commit 5cd68ce386f53c7cb088f2cce0100262f0edbba7
Author: Andrey V. Elsukov <bu7cher@yandex.ru>
Date:   Thu Aug 29 17:35:08 2019 +0300

    Add ck_hs_reset_drain() function

diff --git a/sys/contrib/ck/include/ck_hs.h b/sys/contrib/ck/include/ck_hs.h
index 3c12b6e602a..7f978335162 100644
--- a/sys/contrib/ck/include/ck_hs.h
+++ b/sys/contrib/ck/include/ck_hs.h
@@ -75,6 +75,11 @@ typedef unsigned long ck_hs_hash_cb_t(const void *, unsigned long);
  */
 typedef bool ck_hs_compare_cb_t(const void *, const void *);
 
+/*
+ * Destroy item callback.
+ */
+typedef void ck_hs_destroy_item_cb_t(void *);
+
 #if defined(CK_MD_POINTER_PACK_ENABLE) && defined(CK_MD_VMA_BITS)
 #define CK_HS_PP
 #define CK_HS_KEY_MASK ((1U << ((sizeof(void *) * 8) - CK_MD_VMA_BITS)) - 1)
@@ -131,6 +136,7 @@ bool ck_hs_gc(ck_hs_t *, unsigned long, unsigned long);
 unsigned long ck_hs_count(ck_hs_t *);
 bool ck_hs_reset(ck_hs_t *);
 bool ck_hs_reset_size(ck_hs_t *, unsigned long);
+bool ck_hs_reset_drain(ck_hs_t *, ck_hs_destroy_item_cb_t *);
 void ck_hs_stat(ck_hs_t *, struct ck_hs_stat *);
 
 #endif /* CK_HS_H */
diff --git a/sys/contrib/ck/src/ck_hs.c b/sys/contrib/ck/src/ck_hs.c
index a7e15eaddbe..64218ecc5af 100644
--- a/sys/contrib/ck/src/ck_hs.c
+++ b/sys/contrib/ck/src/ck_hs.c
@@ -246,17 +246,29 @@ ck_hs_map_create(struct ck_hs *hs, unsigned long entries)
 	return map;
 }
 
-bool
-ck_hs_reset_size(struct ck_hs *hs, unsigned long capacity)
+static struct ck_hs_map *
+_ck_hs_reset_size(struct ck_hs *hs, unsigned long capacity)
 {
 	struct ck_hs_map *map, *previous;
 
 	previous = hs->map;
 	map = ck_hs_map_create(hs, capacity);
 	if (map == NULL)
-		return false;
+		return (NULL);
 
 	ck_pr_store_ptr(&hs->map, map);
+	return (previous);
+}
+
+bool
+ck_hs_reset_size(struct ck_hs *hs, unsigned long capacity)
+{
+	struct ck_hs_map *previous;
+
+	previous = _ck_hs_reset_size(hs, capacity);
+	if (previous == NULL)
+		return false;
+
 	ck_hs_map_destroy(hs->m, previous, true);
 	return true;
 }
@@ -270,6 +282,35 @@ ck_hs_reset(struct ck_hs *hs)
 	return ck_hs_reset_size(hs, previous->capacity);
 }
 
+bool
+ck_hs_reset_drain(struct ck_hs *hs, ck_hs_destroy_item_cb_t *fn)
+{
+	struct ck_hs_map *map;
+	unsigned long capacity, offset;
+	void *value;
+
+	capacity = hs->map->capacity;
+	map = _ck_hs_reset_size(hs, capacity);
+	if (map == NULL)
+		return (false);
+
+	offset = 0;
+	do {
+		value = CK_CC_DECONST_PTR(map->entries[offset]);
+		if (value != CK_HS_EMPTY && value != CK_HS_TOMBSTONE) {
+#ifdef CK_HS_PP
+			if (hs->mode & CK_HS_MODE_OBJECT)
+				value = CK_HS_VMA(value);
+#endif
+			offset++;
+			fn(value);
+		}
+	} while (++offset < capacity);
+
+	ck_hs_map_destroy(hs->m, map, true);
+	return (true);
+}
+
 static inline unsigned long
 ck_hs_map_probe_next(struct ck_hs_map *map,
     unsigned long offset,