Merge branch 'ps/refname-avail-check-optim' into kn/non-transactional-batch-updates

* ps/refname-avail-check-optim: (43 commits)
  refs: reuse iterators when determining refname availability
  refs/iterator: implement seeking for files iterators
  refs/iterator: implement seeking for packed-ref iterators
  refs/iterator: implement seeking for ref-cache iterators
  refs/iterator: implement seeking for reftable iterators
  refs/iterator: implement seeking for merged iterators
  refs/iterator: provide infrastructure to re-seek iterators
  refs/iterator: separate lifecycle from iteration
  refs: stop re-verifying common prefixes for availability
  refs/files: batch refname availability checks for initial transactions
  refs/files: batch refname availability checks for normal transactions
  refs/reftable: batch refname availability checks
  refs: introduce function to batch refname availability checks
  builtin/update-ref: skip ambiguity checks when parsing object IDs
  object-name: allow skipping ambiguity checks in `get_oid()` family
  object-name: introduce `repo_get_oid_with_flags()`
  Git 2.49-rc0
  The fourteenth batch
  mailmap: fix check-mailmap with full mailmap line
  The thirteenth batch
  ...

1 files changed, 54 insertions, 34 deletions

diff --git a/refs/ref-cache.c b/refs/ref-cache.c
index 02f09e4df8..c1f1bab1d5 100644
--- a/refs/ref-cache.c
+++ b/refs/ref-cache.c
@@ -362,9 +362,7 @@ struct cache_ref_iterator {
 	struct ref_iterator base;
 
 	/*
-	 * The number of levels currently on the stack. This is always
-	 * at least 1, because when it becomes zero the iteration is
-	 * ended and this struct is freed.
+	 * The number of levels currently on the stack.
 	 */
 	size_t levels_nr;
 
@@ -376,7 +374,7 @@ struct cache_ref_iterator {
 	 * The prefix is matched textually, without regard for path
 	 * component boundaries.
 	 */
-	const char *prefix;
+	char *prefix;
 
 	/*
 	 * A stack of levels. levels[0] is the uppermost level that is
@@ -389,6 +387,9 @@ struct cache_ref_iterator {
 	struct cache_ref_iterator_level *levels;
 
 	struct repository *repo;
+	struct ref_cache *cache;
+
+	int prime_dir;
 };
 
 static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
@@ -396,6 +397,9 @@ static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
 	struct cache_ref_iterator *iter =
 		(struct cache_ref_iterator *)ref_iterator;
 
+	if (!iter->levels_nr)
+		return ITER_DONE;
+
 	while (1) {
 		struct cache_ref_iterator_level *level =
 			&iter->levels[iter->levels_nr - 1];
@@ -409,7 +413,7 @@ static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
 		if (++level->index == level->dir->nr) {
 			/* This level is exhausted; pop up a level */
 			if (--iter->levels_nr == 0)
-				return ref_iterator_abort(ref_iterator);
+				return ITER_DONE;
 
 			continue;
 		}
@@ -444,6 +448,41 @@ static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
 	}
 }
 
+static int cache_ref_iterator_seek(struct ref_iterator *ref_iterator,
+				   const char *prefix)
+{
+	struct cache_ref_iterator *iter =
+		(struct cache_ref_iterator *)ref_iterator;
+	struct cache_ref_iterator_level *level;
+	struct ref_dir *dir;
+
+	dir = get_ref_dir(iter->cache->root);
+	if (prefix && *prefix)
+		dir = find_containing_dir(dir, prefix);
+	if (!dir) {
+		iter->levels_nr = 0;
+		return 0;
+	}
+
+	if (iter->prime_dir)
+		prime_ref_dir(dir, prefix);
+	iter->levels_nr = 1;
+	level = &iter->levels[0];
+	level->index = -1;
+	level->dir = dir;
+
+	if (prefix && *prefix) {
+		free(iter->prefix);
+		iter->prefix = xstrdup(prefix);
+		level->prefix_state = PREFIX_WITHIN_DIR;
+	} else {
+		FREE_AND_NULL(iter->prefix);
+		level->prefix_state = PREFIX_CONTAINS_DIR;
+	}
+
+	return 0;
+}
+
 static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator,
 				   struct object_id *peeled)
 {
@@ -452,21 +491,19 @@ static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator,
 	return peel_object(iter->repo, ref_iterator->oid, peeled) ? -1 : 0;
 }
 
-static int cache_ref_iterator_abort(struct ref_iterator *ref_iterator)
+static void cache_ref_iterator_release(struct ref_iterator *ref_iterator)
 {
 	struct cache_ref_iterator *iter =
 		(struct cache_ref_iterator *)ref_iterator;
-
-	free((char *)iter->prefix);
+	free(iter->prefix);
 	free(iter->levels);
-	base_ref_iterator_free(ref_iterator);
-	return ITER_DONE;
 }
 
 static struct ref_iterator_vtable cache_ref_iterator_vtable = {
 	.advance = cache_ref_iterator_advance,
+	.seek = cache_ref_iterator_seek,
 	.peel = cache_ref_iterator_peel,
-	.abort = cache_ref_iterator_abort
+	.release = cache_ref_iterator_release,
 };
 
 struct ref_iterator *cache_ref_iterator_begin(struct ref_cache *cache,
@@ -474,39 +511,22 @@ struct ref_iterator *cache_ref_iterator_begin(struct ref_cache *cache,
 					      struct repository *repo,
 					      int prime_dir)
 {
-	struct ref_dir *dir;
 	struct cache_ref_iterator *iter;
 	struct ref_iterator *ref_iterator;
-	struct cache_ref_iterator_level *level;
-
-	dir = get_ref_dir(cache->root);
-	if (prefix && *prefix)
-		dir = find_containing_dir(dir, prefix);
-	if (!dir)
-		/* There's nothing to iterate over. */
-		return empty_ref_iterator_begin();
-
-	if (prime_dir)
-		prime_ref_dir(dir, prefix);
 
 	CALLOC_ARRAY(iter, 1);
 	ref_iterator = &iter->base;
 	base_ref_iterator_init(ref_iterator, &cache_ref_iterator_vtable);
 	ALLOC_GROW(iter->levels, 10, iter->levels_alloc);
 
-	iter->levels_nr = 1;
-	level = &iter->levels[0];
-	level->index = -1;
-	level->dir = dir;
+	iter->repo = repo;
+	iter->cache = cache;
+	iter->prime_dir = prime_dir;
 
-	if (prefix && *prefix) {
-		iter->prefix = xstrdup(prefix);
-		level->prefix_state = PREFIX_WITHIN_DIR;
-	} else {
-		level->prefix_state = PREFIX_CONTAINS_DIR;
+	if (cache_ref_iterator_seek(&iter->base, prefix) < 0) {
+		ref_iterator_free(&iter->base);
+		return NULL;
 	}
 
-	iter->repo = repo;
-
 	return ref_iterator;
 }