reftable/stack: provide convenience functions to create iterators

There exist a bunch of call sites in the reftable backend that want to
create iterators for a reftable stack. This is rather convoluted right
now, where you always have to go via the merged table. And it is about
to become even more convoluted when we split up iterator initialization
and seeking in the next commit.

Introduce convenience functions that allow the caller to create an
iterator from a reftable stack directly without going through the merged
table. Adapt callers accordingly.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/reftable/reftable-stack.h b/reftable/reftable-stack.h
index 1b602dda58..26740e6073 100644
--- a/reftable/reftable-stack.h
+++ b/reftable/reftable-stack.h
@@ -66,6 +66,24 @@ int reftable_stack_add(struct reftable_stack *st,
 					  void *write_arg),
 		       void *write_arg);
 
+struct reftable_iterator;
+
+/*
+ * Initialize an iterator for the merged tables contained in the stack that can
+ * be used to iterate through refs. The iterator is valid until the next reload
+ * or write.
+ */
+void reftable_stack_init_ref_iterator(struct reftable_stack *st,
+				      struct reftable_iterator *it);
+
+/*
+ * Initialize an iterator for the merged tables contained in the stack that can
+ * be used to iterate through logs. The iterator is valid until the next reload
+ * or write.
+ */
+void reftable_stack_init_log_iterator(struct reftable_stack *st,
+				      struct reftable_iterator *it);
+
 /* returns the merged_table for seeking. This table is valid until the
  * next write or reload, and should not be closed or deleted.
  */