hashmap: add disallow_rehash setting

[thirdparty/git.git] / hashmap.c

diff --git a/hashmap.c b/hashmap.c
index b10b642229ca0c3e6eb27142f080921dd5c3aece..7d1044eb5de0faf69a151ca16c1a21500d9d8a10 100644 (file)
--- a/hashmap.c
+++ b/hashmap.c
@@ -50,6 +50,23 @@ unsigned int memihash(const void *buf, size_t len)
        return hash;
 }
 
+/*
+ * Incoporate another chunk of data into a memihash
+ * computation.
+ */
+unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len)
+{
+       unsigned int hash = hash_seed;
+       unsigned char *ucbuf = (unsigned char *) buf;
+       while (len--) {
+               unsigned int c = *ucbuf++;
+               if (c >= 'a' && c <= 'z')
+                       c -= 'a' - 'A';
+               hash = (hash * FNV32_PRIME) ^ c;
+       }
+       return hash;
+}
+
 #define HASHMAP_INITIAL_SIZE 64
 /* grow / shrink by 2^2 */
 #define HASHMAP_RESIZE_BITS 2
@@ -87,11 +104,19 @@ static inline unsigned int bucket(const struct hashmap *map,
        return key->hash & (map->tablesize - 1);
 }
 
+int hashmap_bucket(const struct hashmap *map, unsigned int hash)
+{
+       return hash & (map->tablesize - 1);
+}
+
 static void rehash(struct hashmap *map, unsigned int newsize)
 {
        unsigned int i, oldsize = map->tablesize;
        struct hashmap_entry **oldtable = map->table;
 
+       if (map->disallow_rehash)
+               return;
+
        alloc_table(map, newsize);
        for (i = 0; i < oldsize; i++) {
                struct hashmap_entry *e = oldtable[i];
@@ -124,7 +149,9 @@ void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function,
                size_t initial_size)
 {
        unsigned int size = HASHMAP_INITIAL_SIZE;
-       map->size = 0;
+
+       memset(map, 0, sizeof(*map));
+
        map->cmpfn = equals_function ? equals_function : always_equal;
 
        /* calculate initial table size and allocate the table */