MINOR: lru: Add lru64_lookup function
It lookup a key in a LRU cache for use with specified domain and revision. It
differs from lru64_get as it does not create missing keys. The function returns
NULL if an error or a cache miss occurs.
diff --git a/src/lru.c b/src/lru.c
index 1b997d8..273f3a8 100644
--- a/src/lru.c
+++ b/src/lru.c
@@ -28,6 +28,41 @@
#define LIST_ADD(lh, el) ({ (el)->n = (lh)->n; (el)->n->p = (lh)->n = (el); (el)->p = (lh); })
#define LIST_DEL(el) ({ (el)->n->p = (el)->p; (el)->p->n = (el)->n; })
+
+/* Lookup key <key> in LRU cache <lru> for use with domain <domain> whose data's
+ * current version is <revision>. It differs from lru64_get as it does not
+ * create missing keys. The function returns NULL if an error or a cache miss
+ * occurs. */
+struct lru64 *lru64_lookup(unsigned long long key, struct lru64_head *lru,
+ void *domain, unsigned long long revision)
+{
+ struct eb64_node *node;
+ struct lru64 *elem;
+
+ if (!lru->spare) {
+ if (!lru->cache_size)
+ return NULL;
+ lru->spare = malloc(sizeof(*lru->spare));
+ if (!lru->spare)
+ return NULL;
+ lru->spare->domain = NULL;
+ }
+
+ node = __eb64_lookup(&lru->keys, key);
+ elem = container_of(node, typeof(*elem), node);
+ if (elem) {
+ /* Existing entry found, check validity then move it at the
+ * head of the LRU list.
+ */
+ if (elem->domain == domain && elem->revision == revision) {
+ LIST_DEL(&elem->lru);
+ LIST_ADD(&lru->list, &elem->lru);
+ return elem;
+ }
+ }
+ return NULL;
+}
+
/* Get key <key> from LRU cache <lru> for use with domain <domain> whose data's
* current revision is <revision>. If the key doesn't exist it's first created
* with ->domain = NULL. The caller detects this situation by checking ->domain