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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/rappor/bloom_filter.h"
#include "base/logging.h"
#include "third_party/smhasher/src/City.h"
namespace rappor {
BloomFilter::BloomFilter(uint32_t bytes_size,
uint32_t hash_function_count,
uint32_t hash_seed_offset)
: bytes_(bytes_size),
hash_function_count_(hash_function_count),
hash_seed_offset_(hash_seed_offset) {
DCHECK_GT(bytes_size, 0u);
}
BloomFilter::~BloomFilter() {}
void BloomFilter::SetString(const std::string& str) {
for (size_t i = 0; i < bytes_.size(); ++i) {
bytes_[i] = 0;
}
for (size_t i = 0; i < hash_function_count_; ++i) {
// Using CityHash here because we have support for it in Dremel. Many hash
// functions, such as MD5, SHA1, or Murmur, would probably also work.
uint32_t index =
CityHash64WithSeed(str.data(), str.size(), hash_seed_offset_ + i);
// Note that the "bytes" are uint8_t, so they are always 8-bits.
uint32_t byte_index = (index / 8) % bytes_.size();
uint32_t bit_index = index % 8;
bytes_[byte_index] |= 1 << bit_index;
}
}
void BloomFilter::SetBytesForTesting(const ByteVector& bytes) {
DCHECK_EQ(bytes_.size(), bytes.size());
for (size_t i = 0; i < bytes_.size(); ++i) {
bytes_[i] = bytes[i];
}
}
} // namespace rappor
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