changelog: specify checkambig=True to avoid ambiguity around truncation If steps below occurs at "the same time in sec", all of mtime, ctime and size are same between (1) and (3). 1. append data to 00changelog.i (and close transaction) 2. discard appended data by truncation (strip or rollback) 3. append same size but different data to 00changelog.i again Therefore, cache validation doesn't work after (3) as expected. To avoid such file stat ambiguity around truncation, this patch specifies checkambig=True for renaming or opening to write changes out at finalization. Even after this patch, avoiding file stat ambiguity of 00changelog.i around truncation isn't yet completed, because truncation side isn't aware of this issue. This is a part of ExactCacheValidationPlan. https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan

manifest: specify checkambig=True to revlog.__init__, to avoid ambiguity If steps below occurs at "the same time in sec", all of mtime, ctime and size are same between (1) and (3). 1. append data to 00manifest.i (and close transaction) 2. discard appended data by truncation (strip or rollback) 3. append same size but different data to 00manifest.i again Therefore, cache validation doesn't work after (3) as expected. To avoid such file stat ambiguity around truncation, this patch specifies checkambig=True to revlog.__init__(). This makes revlog write changes out with checkambig=True. Even after this patch, avoiding file stat ambiguity of 00manifest.i around truncation isn't yet completed, because truncation side isn't aware of this issue. This is a part of ExactCacheValidationPlan. https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan