size_t cmap_count(const struct cmap *);
bool cmap_is_empty(const struct cmap *);
-/* Insertion and deletion. */
-void cmap_insert(struct cmap *, struct cmap_node *, uint32_t hash);
-void cmap_remove(struct cmap *, struct cmap_node *, uint32_t hash);
-void cmap_replace(struct cmap *, struct cmap_node *old_node,
- struct cmap_node *new_node, uint32_t hash);
+/* Insertion and deletion. Return the current count after the operation. */
+size_t cmap_insert(struct cmap *, struct cmap_node *, uint32_t hash);
+static inline size_t cmap_remove(struct cmap *, struct cmap_node *,
+ uint32_t hash);
+size_t cmap_replace(struct cmap *, struct cmap_node *old_node,
+ struct cmap_node *new_node, uint32_t hash);
/* Search.
*
* Thread-safety
* =============
*
+ * CMAP_NODE_FOR_EACH will reliably visit each of the nodes starting with
+ * CMAP_NODE, even with concurrent insertions and deletions. (Of
+ * course, if nodes are being inserted or deleted, it might or might not visit
+ * the nodes actually being inserted or deleted.)
+ *
+ * CMAP_NODE_FOR_EACH_PROTECTED may only be used if the containing CMAP is
+ * guaranteed not to change during iteration. It may be only slightly faster.
+ *
* CMAP_FOR_EACH_WITH_HASH will reliably visit each of the nodes with the
* specified hash in CMAP, even with concurrent insertions and deletions. (Of
* course, if nodes with the given HASH are being inserted or deleted, it might
* CMAP_FOR_EACH_WITH_HASH_PROTECTED may only be used if CMAP is guaranteed not
* to change during iteration. It may be very slightly faster.
*/
-#define CMAP_FOR_EACH_WITH_HASH(NODE, MEMBER, HASH, CMAP) \
- for (ASSIGN_CONTAINER(NODE, cmap_find(CMAP, HASH), MEMBER); \
- (NODE) != OBJECT_CONTAINING(NULL, NODE, MEMBER); \
+#define CMAP_NODE_FOR_EACH(NODE, MEMBER, CMAP_NODE) \
+ for (INIT_CONTAINER(NODE, CMAP_NODE, MEMBER); \
+ (NODE) != OBJECT_CONTAINING(NULL, NODE, MEMBER); \
ASSIGN_CONTAINER(NODE, cmap_node_next(&(NODE)->MEMBER), MEMBER))
-#define CMAP_FOR_EACH_WITH_HASH_PROTECTED(NODE, MEMBER, HASH, CMAP) \
- for (ASSIGN_CONTAINER(NODE, cmap_find_locked(CMAP, HASH), MEMBER); \
+#define CMAP_NODE_FOR_EACH_PROTECTED(NODE, MEMBER, CMAP_NODE) \
+ for (INIT_CONTAINER(NODE, CMAP_NODE, MEMBER); \
(NODE) != OBJECT_CONTAINING(NULL, NODE, MEMBER); \
ASSIGN_CONTAINER(NODE, cmap_node_next_protected(&(NODE)->MEMBER), \
MEMBER))
+#define CMAP_FOR_EACH_WITH_HASH(NODE, MEMBER, HASH, CMAP) \
+ CMAP_NODE_FOR_EACH(NODE, MEMBER, cmap_find(CMAP, HASH))
+#define CMAP_FOR_EACH_WITH_HASH_PROTECTED(NODE, MEMBER, HASH, CMAP) \
+ CMAP_NODE_FOR_EACH_PROTECTED(NODE, MEMBER, cmap_find_locked(CMAP, HASH))
-struct cmap_node *cmap_find(const struct cmap *, uint32_t hash);
+const struct cmap_node *cmap_find(const struct cmap *, uint32_t hash);
struct cmap_node *cmap_find_protected(const struct cmap *, uint32_t hash);
+/* Looks up multiple 'hashes', when the corresponding bit in 'map' is 1,
+ * and sets the corresponding pointer in 'nodes', if the hash value was
+ * found from the 'cmap'. In other cases the 'nodes' values are not changed,
+ * i.e., no NULL pointers are stored there.
+ * Returns a map where a bit is set to 1 if the corresponding 'nodes' pointer
+ * was stored, 0 otherwise.
+ * Generally, the caller wants to use CMAP_NODE_FOR_EACH to verify for
+ * hash collisions. */
+unsigned long cmap_find_batch(const struct cmap *cmap, unsigned long map,
+ uint32_t hashes[],
+ const struct cmap_node *nodes[]);
+
/* Iteration.
*
*
* node being deleted may be visited once or not at all. Other nodes
* will be visited once.)
*
+ * - If the cmap is changing, it is not safe to quiesce while iterating.
+ * Even if the changes are done by the same thread that's performing the
+ * iteration (Corollary: it is not safe to call cmap_remove() and quiesce
+ * in the loop body).
+ *
*
* Example
* =======
* ...operate on my_node...
* }
*
- * CMAP_FOR_EACH_SAFE variant is useful only in deallocation code already
- * executing at postponed time, when it is known that the RCU grace period
- * has already expired.
+ * CMAP_FOR_EACH is "safe" in the sense of HMAP_FOR_EACH_SAFE. That is, it is
+ * safe to free the current node before going on to the next iteration. Most
+ * of the time, though, this doesn't matter for a cmap because node
+ * deallocation has to be postponed until the next grace period. This means
+ * that this guarantee is useful only in deallocation code already executing at
+ * postponed time, when it is known that the RCU grace period has already
+ * expired.
*/
-#define CMAP_CURSOR_FOR_EACH(NODE, MEMBER, CURSOR, CMAP) \
- for (*(CURSOR) = cmap_cursor_start(CMAP); \
- ((CURSOR)->node \
- ? (ASSIGN_CONTAINER(NODE, (CURSOR)->node, MEMBER), true) \
- : false); \
- cmap_cursor_advance(CURSOR))
-
-#define CMAP_CURSOR_FOR_EACH_SAFE(NODE, MEMBER, CURSOR, CMAP) \
- for (*(CURSOR) = cmap_cursor_start(CMAP); \
- ((CURSOR)->node \
- ? (ASSIGN_CONTAINER(NODE, (CURSOR)->node, MEMBER), \
- cmap_cursor_advance(CURSOR), \
- true) \
- : false); \
+#define CMAP_CURSOR_FOR_EACH__(NODE, CURSOR, MEMBER) \
+ ((CURSOR)->node \
+ ? (INIT_CONTAINER(NODE, (CURSOR)->node, MEMBER), \
+ cmap_cursor_advance(CURSOR), \
+ true) \
+ : false)
+
+#define CMAP_CURSOR_FOR_EACH(NODE, MEMBER, CURSOR, CMAP) \
+ for (*(CURSOR) = cmap_cursor_start(CMAP); \
+ CMAP_CURSOR_FOR_EACH__(NODE, CURSOR, MEMBER); \
)
-#define CMAP_CURSOR_FOR_EACH_CONTINUE(NODE, MEMBER, CURSOR) \
- for (cmap_cursor_advance(CURSOR); \
- ((CURSOR)->node \
- ? (ASSIGN_CONTAINER(NODE, (CURSOR)->node, MEMBER), true) \
- : false); \
- cmap_cursor_advance(CURSOR))
+#define CMAP_CURSOR_FOR_EACH_CONTINUE(NODE, MEMBER, CURSOR) \
+ while (CMAP_CURSOR_FOR_EACH__(NODE, CURSOR, MEMBER))
struct cmap_cursor {
const struct cmap_impl *impl;
struct cmap_cursor cmap_cursor_start(const struct cmap *);
void cmap_cursor_advance(struct cmap_cursor *);
-#define CMAP_FOR_EACH(NODE, MEMBER, CMAP) \
- for (struct cmap_cursor cursor__ = cmap_cursor_start(CMAP); \
- (cursor__.node \
- ? (ASSIGN_CONTAINER(NODE, cursor__.node, MEMBER), true) \
- : false); \
- cmap_cursor_advance(&cursor__))
-
-#define CMAP_FOR_EACH_SAFE(NODE, MEMBER, CMAP) \
+#define CMAP_FOR_EACH(NODE, MEMBER, CMAP) \
for (struct cmap_cursor cursor__ = cmap_cursor_start(CMAP); \
- (cursor__.node \
- ? (ASSIGN_CONTAINER(NODE, cursor__.node, MEMBER), \
- cmap_cursor_advance(&cursor__), \
- true) \
- : false); \
+ CMAP_CURSOR_FOR_EACH__(NODE, &cursor__, MEMBER); \
)
static inline struct cmap_node *cmap_first(const struct cmap *);
return cmap_next_position(cmap, &pos);
}
+/* Removes 'node' from 'cmap'. The caller must ensure that 'cmap' cannot
+ * change concurrently (from another thread).
+ *
+ * 'node' must not be destroyed or modified or inserted back into 'cmap' or
+ * into any other concurrent hash map while any other thread might be accessing
+ * it. One correct way to do this is to free it from an RCU callback with
+ * ovsrcu_postpone().
+ *
+ * Returns the current number of nodes in the cmap after the removal. */
+static inline size_t
+cmap_remove(struct cmap *cmap, struct cmap_node *node, uint32_t hash)
+{
+ return cmap_replace(cmap, node, NULL, hash);
+}
+
#endif /* cmap.h */
projects / cascardo / ovs.git / blobdiff