From 1dd24ca6d2daeaeb0b9d90f432809508a98b259b Mon Sep 17 00:00:00 2001
From: Yinan Zhang <zyn8950@gmail.com>
Date: Thu, 2 Apr 2020 11:11:08 -0700
Subject: [PATCH] Add rotate functionality to ql module

---
 include/jemalloc/internal/ql.h | 10 ++++++++++
 test/unit/ql.c                 | 25 ++++++++++++++++++++++++-
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/include/jemalloc/internal/ql.h b/include/jemalloc/internal/ql.h
index 93ddce58..3b780609 100644
--- a/include/jemalloc/internal/ql.h
+++ b/include/jemalloc/internal/ql.h
@@ -98,6 +98,16 @@ struct {								\
 	ql_first(a_head_b) = (a_elm);					\
 } while (0)
 
+/*
+ * An optimized version of:
+ *	a_type *t = ql_first(a_head);
+ *	ql_remove((a_head), t, a_field);
+ *	ql_tail_insert((a_head), t, a_field);
+ */
+#define ql_rotate(a_head, a_field) do {					\
+	ql_first(a_head) = qr_next(ql_first(a_head), a_field);		\
+} while (0)
+
 #define ql_foreach(a_var, a_head, a_field)				\
 	qr_foreach((a_var), ql_first(a_head), a_field)
 
diff --git a/test/unit/ql.c b/test/unit/ql.c
index c2b19812..662d1e8b 100644
--- a/test/unit/ql.c
+++ b/test/unit/ql.c
@@ -258,6 +258,28 @@ TEST_BEGIN(test_ql_concat_split) {
 }
 TEST_END
 
+TEST_BEGIN(test_ql_rotate) {
+	list_head_t head;
+	list_t entries[NENTRIES];
+	unsigned i;
+
+	ql_new(&head);
+	init_entries(entries, sizeof(entries)/sizeof(list_t));
+	for (i = 0; i < NENTRIES; i++) {
+		ql_tail_insert(&head, &entries[i], link);
+	}
+
+	char head_id = ql_first(&head)->id;
+	for (i = 0; i < NENTRIES; i++) {
+		assert_c_eq(ql_first(&head)->id, head_id, "");
+		ql_rotate(&head, link);
+		assert_c_eq(ql_last(&head, link)->id, head_id, "");
+		head_id++;
+	}
+	test_entries_list(&head, entries, NENTRIES);
+}
+TEST_END
+
 int
 main(void) {
 	return test(
@@ -267,5 +289,6 @@ main(void) {
 	    test_ql_head_insert,
 	    test_ql_head_remove,
 	    test_ql_insert,
-	    test_ql_concat_split);
+	    test_ql_concat_split,
+	    test_ql_rotate);
 }