[PATCH 26/29] lock_ref_for_update(): don't re-read non-symbolic references
From: Michael Haggerty <hidden>
Date: 2016-06-16 02:19:02
Subsystem:
the rest · Maintainer:
Linus Torvalds
Before the previous patch, our first read of the reference happened before the reference was locked, so we couldn't trust its value and had to read it again. But now that our first read of the reference happens after acquiring the lock, there is no need to read it a second time. So move the read_ref_full() call into the (update->type & REF_ISSYMREF) block. Signed-off-by: Michael Haggerty <redacted> --- refs/files-backend.c | 52 ++++++++++++++++++++++++++++++++-------------------- 1 file changed, 32 insertions(+), 20 deletions(-)
diff --git a/refs/files-backend.c b/refs/files-backend.c
index d0e932f..66ceb83 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c@@ -3427,33 +3427,45 @@ static int lock_ref_for_update(struct ref_update *update, lock = update->lock; - if (read_ref_full(update->refname, - mustexist ? RESOLVE_REF_READING : 0, - lock->old_oid.hash, NULL)) { - if (update->flags & REF_HAVE_OLD) { - strbuf_addf(err, "cannot lock ref '%s': can't resolve old value", - update->refname); - return TRANSACTION_GENERIC_ERROR; - } else { - hashclr(lock->old_oid.hash); - } - } - if ((update->flags & REF_HAVE_OLD) && - hashcmp(lock->old_oid.hash, update->old_sha1)) { - strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s", - update->refname, - sha1_to_hex(lock->old_oid.hash), - sha1_to_hex(update->old_sha1)); - return TRANSACTION_GENERIC_ERROR; - } - if (update->type & REF_ISSYMREF) { + if (read_ref_full(update->refname, + mustexist ? RESOLVE_REF_READING : 0, + lock->old_oid.hash, NULL)) { + if (update->flags & REF_HAVE_OLD) { + strbuf_addf(err, "cannot lock ref '%s': can't resolve old value", + update->refname); + return TRANSACTION_GENERIC_ERROR; + } else { + hashclr(lock->old_oid.hash); + } + } + if ((update->flags & REF_HAVE_OLD) && + hashcmp(lock->old_oid.hash, update->old_sha1)) { + strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s", + update->refname, + sha1_to_hex(lock->old_oid.hash), + sha1_to_hex(update->old_sha1)); + return TRANSACTION_GENERIC_ERROR; + } + if (!(update->flags & REF_NODEREF)) { ret = split_symref_update(update, referent.buf, transaction, affected_refnames, err); if (ret) return ret; } + } else if ((update->flags & REF_HAVE_OLD) && + hashcmp(lock->old_oid.hash, update->old_sha1)) { + if (is_null_sha1(update->old_sha1)) + strbuf_addf(err, "cannot lock ref '%s': reference already exists", + update->refname); + else + strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s", + update->refname, + sha1_to_hex(lock->old_oid.hash), + sha1_to_hex(update->old_sha1)); + + return TRANSACTION_GENERIC_ERROR; } if ((update->flags & REF_HAVE_NEW) &&
--
2.8.1