[songgaoye]

What problem does this PR solve?

Issue Number: resolve

Problem Summary:

• bthread_id accesses butex state words as plain uint32_t values even though butex manages them as atomic state. Concurrent bthread_id_join() and bthread_id_unlock_and_destroy() can therefore form a C++ data race.
  What is changed and the side effects?

Changed:

• Store ID butex state as butil::atomic.
• Centralize atomic version-word access helpers.
• Add a concurrent join/destroy regression test.

Side effects:

• Performance effects:

• Breaking backward compatibility:

---

Check List:

• Please make sure your changes are compilable.
• When providing us with a new feature, it is best to add related tests.
• Please follow Contributor Covenant Code of Conduct.

[songgaoye]

run tsan on master branch.

WARNING: ThreadSanitizer: data race (pid=552747)
  Write of size 4 at 0x729400000040 by main thread:
    #0 bthread_id_unlock_and_destroy
       /home/ysg/Github/brpc-tsan-join-destroy/src/bthread/id.cpp:630:17
    #1 (anonymous namespace)::BthreadIdTest_join_races_with_destroy_Test::TestBody()
       /home/ysg/Github/brpc-tsan-join-destroy/test/bthread_id_unittest.cpp:142:9
    #2 testing::Test::Run()
    #3 testing::TestInfo::Run()
    #4 testing::TestSuite::Run()
    #5 testing::internal::UnitTestImpl::RunAllTests()
    #6 testing::UnitTest::Run()
    #7 RUN_ALL_TESTS()
    #8 main

  Previous atomic read of size 4 at 0x729400000040 by thread T2:
    #0 std::__atomic_base<int>::load(std::memory_order) const
       /usr/include/c++/13/bits/atomic_base.h:505:9
    #1 bthread::butex_wait(void*, int, timespec const*, bool)
       /home/ysg/Github/brpc-tsan-join-destroy/src/bthread/butex.cpp:755:18
    #2 bthread_id_join
       /home/ysg/Github/brpc-tsan-join-destroy/src/bthread/id.cpp:530:13
    #3 (anonymous namespace)::join_race_waiter(void*)
       /home/ysg/Github/brpc-tsan-join-destroy/test/bthread_id_unittest.cpp:124:5

  Thread T2 (tid=552759, running) created by main thread at:
    #0 pthread_create
    #1 (anonymous namespace)::BthreadIdTest_join_races_with_destroy_Test::TestBody()
       /home/ysg/Github/brpc-tsan-join-destroy/test/bthread_id_unittest.cpp:136:9

[darion-yaphet]

Thanks for the follow-up.

The new join_races_with_destroy test addresses my earlier concern: the waiter now signals only after the join path has already loaded join_butex, and destroy runs before butex_wait, so the race window is the reported.

From the bthread id / butex side this LGTM. CI is green on this head; approving.