Index: components/rappor/bloom_filter.cc |
diff --git a/components/rappor/bloom_filter.cc b/components/rappor/bloom_filter.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..a832fefefa978e7feaa4e2136bd5ea0fe4aeb464 |
--- /dev/null |
+++ b/components/rappor/bloom_filter.cc |
@@ -0,0 +1,50 @@ |
+// Copyright (c) 2013 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 <string> |
+ |
+#include "base/logging.h" |
+#include "components/rappor/bloom_filter.h" |
+#include "third_party/smhasher/src/MurmurHash3.h" |
+ |
+namespace { |
+ |
+// Distinct seeds are used to create unique hash functions for the bloom filter. |
+const uint32_t kHashSeedCount = 4; |
Alexei Svitkine (slow)
2014/01/09 19:23:09
You can probably get rid of kHashSeedCount and jus
Steven Holte
2014/01/09 22:03:01
Done.
|
+const uint32_t kHashSeeds[kHashSeedCount] = {0xd123957d, 0x6752fc9b, |
+ 0xcb6a0102, 0x1a82ea95}; |
+ |
+uint32_t MurmurHash3String(const std::string& str, uint32_t seed) { |
+ uint32_t output = 0; |
+ // This function is optimized for x86_32, but should work on any platform. |
+ MurmurHash3_x86_32(str.data(), str.size(), seed, &output); |
+ return output; |
+} |
+ |
+} // namespace |
+ |
+namespace rappor { |
+ |
+BloomFilter::BloomFilter(uint32_t bytes_size, uint32_t hash_count) |
+ : bytes_(bytes_size), hash_count_(hash_count) { |
+ DCHECK_LE(hash_count, kHashSeedCount); |
+} |
+ |
+BloomFilter::~BloomFilter() {} |
+ |
+void BloomFilter::AddString(const std::string& str) { |
+ for (size_t j = 0; j < hash_count_; ++j) { |
+ uint32_t index = MurmurHash3String(str, kHashSeeds[j]); |
+ uint32_t byte_index = (index / 8) % bytes_.size(); |
+ uint32_t bit_index = index % 8; |
+ bytes_[byte_index] |= 1 << bit_index; |
+ } |
+} |
+ |
+void BloomFilter::AddStrings(const std::vector<std::string>& strings) { |
+ for (size_t i = 0, len = strings.size(); i < len; ++i) |
Alexei Svitkine (slow)
2014/01/09 19:23:09
Nit: No need for |len|, just use |strings.size()|
Steven Holte
2014/01/09 22:03:01
Done.
|
+ AddString(strings[i]); |
+} |
+ |
+} // namespace rappor |