Kjetil Barvik <barvik@xxxxxxxxxxxx> writes:
> Junio C Hamano <gitster@xxxxxxxxx> writes:
>
>>> + ce->ce_ctime.sec = (unsigned int)st->st_ctime;
>>> + ce->ce_mtime.sec = (unsigned int)st->st_mtime;
>>> +#ifdef USE_NSEC
>>> + ce->ce_ctime.nsec = (unsigned int)st->st_ctim.tv_nsec;
>>> + ce->ce_mtime.nsec = (unsigned int)st->st_mtim.tv_nsec;
>>> +#else
>>> + ce->ce_ctime.nsec = 0;
>>> + ce->ce_mtime.nsec = 0;
>>> +#endif
>>
>> How does this affect a use case where the same index file used with two
>> instances of git (one compiled with and another without USE_NSEC)?
>
> OK, I admit that I was thinking safe here,...
It was not a veiled objection in the guise of a rhetoric question. I just
wanted to know what happens, when you have "/usr/bin/git" compiled without
NSEC and "/usr/local/bin/git" compiled with NSEC, and tried to use the two
interchangeably. A NSEC enabled one will leave nsec in the index entry,
and the normal one reads from the index file (truncating the nsec from
both file timestamp and on-disk index entries), and it is unclear what it
does to the racy-git algorithm. If there is no adverse effect, that is
great. Otherwise, even though the on-disk format might be compatible, we
need to somehow tell people not to use two gits on the same index file.
>>> diff --git a/unpack-trees.c b/unpack-trees.c
>>> index e547282..44714cc 100644
>>> --- a/unpack-trees.c
>>> +++ b/unpack-trees.c
>>> @@ -380,8 +380,12 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
>>>
>>> memset(&o->result, 0, sizeof(o->result));
>>> o->result.initialized = 1;
>>> - if (o->src_index)
>>> - o->result.timestamp = o->src_index->timestamp;
>>> + if (o->src_index) {
>>> + o->result.timestamp.sec = o->src_index->timestamp.sec;
>>> +#ifdef USE_NSEC
>>> + o->result.timestamp.nsec = o->src_index->timestamp.nsec;
>>> +#endif
>>> + }
>>
>> Do we need this hunk?
>
> Since timestamp is now a 'struct cache_time' member, I converted the
> usage of this if-test to be in line with the USE_NSEC usage.
My question was if it is wrong to leave this as "a->timestamp = b->timestamp"
which now becomes structure assignment. You would need to move extra 4
(or 8) bytes if you are not using NSEC, but this is not per index entry
but one assignment for the whole index file, so...
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