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rocksdb/util/dynamic_bloom_test.cc

114 lines
2.9 KiB

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