[CPP] Fix TS_2Diff

[jt2594838]

It is reported that the implementation of the TS_2Diff decoder in TsFile-CPP will mistakenly skip one byte, resulting in a wrong decoding result.

[hongzhi-gao]

#118

The TS2Diff decoder reads an extra byte after processing each group of data（TS2DIFFEncoder.block_size_ = 128）, causing the header of the next group of data to be misaligned.

Here are the unit tests, and the encoder's output is also consistent with the output from Java.

TEST_F(TS2DIFFEncoderTest, TestIntEncoding) {
    common::ByteStream out_stream(1024, common::MOD_TS2DIFF_OBJ, false);
    const int row_num = 10000;
    int32_t data[row_num];
    memset(data, 0, sizeof(int32_t) * row_num);
    for (int i = 0; i < row_num; i++) {
        data[i] = i * i;
    }
    
    for (int i = 0; i < row_num; i++) {
        EXPECT_EQ(encoder_int_->encode(data[i], out_stream), common::E_OK);
    }
    EXPECT_EQ(encoder_int_->flush(out_stream), common::E_OK);

    for (int i = 0; i < row_num; i++) {
        int32_t x;
        EXPECT_EQ(decoder_int_->read_int32(x, out_stream), common::E_OK);
        EXPECT_EQ(x, data[i]);
    }
}

TEST_F(TS2DIFFEncoderTest, TestLongEncoding) {
    common::ByteStream out_stream(1024, common::MOD_TS2DIFF_OBJ, false);
    const int row_num = 10000;
    int64_t data[row_num];
    memset(data, 0, sizeof(int64_t) * row_num);
    for (int i = 0; i < row_num; i++) {
        data[i] = i * i;
    }
    
    for (int i = 0; i < row_num; i++) {
        EXPECT_EQ(encoder_long_->encode(data[i], out_stream), common::E_OK);
    }
    EXPECT_EQ(encoder_long_->flush(out_stream), common::E_OK);

    for (int i = 0; i < row_num; i++) {
        int64_t x;
        EXPECT_EQ(decoder_long_->read_int64(x, out_stream), common::E_OK);
        EXPECT_EQ(x, data[i]);
    }
}