[PATCH v3 3/3] refs.c: change ref_transaction_commit to run the commit loops once all work is finished
From: Ronnie Sahlberg <hidden>
Date: 2016-06-15 23:00:41
Subsystem:
the rest · Maintainer:
Linus Torvalds
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 <redacted>
---
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