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| 1 // Copyright 2014 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #include "components/rappor/bloom_filter.h" |
| 6 |
| 7 #include "base/logging.h" |
| 8 |
| 9 // TODO(holte): we can't include "City.h" due to typedef conflicts. |
| 10 extern uint64 CityHash64WithSeed(const char *buf, size_t len, uint64 seed); |
| 11 |
| 12 namespace rappor { |
| 13 |
| 14 BloomFilter::BloomFilter(uint32_t bytes_size, |
| 15 uint32_t hash_function_count, |
| 16 uint32_t hash_seed_offset) |
| 17 : bytes_(bytes_size), |
| 18 hash_function_count_(hash_function_count), |
| 19 hash_seed_offset_(hash_seed_offset) { |
| 20 DCHECK_GT(bytes_size, 0u); |
| 21 } |
| 22 |
| 23 BloomFilter::~BloomFilter() {} |
| 24 |
| 25 void BloomFilter::AddString(const std::string& str) { |
| 26 for (size_t i = 0; i < hash_function_count_; ++i) { |
| 27 // Using CityHash here because we have support for it in Dremel. |
| 28 uint32_t index = |
| 29 CityHash64WithSeed(str.data(), str.size(), hash_seed_offset_ + i); |
| 30 // Note that the "bytes" are uint8_t, so they are always 8-bits. |
| 31 uint32_t byte_index = (index / 8) % bytes_.size(); |
| 32 uint32_t bit_index = index % 8; |
| 33 bytes_[byte_index] |= 1 << bit_index; |
| 34 } |
| 35 } |
| 36 |
| 37 } // namespace rappor |
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