During a transaction commit we will both update and delete refs.
Since both update and delete now use the same pattern
lock = lock_ref_sha1_basic() (or varient of)
write_ref_sha1(lock)/delete_ref_loose(lock)
unlock_ref(lock) | commit_ref_lock(lock)
we can now simplify ref_transaction_commit to have one loop that locks all
involved refs.
A second loop that writes or flags for deletion, but does not commit, all
the refs.
And a final third loop that commits all the refs once all the work and
preparations are complete.
This makes updating/deleting multiple refs more atomic since we will not start
the commit phase until all the preparations have completed successfully.
Signed-off-by: Ronnie Sahlberg <sahlb...@google.com>
---
refs.c | 39 ++++++++++++++++++++++-----------------
1 file changed, 22 insertions(+), 17 deletions(-)
diff --git a/refs.c b/refs.c
index ec104f2..293bb43 100644
--- a/refs.c
+++ b/refs.c
@@ -3468,42 +3468,47 @@ int ref_transaction_commit(struct ref_transaction
*transaction,
}
}
- /* Perform updates first so live commits remain referenced */
+ /* Prepare all the updates/deletes */
for (i = 0; i < n; i++) {
struct ref_update *update = updates[i];
- if (!is_null_sha1(update->new_sha1)) {
+ if (!is_null_sha1(update->new_sha1))
ret = update_ref_write(msg,
update->refname,
update->new_sha1,
update->lock, onerr);
- if (ret)
- unlock_ref(update->lock);
- else
- commit_ref_lock(update->lock);
- update->lock = NULL;
- if (ret)
- goto cleanup;
+ else {
+ delnames[delnum++] = update->refname;
+ ret = delete_ref_loose(update->lock, update->type);
}
+ if (ret)
+ goto cleanup;
}
- /* Perform deletes now that updates are safely completed */
+ ret |= repack_without_refs(delnames, delnum);
+ for (i = 0; i < delnum; i++)
+ 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++) {
+ struct ref_update *update = updates[i];
+
+ if (update->lock && !update->lock->delete_ref) {
+ ret |= commit_ref_lock(update->lock);
+ update->lock = NULL;
+ }
+ }
+ /* And finally perform all deletes */
for (i = 0; i < n; i++) {
struct ref_update *update = updates[i];
if (update->lock) {
- delnames[delnum++] = update->refname;
- ret |= delete_ref_loose(update->lock, update->type);
ret |= commit_ref_lock(update->lock);
update->lock = NULL;
}
}
- ret |= repack_without_refs(delnames, delnum);
- for (i = 0; i < delnum; i++)
- unlink_or_warn(git_path("logs/%s", delnames[i]));
- clear_loose_ref_cache(&ref_cache);
-
cleanup:
for (i = 0; i < n; i++)
if (updates[i]->lock)
--
1.9.1.505.g4f1e74f
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