The heartbeat of SRS is a timer that requests an HTTP URL. We can use
this heartbeat to report the necessary information for registering the
backend server with the proxy server.
```text
SRS(backend) --heartbeat---> Proxy server
```
A proxy server is a specialized load balancer for media servers. It
operates at the application level rather than the TCP level. For more
information about the proxy server, see issue #4158.
Note that we will merge this PR into SRS 5.0+, allowing the use of SRS
5.0+ as the backend server, not limited to SRS 7.0. However, the proxy
server is introduced in SRS 7.0.
It's also possible to implement a registration service, allowing you to
use other media servers as backend servers. For example, if you gather
information about an nginx-rtmp server and register it with the proxy
server, the proxy will forward RTMP streams to nginx-rtmp. The backend
server is not limited to SRS.
---------
Co-authored-by: Jacob Su <suzp1984@gmail.com>
on_hls and hls_dispose are two coroutines, with potential race
conditions. That is, during on_hls, if the API Server being accessed is
slower, it will switch to the hls_dispose coroutine to start cleaning
up. However, when the API Server is processing the slice, a situation
may occur where the slice does not exist, resulting in the following
log:
```
[2023-08-22 12:03:20.309][WARN][40][x5l48q7b][11] ignore task failed code=4005(HttpStatus)(Invalid HTTP status code) : callback on_hls http://localhost:2024/terraform/v1/hooks/srs/hls : http: post http://localhost:2024/terraform/v1/hooks/srs/hls with {"server_id":"vid-5d7dxn8","service_id":"cu153o7g","action":"on_hls","client_id":"x5l48q7b","ip":"172.17.0.1","vhost":"__defaultVhost__","app":"live","tcUrl":"srt://172.17.0.2/live","stream":"stream-44572-2739617660809856576","param":"secret=1ed8e0ffbc53439c8fc8da30ab8c19f0","duration":4.57,"cwd":"/usr/local/srs-stack/platform","file":"./objs/nginx/html/live/stream-44572-2739617660809856576-1.ts","url":"live/stream-44572-2739617660809856576-1.ts","m3u8":"./objs/nginx/html/live/stream-44572-2739617660809856576.m3u8","m3u8_url":"live/stream-44572-2739617660809856576.m3u8","seq_no":1,"stream_url":"/live/stream-44572-2739617660809856576","stream_id":"vid-0n9zoz3"}, status=500, res=invalid ts file ./objs/nginx/html/live/stream-44572-2739617660809856576-1.ts: stat ./objs/nginx/html/live/stream-44572-2739617660809856576-1.ts: no such file or directory
thread [40][x5l48q7b]: call() [./src/app/srs_app_hls.cpp:122][errno=11]
thread [40][x5l48q7b]: on_hls() [./src/app/srs_app_http_hooks.cpp:401][errno=11]
thread [40][x5l48q7b]: do_post() [./src/app/srs_app_http_hooks.cpp:638][errno=11]
[error] 2023/08/22 12:03:20.076984 [52][1001] Serve /terraform/v1/hooks/srs/hls failed, err is stat ./objs/nginx/html/live/stream-44572-2739617660809856576-1.ts: no such file or directory
invalid ts file ./objs/nginx/html/live/stream-44572-2739617660809856576-1.ts
main.handleOnHls.func1.1
/g/platform/srs-hooks.go:684
main.handleOnHls.func1
/g/platform/srs-hooks.go:720
net/http.HandlerFunc.ServeHTTP
/usr/local/go/src/net/http/server.go:2084
net/http.(*ServeMux).ServeHTTP
/usr/local/go/src/net/http/server.go:2462
net/http.serverHandler.ServeHTTP
/usr/local/go/src/net/http/server.go:2916
net/http.(*conn).serve
/usr/local/go/src/net/http/server.go:1966
runtime.goexit
/usr/local/go/src/runtime/asm_amd64.s:1571
```
Similarly, when stopping the stream, on_hls will also be called to
handle the last slice. If the API Server is slower at this time, it will
enter hls_dispose and call unpublish repeatedly. Since the previous
unpublish is still blocked in on_hls, the following interference log
will appear:
```
[2023-08-22 12:03:18.748][INFO][40][6498088c] hls cycle to dispose hls /live/stream-44572-2739617660809856576, timeout=10000000ms
[2023-08-22 12:03:18.752][WARN][40][6498088c][115] flush audio ignored, for segment is not open.
[2023-08-22 12:03:18.752][WARN][40][6498088c][115] ignore the segment close, for segment is not open.
```
Although this log will not cause problems, it can interfere with
judgment.
The solution is to add an 'unpublishing' status. If it is in the
'unpublishing' status, then do not clean up the slices.
---------
Co-authored-by: Haibo Chen <495810242@qq.com>
1. Ignore audo or video packets if FLV header disable it.
2. Run: Add regression test config and run for IDEA.
3. Test: Refine regression test to allow no audio/video for FLV
4. Config: Whether drop packet if not match header.
* explicitly enable nack, for firefox (#2373)
* For #2371: Add regression test for SDP nack
1. Refine API to change defaule decodes.
2. Add test for publish SDP nack.
3. Add test for play SDP nack.
Co-authored-by: Haibo Chen <495810242@qq.com>
