diff options
Diffstat (limited to 'mesalib/src/gallium/auxiliary/util/u_cache.c')
| -rw-r--r-- | mesalib/src/gallium/auxiliary/util/u_cache.c | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/mesalib/src/gallium/auxiliary/util/u_cache.c b/mesalib/src/gallium/auxiliary/util/u_cache.c new file mode 100644 index 000000000..215236818 --- /dev/null +++ b/mesalib/src/gallium/auxiliary/util/u_cache.c @@ -0,0 +1,351 @@ +/**************************************************************************
+ *
+ * Copyright 2008 VMware, Inc.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+/**
+ * @file
+ * Improved cache implementation.
+ *
+ * Fixed size array with linear probing on collision and LRU eviction
+ * on full.
+ *
+ * @author Jose Fonseca <jfonseca@vmware.com>
+ */
+
+
+#include "pipe/p_compiler.h"
+#include "util/u_debug.h"
+
+#include "util/u_math.h"
+#include "util/u_memory.h"
+#include "util/u_cache.h"
+#include "util/u_simple_list.h"
+
+
+struct util_cache_entry
+{
+ enum { EMPTY = 0, FILLED, DELETED } state;
+ uint32_t hash;
+
+ struct util_cache_entry *next;
+ struct util_cache_entry *prev;
+
+ void *key;
+ void *value;
+
+#ifdef DEBUG
+ unsigned count;
+#endif
+};
+
+
+struct util_cache
+{
+ /** Hash function */
+ uint32_t (*hash)(const void *key);
+
+ /** Compare two keys */
+ int (*compare)(const void *key1, const void *key2);
+
+ /** Destroy a (key, value) pair */
+ void (*destroy)(void *key, void *value);
+
+ uint32_t size;
+
+ struct util_cache_entry *entries;
+
+ unsigned count;
+ struct util_cache_entry lru;
+};
+
+static void
+ensure_sanity(const struct util_cache *cache);
+
+#define CACHE_DEFAULT_ALPHA 2
+
+struct util_cache *
+util_cache_create(uint32_t (*hash)(const void *key),
+ int (*compare)(const void *key1, const void *key2),
+ void (*destroy)(void *key, void *value),
+ uint32_t size)
+{
+ struct util_cache *cache;
+
+ cache = CALLOC_STRUCT(util_cache);
+ if(!cache)
+ return NULL;
+
+ cache->hash = hash;
+ cache->compare = compare;
+ cache->destroy = destroy;
+
+ make_empty_list(&cache->lru);
+
+ size *= CACHE_DEFAULT_ALPHA;
+ cache->size = size;
+
+ cache->entries = CALLOC(size, sizeof(struct util_cache_entry));
+ if(!cache->entries) {
+ FREE(cache);
+ return NULL;
+ }
+
+ ensure_sanity(cache);
+ return cache;
+}
+
+
+static struct util_cache_entry *
+util_cache_entry_get(struct util_cache *cache,
+ uint32_t hash,
+ const void *key)
+{
+ struct util_cache_entry *first_unfilled = NULL;
+ uint32_t index = hash % cache->size;
+ uint32_t probe;
+
+ /* Probe until we find either a matching FILLED entry or an EMPTY
+ * slot (which has never been occupied).
+ *
+ * Deleted or non-matching slots are not indicative of completion
+ * as a previous linear probe for the same key could have continued
+ * past this point.
+ */
+ for (probe = 0; probe < cache->size; probe++) {
+ uint32_t i = (index + probe) % cache->size;
+ struct util_cache_entry *current = &cache->entries[i];
+
+ if (current->state == FILLED) {
+ if (current->hash == hash &&
+ cache->compare(key, current->key) == 0)
+ return current;
+ }
+ else {
+ if (!first_unfilled)
+ first_unfilled = current;
+
+ if (current->state == EMPTY)
+ return first_unfilled;
+ }
+ }
+
+ return NULL;
+}
+
+static INLINE void
+util_cache_entry_destroy(struct util_cache *cache,
+ struct util_cache_entry *entry)
+{
+ void *key = entry->key;
+ void *value = entry->value;
+
+ entry->key = NULL;
+ entry->value = NULL;
+
+ if (entry->state == FILLED) {
+ remove_from_list(entry);
+ cache->count--;
+
+ if(cache->destroy)
+ cache->destroy(key, value);
+
+ entry->state = DELETED;
+ }
+}
+
+
+void
+util_cache_set(struct util_cache *cache,
+ void *key,
+ void *value)
+{
+ struct util_cache_entry *entry;
+ uint32_t hash = cache->hash(key);
+
+ assert(cache);
+ if (!cache)
+ return;
+
+ entry = util_cache_entry_get(cache, hash, key);
+ if (!entry)
+ entry = cache->lru.prev;
+
+ if (cache->count >= cache->size / CACHE_DEFAULT_ALPHA)
+ util_cache_entry_destroy(cache, cache->lru.prev);
+
+ util_cache_entry_destroy(cache, entry);
+
+#ifdef DEBUG
+ ++entry->count;
+#endif
+
+ entry->key = key;
+ entry->hash = hash;
+ entry->value = value;
+ entry->state = FILLED;
+ insert_at_head(&cache->lru, entry);
+ cache->count++;
+
+ ensure_sanity(cache);
+}
+
+
+void *
+util_cache_get(struct util_cache *cache,
+ const void *key)
+{
+ struct util_cache_entry *entry;
+ uint32_t hash = cache->hash(key);
+
+ assert(cache);
+ if (!cache)
+ return NULL;
+
+ entry = util_cache_entry_get(cache, hash, key);
+ if (!entry)
+ return NULL;
+
+ if (entry->state == FILLED)
+ move_to_head(&cache->lru, entry);
+
+ return entry->value;
+}
+
+
+void
+util_cache_clear(struct util_cache *cache)
+{
+ uint32_t i;
+
+ assert(cache);
+ if (!cache)
+ return;
+
+ for(i = 0; i < cache->size; ++i) {
+ util_cache_entry_destroy(cache, &cache->entries[i]);
+ cache->entries[i].state = EMPTY;
+ }
+
+ assert(cache->count == 0);
+ assert(is_empty_list(&cache->lru));
+ ensure_sanity(cache);
+}
+
+
+void
+util_cache_destroy(struct util_cache *cache)
+{
+ assert(cache);
+ if (!cache)
+ return;
+
+#ifdef DEBUG
+ if(cache->count >= 20*cache->size) {
+ /* Normal approximation of the Poisson distribution */
+ double mean = (double)cache->count/(double)cache->size;
+ double stddev = sqrt(mean);
+ unsigned i;
+ for(i = 0; i < cache->size; ++i) {
+ double z = fabs(cache->entries[i].count - mean)/stddev;
+ /* This assert should not fail 99.9999998027% of the times, unless
+ * the hash function is a poor one */
+ assert(z <= 6.0);
+ }
+ }
+#endif
+
+ util_cache_clear(cache);
+
+ FREE(cache->entries);
+ FREE(cache);
+}
+
+
+void
+util_cache_remove(struct util_cache *cache,
+ const void *key)
+{
+ struct util_cache_entry *entry;
+ uint32_t hash;
+
+ assert(cache);
+ if (!cache)
+ return;
+
+ hash = cache->hash(key);
+
+ entry = util_cache_entry_get(cache, hash, key);
+ if (!entry)
+ return;
+
+ if (entry->state == FILLED)
+ util_cache_entry_destroy(cache, entry);
+
+ ensure_sanity(cache);
+}
+
+
+static void
+ensure_sanity(const struct util_cache *cache)
+{
+#ifdef DEBUG
+ unsigned i, cnt = 0;
+
+ assert(cache);
+ for (i = 0; i < cache->size; i++) {
+ struct util_cache_entry *header = &cache->entries[i];
+
+ assert(header);
+ assert(header->state == FILLED ||
+ header->state == EMPTY ||
+ header->state == DELETED);
+ if (header->state == FILLED) {
+ cnt++;
+ assert(header->hash == cache->hash(header->key));
+ }
+ }
+
+ assert(cnt == cache->count);
+ assert(cache->size >= cnt);
+
+ if (cache->count == 0) {
+ assert (is_empty_list(&cache->lru));
+ }
+ else {
+ struct util_cache_entry *header = cache->lru.next;
+
+ assert (header);
+ assert (!is_empty_list(&cache->lru));
+
+ for (i = 0; i < cache->count; i++)
+ header = header->next;
+
+ assert(header == &cache->lru);
+ }
+#endif
+
+ (void)cache;
+}
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