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lock_ref_for_update(): don't re-read non-symbolic references

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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 <mhagger@alum.mit.edu>
This commit is contained in:
Michael Haggerty 2016-04-25 17:38:35 +02:00
parent 92b1551b1d
commit 8169d0d06a
1 changed files with 32 additions and 20 deletions
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52
refs/files-backend.c
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@ -3436,33 +3436,45 @@ 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) &&