view tests/test-dirstate-race.t @ 29352:37c7f9fb7040

localrepo: make restoring from backup at rollback avoid ambiguity of file stat

Rollback of previous transaction restores contents of files below by
renaming from 'undo.*' file. If renaming keeps ctime, mtime and size
of a file, restoring is overlooked, and old contents cached before
restoring isn't invalidated as expected.

  - .hg/bookmarks
  - .hg/phaseroots

To avoid ambiguity of file stat at restoring, this patch invokes
vfs.rename() with checkambig=True.

BTW, .hg/dirstate is also restored at rollback. But it is restored by
dirstate.restorebackup(), and previous patch already made it invoke
vfs.rename() with checkambig=True.

This patch is a part of "Exact Cache Validation Plan":

    https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan

  $ hg init
  $ echo a > a
  $ hg add a
  $ hg commit -m test

Do we ever miss a sub-second change?:

  $ for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; do
  >     hg co -qC 0
  >     echo b > a
  >     hg st
  > done
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a
  M a