Ronnie Sahlberg <sahlb...@google.com> writes:
> We want to make sure that we update all refs before we delete any refs
> so that there is no point in time where the tips may not be reachable
> from any ref in the system.
> We currently acheive this by first looping over all updates and applying
> them before we run a second loop and perform all the deletes.
>
> If we sort the new sha1 for all the refs so that a deleted ref,
> with sha1 0{40} comes at the end of the array, then we can just run
> a single loop and still guarantee that all updates happen before
> any deletes.
>
> Signed-off-by: Ronnie Sahlberg <sahlb...@google.com>
> ---
> refs.c | 18 +++++++++++-------
> 1 file changed, 11 insertions(+), 7 deletions(-)
>
> diff --git a/refs.c b/refs.c
> index 1678e12..453318e 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -3309,6 +3309,15 @@ static int ref_update_compare(const void *r1, const
> void *r2)
> return strcmp((*u1)->ref_name, (*u2)->ref_name);
> }
>
> +static int ref_delete_compare(const void *r1, const void *r2)
> +{
> + const struct ref_update * const *u1 = r1;
> + const struct ref_update * const *u2 = r2;
> +
> + /* -strcmp so that 0{40} sorts to the end */
> + return -strcmp((*u1)->new_sha1, (*u2)->new_sha1);
Two glitches:
- Didn't you mean hashcmp()?
- Don't you have an explicit ->delete_ref field that is a more
direct way, than relying on the convention "updating to 0{40}
is to delte", to express this?
In other words, wouldn't it be more like
return !(*u1)->delete_ref - !(*u2)->delete_ref;
or something (I may be wrong about the sign, tho---I didn't think
carefully)?
> +}
> +
> static int ref_update_reject_duplicates(struct ref_update **updates, int n,
> enum action_on_err onerr)
> {
> @@ -3388,13 +3397,8 @@ int update_refs(const char *action, const struct
> ref_update **updates_orig,
> unlink_or_warn(git_path("logs/%s", delnames[i]));
> clear_loose_ref_cache(&ref_cache);
>
> - /* Perform updates first so live commits remain referenced */
> - for (i = 0; i < n; i++)
> - if (locks[i] && !locks[i]->delete_ref) {
> - ret |= commit_ref_lock(locks[i]);
> - locks[i] = NULL;
> - }
> - /* And finally perform all deletes */
> + /* Sort the array so that we perform all updates before any deletes */
> + qsort(updates, n, sizeof(*updates), ref_delete_compare);
> for (i = 0; i < n; i++)
> if (locks[i]) {
> ret |= commit_ref_lock(locks[i]);
--
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