[all-commits] [llvm/llvm-project] b6087b: Disable LLDB index cache for .o files with no UUID.

[Greg Clayton via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: b6087ba769c612c031b84e6673c438fe44a46c6a
      https://github.com/llvm/llvm-project/commit/b6087ba769c612c031b84e6673c438fe44a46c6a
  Author: Greg Clayton <gclayton at fb.com>
  Date:   2022-04-05 (Tue, 05 Apr 2022)

  Changed paths:
    M lldb/include/lldb/Core/DataFileCache.h
    M lldb/source/Core/DataFileCache.cpp
    M lldb/test/API/functionalities/module_cache/bsd/TestModuleCacheBSD.py
    M lldb/unittests/SymbolFile/DWARF/DWARFIndexCachingTest.cpp

  Log Message:
  -----------
  Disable LLDB index cache for .o files with no UUID.

After enabling the LLDB index cache in production we discovered that some distributed build systems play with the modification times of any .o files that were downloaded from the build cache. This was causing the LLDB index cache to read the wrong cache file for files that didn't have a UUID as all of the modfication times were set to the same value by the build system. When new .o files were downloaded, the only unique identifier was the mod time which were all the same, and we would load an older cache for the updated .o file. So disabling caching of files that have no UUIDs for now until we can create a more solid solution.

Differential Revision: https://reviews.llvm.org/D120948