[core] Fixed broadcast group: cut failed links on partial sending success

[ethouris]

(TRIAL FIX #2959)

This changes the following:

1. In case when sending failed over several links, waiting for unblocking any socket is done only if:
   • in blocking mode
   • no socket has succeeded
2. If at least one link succeeded, but there are any failed, failed links are immediately set closed.

[maxsharabayko]

Seems ok except for those spurious read-ready events on the receiver side. But that's probably another story.

.\bin\Debug\srt-xtransmit.exe receive srt://:4200?groupconnect=1 -v --enable-metrics
10:20:39.732274 [I] SOCKET::SRT srt://:4200: bound to ':4200'.
10:20:39.734158 [D] SOCKET::SRT @925860786 (srt://:4200) Listening
10:20:39.734545 [D] SOCKET::SRT @925860786 (srt://:4200) ASYNC Waiting for incoming connection
10:21:17.811396 [D] SOCKET::SRT @925860786 (srt://:4200) 1 ready, [0]: 0x372F83B2
10:21:17.812261 [E] SOCKET::SRT Failed to get sockopt SRTO_PBKEYLEN.
10:21:17.812594 [E] SOCKET::SRT Failed to get sockopt SRTO_KMSTATE.
10:21:17.812835 [I] SOCKET::SRT @925860786 (srt://:4200) Accepted connection @1999602608. TSBPD Latency RCV 120ms, peer 0ms. KM state INVALID (RCV UNSECURED, SND UNSECURED). PB key length: -1. Cryptomode . Stream ID: not set.
10:21:17.813983 [I] RECEIVE Latency, us: avg n/a, min n/a, max n/a. Jitter: 0us. Delay Factor: 1us. Pkts: rcvd 0, reordered 0 (dist 0), lost 0, MD5 err 0, bad len 0.
10:21:18.828574 [I] RECEIVE Latency, us: avg n/a, min n/a, max n/a. Jitter: 0us. Delay Factor: 1us. Pkts: rcvd 0, reordered 0 (dist 0), lost 0, MD5 err 0, bad len 0.
10:21:19.816634 [I] RECEIVE Latency, us: avg n/a, min n/a, max n/a. Jitter: 0us. Delay Factor: 1us. Pkts: rcvd 0, reordered 0 (dist 0), lost 0, MD5 err 0, bad len 0.
10:21:20.829061 [I] RECEIVE Latency, us: avg n/a, min n/a, max n/a. Jitter: 0us. Delay Factor: 1us. Pkts: rcvd 0, reordered 0 (dist 0), lost 0, MD5 err 0, bad len 0.
10:21:21.822977 [I] RECEIVE Latency, us: avg n/a, min n/a, max n/a. Jitter: 0us. Delay Factor: 1us. Pkts: rcvd 0, reordered 0 (dist 0), lost 0, MD5 err 0, bad len 0.
10:21:22.820212 [I] RECEIVE Latency, us: avg n/a, min n/a, max n/a. Jitter: 0us. Delay Factor: 1us. Pkts: rcvd 0, reordered 0 (dist 0), lost 0, MD5 err 0, bad len 0.
10:21:23.823979 [I] RECEIVE Latency, us: avg n/a, min n/a, max n/a. Jitter: 0us. Delay Factor: 1us. Pkts: rcvd 0, reordered 0 (dist 0), lost 0, MD5 err 0, bad len 0.
10:21:24.815954 [I] RECEIVE Latency, us: avg 6006706, min 6000395, max 6045259. Jitter: 258us. Delay Factor: 44863us. Pkts: rcvd 4682, reordered 0 (dist 0), lost 0, MD5 err 0, bad len 0.
10:21:25.822615 [I] RECEIVE Latency, us: avg 6000625, min 6000392, max 6037859. Jitter: 16us. Delay Factor: 37468us. Pkts: rcvd 9462, reordered 0 (dist 0), lost 0, MD5 err 0, bad len 0.
10:21:26.816404 [I] RECEIVE Latency, us: avg 6001145, min 6000385, max 6040801. Jitter: 18us. Delay Factor: 40414us. Pkts: rcvd 14211, reordered 0 (dist 0), lost 0, MD5 err 0, bad len 0.
10:21:27.830086 [I] RECEIVE Latency, us: avg 6005729, min 6000553, max 6029325. Jitter: 69us. Delay Factor: 28772us. Pkts: rcvd 16384, reordered 0 (dist 0), lost 0, MD5 err 0, bad len 0.
10:21:28.822305 [I] RECEIVE Latency, us: avg 6005729, min n/a, max n/a. Jitter: 69us. Delay Factor: 1us. Pkts: rcvd 16384, reordered 0 (dist 0), lost 0, MD5 err 0, bad len 0.
10:21:29.825920 [I] RECEIVE Latency, us: avg 6005729, min n/a, max n/a. Jitter: 69us. Delay Factor: 1us. Pkts: rcvd 16384, reordered 0 (dist 0), lost 0, MD5 err 0, bad len 0.
10:21:29.872775 [W] [METRICS] Detected loss of 1 packets (seqno [16384; 16385))
10:21:29.910663 [T] SOCKET::SRT recvmsg error 6002: try again (spurious read-ready)
10:21:29.911362 [D] RECEIVE sock::read() returned 0 bytes (spurious read ready?). Retrying.
...
10:21:32.154375 [T] SOCKET::SRT recvmsg error 6002: try again (spurious read-ready)
10:21:32.154744 [D] RECEIVE sock::read() returned 0 bytes (spurious read ready?). Retrying.
10:21:32.155000/T20216*E:SRT.gr: grp/recv: $1999602608: ABANDONING: opened=false connected=false
10:21:32.155728 [D] SOCKET::SRT @1999602608 read::recv ERROR 2002 Connection does not exist
10:21:32.156090 [W] RECEIVE read::recv: Connection does not exist
10:21:32.819594 [D] SOCKET::SRT @1999602608 Releasing epolls before closing
10:21:32.820582 [D] SOCKET::SRT @1999602608 Closing
10:21:32.821167 [D] SOCKET::SRT @925860786 Releasing epolls before closing
10:21:32.821597 [D] SOCKET::SRT @925860786 Closing

srt-xtransmit generate "srt://127.0.0.1:4200?grouptype=broadcast&latency=6000" srt://127.0.0.1:4200 --sendrate 50Mbps -v --enable-metrics --duration 10s

10:21:17.805486 [T] SOCKET::SRT_GROUP Creating a group of callers (type broadcast).
10:21:17.807184 [D] SOCKET::SRT_GROUP @1371969989 SYNC Connecting group to remote SRT
10:21:17.807560 [D] SOCKET::SRT_GROUP srt_connect_group
10:21:17.812131 [E] SOCKET::SRT Failed to get sockopt SRTO_PBKEYLEN.
10:21:17.812388 [E] SOCKET::SRT Failed to get sockopt SRTO_KMSTATE.
10:21:17.812629 [D] SOCKET::SRT_GROUP @1371969989 SYNC Group member connected to remote. TSBPD off. KM state INVALID (RCV UNSECURED, SND UNSECURED). PB key length: -1. Cryptomode . Stream ID: not set.
10:21:17.812837 [I] PACER sendrate 50000000 bps (inter send interval 210 us)
10:21:18.813068 [I] GENERATE Sending at 49292 kbps
10:21:19.813062 [I] GENERATE Sending at 49902 kbps
10:21:20.813628 [I] GENERATE Sending at 50418 kbps
10:21:23.865177 [I] GENERATE Sending at 7494 kbps
10:21:24.865174 [I] GENERATE Sending at 51239 kbps
10:21:25.865933 [I] GENERATE Sending at 48312 kbps
10:21:26.865922 [I] GENERATE Sending at 51724 kbps
10:21:29.903925 [I] GENERATE Sending at 6986 kbps
10:21:29.904982 [D] SOCKET::SRT_GROUP @1371969989 Closing SRT group

[ethouris]

I would apply the changes from #2527 on the receiver side and see if it still holds.