[all-commits] [llvm/llvm-project] 3cd13c: Fix a race between lldb's packet timeout and the p...

[jimingham via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 3cd13c4624b5900c884b691b72d0ca053433f6fe
      https://github.com/llvm/llvm-project/commit/3cd13c4624b5900c884b691b72d0ca053433f6fe
  Author: Jim Ingham <jingham at apple.com>
  Date:   2020-02-25 (Tue, 25 Feb 2020)

  Changed paths:
    A lldb/test/API/macosx/profile_vrs_detach/Makefile
    A lldb/test/API/macosx/profile_vrs_detach/TestDetachVrsProfile.py
    A lldb/test/API/macosx/profile_vrs_detach/main.c
    M lldb/tools/debugserver/source/MacOSX/MachProcess.h
    M lldb/tools/debugserver/source/MacOSX/MachProcess.mm

  Log Message:
  -----------
  Fix a race between lldb's packet timeout and the profile thread's usleep.

The debugserver profile thread used to suspend itself between samples with
a usleep.  When you detach or kill, MachProcess::Clear would delay replying
to the incoming packet until pthread_join of the profile thread returned.
If you are unlucky or the suspend delay is long, it could take longer than
the packet timeout for pthread_join to return.  Then you would get an error
about detach not succeeding from lldb - even though in fact the detach was
successful...

I replaced the usleep with PThreadEvents entity.  Then we just call a timed
WaitForEventBits, and when debugserver wants to stop the profile thread, it
can set the event bit, and the sleep will exit immediately.

Differential Revision: https://reviews.llvm.org/D75004