tdb2: try to fit transactions in existing space before we expand.

[ccan] / ccan / list / list.h

diff --git a/ccan/list/list.h b/ccan/list/list.h
index 5b4f81c965725d473f7cfc6df52812c21fc7cfc4..da2ac73537b6c9d46d67df62c51faa330c927e70 100644 (file)
--- a/ccan/list/list.h
+++ b/ccan/list/list.h
@@ -1,6 +1,7 @@
 #ifndef CCAN_LIST_H
 #define CCAN_LIST_H
 #include <stdbool.h>
+#include <assert.h>
 #include <ccan/container_of/container_of.h>
 
 /**
@@ -94,17 +95,34 @@ struct list_node *list_check_node(const struct list_node *n,
 #endif
 
 /**
- * LIST_HEAD - define and initalize an empty list_head
+ * LIST_HEAD_INIT - initializer for an empty list_head
+ * @name: the name of the list.
+ *
+ * Explicit initializer for an empty list.
+ *
+ * See also:
+ *     LIST_HEAD, list_head_init()
+ *
+ * Example:
+ *     static struct list_head my_list = LIST_HEAD_INIT(my_list);
+ */
+#define LIST_HEAD_INIT(name) { { &name.n, &name.n } }
+
+/**
+ * LIST_HEAD - define and initialize an empty list_head
  * @name: the name of the list.
  *
  * The LIST_HEAD macro defines a list_head and initializes it to an empty
  * list.  It can be prepended by "static" to define a static list_head.
  *
+ * See also:
+ *     LIST_HEAD_INIT, list_head_init()
+ *
  * Example:
  *     static LIST_HEAD(my_global_list);
  */
 #define LIST_HEAD(name) \
-       struct list_head name = { { &name.n, &name.n } }
+       struct list_head name = LIST_HEAD_INIT(name)
 
 /**
  * list_head_init - initialize a list_head
@@ -164,9 +182,30 @@ static inline void list_add_tail(struct list_head *h, struct list_node *n)
 }
 
 /**
- * list_del - delete an entry from a linked list.
+ * list_empty - is a list empty?
+ * @h: the list_head
+ *
+ * If the list is empty, returns true.
+ *
+ * Example:
+ *     assert(list_empty(&parent->children) == (parent->num_children == 0));
+ */
+static inline bool list_empty(const struct list_head *h)
+{
+       (void)list_debug(h);
+       return h->n.next == &h->n;
+}
+
+/**
+ * list_del - delete an entry from an (unknown) linked list.
  * @n: the list_node to delete from the list.
  *
+ * Note that this leaves @n in an undefined state; it can be added to
+ * another list, but not deleted again.
+ *
+ * See also:
+ *     list_del_from()
+ *
  * Example:
  *     list_del(&child->list);
  *     parent->num_children--;
@@ -183,18 +222,33 @@ static inline void list_del(struct list_node *n)
 }
 
 /**
- * list_empty - is a list empty?
- * @h: the list_head
+ * list_del_from - delete an entry from a known linked list.
+ * @h: the list_head the node is in.
+ * @n: the list_node to delete from the list.
  *
- * If the list is empty, returns true.
+ * This explicitly indicates which list a node is expected to be in,
+ * which is better documentation and can catch more bugs.
+ *
+ * See also: list_del()
  *
  * Example:
- *     assert(list_empty(&parent->children) == (parent->num_children == 0));
+ *     list_del_from(&parent->children, &child->list);
+ *     parent->num_children--;
  */
-static inline bool list_empty(const struct list_head *h)
+static inline void list_del_from(struct list_head *h, struct list_node *n)
 {
-       (void)list_debug(h);
-       return h->n.next == &h->n;
+#ifdef CCAN_LIST_DEBUG
+       {
+               /* Thorough check: make sure it was in list! */
+               struct list_node *i;
+               for (i = h->n.next; i != n; i = i->next)
+                       assert(i != &h->n);
+       }
+#endif /* CCAN_LIST_DEBUG */
+
+       /* Quick test that catches a surprising number of bugs. */
+       assert(!list_empty(h));
+       list_del(n);
 }
 
 /**