[PATCH v2 04/33] refs: document how current_ref is used
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---
refs.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/refs.c b/refs.c
index 44cc2fc..efad658 100644
--- a/refs.c
+++ b/refs.c
@@ -528,6 +528,15 @@ static void sort_ref_dir(struct ref_dir *dir)
/* Include broken references in a do_for_each_ref*() iteration: */
#define DO_FOR_EACH_INCLUDE_BROKEN 0x01
+/*
+ * current_ref is a performance hack: when iterating over references
+ * using the for_each_ref*() functions, current_ref is set to the
+ * current reference's entry before calling the callback function. If
+ * the callback function calls peel_ref(), then peel_ref() first
+ * checks whether the reference to be peeled is the current reference
+ * (it usually is) and if so, returns that reference's peeled version
+ * if it is available. This avoids a refname lookup in a common case.
+ */
static struct ref_entry *current_ref;
/*
--
1.8.2.1
Michael Haggerty <mhagger@alum.mit.edu>