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rocksdb/util/dynamic_bloom.cc

60 lines
1.9 KiB

// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#include "dynamic_bloom.h"
#include <algorithm>
#include "port/port.h"
#include "rocksdb/slice.h"
#include "util/hash.h"
namespace rocksdb {
namespace {
static uint32_t BloomHash(const Slice& key) {
return Hash(key.data(), key.size(), 0xbc9f1d34);
}
uint32_t GetNumBlocks(uint32_t total_bits) {
uint32_t num_blocks = (total_bits + CACHE_LINE_SIZE * 8 - 1) /
(CACHE_LINE_SIZE * 8) * (CACHE_LINE_SIZE * 8);
// Make num_blocks an odd number to make sure more bits are involved
// when determining which block.
if (num_blocks % 2 == 0) {
num_blocks++;
}
return num_blocks;
}
}
DynamicBloom::DynamicBloom(uint32_t total_bits, uint32_t locality,
uint32_t num_probes,
uint32_t (*hash_func)(const Slice& key),
size_t huge_page_tlb_size, Logger* logger)
: kTotalBits(((locality > 0) ? GetNumBlocks(total_bits) : total_bits + 7) /
8 * 8),
kNumBlocks((locality > 0) ? kTotalBits / (CACHE_LINE_SIZE * 8) : 0),
kNumProbes(num_probes),
hash_func_(hash_func == nullptr ? &BloomHash : hash_func) {
assert(kNumBlocks > 0 || kTotalBits > 0);
assert(kNumProbes > 0);
uint32_t sz = kTotalBits / 8;
if (kNumBlocks > 0) {
sz += CACHE_LINE_SIZE - 1;
}
raw_ = reinterpret_cast<unsigned char*>(
arena_.AllocateAligned(sz, huge_page_tlb_size, logger));
memset(raw_, 0, sz);
if (kNumBlocks > 0 && (reinterpret_cast<uint64_t>(raw_) % CACHE_LINE_SIZE)) {
data_ = raw_ + CACHE_LINE_SIZE -
reinterpret_cast<uint64_t>(raw_) % CACHE_LINE_SIZE;
} else {
data_ = raw_;
}
}
} // rocksdb