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80 lines
2.1 KiB
C++
80 lines
2.1 KiB
C++
#pragma once
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#include <DB/IO/ReadHelpers.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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/** Считывает данные, из формата, состоящего из чанков
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* (идентификатор запроса, признак последнего чанка, размер чанка, часть данных со сжатием или без).
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*/
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class ChunkedReadBuffer : public ReadBuffer
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{
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protected:
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ReadBuffer & in;
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bool all_read;
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size_t read_in_chunk;
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size_t chunk_size;
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UInt64 assert_query_id;
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bool nextImpl()
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{
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/// Если прочитали ещё не весь блок - получим следующие данные. Если следующих данных нет - ошибка.
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if (read_in_chunk < chunk_size)
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{
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if (!in.next())
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throw Exception("Cannot read all data from chunked input", ErrorCodes::CANNOT_READ_ALL_DATA_FROM_CHUNKED_INPUT);
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working_buffer = in.buffer();
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if (chunk_size - read_in_chunk < working_buffer.size())
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{
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working_buffer.resize(chunk_size - read_in_chunk);
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read_in_chunk = chunk_size;
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}
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else
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read_in_chunk += working_buffer.size();
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in.position() += working_buffer.size();
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}
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else
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{
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if (all_read)
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return false;
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UInt64 query_id = 0;
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readIntBinary(query_id, in);
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if (query_id != assert_query_id)
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throw Exception("Received data for wrong query id (expected "
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+ toString(assert_query_id) + ", got "
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+ toString(query_id) + ")", ErrorCodes::RECEIVED_DATA_FOR_WRONG_QUERY_ID);
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/// Флаг конца.
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readIntBinary(all_read, in);
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/// Размер блока.
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readIntBinary(chunk_size, in);
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read_in_chunk = std::min(chunk_size, in.buffer().size() - in.offset());
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working_buffer = Buffer(in.position(), in.position() + read_in_chunk);
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in.position() += read_in_chunk;
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if (all_read)
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return false;
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}
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return true;
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}
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public:
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ChunkedReadBuffer(ReadBuffer & in_, UInt64 assert_query_id_)
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: ReadBuffer(nullptr, 0), in(in_), all_read(false), read_in_chunk(0), chunk_size(0), assert_query_id(assert_query_id_) {}
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};
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}
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