#include <dirent.h>
#include <string.h>
#include <sys/types.h>
+#include <assert.h>
#if defined(HAVE_MMAP) || defined(__CYGWIN__)
# include <unistd.h>
# include <sys/mman.h>
return ret;
}
+#define FC_CACHE_MIN_MMAP 1024
+
+/*
+ * Skip list element, make sure the 'next' pointer is the last thing
+ * in the structure, it will be allocated large enough to hold all
+ * of the necessary pointers
+ */
+
+typedef struct _FcCacheSkip FcCacheSkip;
+
+struct _FcCacheSkip {
+ FcCache *cache;
+ int ref;
+ intptr_t size;
+ dev_t cache_dev;
+ ino_t cache_ino;
+ time_t cache_mtime;
+ FcCacheSkip *next[1];
+};
+
+/*
+ * The head of the skip list; pointers for every possible level
+ * in the skip list, plus the largest level in the list
+ */
+
+#define FC_CACHE_MAX_LEVEL 16
+
+static FcCacheSkip *fcCacheChains[FC_CACHE_MAX_LEVEL];
+static int fcCacheMaxLevel;
+
+/*
+ * Generate a random level number, distributed
+ * so that each level is 1/4 as likely as the one before
+ *
+ * Note that level numbers run 1 <= level <= MAX_LEVEL
+ */
+static int
+random_level (void)
+{
+ /* tricky bit -- each bit is '1' 75% of the time */
+ long int bits = random () | random ();
+ int level = 0;
+
+ while (++level < FC_CACHE_MAX_LEVEL)
+ {
+ if (bits & 1)
+ break;
+ bits >>= 1;
+ }
+ return level;
+}
+
+/*
+ * Insert cache into the list
+ */
+static FcBool
+FcCacheInsert (FcCache *cache, struct stat *cache_stat)
+{
+ FcCacheSkip **update[FC_CACHE_MAX_LEVEL];
+ FcCacheSkip *s, **next;
+ int i, level;
+
+ /*
+ * Find links along each chain
+ */
+ next = fcCacheChains;
+ for (i = fcCacheMaxLevel; --i >= 0; )
+ {
+ for (; (s = next[i]); next = s->next)
+ if (s->cache > cache)
+ break;
+ update[i] = &next[i];
+ }
+
+ /*
+ * Create new list element
+ */
+ level = random_level ();
+ if (level > fcCacheMaxLevel)
+ {
+ level = fcCacheMaxLevel + 1;
+ update[fcCacheMaxLevel] = &fcCacheChains[fcCacheMaxLevel];
+ fcCacheMaxLevel = level;
+ }
+
+ s = malloc (sizeof (FcCacheSkip) + (level - 1) * sizeof (FcCacheSkip *));
+ if (!s)
+ return FcFalse;
+
+ s->cache = cache;
+ s->size = cache->size;
+ s->ref = 1;
+ s->cache_dev = cache_stat->st_dev;
+ s->cache_ino = cache_stat->st_ino;
+ s->cache_mtime = cache_stat->st_mtime;
+
+ /*
+ * Insert into all fcCacheChains
+ */
+ for (i = 0; i < level; i++)
+ {
+ s->next[i] = *update[i];
+ *update[i] = s;
+ }
+ return FcTrue;
+}
+
+static FcCacheSkip *
+FcCacheFindByAddr (void *object)
+{
+ int i;
+ FcCacheSkip **next = fcCacheChains;
+ FcCacheSkip *s;
+
+ /*
+ * Walk chain pointers one level at a time
+ */
+ for (i = fcCacheMaxLevel; --i >= 0;)
+ while (next[i] && (char *) object >= ((char *) next[i]->cache + next[i]->size))
+ next = next[i]->next;
+ /*
+ * Here we are
+ */
+ s = next[0];
+ if (s && (char *) object < ((char *) s->cache + s->size))
+ return s;
+ return NULL;
+}
+
+static void
+FcCacheRemove (FcCache *cache)
+{
+ FcCacheSkip **update[FC_CACHE_MAX_LEVEL];
+ FcCacheSkip *s, **next;
+ int i;
+
+ /*
+ * Find links along each chain
+ */
+ next = fcCacheChains;
+ for (i = fcCacheMaxLevel; --i >= 0; )
+ {
+ for (; (s = next[i]); next = s->next)
+ if (s->cache >= cache)
+ break;
+ update[i] = &next[i];
+ }
+ s = next[0];
+ assert (s->cache == cache);
+ for (i = 0; i < fcCacheMaxLevel && *update[i] == s; i++)
+ *update[i] = s->next[i];
+ while (fcCacheMaxLevel > 0 && fcCacheChains[fcCacheMaxLevel - 1] == NULL)
+ fcCacheMaxLevel--;
+ free (s);
+}
+
+static FcCache *
+FcCacheFindByStat (struct stat *cache_stat)
+{
+ FcCacheSkip *s;
+
+ for (s = fcCacheChains[0]; s; s = s->next[0])
+ if (s->cache_dev == cache_stat->st_dev &&
+ s->cache_ino == cache_stat->st_ino &&
+ s->cache_mtime == cache_stat->st_mtime)
+ return s->cache;
+ return NULL;
+}
+
static void
FcDirCacheDispose (FcCache *cache)
{
#endif
break;
}
+ FcCacheRemove (cache);
}
-#define FC_CACHE_MIN_MMAP 1024
-
-#define FC_CACHE_HASH_SIZE 67
-
-typedef struct _FcCacheBucket FcCacheBucket;
-
-struct _FcCacheBucket {
- FcCacheBucket *next;
- FcCache *cache;
- dev_t cache_dev;
- ino_t cache_ino;
- time_t cache_mtime;
-};
-
-static FcCacheBucket *FcCacheBuckets[FC_CACHE_HASH_SIZE];
-
-static uint32_t
-FcCacheStatHash (struct stat *cache_stat)
-{
- return ((uint32_t) cache_stat->st_dev ^
- (uint32_t) cache_stat->st_ino ^
- (uint32_t) cache_stat->st_mtime);
-}
-
-static FcCache *
-FcCacheLookup (struct stat *cache_stat)
+void
+FcCacheObjectReference (void *object)
{
- uint32_t hash = FcCacheStatHash(cache_stat);
- FcCacheBucket **bucket = &FcCacheBuckets[hash % FC_CACHE_HASH_SIZE];
- FcCacheBucket *b;
+ FcCacheSkip *skip = FcCacheFindByAddr (object);
- for (b = *bucket; b; b = b->next)
- if (b->cache_dev == cache_stat->st_dev &&
- b->cache_ino == cache_stat->st_ino &&
- b->cache_mtime == cache_stat->st_mtime)
- return b->cache;
- return NULL;
+ if (skip)
+ skip->ref++;
}
-static FcBool
-FcCacheRecord (FcCache *cache, struct stat *cache_stat)
+void
+FcCacheObjectDereference (void *object)
{
- uint32_t hash = FcCacheStatHash(cache_stat);
- FcCacheBucket **bucket = &FcCacheBuckets[hash % FC_CACHE_HASH_SIZE];
- FcCacheBucket *b;
+ FcCacheSkip *skip = FcCacheFindByAddr (object);
- b = malloc (sizeof (FcCacheBucket));
- if (!b)
- return FcFalse;
- b->next = *bucket;
- b->cache = cache;
- b->cache_dev = cache_stat->st_dev;
- b->cache_ino = cache_stat->st_ino;
- b->cache_mtime = cache_stat->st_mtime;
- *bucket = b;
- return FcTrue;
+ if (skip)
+ {
+ skip->ref--;
+ if (skip->ref <= 0)
+ FcDirCacheDispose (skip->cache);
+ }
}
void
FcCacheFini (void)
{
int i;
- FcCacheBucket *b, *next;
- for (i = 0; i < FC_CACHE_HASH_SIZE; i++)
- {
- for (b = FcCacheBuckets[i]; b; b = next)
- {
- next = b->next;
- FcDirCacheDispose (b->cache);
- free (b);
- }
- FcCacheBuckets[i] = NULL;
- }
+ for (i = 0; i < FC_CACHE_MAX_LEVEL; i++)
+ assert (fcCacheChains[i] == NULL);
+ assert (fcCacheMaxLevel == 0);
}
/*
if (fd_stat->st_size < sizeof (FcCache))
return NULL;
- cache = FcCacheLookup (fd_stat);
+ cache = FcCacheFindByStat (fd_stat);
if (cache)
return cache;
/*
if (cache->magic != FC_CACHE_MAGIC_MMAP ||
cache->version < FC_CACHE_CONTENT_VERSION ||
cache->size != fd_stat->st_size ||
- !FcCacheRecord (cache, fd_stat))
+ !FcCacheInsert (cache, fd_stat))
{
if (allocated)
free (cache);
void
FcDirCacheUnload (FcCache *cache)
{
- /* Can't free or unmap the cache as apps may point into it */
+ FcCacheObjectDereference (cache);
}
static FcBool
git.wh0rd.org / fontconfig.git / commitdiff
