Function CheckStreamingDecompressor

cpp/src/arrow/util/compression_test.cc:177–223

// Check the streaming decompressor against one-shot compression

void CheckStreamingDecompressor(Codec* codec, const std::vector<uint8_t>& data) {
  // Create compressed data
  int64_t max_compressed_len = codec->MaxCompressedLen(data.size(), data.data());
  std::vector<uint8_t> compressed(max_compressed_len);
  int64_t compressed_size;
  ASSERT_OK_AND_ASSIGN(
      compressed_size,
      codec->Compress(data.size(), data.data(), max_compressed_len, compressed.data()));
  compressed.resize(compressed_size);

  // Run streaming decompression
  std::shared_ptr<Decompressor> decompressor;
  ASSERT_OK_AND_ASSIGN(decompressor, codec->MakeDecompressor());

  std::vector<uint8_t> decompressed;
  int64_t decompressed_size = 0;
  const uint8_t* input = compressed.data();
  int64_t remaining = compressed.size();

  decompressed.resize(10);
  while (!decompressor->IsFinished()) {
    // Feed a small amount each time
    int64_t input_len = std::min(remaining, static_cast<int64_t>(23));
    int64_t output_len = decompressed.size() - decompressed_size;
    uint8_t* output = decompressed.data() + decompressed_size;
    ASSERT_OK_AND_ASSIGN(auto result,
                         decompressor->Decompress(input_len, input, output_len, output));
    ASSERT_LE(result.bytes_read, input_len);
    ASSERT_LE(result.bytes_written, output_len);
    ASSERT_TRUE(result.need_more_output || result.bytes_written > 0 ||
                result.bytes_read > 0)
        << "Decompression not progressing anymore";
    if (result.need_more_output) {
      decompressed.resize(decompressed.capacity() * 2);
    }
    decompressed_size += result.bytes_written;
    input += result.bytes_read;
    remaining -= result.bytes_read;
  }
  ASSERT_TRUE(decompressor->IsFinished());
  ASSERT_EQ(remaining, 0);

  // Check the decompressed data
  decompressed.resize(decompressed_size);
  ASSERT_EQ(data.size(), decompressed_size);
  ASSERT_EQ(data, decompressed);
}

// Check the streaming compressor and decompressor together