X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Fshash.c;h=82791e31f76e77445ff2bf771df6eb78ee4c687d;hb=eb9b830766044475277a590dbf8d213b77b62188;hp=e2b1fe2c723bb302423f84b01d8d9a68ab523b9e;hpb=1c6d8802c23c64a9439be43fa2064aca8083bfb2;p=openvswitch

diff --git a/lib/shash.c b/lib/shash.c
index e2b1fe2c..82791e31 100644
--- a/lib/shash.c
+++ b/lib/shash.c
@@ -147,12 +147,45 @@ 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;
+    }
+}
+
+/* Deletes 'node' from 'sh' and frees the node's name.  The caller is still
+ * responsible for freeing the node's data, if necessary. */
 void
 shash_delete(struct shash *sh, struct shash_node *node)
 {
+    free(shash_steal(sh, node));
+}
+
+/* Deletes 'node' from 'sh'.  Neither the node's name nor its data is freed;
+ * instead, ownership is transferred to the caller.  Returns the node's
+ * name. */
+char *
+shash_steal(struct shash *sh, struct shash_node *node)
+{
+    char *name = node->name;
+
     hmap_remove(&sh->map, &node->node);
-    free(node->name);
     free(node);
+    return name;
 }
 
 static struct shash_node *
@@ -160,7 +193,7 @@ shash_find__(const struct shash *sh, const char *name, size_t hash)
 {
     struct shash_node *node;
 
-    HMAP_FOR_EACH_WITH_HASH (node, struct shash_node, node, hash, &sh->map) {
+    HMAP_FOR_EACH_WITH_HASH (node, node, hash, &sh->map) {
         if (!strcmp(node->name, name)) {
             return node;
         }
@@ -259,3 +292,14 @@ 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);
+}