X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Fhtable%2Fhtable.c;h=e1d13699ea85811fe2f61adbb1ce4eca942406c8;hp=bbd4fa96e587c64a04446756787bd163ad4dc3c8;hb=e0b86f0ca416d757684e6d98532e1fadf839b830;hpb=d3104024f71cf4f89195787add6c7ac381d62f40 diff --git a/ccan/htable/htable.c b/ccan/htable/htable.c index bbd4fa96..e1d13699 100644 --- a/ccan/htable/htable.c +++ b/ccan/htable/htable.c @@ -1,28 +1,15 @@ +/* Licensed under LGPLv2+ - see LICENSE file for details */ #include #include -#include #include #include #include #include - -/* This means a struct htable takes at least 512 bytes / 1k (32/64 bits). */ -#define HTABLE_BASE_BITS 7 +#include /* We use 0x1 as deleted marker. */ #define HTABLE_DELETED (0x1) -struct htable { - size_t (*rehash)(const void *elem, void *priv); - void *priv; - unsigned int bits; - size_t elems, deleted, max, max_with_deleted; - /* These are the bits which are the same in all pointers. */ - uintptr_t common_mask, common_bits; - uintptr_t perfect_bit; - uintptr_t *table; -}; - /* 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) @@ -56,35 +43,62 @@ static inline uintptr_t get_hash_ptr_bits(const struct htable *ht, & ht->common_mask & ~ht->perfect_bit; } -struct htable *htable_new(size_t (*rehash)(const void *elem, void *priv), - void *priv) +void htable_init(struct htable *ht, + size_t (*rehash)(const void *elem, void *priv), void *priv) { - struct htable *ht = malloc(sizeof(struct htable)); - if (ht) { - ht->bits = HTABLE_BASE_BITS; - ht->rehash = rehash; - ht->priv = priv; - ht->elems = 0; - ht->deleted = 0; - ht->max = (1 << ht->bits) * 2 / 3; - ht->max_with_deleted = (1 << ht->bits) * 4 / 5; - /* This guarantees we enter update_common first add. */ - ht->common_mask = -1; - ht->common_bits = 0; - ht->perfect_bit = 0; - ht->table = calloc(1 << ht->bits, sizeof(uintptr_t)); - if (!ht->table) { - free(ht); - ht = NULL; - } + struct htable empty = HTABLE_INITIALIZER(empty, NULL, NULL); + *ht = empty; + ht->rehash = rehash; + ht->priv = priv; + ht->table = &ht->perfect_bit; +} + +/* We've changed ht->bits, update ht->max and ht->max_with_deleted */ +static void htable_adjust_capacity(struct htable *ht) +{ + ht->max = ((size_t)3 << ht->bits) / 4; + ht->max_with_deleted = ((size_t)9 << ht->bits) / 10; +} + +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; ((size_t)3 << ht->bits) / 4 < expect; ht->bits++) { + if (ht->bits == 30) + break; + } + + ht->table = calloc(1 << ht->bits, sizeof(size_t)); + if (!ht->table) { + ht->table = &ht->perfect_bit; + return false; } - return ht; + htable_adjust_capacity(ht); + return true; +} + +void htable_clear(struct htable *ht) +{ + if (ht->table != &ht->perfect_bit) + free((void *)ht->table); + htable_init(ht, ht->rehash, ht->priv); } -void htable_free(const struct htable *ht) +bool htable_copy(struct htable *dst, const struct htable *src) { - free((void *)ht->table); - free((void *)ht); + uintptr_t *htable = malloc(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) @@ -140,6 +154,17 @@ void *htable_next(const struct htable *ht, struct htable_iter *i) 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]); + } +} + /* 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) { @@ -155,7 +180,7 @@ static void ht_add(struct htable *ht, const void *new, size_t h) ht->table[i] = make_hval(ht, new, get_hash_ptr_bits(ht, h)|perfect); } -static COLD_ATTRIBUTE bool double_table(struct htable *ht) +static COLD bool double_table(struct htable *ht) { unsigned int i; size_t oldnum = (size_t)1 << ht->bits; @@ -168,8 +193,7 @@ static COLD_ATTRIBUTE bool double_table(struct htable *ht) return false; } ht->bits++; - ht->max *= 2; - ht->max_with_deleted *= 2; + htable_adjust_capacity(ht); /* If we lost our "perfect bit", get it back now. */ if (!ht->perfect_bit && ht->common_mask) { @@ -181,18 +205,20 @@ static COLD_ATTRIBUTE bool double_table(struct htable *ht) } } - 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)); + if (oldtable != &ht->perfect_bit) { + 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); } ht->deleted = 0; - free(oldtable); return true; } -static COLD_ATTRIBUTE void rehash_table(struct htable *ht) +static COLD void rehash_table(struct htable *ht) { size_t start, i; uintptr_t e; @@ -217,14 +243,23 @@ static COLD_ATTRIBUTE void rehash_table(struct htable *ht) } /* We stole some bits, now we need to put them back... */ -static COLD_ATTRIBUTE void update_common(struct htable *ht, const void *p) +static COLD void update_common(struct htable *ht, const void *p) { unsigned int i; uintptr_t maskdiff, bitsdiff; if (ht->elems == 0) { - ht->common_mask = -1; - ht->common_bits = (uintptr_t)p; + /* 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_bits = ((uintptr_t)p & ht->common_mask); ht->perfect_bit = 1; return; }