which causes
             * problems when Asterisk runs at a different priority than other
             * user processes.  As long as we check for new channels at least
             * once every 10ms, we should be fine. */
            usleep(10000);
            continue;
        }
 
        chan = ast_waitfor_n(mons, x, &ms);
        if (!chan) {
            continue;
        }
 
        callid = ast_channel_callid(chan);
        ast_callid_threadassoc_change(callid);
 
        f = ast_read(chan);
 
        if (!f) {
            /* No frame means the channel has been hung up.
             * A hangup frame needs to be queued here as ast_waitfor() may
             * never return again for the condition to be detected outside
             * of autoservice.  So, we'll leave a HANGUP queued up so the
             * thread in charge of this channel will know. */
 
            defer_frame = &hangup_frame;
        } else if (ast_is_deferrable_frame(f)) {
            defer_frame = f;
        } else {
            /* Can't defer. Discard and continue with next. */
            ast_frfree(f);
            continue;
        }
 
        for (i = 0; i < x; i++) {
            struct ast_frame *dup_f;
 
            if (mons[i] != chan) {
                continue;
            }
 
            if (!f) { /* defer_frame == &hangup_frame */
                if ((dup_f = ast_frdup(defer_frame))) {
                    AST_LIST_INSERT_HEAD(&ents[i]->deferred_frames, dup_f, frame_list);
                }
            } else {
                if (defer_frame->frametype == AST_FRAME_CONTROL &&
                    defer_frame->subclass.integer == AST_CONTROL_VIDUPDATE) {
 
                    /* If a video update is already queued don't needlessly queue another */
                    if (ents[i]->video_update) {
                        ast_frfree(defer_frame);
                        break;
                    }
 
                    ents[i]->video_update = 1;
                }
                if ((dup_f = ast_frisolate(defer_frame))) {
                    AST_LIST_INSERT_HEAD(&ents[i]->deferred_frames, dup_f, frame_list);
                }
                if (dup_f != defer_frame) {
                    ast_frfree(defer_frame);
                }
            }
 
            break;
        }
        /* The ast_waitfor_n() call will only read frames from
         * the channels' file descriptors. If ast_waitfor_n()
         * returns non-NULL, then one of the channels in the
         * mons array must have triggered the return. It's
         * therefore impossible that we got here while (i >= x).
         * If we did, we'd need to ast_frfree(f) if (f). */
    }
 
    ast_callid_threadassoc_change(0);
    asthread = AST_PTHREADT_NULL;
 
    return NULL;
}
 
int ast_autoservice_start(struct ast_channel *chan)
{
    int res = 0;
    struct asent *as;
 
    if (ast_thread_is_user_interface()) {
        /* User interface threads do not handle channel media. */
        ast_debug(1, "Thread is a user interface, not putting channel %s into autoservice\n",
            ast_channel_name(chan));
        return 0;
    }
 
    AST_LIST_LOCK(&aslist);
    AST_LIST_TRAVERSE(&aslist, as, list) {
        if (as->chan == chan) {
            as->use_count++;
            break;
        }
    }
    AST_LIST_UNLOCK(&aslist);
 
    if (as) {
        /* Entry exists, autoservice is already handling this channel */
        return 0;
    }
 
    if (!(as = ast_calloc(1, sizeof(*as))))
        return -1;
 
    /* New entry created */
    as->chan = chan;
    as->use_count = 1;
 
    ast_channel_lock(chan);
    as->orig_end_dtmf_flag = ast_test_flag(ast_channel_flags(chan), AST_FLAG_END_DTMF_ONLY) ? 1 : 0;
    if (!as->orig_end_dtmf_flag)
        ast_set_flag(ast_channel_flags(chan), AST_FLAG_END_DTMF_ONLY);
    ast_channel_unlock(chan);
 
    AST_LIST_LOCK(&aslist);
 
    if (AST_LIST_EMPTY(&aslist) && asthread != AST_PTHREADT_NULL) {
        ast_cond_signal(&as_cond);
    }
 
    AST_LIST_INSERT_HEAD(&aslist, as, list);
 
    if (asthread == AST_PTHREADT_NULL) { /* need start the thread */
        if (ast_pthread_create_background(&asthread, NULL, autoservice_run, NULL)) {
            ast_log(LOG_WARNING, "Unable to create autoservice thread :(\n");
            /* There will only be a single member in the list at this point,
               the one we just added. */
            AST_LIST_REMOVE(&aslist, as, list);
            ast_free(as);
            asthread = AST_PTHREADT_NULL;
            res = -1;
        } else {
            pthread_kill(asthread, SIGURG);
        }
    }
 
    AST_LIST_UNLOCK(&aslist);
 
    return res;
}
 
int ast_autoservice_stop(struct ast_channel *chan)
{
    int res = -1;
    struct asent *as, *removed = NULL;
    struct ast_frame *f;
    int chan_list_state;
 
    if (ast_thread_is_user_interface()) {
        /* User interface threads do not handle channel media. */
        ast_debug(1, "Thread is a user interface, not removing channel %s from autoservice\n",
            ast_channel_name(chan));
        return 0;
    }
 
    AST_LIST_LOCK(&aslist);
 
    /* Save the autoservice channel list state.  We _must_ verify that the channel
     * list has been rebuilt before we return.  Because, after we return, the channel
     * could get destroyed and we don't want our poor autoservice thread to step on
     * it after its gone! */
    chan_list_state = as_chan_list_state;
 
    /* Find the entry, but do not free it because it still can be in the
       autoservice thread array */
    AST_LIST_TRAVERSE_SAFE_BEGIN(&aslist, as, list) {
        if (as->chan == chan) {
            as->use_count--;
            if (as->use_count < 1) {
                AST_LIST_REMOVE_CURRENT(list);
                removed = as;
            }
            break;
        }
    }
    AST_LIST_TRAVERSE_SAFE_END;
 
    if (removed && asthread != AST_PTHREADT_NULL) {
        pthread_kill(asthread, SIGURG);
    }
 
    AST_LIST_UNLOCK(&aslist);
 
    if (!removed) {
        return 0;
    }
 
    if (asthread != AST_PTHREADT_NULL && pthread_equal(pthread_self(), asthread)) {
        /* Do not sleep if ast_autoservice_stop is called within the autoservice thread,
           otherwise the thread will be stuck in an endless sleep. */
        ast_debug(1, "ast_autoservice_stop is called within the autoservice thread, channel %s\n",
            ast_channel_name(chan));
    } else {
        /* Wait while autoservice thread rebuilds its list. */
        while (chan_list_state == as_chan_list_state) {
            usleep(1000);
        }
    }
 
    /* Now autoservice thread should have no references to our entry
       and we can safely destroy it */
 
    if (!ast_channel_softhangup_internal_flag(chan)) {
        res = 0;
    }
 
    ast_channel_lock(chan);
    if (!as->orig_end_dtmf_flag) {
        ast_clear_flag(ast_channel_flags(chan), AST_FLAG_END_DTMF_ONLY);
    }
 
    while ((f = AST_LIST_REMOVE_HEAD(&as->deferred_frames, frame_list))) {
        if (!((1 << f->frametype) & as->ignore_frame_types)) {
            ast_queue_frame_head(chan, f);
        }
        ast_frfree(f);
    }
    ast_channel_unlock(chan);
 
    ast_free(as);
 
    return res;
}
 
void ast_autoservice_chan_hangup_peer(struct ast_channel *chan, struct ast_channel *peer)
{
    if (chan && !ast_autoservice_start(chan)) {
        ast_hangup(peer);
        ast_autoservice_stop(chan);
    } else {
        ast_hangup(peer);
    }
}
 
int ast_autoservice_ignore(struct ast_channel *chan, enum ast_frame_type ftype)
{
    struct asent *as;
    int res = -1;
 
    AST_LIST_LOCK(&aslist);
    AST_LIST_TRAVERSE(&aslist, as, list) {
        if (as->chan == chan) {
            res = 0;
            as->ignore_frame_types |= (1 << ftype);
            break;
        }
    }
    AST_LIST_UNLOCK(&aslist);
    return res;
}
 
static void autoservice_shutdown(void)
{
    pthread_t th = asthread;
    asexit = 1;
    if (th != AST_PTHREADT_NULL) {
        ast_cond_signal(&as_cond);
        pthread_kill(th, SIGURG);
        pthread_join(th, NULL);
    }
}
 
void ast_autoservice_init(void)
{
    ast_register_cleanup(autoservice_shutdown);
    ast_cond_init(&as_cond, NULL);
}