lib/bloom.c

#include <stdlib.h>

#include "bloom.h"
#include "../hash.h"
#include "../crc/xxhash.h"
#include "../crc/murmur3.h"
#include "../crc/crc32c.h"
#include "../crc/fnv.h"

struct bloom {
	uint64_t nentries;

	uint32_t *map;
};

#define BITS_PER_INDEX	(sizeof(uint32_t) * 8)
#define BITS_INDEX_MASK	(BITS_PER_INDEX - 1)

struct bloom_hash {
	unsigned int seed;
	uint32_t (*fn)(const void *, uint32_t, uint32_t);
};

static uint32_t bloom_crc32c(const void *buf, uint32_t len, uint32_t seed)
{
	return fio_crc32c(buf, len);
}

static uint32_t bloom_fnv(const void *buf, uint32_t len, uint32_t seed)
{
	return fnv(buf, len, seed);
}

#define BLOOM_SEED	0x8989

static struct bloom_hash hashes[] = {
	{
		.seed = BLOOM_SEED,
		.fn = jhash,
	},
	{
		.seed = BLOOM_SEED,
		.fn = XXH32,
	},
	{
		.seed = BLOOM_SEED,
		.fn = murmurhash3,
	},
	{
		.seed = BLOOM_SEED,
		.fn = bloom_crc32c,
	},
	{
		.seed = BLOOM_SEED,
		.fn = bloom_fnv,
	},
};

#define N_HASHES	5

struct bloom *bloom_new(uint64_t entries)
{
	struct bloom *b;
	size_t no_uints;

	crc32c_arm64_probe();
	crc32c_intel_probe();

	b = malloc(sizeof(*b));
	b->nentries = entries;
	no_uints = (entries + BITS_PER_INDEX - 1) / BITS_PER_INDEX;
	b->map = calloc(no_uints, sizeof(uint32_t));
	if (!b->map) {
		free(b);
		return NULL;
	}

	return b;
}

void bloom_free(struct bloom *b)
{
	free(b->map);
	free(b);
}

static bool __bloom_check(struct bloom *b, const void *data, unsigned int len,
			  bool set)
{
	uint32_t hash[N_HASHES];
	int i, was_set;

	for (i = 0; i < N_HASHES; i++) {
		hash[i] = hashes[i].fn(data, len, hashes[i].seed);
		hash[i] = hash[i] % b->nentries;
	}

	was_set = 0;
	for (i = 0; i < N_HASHES; i++) {
		const unsigned int index = hash[i] / BITS_PER_INDEX;
		const unsigned int bit = hash[i] & BITS_INDEX_MASK;

		if (b->map[index] & (1U << bit))
			was_set++;
		else if (set)
			b->map[index] |= 1U << bit;
		else
			break;
	}

	return was_set == N_HASHES;
}

bool bloom_set(struct bloom *b, uint32_t *data, unsigned int nwords)
{
	return __bloom_check(b, data, nwords * sizeof(uint32_t), true);
}

bool bloom_string(struct bloom *b, const char *data, unsigned int len,
		  bool set)
{
	return __bloom_check(b, data, len, set);
}