diff options
Diffstat (limited to 'ccan/ccan/htable/htable.c')
-rw-r--r-- | ccan/ccan/htable/htable.c | 491 |
1 files changed, 491 insertions, 0 deletions
diff --git a/ccan/ccan/htable/htable.c b/ccan/ccan/htable/htable.c new file mode 100644 index 0000000..f631ffe --- /dev/null +++ b/ccan/ccan/htable/htable.c @@ -0,0 +1,491 @@ +/* Licensed under LGPLv2+ - see LICENSE file for details */ +#include <ccan/htable/htable.h> +#include <ccan/compiler/compiler.h> +#include <stdlib.h> +#include <stdio.h> +#include <limits.h> +#include <stdbool.h> +#include <assert.h> +#include <string.h> + +/* 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); +} + +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) +{ + return e & ht->common_mask; +} + +static inline void *get_raw_ptr(const struct htable *ht, uintptr_t e) +{ + return (void *)((e & ~ht->common_mask) | ht->common_bits); +} + +static inline uintptr_t make_hval(const struct htable *ht, + const void *p, uintptr_t bits) +{ + return ((uintptr_t)p & ~ht->common_mask) | bits; +} + +static inline bool entry_is_valid(uintptr_t e) +{ + 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) +{ + /* Shuffling the extra bits (as specified in mask) down the + * 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_mask(ht); +} + +void htable_init(struct htable *ht, + size_t (*rehash)(const void *elem, void *priv), void *priv) +{ + struct htable empty = HTABLE_INITIALIZER(empty, NULL, NULL); + *ht = empty; + ht->rehash = rehash; + ht->priv = priv; + ht->table = &ht->common_bits; +} + +/* Fill to 87.5% */ +static inline size_t ht_max(const struct htable *ht) +{ + return ((size_t)7 << ht->bits) / 8; +} + +/* 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)1 << ht->bits) / 8; +} + +bool htable_init_sized(struct htable *ht, + size_t (*rehash)(const void *, void *), + void *priv, size_t expect) +{ + htable_init(ht, rehash, priv); + + /* Don't go insane with sizing. */ + 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->common_bits; + return false; + } + (void)htable_debug(ht, HTABLE_LOC); + return true; +} + +void htable_clear(struct htable *ht) +{ + 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 = htable_alloc(dst, sizeof(size_t) << src->bits); + + if (!htable) + return false; + + *dst = *src; + dst->table = htable; + memcpy(dst->table, src->table, sizeof(size_t) << src->bits); + return true; +} + +static size_t hash_bucket(const struct htable *ht, size_t h) +{ + return h & ((1 << ht->bits)-1); +} + +static void *htable_val(const struct htable *ht, + struct htable_iter *i, size_t hash, uintptr_t perfect) +{ + uintptr_t h2 = get_hash_ptr_bits(ht, hash) | perfect; + + while (ht->table[i->off]) { + if (ht->table[i->off] != HTABLE_DELETED) { + if (get_extra_ptr_bits(ht, ht->table[i->off]) == h2) + return get_raw_ptr(ht, ht->table[i->off]); + } + i->off = (i->off + 1) & ((1 << ht->bits)-1); + h2 &= ~perfect; + } + return NULL; +} + +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_mask(ht)); +} + +void *htable_nextval_(const struct htable *ht, + struct htable_iter *i, size_t hash) +{ + i->off = (i->off + 1) & ((1 << ht->bits)-1); + return htable_val(ht, i, hash, 0); +} + +void *htable_first_(const struct htable *ht, struct htable_iter *i) +{ + for (i->off = 0; i->off < (size_t)1 << ht->bits; i->off++) { + if (entry_is_valid(ht->table[i->off])) + return get_raw_ptr(ht, ht->table[i->off]); + } + return NULL; +} + +void *htable_next_(const struct htable *ht, struct htable_iter *i) +{ + for (i->off++; i->off < (size_t)1 << ht->bits; i->off++) { + if (entry_is_valid(ht->table[i->off])) + return get_raw_ptr(ht, ht->table[i->off]); + } + return NULL; +} + +void *htable_prev_(const struct htable *ht, struct htable_iter *i) +{ + for (;;) { + if (!i->off) + return NULL; + 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_mask(ht); + + i = hash_bucket(ht, h); + + while (entry_is_valid(ht->table[i])) { + perfect = 0; + 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) +{ + unsigned int i; + size_t oldnum = (size_t)1 << ht->bits; + uintptr_t *oldtable, e; + + oldtable = ht->table; + ht->table = htable_alloc(ht, sizeof(size_t) << (ht->bits+1)); + if (!ht->table) { + ht->table = oldtable; + return false; + } + ht->bits++; + + /* If we lost our "perfect bit", get it back now. */ + 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)2 << i)) { + ht->perfect_bitnum = i; + break; + } + } + } + + 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)); + } + } + htable_free(ht, oldtable); + } + ht->deleted = 0; + + (void)htable_debug(ht, HTABLE_LOC); + return true; +} + +static COLD void rehash_table(struct htable *ht) +{ + size_t start, i; + 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++); + + for (i = 0; i < (size_t)1 << ht->bits; i++) { + size_t h = (i + start) & ((1 << ht->bits)-1); + e = ht->table[h]; + if (!e) + continue; + if (e == HTABLE_DELETED) + ht->table[h] = 0; + else if (!(e & perfect)) { + void *p = get_raw_ptr(ht, e); + ht->table[h] = 0; + ht_add(ht, p, ht->rehash(p, ht->priv)); + } + } + ht->deleted = 0; + (void)htable_debug(ht, HTABLE_LOC); +} + +/* We stole some bits, now we need to put them back... */ +static COLD void update_common(struct htable *ht, const void *p) +{ + uintptr_t maskdiff; + + if (ht->elems == 0) { + ht->common_mask = -1; + ht->common_bits = ((uintptr_t)p & ht->common_mask); + 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); + + fixup_table_common(ht, maskdiff); + (void)htable_debug(ht, HTABLE_LOC); +} + +bool htable_add_(struct htable *ht, size_t hash, const void *p) +{ + /* 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); + + ht_add(ht, p, hash); + ht->elems++; + return true; +} + +bool htable_del_(struct htable *ht, size_t h, const void *p) +{ + struct htable_iter i; + void *c; + + for (c = htable_firstval(ht,&i,h); c; c = htable_nextval(ht,&i,h)) { + if (c == p) { + htable_delval(ht, &i); + return true; + } + } + return false; +} + +void htable_delval_(struct htable *ht, struct htable_iter *i) +{ + assert(i->off < (size_t)1 << ht->bits); + assert(entry_is_valid(ht->table[i->off])); + + ht->elems--; + /* 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) +{ + void *p; + struct htable_iter i; + size_t n = 0; + + /* Use non-DEBUG versions here, to avoid infinite recursion with + * CCAN_HTABLE_DEBUG! */ + for (p = htable_first_(ht, &i); p; p = htable_next_(ht, &i)) { + struct htable_iter i2; + void *c; + size_t h = ht->rehash(p, ht->priv); + bool found = false; + + n++; + + /* Open-code htable_get to avoid CCAN_HTABLE_DEBUG */ + for (c = htable_firstval_(ht, &i2, h); + c; + c = htable_nextval_(ht, &i2, h)) { + if (c == p) { + found = true; + break; + } + } + + if (!found) { + if (abortstr) { + fprintf(stderr, + "%s: element %p in position %zu" + " cannot find itself\n", + abortstr, p, i.off); + abort(); + } + return NULL; + } + } + if (n != ht->elems) { + if (abortstr) { + fprintf(stderr, + "%s: found %zu elems, expected %zu\n", + abortstr, n, ht->elems); + abort(); + } + return NULL; + } + + return (struct htable *)ht; +} |