oidtree: extend iteration to allow for arbitrary return codes

The interface `cb_each()` iterates through a crit-bit tree and calls a
specific callback function for each of the contained items. The callback
function is expected to return either:

  - `CB_CONTINUE` in case iteration shall continue.

  - `CB_BREAK` to abort iteration.

This is needlessly restrictive though, as callers may want to return
arbitrary values and have them be bubbled up to the `cb_each()` call
site. In fact, this is a rather common pattern we have: whenever such a
callback function returns a non-zero error code, we abort iteration and
bubble up the code as-is.

Refactor both the crit-bit tree and oidtree subsystems to behave
accordingly.

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

1 files changed, 12 insertions, 6 deletions

diff --git a/oidtree.h b/oidtree.h
index 0651401017..2b7bad2e60 100644
--- a/oidtree.h
+++ b/oidtree.h
@@ -35,16 +35,22 @@ void oidtree_insert(struct oidtree *ot, const struct object_id *oid);
 /* Check whether the tree contains the given object ID. */
 bool oidtree_contains(struct oidtree *ot, const struct object_id *oid);
 
-/* Callback function used for `oidtree_each()`. */
-typedef enum cb_next (*oidtree_each_cb)(const struct object_id *oid,
-					void *cb_data);
+/*
+ * Callback function used for `oidtree_each()`. Returning a non-zero exit code
+ * will cause iteration to stop. The exit code will be propagated to the caller
+ * of `oidtree_each()`.
+ */
+typedef int (*oidtree_each_cb)(const struct object_id *oid,
+			       void *cb_data);
 
 /*
  * Iterate through all object IDs in the tree whose prefix matches the given
  * object ID prefix and invoke the callback function on each of them.
+ *
+ * Returns any non-zero exit code from the provided callback function.
  */
-void oidtree_each(struct oidtree *ot,
-		  const struct object_id *prefix, size_t prefix_hex_len,
-		  oidtree_each_cb cb, void *cb_data);
+int oidtree_each(struct oidtree *ot,
+		 const struct object_id *prefix, size_t prefix_hex_len,
+		 oidtree_each_cb cb, void *cb_data);
 
 #endif /* OIDTREE_H */