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rocksdb/util/dynamic_bloom.cc

50 lines
1.5 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);
}
}
DynamicBloom::DynamicBloom(uint32_t total_bits,
uint32_t cl_per_block,
uint32_t num_probes,
uint32_t (*hash_func)(const Slice& key))
: kBlocked(cl_per_block > 0),
kBitsPerBlock(std::min(cl_per_block, num_probes) * CACHE_LINE_SIZE * 8),
kTotalBits((kBlocked ? (total_bits + kBitsPerBlock - 1) / kBitsPerBlock
* kBitsPerBlock :
total_bits + 7) / 8 * 8),
kNumBlocks(kBlocked ? kTotalBits / kBitsPerBlock : 1),
kNumProbes(num_probes),
hash_func_(hash_func == nullptr ? &BloomHash : hash_func) {
assert(kBlocked ? kTotalBits > 0 : kTotalBits >= kBitsPerBlock);
assert(kNumProbes > 0);
uint32_t sz = kTotalBits / 8;
if (kBlocked) {
sz += CACHE_LINE_SIZE - 1;
}
raw_ = new unsigned char[sz]();
if (kBlocked) {
data_ = raw_ + CACHE_LINE_SIZE -
reinterpret_cast<uint64_t>(raw_) % CACHE_LINE_SIZE;
} else {
data_ = raw_;
}
}
} // rocksdb