/* We use 0x1 as deleted marker. */
#define HTABLE_DELETED (0x1)
+/* perfect_bitnum 63 means there's no perfect bitnum */
+#define NO_PERFECT_BIT (sizeof(uintptr_t) * CHAR_BIT - 1)
+
static void *htable_default_alloc(struct htable *ht, size_t len)
{
return calloc(len, 1);
return e > HTABLE_DELETED;
}
+static inline uintptr_t ht_perfect_mask(const struct htable *ht)
+{
+ return (uintptr_t)2 << ht->perfect_bitnum;
+}
+
static inline uintptr_t get_hash_ptr_bits(const struct htable *ht,
size_t hash)
{
* 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,
*ht = empty;
ht->rehash = rehash;
ht->priv = priv;
- ht->table = &ht->perfect_bit;
+ ht->table = &ht->common_bits;
}
+/* Fill to 87.5% */
static inline size_t ht_max(const struct htable *ht)
{
- return ((size_t)3 << ht->bits) / 4;
+ return ((size_t)7 << ht->bits) / 8;
}
-static inline size_t ht_max_with_deleted(const struct htable *ht)
+/* Clean deleted if we're full, and more than 12.5% deleted */
+static inline size_t ht_max_deleted(const struct htable *ht)
{
- return ((size_t)9 << ht->bits) / 10;
+ return ((size_t)1 << ht->bits) / 8;
}
bool htable_init_sized(struct htable *ht,
htable_init(ht, rehash, priv);
/* Don't go insane with sizing. */
- for (ht->bits = 1; ((size_t)3 << ht->bits) / 4 < expect; ht->bits++) {
+ for (ht->bits = 1; ht_max(ht) < expect; ht->bits++) {
if (ht->bits == 30)
break;
}
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;
}
(void)htable_debug(ht, HTABLE_LOC);
void htable_clear(struct htable *ht)
{
- if (ht->table != &ht->perfect_bit)
+ if (ht->table != &ht->common_bits)
htable_free(ht, (void *)ht->table);
htable_init(ht, ht->rehash, ht->priv);
}
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,
for (;;) {
if (!i->off)
return NULL;
- i->off --;
+ i->off--;
if (entry_is_valid(ht->table[i->off]))
return get_raw_ptr(ht, ht->table[i->off]);
}
}
+/* Another bit currently in mask needs to be exposed, so that a bucket with p in
+ * it won't appear invalid */
+static COLD void unset_another_common_bit(struct htable *ht,
+ uintptr_t *maskdiff,
+ const void *p)
+{
+ size_t i;
+
+ for (i = sizeof(uintptr_t) * CHAR_BIT - 1; i > 0; i--) {
+ if (((uintptr_t)p & ((uintptr_t)1 << i))
+ && ht->common_mask & ~*maskdiff & ((uintptr_t)1 << i))
+ break;
+ }
+ /* There must have been one, right? */
+ assert(i > 0);
+
+ *maskdiff |= ((uintptr_t)1 << i);
+}
+
+/* We want to change the common mask: this fixes up the table */
+static COLD void fixup_table_common(struct htable *ht, uintptr_t maskdiff)
+{
+ size_t i;
+ uintptr_t bitsdiff;
+
+again:
+ bitsdiff = ht->common_bits & maskdiff;
+
+ for (i = 0; i < (size_t)1 << ht->bits; i++) {
+ uintptr_t e;
+ if (!entry_is_valid(e = ht->table[i]))
+ continue;
+
+ /* Clear the bits no longer in the mask, set them as
+ * expected. */
+ e &= ~maskdiff;
+ e |= bitsdiff;
+ /* If this made it invalid, restart with more exposed */
+ if (!entry_is_valid(e)) {
+ unset_another_common_bit(ht, &maskdiff, get_raw_ptr(ht, e));
+ goto again;
+ }
+ ht->table[i] = e;
+ }
+
+ /* Take away those bits from our mask, bits and perfect bit. */
+ ht->common_mask &= ~maskdiff;
+ ht->common_bits &= ~maskdiff;
+ if (ht_perfect_mask(ht) & maskdiff)
+ ht->perfect_bitnum = NO_PERFECT_BIT;
+}
+
+/* Limited recursion */
+static void ht_add(struct htable *ht, const void *new, size_t h);
+
+/* We tried to add this entry, but it looked invalid! We need to
+ * let another pointer bit through mask */
+static COLD void update_common_fix_invalid(struct htable *ht, const void *p, size_t h)
+{
+ uintptr_t maskdiff;
+
+ assert(ht->elems != 0);
+
+ maskdiff = 0;
+ unset_another_common_bit(ht, &maskdiff, p);
+ fixup_table_common(ht, maskdiff);
+
+ /* Now won't recurse */
+ ht_add(ht, p, h);
+}
+
/* This does not expand the hash table, that's up to caller. */
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);
i = (i + 1) & ((1 << ht->bits)-1);
}
ht->table[i] = make_hval(ht, new, get_hash_ptr_bits(ht, h)|perfect);
+ if (!entry_is_valid(ht->table[i]))
+ update_common_fix_invalid(ht, new, h);
}
static COLD bool double_table(struct htable *ht)
ht->bits++;
/* If we lost our "perfect bit", get it back now. */
- if (!ht->perfect_bit && ht->common_mask) {
+ if (ht->perfect_bitnum == NO_PERFECT_BIT && 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;
+ if (ht->common_mask & ((size_t)2 << i)) {
+ ht->perfect_bitnum = i;
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);
static COLD void rehash_table(struct htable *ht)
{
size_t start, i;
- uintptr_t e;
+ uintptr_t e, perfect = ht_perfect_mask(ht);
/* Beware wrap cases: we need to start from first empty bucket. */
for (start = 0; ht->table[start]; start++);
continue;
if (e == HTABLE_DELETED)
ht->table[h] = 0;
- else if (!(e & ht->perfect_bit)) {
+ else if (!(e & perfect)) {
void *p = get_raw_ptr(ht, e);
ht->table[h] = 0;
ht_add(ht, p, ht->rehash(p, ht->priv));
/* We stole some bits, now we need to put them back... */
static COLD void update_common(struct htable *ht, const void *p)
{
- unsigned int i;
- uintptr_t maskdiff, bitsdiff;
+ uintptr_t maskdiff;
if (ht->elems == 0) {
- /* Always reveal one bit of the pointer in the bucket,
- * so it's not zero or HTABLE_DELETED (1), even if
- * hash happens to be 0. Assumes (void *)1 is not a
- * valid pointer. */
- for (i = sizeof(uintptr_t)*CHAR_BIT - 1; i > 0; i--) {
- if ((uintptr_t)p & ((uintptr_t)1 << i))
- break;
- }
-
- ht->common_mask = ~((uintptr_t)1 << i);
+ ht->common_mask = -1;
ht->common_bits = ((uintptr_t)p & ht->common_mask);
- ht->perfect_bit = 1;
+ ht->perfect_bitnum = 0;
(void)htable_debug(ht, HTABLE_LOC);
return;
}
/* Find bits which are unequal to old common set. */
maskdiff = ht->common_bits ^ ((uintptr_t)p & ht->common_mask);
- /* These are the bits which go there in existing entries. */
- bitsdiff = ht->common_bits & maskdiff;
-
- for (i = 0; i < (size_t)1 << ht->bits; i++) {
- if (!entry_is_valid(ht->table[i]))
- continue;
- /* Clear the bits no longer in the mask, set them as
- * expected. */
- ht->table[i] &= ~maskdiff;
- ht->table[i] |= bitsdiff;
- }
-
- /* Take away those bits from our mask, bits and perfect bit. */
- ht->common_mask &= ~maskdiff;
- ht->common_bits &= ~maskdiff;
- ht->perfect_bit &= ~maskdiff;
+ fixup_table_common(ht, maskdiff);
(void)htable_debug(ht, HTABLE_LOC);
}
bool htable_add_(struct htable *ht, size_t hash, const void *p)
{
- if (ht->elems+1 > ht_max(ht) && !double_table(ht))
- return false;
- if (ht->elems+1 + ht->deleted > ht_max_with_deleted(ht))
- rehash_table(ht);
+ /* Cannot insert NULL, or (void *)1. */
assert(p);
+ assert(entry_is_valid((uintptr_t)p));
+
+ /* Getting too full? */
+ if (ht->elems+1 + ht->deleted > ht_max(ht)) {
+ /* If we're more than 1/8 deleted, clean those,
+ * otherwise double table size. */
+ if (ht->deleted > ht_max_deleted(ht))
+ rehash_table(ht);
+ else if (!double_table(ht))
+ return false;
+ }
if (((uintptr_t)p & ht->common_mask) != ht->common_bits)
update_common(ht, p);
assert(entry_is_valid(ht->table[i->off]));
ht->elems--;
- ht->table[i->off] = HTABLE_DELETED;
- ht->deleted++;
+ /* Cheap test: if the next bucket is empty, don't need delete marker */
+ if (ht->table[hash_bucket(ht, i->off+1)] != 0) {
+ ht->table[i->off] = HTABLE_DELETED;
+ ht->deleted++;
+ } else
+ ht->table[i->off] = 0;
+}
+
+void *htable_pick_(const struct htable *ht, size_t seed, struct htable_iter *i)
+{
+ void *e;
+ struct htable_iter unwanted;
+
+ if (!i)
+ i = &unwanted;
+ i->off = seed % ((size_t)1 << ht->bits);
+ e = htable_next(ht, i);
+ if (!e)
+ e = htable_first(ht, i);
+ return e;
}
struct htable *htable_check(const struct htable *ht, const char *abortstr)
projects / ccan / blobdiff