mirror of https://github.com/facebook/rocksdb.git
114 lines
2.9 KiB
C++
114 lines
2.9 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#include <gflags/gflags.h>
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#include "dynamic_bloom.h"
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#include "util/logging.h"
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#include "util/testharness.h"
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#include "util/testutil.h"
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DEFINE_int32(bits_per_key, 10, "");
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DEFINE_int32(num_probes, 6, "");
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namespace rocksdb {
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static Slice Key(int i, char* buffer) {
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memcpy(buffer, &i, sizeof(i));
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return Slice(buffer, sizeof(i));
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}
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class DynamicBloomTest {
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};
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TEST(DynamicBloomTest, EmptyFilter) {
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DynamicBloom bloom(100, 2);
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ASSERT_TRUE(! bloom.MayContain("hello"));
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ASSERT_TRUE(! bloom.MayContain("world"));
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}
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TEST(DynamicBloomTest, Small) {
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DynamicBloom bloom(100, 2);
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bloom.Add("hello");
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bloom.Add("world");
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ASSERT_TRUE(bloom.MayContain("hello"));
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ASSERT_TRUE(bloom.MayContain("world"));
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ASSERT_TRUE(! bloom.MayContain("x"));
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ASSERT_TRUE(! bloom.MayContain("foo"));
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}
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static int NextLength(int length) {
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if (length < 10) {
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length += 1;
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} else if (length < 100) {
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length += 10;
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} else if (length < 1000) {
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length += 100;
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} else {
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length += 1000;
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}
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return length;
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}
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TEST(DynamicBloomTest, VaryingLengths) {
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char buffer[sizeof(int)];
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// Count number of filters that significantly exceed the false positive rate
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int mediocre_filters = 0;
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int good_filters = 0;
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fprintf(stderr, "bits_per_key: %d num_probes: %d\n",
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FLAGS_bits_per_key, FLAGS_num_probes);
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for (int length = 1; length <= 10000; length = NextLength(length)) {
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uint32_t bloom_bits = std::max(length * FLAGS_bits_per_key, 64);
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DynamicBloom bloom(bloom_bits, FLAGS_num_probes);
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for (int i = 0; i < length; i++) {
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bloom.Add(Key(i, buffer));
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ASSERT_TRUE(bloom.MayContain(Key(i, buffer)));
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}
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// All added keys must match
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for (int i = 0; i < length; i++) {
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ASSERT_TRUE(bloom.MayContain(Key(i, buffer)))
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<< "Length " << length << "; key " << i;
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}
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// Check false positive rate
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int result = 0;
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for (int i = 0; i < 10000; i++) {
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if (bloom.MayContain(Key(i + 1000000000, buffer))) {
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result++;
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}
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}
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double rate = result / 10000.0;
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fprintf(stderr, "False positives: %5.2f%% @ length = %6d ; \n",
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rate*100.0, length);
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//ASSERT_LE(rate, 0.02); // Must not be over 2%
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if (rate > 0.0125)
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mediocre_filters++; // Allowed, but not too often
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else
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good_filters++;
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}
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fprintf(stderr, "Filters: %d good, %d mediocre\n",
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good_filters, mediocre_filters);
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ASSERT_LE(mediocre_filters, good_filters/5);
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}
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// Different bits-per-byte
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} // namespace rocksdb
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int main(int argc, char** argv) {
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google::ParseCommandLineFlags(&argc, &argv, true);
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return rocksdb::test::RunAllTests();
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}
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