Save cache misses by keeping a copy of the hash value next to the pointer.

[libucw.git] / lib / qache.h

diff --git a/lib/qache.h b/lib/qache.h
index b5d65f192763d97eb11364694a975ec85d925f0e..5c242a45b460d7d8bab30c3c3f916203990c6c49 100644 (file)
--- a/lib/qache.h
+++ b/lib/qache.h
@@ -8,22 +8,25 @@
 #define _UCW_QACHE_H
 
 struct qache_params {
-  byte *file_name;
+  char *file_name;
   uns block_size;                      /* Cache block size (a power of two) */
   uns cache_size;                      /* Size of the whole cache */
+  uns max_entries;                     /* Maximum number of cached entries */
   int force_reset;                     /* Force creation of a new cache even if the old one seems usable, -1 if reset should never be done */
   uns format_id;                       /* Data format ID (old cache not used if formats differ) */
 };
 
 typedef byte qache_key_t[16];
 
+struct qache;
+
 /* Create and destroy a cache */
-struct qache *qache_init(struct qache_params *p);
-void qache_cleanup(struct qache *q, uns retain_data);
+struct qache *qache_open(struct qache_params *p);
+void qache_close(struct qache *q, uns retain_data);
 
 /* Insert new item to the cache with a given key and data. If pos_hint is non-zero, it serves
  * as a hint about the position of the entry (if it's known that an entry with the particular key
- * was located there a moment ago. Returns position of the new entry.
+ * was located there a moment ago). Returns position of the new entry.
  */
 uns qache_insert(struct qache *q, qache_key_t *key, uns pos_hint, void *data, uns size);
 
@@ -34,9 +37,21 @@ uns qache_insert(struct qache *q, qache_key_t *key, uns pos_hint, void *data, un
  * can be greater than the original value requested). The start indicates starting offset inside the
  * entry's data.
  */
-uns qache_lookup(struct qache *q, qache_key_t *key, uns pos_hint, void **datap, uns **sizep, uns start);
+uns qache_lookup(struct qache *q, qache_key_t *key, uns pos_hint, byte **datap, uns *sizep, uns start);
+
+/* Inspect data in the cache (but don't modify LRU nor anything else), given a position.
+ * If key is non-NULL, it's filled with the cache key. The rest works as in qache_lookup.
+ * Returns 0 if the entry is empty, ~0 for position out of range, entry number otherwise.
+ */
+uns qache_probe(struct qache *q, qache_key_t *key, uns pos, byte **datap, uns *sizep, uns start);
 
 /* Delete data from the cache, given a key and a position hint. */
 uns qache_delete(struct qache *q, qache_key_t *key, uns pos_hint);
 
+/* Debugging dump (beware, doesn't lock the cache!) */
+void qache_debug(struct qache *q);
+
+/* Check consistency of the cache structure */
+void qache_audit(struct qache *q);
+
 #endif