SRS流媒體服務器——Forward集群搭建和源碼分析

目錄

Forward集群原理

RTMP流轉發（Forward）部署實例

Forward集群源碼分析

1. Forward集群原理

Forward 表示向前、前頭的、發送等意思。

在SRS中可以理解為把Master節點獲得直播流?播（轉發）給所有的Slave節點，master節點由多少路直播流，那么在每個slave節點也會多少路直播流。

注：在SRS中還有另外?種集群?式，edge?式。注意兩種?式的?詞不同。
a. 在Forward模式中，中?節點叫Master，邊緣節點叫Slave。
b. 在edge模式中，中?節點叫origin（源站），邊緣節點叫做edge。

1. 適用場景

Forward適合搭建?型集群。

推流者推流給master，那么master就會Forward到每?個Slave，那么在slave節點上不論需不需要都會有master過來的流。

如果推流者的數量為10，那么master到slave之間的帶寬就是：帶寬=10 *slave的個數 *直播流碼率，隨著slave的增多，master的出?帶寬會不斷提?。

?現實是，在某些slave節點其實沒有?看，這樣就造成了master到slave之間的帶寬浪費。

所以說Forward適合?于搭建?型集群。

2. RTMP流轉發（Forward）部署實例

SRS可以將送到SRS的流轉發給其他RTMP服務器，實現簡單集群/熱備功能，也可以實現?路流熱備
a. 如編碼器由于帶寬限制，只能送?路流到RTMP服務器，要求RTMP服務器能將這路流也轉發給其他RTMP備?服務器，實現主備容錯集群。

假設服務器的IP是：8.141.75.248

Forward就是SRS將流拷?輸出給其他的RTMP服務器，以SRS轉發給SRS為例：

主SRS：Master，編碼器推流到主SRS，主SRS將流處理的同時，將流轉發到備SRS。

備SRS：Slave，主SRS轉發流到備SRS，就像編碼器推送流到備?SRS?樣。

測試部署的實例中，主SRS偵聽1935端?，備SRS偵聽19350和19351端?。

1. 編寫主SRS配置?件

vim conf/forward.master.conf

# the config for srs to forward # @see https://github.com/ossrs/srs/wiki/v1_CN_SampleForward # @see full.conf for detail config.listen 1935; max_connections 1000; pid ./objs/srs.master.pid; vhost __defaultVhost__ {forward {enabled on;destination 127.0.0.1:19350 127.0.0.1:19351; #forward目的地址，增加一個19351端口} }

啟動srs服務器。

./objs/srs -c conf/forward.master.conf

監聽日志信息：tail -f ./objs/srs.log

2. 編寫從SRS配置文件

復制conf/forward.slave.conf到conf/forward.slave1.conf，conf/forward.slave2.conf。

cp conf/forward.slave.conf conf/forward.slave1.conf cp conf/forward.slave.conf conf/forward.slave2.conf

修改conf/forward.slave1.conf配置文件。

# the config for srs to forward # @see https://github.com/ossrs/srs/wiki/v1_CN_SampleForward # @see full.conf for detail config.listen 19350; #注意端口 max_connections 1000; pid ./objs/srs.slave1.pid; #./objs/srs.slave.pid改為./objs/srs.slave1.pid srs_log_tank file; srs_log_file ./objs/srs.slave1.log; vhost __defaultVhost__ { }

修改conf/forward.slave2.conf配置文件。

# the config for srs to forward # @see https://github.com/ossrs/srs/wiki/v1_CN_SampleForward # @see full.conf for detail config.listen 19351; max_connections 1000; pid ./objs/srs.slave2.pid; srs_log_tank file; srs_log_file ./objs/srs.slave2.log; vhost __defaultVhost__ { }

啟動slave1和slave2

./objs/srs -c conf/forward.slave1.conf ./objs/srs -c conf/forward.slave2.conf監聽日志信息：tail -f ./objs/srs.log

啟動srs后查看srs是否啟動成功：netstat -anp|grep srs

3. 驗證是否部署成功

1. 啟動推流編碼器

使用FFmpeg進行推流

ffmpeg -re -i source.200kbps.768x320.flv -vcodec copy -acodec copy -f flv -y rtmp://8.141.75.248/live/livestream

涉及到的流包括：

編碼器推送的流：rtmp://8.141.75.248/live/livestream主SRS轉發的流：rtmp://8.141.75.248:19350/live/livestream 主SRS轉發的流：rtmp://8.141.75.248:19351/live/livestream觀看主SRS的流：rtmp://8.141.75.248/live/livestream 觀看從1 SRS的流：rtmp://8.141.75.248:19350/live/livestream 觀看從2 SRS的流：rtmp://8.141.75.248:19351/live/livestream

2. 觀看主從SRS的RTMP流

主RTMP流地址為：rtmp://8.141.75.248/live/livestream

從1 SRS的流：rtmp://8.141.75.248:19350/live/livestream

從2 SRS的流：rtmp://8.141.75.248:19351/live/livestream

可以使用VLC觀看或者SRS播放器播放：srs播放器

注意：19350和19351端口需要在服務器開放，不然從節點無法拉流

3. Forward集群源碼分析

從原理上來分析，要實現forward功能：

讀取配置?件獲取forward server的地址

創建RTMP推流客戶端

從source??拉取消息，然后推送給forward server

1. 從配置文件開始分析

打開 conf/forward.master.conf 配置文件。

listen 1935; max_connections 1000; pid ./objs/srs.master.pid; srs_log_tank file; srs_log_file ./objs/srs.master.log; vhost __defaultVhost__ {forward {enabled on;destination 127.0.0.1:19350 127.0.0.1:19351;} }日志打印在終端設置方法： #srs_log_tank file; #srs_log_file ./objs/srs.log; daemon off; srs_log_tank console;

在srs_app_config.cpp中搜索“forward”即可發現讀取“forward”的代碼。

bool SrsConfig::get_forward_enabled(string vhost) {static bool DEFAULT = false;SrsConfDirective* conf = get_vhost(vhost);if (!conf) {return DEFAULT;}conf = conf->get("forward");if (!conf) {return DEFAULT;}conf = conf->get("enabled");if (!conf || conf->arg0().empty()) {return DEFAULT;}return SRS_CONF_PERFER_FALSE(conf->arg0()); }SrsConfDirective* SrsConfig::get_forwards(string vhost) {SrsConfDirective* conf = get_vhost(vhost);if (!conf) {return NULL;}conf = conf->get("forward");if (!conf) {return NULL;}return conf->get("destination"); }

2. 使用gdb打斷點進行分析：

使用gdb打斷點進行分析：

gdb ./objs/srs(gdb) set args -c conf/forward.master.conf (gdb) b SrsConfig::get_forward_enabled(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) Breakpoint 1 at 0x53701d: file src/app/srs_app_config.cpp, line 4837. (gdb) b SrsConfig::get_forwards(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) Breakpoint 2 at 0x5372df: file src/app/srs_app_config.cpp, line 4859.

推流后才能進行調試：

ffmpeg -re -i source.200kbps.768x320.flv -vcodec copy -acodec copy -f flv -y rtmp://8.141.75.248/live/livestream

SrsConfig::get_forward_enabled 對應調試信息：

Breakpoint 1, SrsConfig::get_forward_enabled (this=0xa0fcf0, vhost="__defaultVhost__") at src/app/srs_app_config.cpp:4837 4837 { (gdb) bt #0 SrsConfig::get_forward_enabled (this=0xa0fcf0, vhost="__defaultVhost__") at src/app/srs_app_config.cpp:4837 #1 0x00000000004e277a in SrsOriginHub::create_forwarders (this=0xab8000) at src/app/srs_app_source.cpp:1467 #2 0x00000000004e1214 in SrsOriginHub::on_publish (this=0xab8000) at src/app/srs_app_source.cpp:1120 #3 0x00000000004e76ce in SrsSource::on_publish (this=0xab7cd0) at src/app/srs_app_source.cpp:2457 #4 0x00000000004d96ca in SrsRtmpConn::acquire_publish (this=0xa9be50, source=0xab7cd0) at src/app/srs_app_rtmp_conn.cpp:940 #5 0x00000000004d874c in SrsRtmpConn::publishing (this=0xa9be50, source=0xab7cd0) at src/app/srs_app_rtmp_conn.cpp:822 #6 0x00000000004d5ee7 in SrsRtmpConn::stream_service_cycle (this=0xa9be50) at src/app/srs_app_rtmp_conn.cpp:534 #7 0x00000000004d4ddf in SrsRtmpConn::service_cycle (this=0xa9be50) at src/app/srs_app_rtmp_conn.cpp:388 #8 0x00000000004d3ba7 in SrsRtmpConn::do_cycle (this=0xa9be50) at src/app/srs_app_rtmp_conn.cpp:209 #9 0x00000000004d1d99 in SrsConnection::cycle (this=0xa9bec8) at src/app/srs_app_conn.cpp:171 #10 0x000000000050ab08 in SrsSTCoroutine::cycle (this=0xa9c130) at src/app/srs_app_st.cpp:198 #11 0x000000000050ab7d in SrsSTCoroutine::pfn (arg=0xa9c130) at src/app/srs_app_st.cpp:213 #12 0x00000000005bed1a in _st_thread_main () at sched.c:337 #13 0x00000000005bf492 in st_thread_create (start=0x5be696 <_st_vp_schedule+170>, arg=0x700000001, joinable=1, stk_size=1) at sched.c:616 Backtrace stopped: previous frame inner to this frame (corrupt stack?)

forward metadata，video，audio數據。

b SrsForwarder::on_meta_data(SrsSharedPtrMessage*)(gdb) bt #0 SrsForwarder::on_meta_data (this=0xab9e60, shared_metadata=0xb28490) at src/app/srs_app_forward.cpp:114 #1 0x00000000004df741 in SrsOriginHub::on_meta_data (this=0xab8000, shared_metadata=0xb28490, packet=0xb283f0) at src/app/srs_app_source.cpp:924 #2 0x00000000004e5e23 in SrsSource::on_meta_data (this=0xab7cd0, msg=0xb28210, metadata=0xb283f0) at src/app/srs_app_source.cpp:2113 #3 0x00000000004d9e93 in SrsRtmpConn::process_publish_message (this=0xa9be50, source=0xab7cd0, msg=0xb28210) at src/app/srs_app_rtmp_conn.cpp:1045 #4 0x00000000004d9aa6 in SrsRtmpConn::handle_publish_message (this=0xa9be50, source=0xab7cd0, msg=0xb28210) at src/app/srs_app_rtmp_conn.cpp:993 #5 0x0000000000582720 in SrsPublishRecvThread::consume (this=0xab6480, msg=0xb28210) at src/app/srs_app_recv_thread.cpp:389 #6 0x000000000058123e in SrsRecvThread::do_cycle (this=0xab6488) at src/app/srs_app_recv_thread.cpp:146 #7 0x000000000058108f in SrsRecvThread::cycle (this=0xab6488) at src/app/srs_app_recv_thread.cpp:115 #8 0x000000000050ab08 in SrsSTCoroutine::cycle (this=0xb024f0) at src/app/srs_app_st.cpp:198 #9 0x000000000050ab7d in SrsSTCoroutine::pfn (arg=0xb024f0) at src/app/srs_app_st.cpp:213 #10 0x00000000005bed1a in _st_thread_main () at sched.c:337 #11 0x00000000005bf492 in st_thread_create (start=0xab8290, arg=0xab61b0, joinable=0, stk_size=11231648) at sched.c:616 Backtrace stopped: previous frame inner to this frame (corrupt stack?) b SrsForwarder::on_video(SrsSharedPtrMessage*)(gdb) bt #0 SrsForwarder::on_video (this=0xab9e60, shared_video=0xb13080) at src/app/srs_app_forward.cpp:155 #1 0x00000000004e1037 in SrsOriginHub::on_video (this=0xab8000, shared_video=0xb13080, is_sequence_header=true) at src/app/srs_app_source.cpp:1106 #2 0x00000000004e6c59 in SrsSource::on_video_imp (this=0xab7cd0, msg=0xb13080) at src/app/srs_app_source.cpp:2303 #3 0x00000000004e68ad in SrsSource::on_video (this=0xab7cd0, shared_video=0xb28210) at src/app/srs_app_source.cpp:2258 #4 0x00000000004d9c7f in SrsRtmpConn::process_publish_message (this=0xa9be50, source=0xab7cd0, msg=0xb28210) at src/app/srs_app_rtmp_conn.cpp:1021 #5 0x00000000004d9aa6 in SrsRtmpConn::handle_publish_message (this=0xa9be50, source=0xab7cd0, msg=0xb28210) at src/app/srs_app_rtmp_conn.cpp:993 #6 0x0000000000582720 in SrsPublishRecvThread::consume (this=0xab6480, msg=0xb28210) at src/app/srs_app_recv_thread.cpp:389 #7 0x000000000058123e in SrsRecvThread::do_cycle (this=0xab6488) at src/app/srs_app_recv_thread.cpp:146 #8 0x000000000058108f in SrsRecvThread::cycle (this=0xab6488) at src/app/srs_app_recv_thread.cpp:115 #9 0x000000000050ab08 in SrsSTCoroutine::cycle (this=0xb024f0) at src/app/srs_app_st.cpp:198 #10 0x000000000050ab7d in SrsSTCoroutine::pfn (arg=0xb024f0) at src/app/srs_app_st.cpp:213 #11 0x00000000005bed1a in _st_thread_main () at sched.c:337 #12 0x00000000005bf492 in st_thread_create (start=0xab8290, arg=0xab61b0, joinable=0, stk_size=11231648) at sched.c:616 Backtrace stopped: previous frame inner to this frame (corrupt stack?) b SrsForwarder::on_audio(SrsSharedPtrMessage*)(gdb) bt #0 SrsForwarder::on_audio (this=0xab9e60, shared_audio=0xb13090) at src/app/srs_app_forward.cpp:132 #1 0x00000000004e02d9 in SrsOriginHub::on_audio (this=0xab8000, shared_audio=0xb13090) at src/app/srs_app_source.cpp:1013 #2 0x00000000004e644e in SrsSource::on_audio_imp (this=0xab7cd0, msg=0xb13090) at src/app/srs_app_source.cpp:2188 #3 0x00000000004e6051 in SrsSource::on_audio (this=0xab7cd0, shared_audio=0xb28210) at src/app/srs_app_source.cpp:2138 #4 0x00000000004d9c00 in SrsRtmpConn::process_publish_message (this=0xa9be50, source=0xab7cd0, msg=0xb28210) at src/app/srs_app_rtmp_conn.cpp:1014 #5 0x00000000004d9aa6 in SrsRtmpConn::handle_publish_message (this=0xa9be50, source=0xab7cd0, msg=0xb28210) at src/app/srs_app_rtmp_conn.cpp:993 #6 0x0000000000582720 in SrsPublishRecvThread::consume (this=0xab6480, msg=0xb28210) at src/app/srs_app_recv_thread.cpp:389 #7 0x000000000058123e in SrsRecvThread::do_cycle (this=0xab6488) at src/app/srs_app_recv_thread.cpp:146 #8 0x000000000058108f in SrsRecvThread::cycle (this=0xab6488) at src/app/srs_app_recv_thread.cpp:115 #9 0x000000000050ab08 in SrsSTCoroutine::cycle (this=0xb024f0) at src/app/srs_app_st.cpp:198 #10 0x000000000050ab7d in SrsSTCoroutine::pfn (arg=0xb024f0) at src/app/srs_app_st.cpp:213 #11 0x00000000005bed1a in _st_thread_main () at sched.c:337 #12 0x00000000005bf492 in st_thread_create (start=0xab8290, arg=0xab61b0, joinable=0, stk_size=11231648) at sched.c:616 Backtrace stopped: previous frame inner to this frame (corrupt stack?)

SrsForwarder::do_cycle() 完成建聯，推流到slave操作。

主要邏輯在：SrsForwarder::forward()

b SrsForwarder::forward()(gdb) bt #0 SrsForwarder::forward (this=0xab9e60) at src/app/srs_app_forward.cpp:248 #1 0x00000000004f8648 in SrsForwarder::do_cycle (this=0xab9e60) at src/app/srs_app_forward.cpp:237 #2 0x00000000004f7fd7 in SrsForwarder::cycle (this=0xab9e60) at src/app/srs_app_forward.cpp:190 #3 0x000000000050ab08 in SrsSTCoroutine::cycle (this=0xab9c20) at src/app/srs_app_st.cpp:198 #4 0x000000000050ab7d in SrsSTCoroutine::pfn (arg=0xab9c20) at src/app/srs_app_st.cpp:213 #5 0x00000000005bed1a in _st_thread_main () at sched.c:337 #6 0x00000000005bf492 in st_thread_create (start=0xab8290, arg=0xab61b0, joinable=0, stk_size=11231648) at sched.c:616 Backtrace stopped: previous frame inner to this frame (corrupt stack?)

后續會補充更詳細的代碼分析和流程圖，現在先自行根據調用stack看源碼。

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