| // 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. |
| |
| #ifndef COMPONENTS_RAPPOR_BLOOM_FILTER_H_ |
| #define COMPONENTS_RAPPOR_BLOOM_FILTER_H_ |
| |
| #include <string> |
| |
| #include "base/basictypes.h" |
| #include "base/macros.h" |
| #include "components/rappor/byte_vector_utils.h" |
| |
| namespace rappor { |
| |
| // BloomFilter is a simple Bloom filter for keeping track of a set of strings. |
| class BloomFilter { |
| public: |
| // Constructs a BloomFilter using |bytes_size| bytes of Bloom filter bits, |
| // and |hash_function_count| hash functions to set bits in the filter. The |
| // hash functions will be generated by using seeds in the range |
| // |hash_seed_offset| to (|hash_seed_offset| + |hash_function_count|). |
| BloomFilter(uint32_t bytes_size, |
| uint32_t hash_function_count, |
| uint32_t hash_seed_offset); |
| ~BloomFilter(); |
| |
| // Sets the Bloom filter bits to contain a single string. |
| void SetString(const std::string& str); |
| |
| // Returns the current value of the Bloom filter's bit array. |
| const ByteVector& bytes() const { return bytes_; }; |
| |
| // Sets bytes for testing purposes. |
| void SetBytesForTesting(const ByteVector& bytes); |
| |
| private: |
| // Stores the byte array of the Bloom filter. |
| ByteVector bytes_; |
| |
| // The number of bits to set for each string added. |
| uint32_t hash_function_count_; |
| |
| // A number add to a hash function index to get a seed for that hash function. |
| uint32_t hash_seed_offset_; |
| |
| DISALLOW_COPY_AND_ASSIGN(BloomFilter); |
| }; |
| |
| |
| namespace internal { |
| |
| // A function for getting bloom filters less than or equal to 64 bits. |
| uint64_t GetBloomBits(uint32_t bytes_size, |
| uint32_t hash_function_count, |
| uint32_t hash_seed_offset, |
| const std::string& str); |
| |
| } // namespace internal |
| |
| } // namespace rappor |
| |
| #endif // COMPONENTS_RAPPOR_BLOOM_FILTER_H_ |