Tools/TestWebKitAPI/Tests/WTF/BloomFilter.cpp

/*
 * Copyright (C) 2015 Apple Inc. All rights reserved.
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#include "config.h"

#include <wtf/BloomFilter.h>
#include <wtf/RandomNumber.h>
#include <wtf/SHA1.h>

namespace TestWebKitAPI {

static Vector<unsigned> generateRandomHashes(size_t hashCount)
{
    Vector<unsigned> hashes;
    for (unsigned i = 0; i < hashCount; ++i)
        hashes.append(static_cast<unsigned>(randomNumber() * std::numeric_limits<unsigned>::max()));
    return hashes;
}

static Vector<SHA1::Digest> generateRandomDigests(size_t hashCount)
{
    Vector<SHA1::Digest> hashes;
    SHA1 sha1;
    for (unsigned i = 0; i < hashCount; ++i) {
        double random = randomNumber();
        sha1.addBytes(reinterpret_cast<uint8_t*>(&random), sizeof(double));
        SHA1::Digest digest;
        sha1.computeHash(digest);
        hashes.append(digest);
    }
    return hashes;
}

TEST(WTF_BloomFilter, Basic)
{
    const unsigned hashCount = 1000;
    auto hashes = generateRandomHashes(hashCount);

    BloomFilter<16> filter;
    for (auto hash : hashes)
        filter.add(hash);

    for (auto hash : hashes)
        EXPECT_TRUE(filter.mayContain(hash));

    auto moreHashes = generateRandomHashes(hashCount);
    unsigned mayContainCount = 0;
    for (auto hash : moreHashes)
        mayContainCount += filter.mayContain(hash) ? 1 : 0;
    // False positive rate is ~0.09% so this should always be true.
    EXPECT_TRUE(mayContainCount < hashCount / 10);

    for (auto hash : moreHashes)
        filter.add(hash);

    for (auto hash : hashes)
        EXPECT_TRUE(filter.mayContain(hash));
    for (auto hash : moreHashes)
        EXPECT_TRUE(filter.mayContain(hash));
}

TEST(WTF_BloomFilter, BasicDigest)
{
    const unsigned hashCount = 1000;
    auto hashes = generateRandomDigests(hashCount);

    BloomFilter<20> filter;
    for (auto hash : hashes)
        filter.add(hash);

    for (auto hash : hashes)
        EXPECT_TRUE(filter.mayContain(hash));

    auto moreHashes = generateRandomDigests(hashCount);
    unsigned mayContainCount = 0;
    for (auto hash : moreHashes)
        mayContainCount += filter.mayContain(hash) ? 1 : 0;
    // False positive rate is ~0.000004% so this should always be true.
    EXPECT_TRUE(mayContainCount < hashCount / 10);

    for (auto hash : moreHashes)
        filter.add(hash);

    for (auto hash : hashes)
        EXPECT_TRUE(filter.mayContain(hash));
    for (auto hash : moreHashes)
        EXPECT_TRUE(filter.mayContain(hash));
}

TEST(WTF_BloomFilter, BasicCounting)
{
    const unsigned hashCount = 1000;
    auto hashes = generateRandomHashes(hashCount);

    CountingBloomFilter<16> filter;
    for (auto hash : hashes)
        filter.add(hash);

    for (auto hash : hashes)
        EXPECT_TRUE(filter.mayContain(hash));

    for (auto hash : hashes)
        filter.add(hash);

    for (auto hash : hashes)
        EXPECT_TRUE(filter.mayContain(hash));

    for (auto hash : hashes)
        filter.remove(hash);

    for (auto hash : hashes)
        EXPECT_TRUE(filter.mayContain(hash));

    auto moreHashes = generateRandomHashes(hashCount);
    unsigned mayContainCount = 0;
    for (auto hash : moreHashes)
        mayContainCount += filter.mayContain(hash) ? 1 : 0;
    // False positive rate is ~0.09% so this should always be true.
    EXPECT_TRUE(mayContainCount < hashCount / 10);

    for (auto hash : moreHashes)
        filter.add(hash);
    for (auto hash : hashes)
        filter.remove(hash);

    for (auto hash : moreHashes)
        EXPECT_TRUE(filter.mayContain(hash));

    for (auto hash : moreHashes)
        filter.remove(hash);

    for (auto hash : hashes)
        EXPECT_TRUE(!filter.mayContain(hash));
    for (auto hash : moreHashes)
        EXPECT_TRUE(!filter.mayContain(hash));
}

TEST(WTF_BloomFilter, Clear)
{
    const unsigned hashCount = 1000;
    auto hashes = generateRandomHashes(hashCount);

    BloomFilter<16> filter;
    for (auto hash : hashes)
        filter.add(hash);

    filter.clear();

    for (auto hash : hashes)
        EXPECT_TRUE(!filter.mayContain(hash));
}

TEST(WTF_BloomFilter, ClearCounting)
{
    const unsigned hashCount = 1000;
    auto hashes = generateRandomHashes(hashCount);

    CountingBloomFilter<16> filter;
    for (auto hash : hashes)
        filter.add(hash);
    for (auto hash : hashes)
        filter.add(hash);

    filter.clear();

    for (auto hash : hashes)
        EXPECT_TRUE(!filter.mayContain(hash));
}

TEST(WTF_BloomFilter, CountingOverflow)
{
    const unsigned hashCount = 1000;
    auto hashes = generateRandomHashes(hashCount);

    CountingBloomFilter<16> filter;
    for (auto hash : hashes)
        filter.add(hash);

    for (unsigned i = 0; i < filter.maximumCount() + 100; ++i)
        filter.add(hashes[0]);

    for (auto hash : hashes)
        EXPECT_TRUE(filter.mayContain(hash));

    for (auto hash : hashes)
        filter.remove(hash);

    unsigned mayContainCount = 0;
    for (auto hash : hashes) {
        if (hash == hashes[0])
            EXPECT_TRUE(filter.mayContain(hash));
        else
            mayContainCount += filter.mayContain(hash) ? 1 : 0;
    }
    // False positive rate should be very low.
    EXPECT_TRUE(mayContainCount < hashCount / 100);

    for (unsigned i = 0; i < filter.maximumCount() + 100; ++i)
        filter.remove(hashes[0]);

    // The bucket has overflowed and is stuck.
    EXPECT_TRUE(filter.mayContain(hashes[0]));
}

TEST(WTF_BloomFilter, Combine)
{
    const unsigned hashCount = 1000;
    auto hashes = generateRandomHashes(hashCount);

    BloomFilter<16> filter;
    for (auto hash : hashes)
        filter.add(hash);

    auto moreHashes = generateRandomHashes(hashCount);

    BloomFilter<16> anotherFilter;
    for (auto hash : moreHashes)
        anotherFilter.add(hash);

    filter.add(anotherFilter);

    for (auto hash : hashes)
        EXPECT_TRUE(filter.mayContain(hash));
    for (auto hash : moreHashes)
        EXPECT_TRUE(filter.mayContain(hash));
}

}