[all-commits] [llvm/llvm-project] 127a14: [clangd] Add command-line flag to set background i...

[Sam McCall via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 127a1492d72902e2b2cd8905c1198743761f52fb
      https://github.com/llvm/llvm-project/commit/127a1492d72902e2b2cd8905c1198743761f52fb
  Author: Sam McCall <sam.mccall at gmail.com>
  Date:   2022-05-17 (Tue, 17 May 2022)

  Changed paths:
    M clang-tools-extra/clangd/ClangdServer.h
    M clang-tools-extra/clangd/index/Background.cpp
    M clang-tools-extra/clangd/index/Background.h
    M clang-tools-extra/clangd/tool/ClangdMain.cpp

  Log Message:
  -----------
  [clangd] Add command-line flag to set background indexing thread priority.

This is a followup to D124715, which changed the default, and it anticipates
future patches raising the priority of Low (which is currently equal to
Background on Windows & Linux).
The main point is to allow users to restore the old behavior, which e.g.
allows efficiency cores to remain idle.

I did consider making this a config setting, this is a more complicated change:
 - needs to touch queue priorities as well as thread priorities
 - we don't know the priority until evaluating the config inside the task
 - users would want the ability to prioritize background indexing tasks relative
   to each other without necessarily affecting thread priority, so using one
   option for both may be confusing
I don't really have a use case, so I prefer the simpler thing.

Differential Revision: https://reviews.llvm.org/D125673