be/test/util/rle_encoding_test.cpp

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

#include <algorithm>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <limits>
#include <ostream>
#include <string>
#include <vector>

// Must come before gtest.h.
#include <glog/logging.h>
#include <gtest/gtest.h>

#include <boost/utility/binary.hpp>

#include "util/bit_stream_utils.h"
#include "util/bit_stream_utils.inline.h"
#include "util/bit_util.h"
#include "util/debug_util.h"
#include "util/faststring.h"
#include "util/rle_encoding.h"
#include "test_util/test_util.h"

using std::string;
using std::vector;

namespace doris {

const int kMaxWidth = 64;

class TestRle : public testing::Test {};
// Validates encoding of values by encoding and decoding them.  If
// expected_encoding != NULL, also validates that the encoded buffer is
// exactly 'expected_encoding'.
// if expected_len is not -1, it will validate the encoded size is correct.
template <typename T>
void ValidateRle(const std::vector<T>& values, int bit_width, uint8_t* expected_encoding,
                 int expected_len) {
    faststring buffer;
    RleEncoder<T> encoder(&buffer, bit_width);

    for (const auto& value : values) {
        encoder.Put(value);
    }
    int encoded_len = encoder.Flush();

    if (expected_len != -1) {
        EXPECT_EQ(encoded_len, expected_len);
    }
    if (expected_encoding != nullptr) {
        EXPECT_EQ(memcmp(buffer.data(), expected_encoding, expected_len), 0)
                << "\n"
                << "Expected: " << hexdump((const char*)expected_encoding, expected_len) << "\n"
                << "Got:      " << hexdump((const char*)buffer.data(), buffer.size());
    }

    // Verify read
    RleDecoder<T> decoder(buffer.data(), encoded_len, bit_width);
    for (const auto& value : values) {
        T val = 0;
        bool result = decoder.Get(&val);
        EXPECT_TRUE(result);
        EXPECT_EQ(value, val);
    }
}

TEST(Rle, SpecificSequences) {
    const int kTestLen = 1024;
    uint8_t expected_buffer[kTestLen];
    std::vector<uint64_t> values;

    // Test 50 0' followed by 50 1's
    values.resize(100);
    for (int i = 0; i < 50; ++i) {
        values[i] = 0;
    }
    for (int i = 50; i < 100; ++i) {
        values[i] = 1;
    }

    // expected_buffer valid for bit width <= 1 byte
    expected_buffer[0] = (50 << 1);
    expected_buffer[1] = 0;
    expected_buffer[2] = (50 << 1);
    expected_buffer[3] = 1;
    for (int width = 1; width <= 8; ++width) {
        ValidateRle(values, width, expected_buffer, 4);
    }

    for (int width = 9; width <= kMaxWidth; ++width) {
        ValidateRle(values, width, nullptr, 2 * (1 + BitUtil::Ceil(width, 8)));
    }

    // Test 100 0's and 1's alternating
    for (int i = 0; i < 100; ++i) {
        values[i] = i % 2;
    }
    int num_groups = BitUtil::Ceil(100, 8);
    expected_buffer[0] = (num_groups << 1) | 1;
    for (int i = 0; i < 100 / 8; ++i) {
        expected_buffer[i + 1] = BOOST_BINARY(1 0 1 0 1 0 1 0); // 0xaa
    }
    // Values for the last 4 0 and 1's
    expected_buffer[1 + 100 / 8] = BOOST_BINARY(0 0 0 0 1 0 1 0); // 0x0a

    // num_groups and expected_buffer only valid for bit width = 1
    ValidateRle(values, 1, expected_buffer, 1 + num_groups);
    for (int width = 2; width <= kMaxWidth; ++width) {
        ValidateRle(values, width, nullptr, 1 + BitUtil::Ceil(width * 100, 8));
    }
}

// ValidateRle on 'num_vals' values with width 'bit_width'. If 'value' != -1, that value
// is used, otherwise alternating values are used.
void TestRleValues(int bit_width, int num_vals, int value = -1) {
    const uint64_t mod = bit_width == 64 ? 1ULL : 1ULL << bit_width;
    std::vector<uint64_t> values;
    for (uint64_t v = 0; v < num_vals; ++v) {
        values.push_back((value != -1) ? value : (bit_width == 64 ? v : (v % mod)));
    }
    ValidateRle(values, bit_width, nullptr, -1);
}

TEST(Rle, TestValues) {
    for (int width = 1; width <= kMaxWidth; ++width) {
        TestRleValues(width, 1);
        TestRleValues(width, 1024);
        TestRleValues(width, 1024, 0);
        TestRleValues(width, 1024, 1);
    }
}

class BitRle : public testing::Test {
public:
    BitRle() {}

    virtual ~BitRle() {}
};

// Tests all true/false values
TEST_F(BitRle, AllSame) {
    const int kTestLen = 1024;
    std::vector<bool> values;

    for (int v = 0; v < 2; ++v) {
        values.clear();
        for (int i = 0; i < kTestLen; ++i) {
            values.push_back(v ? true : false);
        }

        ValidateRle(values, 1, nullptr, 3);
    }
}

// Test that writes out a repeated group and then a literal
// group but flush before finishing.
TEST_F(BitRle, Flush) {
    std::vector<bool> values;
    for (int i = 0; i < 16; ++i) values.push_back(1);
    values.push_back(false);
    ValidateRle(values, 1, nullptr, -1);
    values.push_back(true);
    ValidateRle(values, 1, nullptr, -1);
    values.push_back(true);
    ValidateRle(values, 1, nullptr, -1);
    values.push_back(true);
    ValidateRle(values, 1, nullptr, -1);
}

// Test some random bool sequences.
TEST_F(BitRle, RandomBools) {
    int iters = 0;
    const int n_iters = LOOP_LESS_OR_MORE(5, 20);
    while (iters < n_iters) {
        srand(iters++);
        if (iters % 10000 == 0) LOG(ERROR) << "Seed: " << iters;
        std::vector<uint64_t> values;
        bool parity = 0;
        for (int i = 0; i < 1000; ++i) {
            int group_size = rand() % 20 + 1; // NOLINT(*)
            if (group_size > 16) {
                group_size = 1;
            }
            for (int i = 0; i < group_size; ++i) {
                values.push_back(parity);
            }
            parity = !parity;
        }
        ValidateRle(values, (iters % kMaxWidth) + 1, nullptr, -1);
    }
}

// Test some random 64-bit sequences.
TEST_F(BitRle, Random64Bit) {
    int iters = 0;
    const int n_iters = LOOP_LESS_OR_MORE(5, 20);
    while (iters < n_iters) {
        srand(iters++);
        if (iters % 10000 == 0) LOG(ERROR) << "Seed: " << iters;
        std::vector<uint64_t> values;
        for (int i = 0; i < LOOP_LESS_OR_MORE(10, 1000); ++i) {
            int group_size = rand() % 20 + 1; // NOLINT(*)
            uint64_t cur_value =
                    (static_cast<uint64_t>(rand()) << 32) + static_cast<uint64_t>(rand());
            if (group_size > 16) {
                group_size = 1;
            }
            for (int i = 0; i < group_size; ++i) {
                values.push_back(cur_value);
            }
        }
        ValidateRle(values, 64, nullptr, -1);
    }
}

// Test a sequence of 1 0's, 2 1's, 3 0's. etc
// e.g. 011000111100000
TEST_F(BitRle, RepeatedPattern) {
    std::vector<bool> values;
    const int min_run = 1;
    const int max_run = 32;

    for (int i = min_run; i <= max_run; ++i) {
        int v = i % 2;
        for (int j = 0; j < i; ++j) {
            values.push_back(v);
        }
    }

    // And go back down again
    for (int i = max_run; i >= min_run; --i) {
        int v = i % 2;
        for (int j = 0; j < i; ++j) {
            values.push_back(v);
        }
    }

    ValidateRle(values, 1, nullptr, -1);
}

TEST_F(TestRle, TestBulkPut) {
    size_t run_length;
    bool val = false;

    faststring buffer(1);
    RleEncoder<bool> encoder(&buffer, 1);
    encoder.Put(true, 10);
    encoder.Put(false, 7);
    encoder.Put(true, 5);
    encoder.Put(true, 15);
    encoder.Flush();

    RleDecoder<bool> decoder(buffer.data(), encoder.len(), 1);
    run_length = decoder.GetNextRun(&val, std::numeric_limits<std::size_t>::max());
    ASSERT_TRUE(val);
    ASSERT_EQ(10, run_length);

    run_length = decoder.GetNextRun(&val, std::numeric_limits<std::size_t>::max());
    ASSERT_FALSE(val);
    ASSERT_EQ(7, run_length);

    run_length = decoder.GetNextRun(&val, std::numeric_limits<std::size_t>::max());
    ASSERT_TRUE(val);
    ASSERT_EQ(20, run_length);

    ASSERT_EQ(0, decoder.GetNextRun(&val, std::numeric_limits<std::size_t>::max()));
}

TEST_F(TestRle, TestGetNextRun) {
    // Repeat the test with different number of items
    for (int num_items = 7; num_items < 200; num_items += 13) {
        // Test different block patterns
        //    1: 01010101 01010101
        //    2: 00110011 00110011
        //    3: 00011100 01110001
        //    ...
        for (int block = 1; block <= 20; ++block) {
            faststring buffer(1);
            RleEncoder<bool> encoder(&buffer, 1);
            for (int j = 0; j < num_items; ++j) {
                encoder.Put(!!(j & 1), block);
            }
            encoder.Flush();

            RleDecoder<bool> decoder(buffer.data(), encoder.len(), 1);
            size_t count = num_items * block;
            for (int j = 0; j < num_items; ++j) {
                size_t run_length;
                bool val = false;
                DCHECK_GT(count, 0);
                run_length = decoder.GetNextRun(&val, std::numeric_limits<std::size_t>::max());
                run_length = std::min(run_length, count);

                ASSERT_EQ(!!(j & 1), val);
                ASSERT_EQ(block, run_length);
                count -= run_length;
            }
            DCHECK_EQ(count, 0);
        }
    }
}

// Generate a random bit string which consists of 'num_runs' runs,
// each with a random length between 1 and 100. Returns the number
// of values encoded (i.e the sum run length).
static size_t GenerateRandomBitString(int num_runs, faststring* enc_buf, string* string_rep) {
    RleEncoder<bool> enc(enc_buf, 1);
    int num_bits = 0;
    for (int i = 0; i < num_runs; i++) {
        int run_length = random() % 100;
        bool value = static_cast<bool>(i & 1);
        enc.Put(value, run_length);
        string_rep->append(run_length, value ? '1' : '0');
        num_bits += run_length;
    }
    enc.Flush();
    return num_bits;
}

TEST_F(TestRle, TestRoundTripRandomSequencesWithRuns) {
    srand(time(nullptr));

    // Test the limiting function of GetNextRun.
    const int kMaxToReadAtOnce = (random() % 20) + 1;

    // Generate a bunch of random bit sequences, and "round-trip" them
    // through the encode/decode sequence.
    for (int rep = 0; rep < 100; rep++) {
        faststring buf;
        std::string string_rep;
        int num_bits = GenerateRandomBitString(10, &buf, &string_rep);
        RleDecoder<bool> decoder(buf.data(), buf.size(), 1);
        std::string roundtrip_str;
        int rem_to_read = num_bits;
        size_t run_len;
        bool val;
        while (rem_to_read > 0 &&
               (run_len = decoder.GetNextRun(&val, std::min(kMaxToReadAtOnce, rem_to_read))) != 0) {
            ASSERT_LE(run_len, kMaxToReadAtOnce);
            roundtrip_str.append(run_len, val ? '1' : '0');
            rem_to_read -= run_len;
        }

        ASSERT_EQ(string_rep, roundtrip_str);
    }
}
TEST_F(TestRle, TestSkip) {
    faststring buffer(1);
    RleEncoder<bool> encoder(&buffer, 1);

    // 0101010[1] 01010101 01
    //        "A"
    for (int j = 0; j < 18; ++j) {
        encoder.Put(!!(j & 1));
    }

    // 0011[00] 11001100 11001100 11001100 11001100
    //      "B"
    for (int j = 0; j < 19; ++j) {
        encoder.Put(!!(j & 1), 2);
    }

    // 000000000000 11[1111111111] 000000000000 111111111111
    //                   "C"
    // 000000000000 111111111111 0[00000000000] 111111111111
    //                                  "D"
    // 000000000000 111111111111 000000000000 111111111111
    for (int j = 0; j < 12; ++j) {
        encoder.Put(!!(j & 1), 12);
    }
    encoder.Flush();

    bool val = false;
    size_t run_length;
    RleDecoder<bool> decoder(buffer.data(), encoder.len(), 1);

    // position before "A"
    ASSERT_EQ(3, decoder.Skip(7));
    run_length = decoder.GetNextRun(&val, std::numeric_limits<std::size_t>::max());
    ASSERT_TRUE(val);
    ASSERT_EQ(1, run_length);

    // position before "B"
    ASSERT_EQ(7, decoder.Skip(14));
    run_length = decoder.GetNextRun(&val, std::numeric_limits<std::size_t>::max());
    ASSERT_FALSE(val);
    ASSERT_EQ(2, run_length);

    // position before "C"
    ASSERT_EQ(18, decoder.Skip(46));
    run_length = decoder.GetNextRun(&val, std::numeric_limits<std::size_t>::max());
    ASSERT_TRUE(val);
    ASSERT_EQ(10, run_length);

    // position before "D"
    ASSERT_EQ(24, decoder.Skip(49));
    run_length = decoder.GetNextRun(&val, std::numeric_limits<std::size_t>::max());
    ASSERT_FALSE(val);
    ASSERT_EQ(11, run_length);

    encoder.Flush();
}

} // namespace doris

int main(int argc, char** argv) {
    ::testing::InitGoogleTest(&argc, argv);
    return RUN_ALL_TESTS();
}