| 1 | #include <stdlib.h> |
| 2 | #include <inttypes.h> |
| 3 | |
| 4 | #include "bloom.h" |
| 5 | #include "../hash.h" |
| 6 | #include "../minmax.h" |
| 7 | #include "../crc/xxhash.h" |
| 8 | #include "../crc/murmur3.h" |
| 9 | |
| 10 | struct bloom { |
| 11 | uint64_t nentries; |
| 12 | |
| 13 | uint32_t *map; |
| 14 | }; |
| 15 | |
| 16 | #define BITS_PER_INDEX (sizeof(uint32_t) * 8) |
| 17 | #define BITS_INDEX_MASK (BITS_PER_INDEX - 1) |
| 18 | |
| 19 | struct bloom_hash { |
| 20 | unsigned int seed; |
| 21 | uint32_t (*fn)(const void *, uint32_t, uint32_t); |
| 22 | }; |
| 23 | |
| 24 | struct bloom_hash hashes[] = { |
| 25 | { |
| 26 | .seed = 0x8989, |
| 27 | .fn = jhash, |
| 28 | }, |
| 29 | { |
| 30 | .seed = 0x8989, |
| 31 | .fn = XXH32, |
| 32 | }, |
| 33 | { |
| 34 | .seed = 0x8989, |
| 35 | .fn = murmurhash3, |
| 36 | }, |
| 37 | }; |
| 38 | |
| 39 | #define N_HASHES 3 |
| 40 | |
| 41 | #define MIN_ENTRIES 1073741824UL |
| 42 | |
| 43 | struct bloom *bloom_new(uint64_t entries) |
| 44 | { |
| 45 | struct bloom *b; |
| 46 | size_t no_uints; |
| 47 | |
| 48 | b = malloc(sizeof(*b)); |
| 49 | b->nentries = entries; |
| 50 | no_uints = (entries + BITS_PER_INDEX - 1) / BITS_PER_INDEX; |
| 51 | no_uints = max((unsigned long) no_uints, MIN_ENTRIES); |
| 52 | b->map = calloc(no_uints, sizeof(uint32_t)); |
| 53 | if (!b->map) { |
| 54 | free(b); |
| 55 | return NULL; |
| 56 | } |
| 57 | |
| 58 | return b; |
| 59 | } |
| 60 | |
| 61 | void bloom_free(struct bloom *b) |
| 62 | { |
| 63 | free(b->map); |
| 64 | free(b); |
| 65 | } |
| 66 | |
| 67 | static int __bloom_check(struct bloom *b, uint32_t *data, unsigned int nwords, |
| 68 | int set) |
| 69 | { |
| 70 | uint32_t hash[N_HASHES]; |
| 71 | int i, was_set; |
| 72 | |
| 73 | for (i = 0; i < N_HASHES; i++) { |
| 74 | hash[i] = hashes[i].fn(data, nwords, hashes[i].seed); |
| 75 | hash[i] = hash[i] % b->nentries; |
| 76 | } |
| 77 | |
| 78 | was_set = 0; |
| 79 | for (i = 0; i < N_HASHES; i++) { |
| 80 | const unsigned int index = hash[i] / BITS_PER_INDEX; |
| 81 | const unsigned int bit = hash[i] & BITS_INDEX_MASK; |
| 82 | |
| 83 | if (b->map[index] & (1U << bit)) |
| 84 | was_set++; |
| 85 | if (set) |
| 86 | b->map[index] |= 1U << bit; |
| 87 | } |
| 88 | |
| 89 | return was_set == N_HASHES; |
| 90 | } |
| 91 | |
| 92 | int bloom_check(struct bloom *b, uint32_t *data, unsigned int nwords) |
| 93 | { |
| 94 | return __bloom_check(b, data, nwords, 0); |
| 95 | } |
| 96 | |
| 97 | int bloom_set(struct bloom *b, uint32_t *data, unsigned int nwords) |
| 98 | { |
| 99 | return __bloom_check(b, data, nwords, 1); |
| 100 | } |