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75 lines
2.7 KiB
C++
75 lines
2.7 KiB
C++
#pragma once
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#include <memory>
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#include <IO/ReadBuffer.h>
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#include <IO/WriteBuffer.h>
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#include <IO/BufferWithOwnMemory.h>
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#include <DataTypes/IDataType.h>
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#include <boost/noncopyable.hpp>
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#include <IO/UncompressedCache.h>
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#include <Compression/LZ4_decompress_faster.h>
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#include <Compression/CompressionInfo.h>
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namespace DB
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{
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class ICompressionCodec;
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using CompressionCodecPtr = std::shared_ptr<ICompressionCodec>;
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using Codecs = std::vector<CompressionCodecPtr>;
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/**
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* Represents interface for compression codecs like LZ4, ZSTD, etc.
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*/
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class ICompressionCodec : private boost::noncopyable
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{
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public:
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virtual ~ICompressionCodec() = default;
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/// Byte which indicates codec in compressed file
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virtual uint8_t getMethodByte() const = 0;
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/// Codec description, for example "ZSTD(2)" or "LZ4,LZ4HC(5)"
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virtual String getCodecDesc() const = 0;
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/// Compressed bytes from uncompressed source to dest. Dest should preallocate memory
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UInt32 compress(const char * source, UInt32 source_size, char * dest) const;
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/// Decompress bytes from compressed source to dest. Dest should preallocate memory
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UInt32 decompress(const char * source, UInt32 source_size, char * dest) const;
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/// Number of bytes, that will be used to compress uncompressed_size bytes with current codec
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virtual UInt32 getCompressedReserveSize(UInt32 uncompressed_size) const { return getHeaderSize() + getMaxCompressedDataSize(uncompressed_size); }
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/// Some codecs (LZ4, for example) require additional bytes at end of buffer
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virtual UInt32 getAdditionalSizeAtTheEndOfBuffer() const { return 0; }
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/// Size of header in compressed data on disk
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static constexpr UInt8 getHeaderSize() { return COMPRESSED_BLOCK_HEADER_SIZE; }
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/// Read size of compressed block from compressed source
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static UInt32 readCompressedBlockSize(const char * source);
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/// Read size of decompressed block from compressed source
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static UInt32 readDecompressedBlockSize(const char * source);
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/// Read method byte from compressed source
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static uint8_t readMethod(const char * source);
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/// Some codecs may use information about column type which appears after codec creation
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virtual void useInfoAboutType(DataTypePtr /* data_type */) { }
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protected:
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/// Return size of compressed data without header
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virtual UInt32 getMaxCompressedDataSize(UInt32 uncompressed_size) const { return uncompressed_size; }
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/// Actually compress data, without header
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virtual UInt32 doCompressData(const char * source, UInt32 source_size, char * dest) const = 0;
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/// Actually decompress data without header
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virtual void doDecompressData(const char * source, UInt32 source_size, char * dest, UInt32 uncompressed_size) const = 0;
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};
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}
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