rcuja: implement node add recompaction

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/rcuja/rcuja.c b/rcuja/rcuja.c
index 7364e074252eaf5ee36d2042cee7788a7539b447..e94031d9737f27731a9051a2f74ca1de93f24ce7 100644 (file)
--- a/rcuja/rcuja.c
+++ b/rcuja/rcuja.c
@@ -260,7 +260,7 @@ struct rcu_ja_node *ja_node_ptr(struct rcu_ja_node_flag *node)
        return (struct rcu_ja_node *) (((unsigned long) node) | JA_PTR_MASK);
 }
 
-struct rcu_ja_node *alloc_rcu_ja_node(struct rcu_ja_type *ja_type)
+struct rcu_ja_node *alloc_rcu_ja_node(const struct rcu_ja_type *ja_type)
 {
        return calloc(1U << ja_type->order, sizeof(char));
 }
@@ -436,12 +436,12 @@ int ja_pigeon_node_set_nth(const struct rcu_ja_type *type,
 }
 
 /*
- * ja_node_set_nth: set nth item within a node. Return an error
+ * _ja_node_set_nth: set nth item within a node. Return an error
  * (negative error value) if it is already there.
  * TODO: exclusive access on node.
  */
 static
-int ja_node_set_nth(struct rcu_ja_node_flag *node_flag, uint8_t n,
+int _ja_node_set_nth(struct rcu_ja_node_flag *node_flag, uint8_t n,
                struct rcu_ja_node_flag *child_node_flag)
 {
        unsigned int type_index;
@@ -470,3 +470,64 @@ int ja_node_set_nth(struct rcu_ja_node_flag *node_flag, uint8_t n,
 
        return 0;
 }
+
+/*
+ * ja_node_recompact_add: recompact a node, adding a new child.
+ */
+static
+int ja_node_recompact_add(struct rcu_ja_node_flag **old_node_flag, uint8_t n,
+               struct rcu_ja_node_flag *child_node_flag)
+
+{
+       unsigned int old_type_index, new_type_index;
+       struct rcu_ja_node *old_node, *new_node;
+       const struct rcu_ja_type *old_type, *new_type;
+       struct rcu_ja_node_flag *new_node_flag;
+       unsigned int i;
+       int ret;
+
+       old_node = ja_node_ptr(*old_node_flag);
+       if (old_node == NULL) {
+               new_type_index = 0;
+       } else {
+               old_type_index = ja_node_type(*old_node_flag);
+               old_type = &ja_types[old_type_index];
+               new_type_index = old_type_index + 1;
+       }
+       new_type = &ja_types[new_type_index];
+       new_node = alloc_rcu_ja_node(new_type);
+       if (!new_node)
+               return -ENOMEM;
+       new_node_flag = ja_node_flag(new_node, new_type_index);
+
+       for (i = 0; i < old_type->max_child; i++) {
+               struct rcu_ja_node_flag *iter;
+
+               iter = ja_node_get_nth(*old_node_flag, i);
+               if (!iter)
+                       continue;
+               ret = _ja_node_set_nth(new_node_flag, i, iter);
+               assert(!ret);
+       }
+       /* add node */
+       ret = _ja_node_set_nth(new_node_flag, n, child_node_flag);
+       assert(!ret);
+       return 0;
+}
+
+static
+int ja_node_set_nth(struct rcu_ja_node_flag **node_flag, uint8_t n,
+               struct rcu_ja_node_flag *child_node_flag)
+{
+       int ret;
+
+       ret = _ja_node_set_nth(*node_flag, n, child_node_flag);
+       if (ret == -ENOSPC) {
+               /* Not enough space in node, need to recompact */
+               ret = ja_node_recompact_add(node_flag, n,
+                               child_node_flag);
+               if (ret < 0)
+                       return ret;
+       }
+       return ret;
+}