On 09/05, Junio C Hamano wrote:
> Thomas Gummerer <t.gummerer@xxxxxxxxx> writes:
>
> > Getting the lock for the index, refreshing it and then writing it is a
> > pattern that happens more than once throughout the codebase, and isn't
> > trivial to get right. Factor out the refresh_and_write_cache function
> > from builtin/am.c to read-cache.c, so it can be re-used in other
> > places in a subsequent commit.
> >
> > Note that we return different error codes for failing to refresh the
> > cache, and failing to write the index. The current caller only cares
> > about failing to write the index. However for other callers we're
> > going to convert in subsequent patches we will need this distinction.
> >
> > Signed-off-by: Thomas Gummerer <t.gummerer@xxxxxxxxx>
> > ---
> > builtin/am.c | 16 ++--------------
> > cache.h | 16 ++++++++++++++++
> > read-cache.c | 19 +++++++++++++++++++
> > 3 files changed, 37 insertions(+), 14 deletions(-)
>
> I think this goes in the right direction, but obviously conflicts
> with what Dscho wants to do in the builtin-add-i series, and needs
> to be reconciled by working better together.
Oops, I didn't realize there was another series in flight that also
introduces 'repo_refresh_and_write_index'. Probably should have done
a test merge of this with pu.
> For now, I'll eject builtin-add-i and queue this for a few days to
> give it a bit more exposure, but after that requeue builtin-add-i
> and discard these three patches. By that time, hopefully you two
> would have a rerolled version of this one and builtin-add-i that
> agree what kind of refresh-and-write-index behaviour they both want.
>
> The differences I see that need reconciling are:
Thanks for writing these down.
> - builtin-add-i seems to allow 'gentle' and allow returning an
> error when we cannot open the index for writing by passing false
> to 'gentle'; this feature is not used yet, though.
Right, and if gentle is set to false, it avoids writing the index,
which seems fine from my perspective.
> - This version allows to pass pathspec, seen and header_msg, while
> the one in builtin-add-i cannot limit the part of the index
> getting refreshed with pathspec. It wouldn't be a brain surgery
> to use this version and adjust the caller (there only is one) in
> the builtin-add-i topic.
'pathspec', 'seen' and 'header_msg' are not used in my version either,
I just implemented it for completeness and compatibility. So I'd be
fine to do without them.
> - This version does not write the index back when refresh_index()
> returns non-zero, but the one in builtin-add-i ignores the
> returned value. I think, as a performance measure, it probably
> is a better idea to write it back, even when the function returns
> non-zero (the local variable's name is has_errors, but having an
> entry in the index that does not get refreshed is *not* an error;
> e.g. an unmerged entry is a normal thing in the index, and as
> long as we refreshed other entries while having an unmerged and
> unrefreshable entry, we are making progress that is worth writing
> out).
I'm happy with writing the index back even if there are errors.
However I think we still need the option to get the return code from
'refresh_index()', as some callers where I'm using
'refresh_and_write_index()' in this series behave differently
depending on its return code.
There's two more differences between the versions:
- The version in my series allows passing in write_flags to be passed
to write_locked_index, which is required to convert the callers in
builtin/merge.c.
- Dscho's version also calls 'repo_read_index_preload()', which I
don't do in mine. Some callers don't need to do that, so I think it
would be nice to keep that outside of the
'repo_refresh_and_write_index()' function.
I can think of a few ways forward here:
- I incorporate features that are needed for the builtin-add-i series
here, and that is rebased on top of this series.
- We drop the first two patches of this series, so we only fix the
problems in 'git stash' for now. Later we can have a refactoring
series that uses repo_refresh_and_write_index in the places we
converted here, once the dust of the builtin-add-i series settled.
- I rebase this on top of builtin-add-i.
I'm happy with either of the first two, but less so with the last
option. I was hoping this series could potentially go to maint as it
was a bugfix, which we obviously can't do with that option.
Dscho, what do you think? :)
> Thanks.
>
> > +int repo_refresh_and_write_index(struct repository *repo,
> > + unsigned int refresh_flags,
> > + unsigned int write_flags,
> > + const struct pathspec *pathspec,
> > + char *seen, const char *header_msg)
> > +{
> > + struct lock_file lock_file = LOCK_INIT;
> > +
> > + repo_hold_locked_index(repo, &lock_file, LOCK_DIE_ON_ERROR);
> > + if (refresh_index(repo->index, refresh_flags, pathspec, seen, header_msg)) {
> > + rollback_lock_file(&lock_file);
> > + return 1;
> > + }
> > + if (write_locked_index(repo->index, &lock_file, COMMIT_LOCK | write_flags))
> > + return -1;
> > + return 0;
> > +}
> > +
> > +
> > int refresh_index(struct index_state *istate, unsigned int flags,
> > const struct pathspec *pathspec,
> > char *seen, const char *header_msg)
