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-rw-r--r--src/vppinfra/hash.h15
1 files changed, 15 insertions, 0 deletions
diff --git a/src/vppinfra/hash.h b/src/vppinfra/hash.h
index 21986ea774c..de155e6ac1c 100644
--- a/src/vppinfra/hash.h
+++ b/src/vppinfra/hash.h
@@ -77,6 +77,7 @@ typedef struct hash_header
#define KEY_FUNC_POINTER_UWORD (1) /*< sum = *(uword *) key */
#define KEY_FUNC_POINTER_U32 (2) /*< sum = *(u32 *) key */
#define KEY_FUNC_STRING (3) /*< sum = string_key_sum, etc. */
+#define KEY_FUNC_MEM (4) /*< sum = mem_key_sum */
/* key comparison function */
hash_key_equal_function_t *key_equal;
@@ -672,6 +673,20 @@ extern uword string_key_sum (hash_t * h, uword key);
extern uword string_key_equal (hash_t * h, uword key1, uword key2);
extern u8 *string_key_format_pair (u8 * s, va_list * args);
+/*
+ * Note: if you plan to put a hash into shared memory,
+ * the key sum and key equal functions MUST be set to magic constants!
+ * PIC means that whichever process sets up the hash won't have
+ * the actual key sum functions at the same place, leading to
+ * very hard-to-find bugs...
+ */
+
+#define hash_create_shmem(elts,key_bytes,value_bytes) \
+ hash_create2((elts),(key_bytes),(value_bytes), \
+ (hash_key_sum_function_t *) KEY_FUNC_MEM, \
+ (hash_key_equal_function_t *)KEY_FUNC_MEM, \
+ 0, 0)
+
#define hash_create_string(elts,value_bytes) \
hash_create2((elts),0,(value_bytes), \
(hash_key_sum_function_t *) KEY_FUNC_STRING, \