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70 lines
1.7 KiB
C++
70 lines
1.7 KiB
C++
#pragma once
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#include <DB/IO/WriteBuffer.h>
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#include <DB/IO/WriteHelpers.h>
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#include <iostream>
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namespace DB
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{
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/** Записывает данные в формат, состоящий из чанков
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* (идентификатор запроса, признак последнего чанка, размер чанка, часть данных со сжатием или без).
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* Нельзя использовать out напрямую.
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*/
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class ChunkedWriteBuffer : public WriteBuffer
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{
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protected:
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WriteBuffer & out;
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UInt64 query_id;
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inline size_t headerSize() { return sizeof(query_id) + sizeof(bool) + sizeof(size_t); }
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void checkBufferSize()
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{
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if (out.buffer().end() - out.position() < 2 * static_cast<int>(headerSize()))
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throw Exception("Too small remaining buffer size to write chunked data", ErrorCodes::TOO_SMALL_BUFFER_SIZE);
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}
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void nextImpl()
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{
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/* std::cerr << out.offset() << std::endl;
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std::cerr << query_id << std::endl;
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std::cerr << offset() << std::endl;*/
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checkBufferSize();
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writeIntBinary(query_id, out);
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writeIntBinary(false, out);
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writeIntBinary(offset(), out);
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// std::cerr << out.offset() << std::endl;
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out.position() = position();
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out.next();
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working_buffer = Buffer(out.buffer().begin() + headerSize(), out.buffer().end());
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pos = working_buffer.begin();
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}
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public:
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ChunkedWriteBuffer(WriteBuffer & out_, UInt64 query_id_)
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: WriteBuffer(out_.position() + headerSize(), out_.buffer().size() - out_.offset() - headerSize()), out(out_), query_id(query_id_)
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{
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checkBufferSize();
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}
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void finish()
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{
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next();
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writeIntBinary(query_id, out);
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writeIntBinary(true, out);
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writeIntBinary(static_cast<size_t>(0), out);
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}
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};
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}
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