ClickHouse/src/Compression/getCompressionCodecForFile.cpp
2022-10-23 15:24:20 +00:00

43 lines
1.6 KiB
C++

#include <Compression/getCompressionCodecForFile.h>
#include <Compression/CompressionInfo.h>
#include <Compression/CompressionFactory.h>
#include <IO/ReadBufferFromFileBase.h>
#include <Compression/CompressionCodecMultiple.h>
#include <Common/PODArray.h>
#include <Common/logger_useful.h>
#include <Storages/MergeTree/IDataPartStorage.h>
namespace DB
{
using Checksum = CityHash_v1_0_2::uint128;
CompressionCodecPtr getCompressionCodecForFile(const IDataPartStorage & data_part_storage, const String & relative_path)
{
auto read_buffer = data_part_storage.readFile(relative_path, {}, std::nullopt, std::nullopt);
read_buffer->ignore(sizeof(Checksum));
UInt8 header_size = ICompressionCodec::getHeaderSize();
PODArray<char> compressed_buffer;
compressed_buffer.resize(header_size);
read_buffer->readStrict(compressed_buffer.data(), header_size);
uint8_t method = ICompressionCodec::readMethod(compressed_buffer.data());
if (method == static_cast<uint8_t>(CompressionMethodByte::Multiple))
{
compressed_buffer.resize(1);
read_buffer->readStrict(compressed_buffer.data(), 1);
compressed_buffer.resize(1 + compressed_buffer[0]);
read_buffer->readStrict(compressed_buffer.data() + 1, compressed_buffer[0]);
auto codecs_bytes = CompressionCodecMultiple::getCodecsBytesFromData(compressed_buffer.data());
Codecs codecs;
for (auto byte : codecs_bytes)
codecs.push_back(CompressionCodecFactory::instance().get(byte));
return std::make_shared<CompressionCodecMultiple>(codecs);
}
return CompressionCodecFactory::instance().get(method);
}
}