htable: reduce size of htable by storing perfect bitnum, not mask.

[ccan] / ccan / htable / htable.c

diff --git a/ccan/htable/htable.c b/ccan/htable/htable.c
index f3568230af6136e99da51d1434a435d51ac843cf..b27d063f207000b65fbbdd14aed05f171c279d09 100644 (file)
--- a/ccan/htable/htable.c
+++ b/ccan/htable/htable.c
@@ -11,6 +11,30 @@
 /* We use 0x1 as deleted marker. */
 #define HTABLE_DELETED (0x1)
 
+static void *htable_default_alloc(struct htable *ht, size_t len)
+{
+       return calloc(len, 1);
+}
+
+static void htable_default_free(struct htable *ht, void *p)
+{
+       free(p);
+}
+
+static void *(*htable_alloc)(struct htable *, size_t) = htable_default_alloc;
+static void (*htable_free)(struct htable *, void *) = htable_default_free;
+
+void htable_set_allocator(void *(*alloc)(struct htable *, size_t len),
+                         void (*free)(struct htable *, void *p))
+{
+       if (!alloc)
+               alloc = htable_default_alloc;
+       if (!free)
+               free = htable_default_free;
+       htable_alloc = alloc;
+       htable_free = free;
+}
+
 /* We clear out the bits which are always the same, and put metadata there. */
 static inline uintptr_t get_extra_ptr_bits(const struct htable *ht,
                                           uintptr_t e)
@@ -34,6 +58,15 @@ static inline bool entry_is_valid(uintptr_t e)
        return e > HTABLE_DELETED;
 }
 
+/* We use 0 to mean we don't have a perfect bit, otherwise it's
+ * bit n - 1 */
+static inline uintptr_t ht_perfect_mask(const struct htable *ht)
+{
+       if (ht->perfect_bitnum > 0)
+               return (uintptr_t)1 << (ht->perfect_bitnum - 1);
+       return 0;
+}
+
 static inline uintptr_t get_hash_ptr_bits(const struct htable *ht,
                                          size_t hash)
 {
@@ -41,7 +74,7 @@ static inline uintptr_t get_hash_ptr_bits(const struct htable *ht,
         * end is quite expensive.  But the lower bits are redundant, so
         * we fold the value first. */
        return (hash ^ (hash >> ht->bits))
-               & ht->common_mask & ~ht->perfect_bit;
+               & ht->common_mask & ~ht_perfect_mask(ht);
 }
 
 void htable_init(struct htable *ht,
@@ -51,14 +84,17 @@ void htable_init(struct htable *ht,
        *ht = empty;
        ht->rehash = rehash;
        ht->priv = priv;
-       ht->table = &ht->perfect_bit;
+       ht->table = &ht->common_bits;
+}
+
+static inline size_t ht_max(const struct htable *ht)
+{
+       return ((size_t)3 << ht->bits) / 4;
 }
 
-/* We've changed ht->bits, update ht->max and ht->max_with_deleted */
-static void htable_adjust_capacity(struct htable *ht)
+static inline size_t ht_max_with_deleted(const struct htable *ht)
 {
-       ht->max = ((size_t)3 << ht->bits) / 4;
-       ht->max_with_deleted = ((size_t)9 << ht->bits) / 10;
+       return ((size_t)9 << ht->bits) / 10;
 }
 
 bool htable_init_sized(struct htable *ht,
@@ -73,26 +109,25 @@ bool htable_init_sized(struct htable *ht,
                        break;
        }
 
-       ht->table = calloc(1 << ht->bits, sizeof(size_t));
+       ht->table = htable_alloc(ht, sizeof(size_t) << ht->bits);
        if (!ht->table) {
-               ht->table = &ht->perfect_bit;
+               ht->table = &ht->common_bits;
                return false;
        }
-       htable_adjust_capacity(ht);
        (void)htable_debug(ht, HTABLE_LOC);
        return true;
 }
        
 void htable_clear(struct htable *ht)
 {
-       if (ht->table != &ht->perfect_bit)
-               free((void *)ht->table);
+       if (ht->table != &ht->common_bits)
+               htable_free(ht, (void *)ht->table);
        htable_init(ht, ht->rehash, ht->priv);
 }
 
 bool htable_copy_(struct htable *dst, const struct htable *src)
 {
-       uintptr_t *htable = malloc(sizeof(size_t) << src->bits);
+       uintptr_t *htable = htable_alloc(dst, sizeof(size_t) << src->bits);
 
        if (!htable)
                return false;
@@ -128,7 +163,7 @@ void *htable_firstval_(const struct htable *ht,
                       struct htable_iter *i, size_t hash)
 {
        i->off = hash_bucket(ht, hash);
-       return htable_val(ht, i, hash, ht->perfect_bit);
+       return htable_val(ht, i, hash, ht_perfect_mask(ht));
 }
 
 void *htable_nextval_(const struct htable *ht,
@@ -171,7 +206,7 @@ void *htable_prev_(const struct htable *ht, struct htable_iter *i)
 static void ht_add(struct htable *ht, const void *new, size_t h)
 {
        size_t i;
-       uintptr_t perfect = ht->perfect_bit;
+       uintptr_t perfect = ht_perfect_mask(ht);
 
        i = hash_bucket(ht, h);
 
@@ -189,32 +224,31 @@ static COLD bool double_table(struct htable *ht)
        uintptr_t *oldtable, e;
 
        oldtable = ht->table;
-       ht->table = calloc(1 << (ht->bits+1), sizeof(size_t));
+       ht->table = htable_alloc(ht, sizeof(size_t) << (ht->bits+1));
        if (!ht->table) {
                ht->table = oldtable;
                return false;
        }
        ht->bits++;
-       htable_adjust_capacity(ht);
 
        /* If we lost our "perfect bit", get it back now. */
-       if (!ht->perfect_bit && ht->common_mask) {
+       if (ht->perfect_bitnum == 0 && ht->common_mask) {
                for (i = 0; i < sizeof(ht->common_mask) * CHAR_BIT; i++) {
                        if (ht->common_mask & ((size_t)1 << i)) {
-                               ht->perfect_bit = (size_t)1 << i;
+                               ht->perfect_bitnum = i + 1;
                                break;
                        }
                }
        }
 
-       if (oldtable != &ht->perfect_bit) {
+       if (oldtable != &ht->common_bits) {
                for (i = 0; i < oldnum; i++) {
                        if (entry_is_valid(e = oldtable[i])) {
                                void *p = get_raw_ptr(ht, e);
                                ht_add(ht, p, ht->rehash(p, ht->priv));
                        }
                }
-               free(oldtable);
+               htable_free(ht, oldtable);
        }
        ht->deleted = 0;
 
@@ -237,7 +271,7 @@ static COLD void rehash_table(struct htable *ht)
                        continue;
                if (e == HTABLE_DELETED)
                        ht->table[h] = 0;
-               else if (!(e & ht->perfect_bit)) {
+               else if (!(e & ht_perfect_mask(ht))) {
                        void *p = get_raw_ptr(ht, e);
                        ht->table[h] = 0;
                        ht_add(ht, p, ht->rehash(p, ht->priv));
@@ -265,7 +299,7 @@ static COLD void update_common(struct htable *ht, const void *p)
 
                ht->common_mask = ~((uintptr_t)1 << i);
                ht->common_bits = ((uintptr_t)p & ht->common_mask);
-               ht->perfect_bit = 1;
+               ht->perfect_bitnum = 1;
                (void)htable_debug(ht, HTABLE_LOC);
                return;
        }
@@ -288,15 +322,16 @@ static COLD void update_common(struct htable *ht, const void *p)
        /* Take away those bits from our mask, bits and perfect bit. */
        ht->common_mask &= ~maskdiff;
        ht->common_bits &= ~maskdiff;
-       ht->perfect_bit &= ~maskdiff;
+       if (ht_perfect_mask(ht) & maskdiff)
+               ht->perfect_bitnum = 0;
        (void)htable_debug(ht, HTABLE_LOC);
 }
 
 bool htable_add_(struct htable *ht, size_t hash, const void *p)
 {
-       if (ht->elems+1 > ht->max && !double_table(ht))
+       if (ht->elems+1 > ht_max(ht) && !double_table(ht))
                return false;
-       if (ht->elems+1 + ht->deleted > ht->max_with_deleted)
+       if (ht->elems+1 + ht->deleted > ht_max_with_deleted(ht))
                rehash_table(ht);
        assert(p);
        if (((uintptr_t)p & ht->common_mask) != ht->common_bits)