X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Fshash.c;h=8fd2eb18fcf83a10a244f61190c8ff908c1d6821;hb=aed133bf9bce8f35b666c3052907f525c803c83b;hp=e2b1fe2c723bb302423f84b01d8d9a68ab523b9e;hpb=1c6d8802c23c64a9439be43fa2064aca8083bfb2;p=openvswitch

diff --git a/lib/shash.c b/lib/shash.c
index e2b1fe2c..8fd2eb18 100644
--- a/lib/shash.c
+++ b/lib/shash.c
@@ -147,6 +147,26 @@ shash_add_assert(struct shash *sh, const char *name, const void *data)
     assert(added);
 }
 
+/* Searches for 'name' in 'sh'.  If it does not already exist, adds it along
+ * with 'data' and returns NULL.  If it does already exist, replaces its data
+ * by 'data' and returns the data that it formerly contained. */
+void *
+shash_replace(struct shash *sh, const char *name, const void *data)
+{
+    size_t hash = hash_name(name);
+    struct shash_node *node;
+
+    node = shash_find__(sh, name, hash);
+    if (!node) {
+        shash_add_nocopy__(sh, xstrdup(name), data, hash);
+        return NULL;
+    } else {
+        void *old_data = node->data;
+        node->data = (void *) data;
+        return old_data;
+    }
+}
+
 void
 shash_delete(struct shash *sh, struct shash_node *node)
 {
@@ -259,3 +279,14 @@ shash_equal_keys(const struct shash *a, const struct shash *b)
     }
     return true;
 }
+
+/* Chooses and returns a randomly selected node from 'sh', which must not be
+ * empty.
+ *
+ * I wouldn't depend on this algorithm to be fair, since I haven't analyzed it.
+ * But it does at least ensure that any node in 'sh' can be chosen. */
+struct shash_node *
+shash_random_node(struct shash *sh)
+{
+    return CONTAINER_OF(hmap_random_node(&sh->map), struct shash_node, node);
+}