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77 lines
1.5 KiB
C++
77 lines
1.5 KiB
C++
#ifndef DBMS_COMMON_COMPRESSED_WRITEBUFFER_H
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#define DBMS_COMMON_COMPRESSED_WRITEBUFFER_H
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#include <vector>
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#include <city.h>
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#include <quicklz/quicklz_level1.h>
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#include <DB/IO/WriteBuffer.h>
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#include <DB/IO/BufferWithOwnMemory.h>
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#include <DB/IO/CompressedStream.h>
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namespace DB
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{
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class CompressedWriteBuffer : public BufferWithOwnMemory<WriteBuffer>
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{
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private:
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WriteBuffer & out;
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std::vector<char> compressed_buffer;
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char scratch[QLZ_SCRATCH_COMPRESS];
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void nextImpl()
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{
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if (!offset())
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return;
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size_t uncompressed_size = offset();
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compressed_buffer.resize(uncompressed_size + QUICKLZ_ADDITIONAL_SPACE);
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size_t compressed_size = qlz_compress(
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working_buffer.begin(),
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&compressed_buffer[0],
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uncompressed_size,
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scratch);
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uint128 checksum = CityHash128(&compressed_buffer[0], compressed_size);
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out.write(reinterpret_cast<const char *>(&checksum), sizeof(checksum));
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out.write(&compressed_buffer[0], compressed_size);
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}
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public:
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CompressedWriteBuffer(WriteBuffer & out_) : out(out_) {}
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/// Объём сжатых данных
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size_t getCompressedBytes()
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{
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nextIfAtEnd();
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return out.count();
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}
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/// Сколько несжатых байт было записано в буфер
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size_t getUncompressedBytes()
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{
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return count();
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}
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/// Сколько байт находится в буфере (ещё не сжато)
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size_t getRemainingBytes()
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{
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nextIfAtEnd();
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return offset();
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}
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~CompressedWriteBuffer()
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{
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nextImpl();
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}
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};
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}
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#endif
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