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cache-tree: simplify locking logic

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After we have taken the lock using `LOCK_DIE_ON_ERROR`, we know that
`newfd` is non-negative. So when we check for exactly that property
before calling `write_locked_index()`, the outcome is guaranteed.

If we write and commit successfully, we set `newfd = -1`, so that we can
later avoid calling `rollback_lock_file` on an already-committed lock.
But we might just as well unconditionally call `rollback_lock_file()` --
it will be a no-op if we have already committed.

All in all, we use `newfd` as a bool and the only benefit we get from it
is that we can avoid calling a no-op. Remove `newfd` so that we have one
variable less to reason about.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Martin Ågren 2017-10-05 22:32:08 +02:00 committed by Junio C Hamano
parent 02ae242fdd
commit 2954e5ec43
1 changed files with 4 additions and 8 deletions
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12
cache-tree.c
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@ -602,11 +602,11 @@ static struct cache_tree *cache_tree_find(struct cache_tree *it, const char *pat
int write_index_as_tree(unsigned char *sha1, struct index_state *index_state, const char *index_path, int flags, const char *prefix)
{
int entries, was_valid, newfd;
int entries, was_valid;
struct lock_file lock_file = LOCK_INIT;
int ret = 0;
newfd = hold_lock_file_for_update(&lock_file, index_path, LOCK_DIE_ON_ERROR);
hold_lock_file_for_update(&lock_file, index_path, LOCK_DIE_ON_ERROR);
entries = read_index_from(index_state, index_path);
if (entries < 0) {
@ -625,10 +625,7 @@ int write_index_as_tree(unsigned char *sha1, struct index_state *index_state, co
ret = WRITE_TREE_UNMERGED_INDEX;
goto out;
}
if (0 <= newfd) {
if (!write_locked_index(index_state, &lock_file, COMMIT_LOCK))
newfd = -1;
}
write_locked_index(index_state, &lock_file, COMMIT_LOCK);
/* Not being able to write is fine -- we are only interested
* in updating the cache-tree part, and if the next caller
* ends up using the old index with unupdated cache-tree part
@ -650,8 +647,7 @@ int write_index_as_tree(unsigned char *sha1, struct index_state *index_state, co
hashcpy(sha1, index_state->cache_tree->oid.hash);
out:
if (0 <= newfd)
rollback_lock_file(&lock_file);
rollback_lock_file(&lock_file);
return ret;
}