流媒体分析之rtmp协议srs服务器数据收发

根据上篇文章，rtmp 推流处理publishing 。do_publishing 处理SrsLiveSource及传入收发SrsPublishRecvThread协程。

srs_error_t SrsRtmpConn::publishing(SrsLiveSource* source)
{
    srs_error_t err = srs_success;
    
    SrsRequest* req = info->req;
    
    if (_srs_config->get_refer_enabled(req->vhost)) {
        if ((err = refer->check(req->pageUrl, _srs_config->get_refer_publish(req->vhost))) != srs_success) {
            return srs_error_wrap(err, "rtmp: referer check");
        }
    }
    
    if ((err = http_hooks_on_publish()) != srs_success) {
        return srs_error_wrap(err, "rtmp: callback on publish");
    }
    
    // TODO: FIXME: Should refine the state of publishing.
    if ((err = acquire_publish(source)) == srs_success) {
        // use isolate thread to recv,
        // @see: https://github.com/ossrs/srs/issues/237
        SrsPublishRecvThread rtrd(rtmp, req, srs_netfd_fileno(stfd), 0, this, source, _srs_context->get_id());
        err = do_publishing(source, &rtrd);
        rtrd.stop();
    }
    
    // whatever the acquire publish, always release publish.
    // when the acquire error in the midlle-way, the publish state changed,
    // but failed, so we must cleanup it.
    // @see https://github.com/ossrs/srs/issues/474
    // @remark when stream is busy, should never release it.
    if (srs_error_code(err) != ERROR_SYSTEM_STREAM_BUSY) {
        release_publish(source);
    }
    
    http_hooks_on_unpublish();
    
    return err;
}

 do_publishing  ：协程执行，处理数据统计。

srs_error_t SrsRtmpConn::do_publishing(SrsLiveSource* source, SrsPublishRecvThread* rtrd)
{
    srs_error_t err = srs_success;
    
    SrsRequest* req = info->req;
    SrsPithyPrint* pprint = SrsPithyPrint::create_rtmp_publish();
    SrsAutoFree(SrsPithyPrint, pprint);

    // update the statistic when source disconveried.
    SrsStatistic* stat = SrsStatistic::instance();
    if ((err = stat->on_client(_srs_context->get_id().c_str(), req, this, info->type)) != srs_success) {
        return srs_error_wrap(err, "rtmp: stat client");
    }

    // start isolate recv thread.
    // TODO: FIXME: Pass the callback here.
    if ((err = rtrd->start()) != srs_success) {
        return srs_error_wrap(err, "rtmp: receive thread");
    }
    
    // initialize the publish timeout.
    publish_1stpkt_timeout = _srs_config->get_publish_1stpkt_timeout(req->vhost);
    publish_normal_timeout = _srs_config->get_publish_normal_timeout(req->vhost);
    
    // set the sock options.
    set_sock_options();
    
    if (true) {
        bool mr = _srs_config->get_mr_enabled(req->vhost);
        srs_utime_t mr_sleep = _srs_config->get_mr_sleep(req->vhost);
        srs_trace("start publish mr=%d/%d, p1stpt=%d, pnt=%d, tcp_nodelay=%d",
            mr, srsu2msi(mr_sleep), srsu2msi(publish_1stpkt_timeout), srsu2msi(publish_normal_timeout), tcp_nodelay);
    }
    
    int64_t nb_msgs = 0;
    uint64_t nb_frames = 0;
    while (true) {
        if ((err = trd->pull()) != srs_success) {
            return srs_error_wrap(err, "rtmp: thread quit");
        }

        pprint->elapse();

        // cond wait for timeout.
        if (nb_msgs == 0) {
            // when not got msgs, wait for a larger timeout.
            // @see https://github.com/ossrs/srs/issues/441
            rtrd->wait(publish_1stpkt_timeout);
        } else {
            rtrd->wait(publish_normal_timeout);
        }
        
        // check the thread error code.
        if ((err = rtrd->error_code()) != srs_success) {
            return srs_error_wrap(err, "rtmp: receive thread");
        }
        
        // when not got any messages, timeout.
        if (rtrd->nb_msgs() <= nb_msgs) {
            return srs_error_new(ERROR_SOCKET_TIMEOUT, "rtmp: publish timeout %dms, nb_msgs=%d",
                nb_msgs? srsu2msi(publish_normal_timeout) : srsu2msi(publish_1stpkt_timeout), (int)nb_msgs);
        }
        nb_msgs = rtrd->nb_msgs();
        
        // Update the stat for video fps.
        // @remark https://github.com/ossrs/srs/issues/851
        SrsStatistic* stat = SrsStatistic::instance();
        if ((err = stat->on_video_frames(req, (int)(rtrd->nb_video_frames() - nb_frames))) != srs_success) {
            return srs_error_wrap(err, "rtmp: stat video frames");
        }
        nb_frames = rtrd->nb_video_frames();

        // reportable
        if (pprint->can_print()) {
            kbps->sample();
            bool mr = _srs_config->get_mr_enabled(req->vhost);
            srs_utime_t mr_sleep = _srs_config->get_mr_sleep(req->vhost);
            srs_trace("<- " SRS_CONSTS_LOG_CLIENT_PUBLISH " time=%d, okbps=%d,%d,%d, ikbps=%d,%d,%d, mr=%d/%d, p1stpt=%d, pnt=%d",
                (int)pprint->age(), kbps->get_send_kbps(), kbps->get_send_kbps_30s(), kbps->get_send_kbps_5m(),
                kbps->get_recv_kbps(), kbps->get_recv_kbps_30s(), kbps->get_recv_kbps_5m(), mr, srsu2msi(mr_sleep),
                srsu2msi(publish_1stpkt_timeout), srsu2msi(publish_normal_timeout));
        }
    }
    
    return err;
}

SrsPublishRecvThread::start   执行：trd.start 。trd指向SrsRecvThread 。

srs_error_t SrsPublishRecvThread::start()
{
    srs_error_t err = srs_success;
    
    if ((err = trd.start()) != srs_success) {
        err = srs_error_wrap(err, "publish recv thread");
    }
    
    ncid = cid = trd.cid();

    return err;
}

 SrsRecvThread 执行SrsSTCoroutine。SrsSTCoroutine传入this对象cycle()

srs_error_t SrsRecvThread::start()
{
    srs_error_t err = srs_success;
    
    srs_freep(trd);
    trd = new SrsSTCoroutine("recv", this, _parent_cid);

    //change stack size to 256K, fix crash when call some 3rd-part api.
    ((SrsSTCoroutine*)trd)->set_stack_size(1 << 18);
    
    if ((err = trd->start()) != srs_success) {
        return srs_error_wrap(err, "recv thread");
    }
    
    return err;
}

 SrsRecvThread::cycle

srs_error_t SrsRecvThread::cycle()
{
    srs_error_t err = srs_success;
    
    // the multiple messages writev improve performance large,
    // but the timeout recv will cause 33% sys call performance,
    // to use isolate thread to recv, can improve about 33% performance.
    rtmp->set_recv_timeout(SRS_UTIME_NO_TIMEOUT);
    
    pumper->on_start();
    
    if ((err = do_cycle()) != srs_success) {
        err = srs_error_wrap(err, "recv thread");
    }
    
    // reset the timeout to pulse mode.
    rtmp->set_recv_timeout(timeout);
    
    pumper->on_stop();
    
    return err;
}

 do_cycle  执行。

rtmp->recv_message ，rtmp 收数据。

pumper->consume     数据推流到。pumper->consume   指向。 SrsPublishRecvThread::consume(SrsCommonMessage* msg)

srs_error_t SrsRecvThread::do_cycle()
{
    srs_error_t err = srs_success;
    
    while (true) {
        if ((err = trd->pull()) != srs_success) {
            return srs_error_wrap(err, "recv thread");
        }
        
        // When the pumper is interrupted, wait then retry.
        if (pumper->interrupted()) {
            srs_usleep(timeout);
            continue;
        }
        
        SrsCommonMessage* msg = NULL;
        
        // Process the received message.
        if ((err = rtmp->recv_message(&msg)) == srs_success) {
            err = pumper->consume(msg);
        }
        
        if (err != srs_success) {
            // Interrupt the receive thread for any error.
            trd->interrupt();
            
            // Notify the pumper to quit for error.
            pumper->interrupt(err);
            
            return srs_error_wrap(err, "recv thread");
        }
    }
    
    return err;
}

 SrsPublishRecvThread::consume 。执行_conn->handle_publish_message 函数。

_conn->handle_publish_message  指向SrsRtmpConn::handle_publish_message。

srs_error_t SrsPublishRecvThread::consume(SrsCommonMessage* msg)
{
    srs_error_t err = srs_success;
    
    // when cid changed, change it.
    if (ncid.compare(cid)) {
        _srs_context->set_id(ncid);
        cid = ncid;
    }
    
    _nb_msgs++;
    
    if (msg->header.is_video()) {
        video_frames++;
    }
    
    // log to show the time of recv thread.
    srs_verbose("recv thread now=%" PRId64 "us, got msg time=%" PRId64 "ms, size=%d",
                srs_update_system_time(), msg->header.timestamp, msg->size);
    
    // the rtmp connection will handle this message
    err = _conn->handle_publish_message(_source, msg);
    
    // must always free it,
    // the source will copy it if need to use.
    srs_freep(msg);
    
    if (err != srs_success) {
        return srs_error_wrap(err, "handle publish message");
    }

    // Yield to another coroutines.
    // @see https://github.com/ossrs/srs/issues/2194#issuecomment-777463768
    if (++nn_msgs_for_yield_ >= 15) {
        nn_msgs_for_yield_ = 0;
        srs_thread_yield();
    }
    
    return err;
}

 handle_publish_message 处理。

srs_error_t SrsRtmpConn::handle_publish_message(SrsLiveSource* source, SrsCommonMessage* msg)
{
    srs_error_t err = srs_success;
    
    // process publish event.
    if (msg->header.is_amf0_command() || msg->header.is_amf3_command()) {
        SrsPacket* pkt = NULL;
        if ((err = rtmp->decode_message(msg, &pkt)) != srs_success) {
            return srs_error_wrap(err, "rtmp: decode message");
        }
        SrsAutoFree(SrsPacket, pkt);
        
        // for flash, any packet is republish.
        if (info->type == SrsRtmpConnFlashPublish) {
            // flash unpublish.
            // TODO: maybe need to support republish.
            srs_trace("flash flash publish finished.");
            return srs_error_new(ERROR_CONTROL_REPUBLISH, "rtmp: republish");
        }
        
        // for fmle, drop others except the fmle start packet.
        if (dynamic_cast(pkt)) {
            SrsFMLEStartPacket* unpublish = dynamic_cast(pkt);
            if ((err = rtmp->fmle_unpublish(info->res->stream_id, unpublish->transaction_id)) != srs_success) {
                return srs_error_wrap(err, "rtmp: republish");
            }
            return srs_error_new(ERROR_CONTROL_REPUBLISH, "rtmp: republish");
        }
        
        srs_trace("fmle ignore AMF0/AMF3 command message.");
        return err;
    }
    
    // video, audio, data message
    if ((err = process_publish_message(source, msg)) != srs_success) {
        return srs_error_wrap(err, "rtmp: consume message");
    }
    
    return err;
}

   process_publish_message ，处理source->on_audio 及source->on_video 函数。

srs_error_t SrsRtmpConn::process_publish_message(SrsLiveSource* source, SrsCommonMessage* msg)
{
    srs_error_t err = srs_success;
    
    // for edge, directly proxy message to origin.
    if (info->edge) {
        if ((err = source->on_edge_proxy_publish(msg)) != srs_success) {
            return srs_error_wrap(err, "rtmp: proxy publish");
        }
        return err;
    }
    
    // process audio packet
    if (msg->header.is_audio()) {
        if ((err = source->on_audio(msg)) != srs_success) {
            return srs_error_wrap(err, "rtmp: consume audio");
        }
        return err;
    }
    // process video packet
    if (msg->header.is_video()) {
        if ((err = source->on_video(msg)) != srs_success) {
            return srs_error_wrap(err, "rtmp: consume video");
        }
        return err;
    }
    
    // process aggregate packet
    if (msg->header.is_aggregate()) {
        if ((err = source->on_aggregate(msg)) != srs_success) {
            return srs_error_wrap(err, "rtmp: consume aggregate");
        }
        return err;
    }
    
    // process onMetaData
    if (msg->header.is_amf0_data() || msg->header.is_amf3_data()) {
        SrsPacket* pkt = NULL;
        if ((err = rtmp->decode_message(msg, &pkt)) != srs_success) {
            return srs_error_wrap(err, "rtmp: decode message");
        }
        SrsAutoFree(SrsPacket, pkt);
        
        if (dynamic_cast(pkt)) {
            SrsOnMetaDataPacket* metadata = dynamic_cast(pkt);
            if ((err = source->on_meta_data(msg, metadata)) != srs_success) {
                return srs_error_wrap(err, "rtmp: consume metadata");
            }
            return err;
        }
        return err;
    }
    
    return err;
}

2. 数据发送：

srs_error_t SrsRtmpConn::playing(SrsLiveSource* source)
{
    srs_error_t err = srs_success;
    
    // Check page referer of player.
    SrsRequest* req = info->req;
    if (_srs_config->get_refer_enabled(req->vhost)) {
        if ((err = refer->check(req->pageUrl, _srs_config->get_refer_play(req->vhost))) != srs_success) {
            return srs_error_wrap(err, "rtmp: referer check");
        }
    }
    
    // When origin cluster enabled, try to redirect to the origin which is active.
    // A active origin is a server which is delivering stream.
    if (!info->edge && _srs_config->get_vhost_origin_cluster(req->vhost) && source->inactive()) {
        vector coworkers = _srs_config->get_vhost_coworkers(req->vhost);
        for (int i = 0; i < (int)coworkers.size(); i++) {
            // TODO: FIXME: User may config the server itself as coworker, we must identify and ignore it.
            string host; int port = 0; string coworker = coworkers.at(i);

            string url = "http://" + coworker + "/api/v1/clusters?"
                + "vhost=" + req->vhost + "&ip=" + req->host + "&app=" + req->app + "&stream=" + req->stream
                + "&coworker=" + coworker;
            if ((err = SrsHttpHooks::discover_co_workers(url, host, port)) != srs_success) {
                // If failed to discovery stream in this coworker, we should request the next one util the last.
                // @see https://github.com/ossrs/srs/issues/1223
                if (i < (int)coworkers.size() - 1) {
                    continue;
                }
                return srs_error_wrap(err, "discover coworkers, url=%s", url.c_str());
            }

            string rurl = srs_generate_rtmp_url(host, port, req->host, req->vhost, req->app, req->stream, req->param);
            srs_trace("rtmp: redirect in cluster, from=%s:%d, target=%s:%d, url=%s, rurl=%s",
                req->host.c_str(), req->port, host.c_str(), port, url.c_str(), rurl.c_str());

            // Ignore if host or port is invalid.
            if (host.empty() || port == 0) {
                continue;
            }
            
            bool accepted = false;
            if ((err = rtmp->redirect(req, rurl, accepted)) != srs_success) {
                srs_error_reset(err);
            } else {
                return srs_error_new(ERROR_CONTROL_REDIRECT, "redirected");
            }
        }
        
        return srs_error_new(ERROR_OCLUSTER_REDIRECT, "no origin");
    }
    
    // Set the socket options for transport.
    set_sock_options();
    
    // Create a consumer of source.
    SrsLiveConsumer* consumer = NULL;
    SrsAutoFree(SrsLiveConsumer, consumer);
    if ((err = source->create_consumer(consumer)) != srs_success) {
        return srs_error_wrap(err, "rtmp: create consumer");
    }
    if ((err = source->consumer_dumps(consumer)) != srs_success) {
        return srs_error_wrap(err, "rtmp: dumps consumer");
    }
    
    // Use receiving thread to receive packets from peer.
    SrsQueueRecvThread trd(consumer, rtmp, SRS_PERF_MW_SLEEP, _srs_context->get_id());
    
    if ((err = trd.start()) != srs_success) {
        return srs_error_wrap(err, "rtmp: start receive thread");
    }
    
    // Deliver packets to peer.
    wakable = consumer;
    err = do_playing(source, consumer, &trd);
    wakable = NULL;
    
    trd.stop();
    
    // Drop all packets in receiving thread.
    if (!trd.empty()) {
        srs_warn("drop the received %d messages", trd.size());
    }
    
    return err;
}

do_playing  函数。

consumer->dump_packets 从缓存 取出数据，

rtmp->send_and_free_messages 发送数据。

srs_error_t SrsRtmpConn::do_playing(SrsLiveSource* source, SrsLiveConsumer* consumer, SrsQueueRecvThread* rtrd)
{
    srs_error_t err = srs_success;
    
    SrsRequest* req = info->req;
    srs_assert(req);
    srs_assert(consumer);

    // update the statistic when source disconveried.
    SrsStatistic* stat = SrsStatistic::instance();
    if ((err = stat->on_client(_srs_context->get_id().c_str(), req, this, info->type)) != srs_success) {
        return srs_error_wrap(err, "rtmp: stat client");
    }
    
    // initialize other components
    SrsPithyPrint* pprint = SrsPithyPrint::create_rtmp_play();
    SrsAutoFree(SrsPithyPrint, pprint);
    
    SrsMessageArray msgs(SRS_PERF_MW_MSGS);
    bool user_specified_duration_to_stop = (req->duration > 0);
    int64_t starttime = -1;

    // setup the realtime.
    realtime = _srs_config->get_realtime_enabled(req->vhost);
    // setup the mw config.
    // when mw_sleep changed, resize the socket send buffer.
    mw_msgs = _srs_config->get_mw_msgs(req->vhost, realtime);
    mw_sleep = _srs_config->get_mw_sleep(req->vhost);
    skt->set_socket_buffer(mw_sleep);
    // initialize the send_min_interval
    send_min_interval = _srs_config->get_send_min_interval(req->vhost);
    
    srs_trace("start play smi=%dms, mw_sleep=%d, mw_msgs=%d, realtime=%d, tcp_nodelay=%d",
        srsu2msi(send_min_interval), srsu2msi(mw_sleep), mw_msgs, realtime, tcp_nodelay);
    
    while (true) {
        // when source is set to expired, disconnect it.
        if ((err = trd->pull()) != srs_success) {
            return srs_error_wrap(err, "rtmp: thread quit");
        }

        // collect elapse for pithy print.
        pprint->elapse();

        // to use isolate thread to recv, can improve about 33% performance.
        while (!rtrd->empty()) {
            SrsCommonMessage* msg = rtrd->pump();
            if ((err = process_play_control_msg(consumer, msg)) != srs_success) {
                return srs_error_wrap(err, "rtmp: play control message");
            }
        }
        
        // quit when recv thread error.
        if ((err = rtrd->error_code()) != srs_success) {
            return srs_error_wrap(err, "rtmp: recv thread");
        }
        
#ifdef SRS_PERF_QUEUE_COND_WAIT
        // wait for message to incoming.
        // @see https://github.com/ossrs/srs/issues/257
        consumer->wait(mw_msgs, mw_sleep);
#endif
        
        // get messages from consumer.
        // each msg in msgs.msgs must be free, for the SrsMessageArray never free them.
        // @remark when enable send_min_interval, only fetch one message a time.
        int count = (send_min_interval > 0)? 1 : 0;
        if ((err = consumer->dump_packets(&msgs, count)) != srs_success) {
            return srs_error_wrap(err, "rtmp: consumer dump packets");
        }

        // reportable
        if (pprint->can_print()) {
            kbps->sample();
            srs_trace("-> " SRS_CONSTS_LOG_PLAY " time=%d, msgs=%d, okbps=%d,%d,%d, ikbps=%d,%d,%d, mw=%d/%d",
                (int)pprint->age(), count, kbps->get_send_kbps(), kbps->get_send_kbps_30s(), kbps->get_send_kbps_5m(),
                kbps->get_recv_kbps(), kbps->get_recv_kbps_30s(), kbps->get_recv_kbps_5m(), srsu2msi(mw_sleep), mw_msgs);
        }
        
        if (count <= 0) {
#ifndef SRS_PERF_QUEUE_COND_WAIT
            srs_usleep(mw_sleep);
#endif
            // ignore when nothing got.
            continue;
        }
        
        // only when user specifies the duration,
        // we start to collect the durations for each message.
        if (user_specified_duration_to_stop) {
            for (int i = 0; i < count; i++) {
                SrsSharedPtrMessage* msg = msgs.msgs[i];
                
                // foreach msg, collect the duration.
                // @remark: never use msg when sent it, for the protocol sdk will free it.
                if (starttime < 0 || starttime > msg->timestamp) {
                    starttime = msg->timestamp;
                }
                duration += (msg->timestamp - starttime) * SRS_UTIME_MILLISECONDS;
                starttime = msg->timestamp;
            }
        }
        
        // sendout messages, all messages are freed by send_and_free_messages().
        // no need to assert msg, for the rtmp wilal assert it.
        printf("%s %d %d\n",__FUNCTION__,__LINE__,count);
        if (count > 0 && (err = rtmp->send_and_free_messages(msgs.msgs, count, info->res->stream_id)) != srs_success) {
            return srs_error_wrap(err, "rtmp: send %d messages", count);
        }
        
        // if duration specified, and exceed it, stop play live.
        // @see: https://github.com/ossrs/srs/issues/45
        if (user_specified_duration_to_stop) {
            if (duration >= req->duration) {
                return srs_error_new(ERROR_RTMP_DURATION_EXCEED, "rtmp: time %d up %d", srsu2msi(duration), srsu2msi(req->duration));
            }
        }
        
        // apply the minimal interval for delivery stream in srs_utime_t.
        if (send_min_interval > 0) {
            srs_usleep(send_min_interval);
        }

        // Yield to another coroutines.
        // @see https://github.com/ossrs/srs/issues/2194#issuecomment-777437476
        srs_thread_yield();
    }
    
    return err;
}