[REFAX] Refactored function calls at close socket for preparing a change

[ethouris]

No description provided.

[maxsharabayko]

Extracted from #1829.

[ethouris]

Careful. This last fix has caused tests to crash.

[ethouris]

Now the refax should be ok, but all attempts to provide a reliable closing a socket have failed, so this refax is useless.

[maxsharabayko]

I am concerned with this function because it provides not much hints of what it does internally.
It notably comes from the overall mess with socket lifetime management.

There is m_ClosedSockets for sockets to be closed and m_Sockets for active sockets.
A socket can sometimes be present in both lists for a short time.
swipeSocket_LOCKED(i->first, s, SWIPE_LATER) with SWIPE_LATER is only used in checkBrokenSockets(..). All other places use SWIPE_NOW. Does it make sense to have a function that does both?

newConnection error, srt_close, removeSocket -> SWIPE_NOW.
checkBrokenSockets(..), srt_cleanup -> SWIPE_LATER.

[ethouris]

The SWIPE_NOW and SWIPE_LATER differ only with that when SWIPE_LATER is used, then the call will be followed by a loop that will delete all sockets that were collected in the temporary list. So the socket being worked about at this call need not be swiped at this moment.

[codecov]

Codecov Report

Attention: Patch coverage is 86.66667% with 2 lines in your changes missing coverage. Please review.

Project coverage is 70.02%. Comparing base (53a09f3) to head (a1b84c7).
Report is 263 commits behind head on dev.

Files with missing lines	Patch %	Lines
srtcore/api.cpp	86.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #2639      +/-   ##
==========================================
+ Coverage   69.38%   70.02%   +0.64%     
==========================================
  Files         101      101              
  Lines       18729    19522     +793     
==========================================
+ Hits        12995    13671     +676     
- Misses       5734     5851     +117     

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[ethouris]

Crash found (address sanitizer):

==9685==ERROR: AddressSanitizer: heap-use-after-free on address 0x52800001a6f8 at pc 0x0000007f4c7e bp 0x7f0404dfb960 sp 0x7f0404dfb958
WRITE of size 1 at 0x52800001a6f8 thread T1
    #0 0x7f4c7d in std::__atomic_base<bool>::store(bool, std::memory_order) /usr/include/c++/14/bits/atomic_base.h:477
    #1 0x7f4c7d in std::atomic<bool>::store(bool, std::memory_order) /usr/include/c++/14/atomic:109
    #2 0x7f4c7d in srt::sync::atomic<bool>::store(bool) /home/sektor/repos/srt.gitd/main/srtcore/atomic.h:243
    #3 0x7f4c7d in srt::CUnitQueue::makeUnitFree(srt::CUnit*) /home/sektor/repos/srt.gitd/main/srtcore/queue.cpp:192
    #4 0x5e8fd8 in srt::CRcvBuffer::~CRcvBuffer() /home/sektor/repos/srt.gitd/main/srtcore/buffer_rcv.cpp:132
    #5 0x62c86c in srt::CUDT::~CUDT() /home/sektor/repos/srt.gitd/main/srtcore/core.cpp:395
    #6 0x58280e in srt::CUDTUnited::removeSocket(int) /home/sektor/repos/srt.gitd/main/srtcore/api.cpp:3264
    #7 0x599f55 in srt::CUDTUnited::checkBrokenSockets() /home/sektor/repos/srt.gitd/main/srtcore/api.cpp:3155
    #8 0x5a0132 in srt::CUDTUnited::garbageCollect(void*) /home/sektor/repos/srt.gitd/main/srtcore/api.cpp:3802
    #9 0x7f0408330ff5  (/usr/lib64/libasan.so.8+0x5eff5) (BuildId: 4ee117fa2a132af1da9f17a0a5fe1f888398d50f)
    #10 0x7f0407ed46e9 in start_thread (/lib64/libpthread.so.0+0xa6e9) (BuildId: 938e42b7e407d175ee3ef9a89c038168101d330c)
    #11 0x7f0407a1258e in clone (/lib64/libc.so.6+0x11858e) (BuildId: 74f77bf013a66413c77197c121955e029c32d259)

0x52800001a6f8 is located 9720 bytes inside of 15368-byte region [0x528000018100,0x52800001bd08)
freed by thread T1 here:
    #0 0x7f04083cae08 in operator delete[](void*, unsigned long) (/usr/lib64/libasan.so.8+0xf8e08) (BuildId: 4ee117fa2a132af1da9f17a0a5fe1f888398d50f)
    #1 0x7f3274 in srt::CUnitQueue::~CUnitQueue() /home/sektor/repos/srt.gitd/main/srtcore/queue.cpp:92

previously allocated by thread T0 (srt-live-transm) here:
    #0 0x7f04083c9f38 in operator new[](unsigned long) (/usr/lib64/libasan.so.8+0xf7f38) (BuildId: 4ee117fa2a132af1da9f17a0a5fe1f888398d50f)
    #1 0x7f34d6 in srt::CUnitQueue::allocateEntry(int, int) /home/sektor/repos/srt.gitd/main/srtcore/queue.cpp:113

Thread T1 created by T0 (srt-live-transm) here:
    #0 0x7f04083c1191 in pthread_create (/usr/lib64/libasan.so.8+0xef191) (BuildId: 4ee117fa2a132af1da9f17a0a5fe1f888398d50f)
    #1 0x8fd4b4 in srt::sync::CThread::create(void* (*)(void*), void*) /home/sektor/repos/srt.gitd/main/srtcore/sync_posix.cpp:436

[ethouris]

Seems like all previous problems have been solved. Clearing draft state.