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51 lines
1.1 KiB
C++
51 lines
1.1 KiB
C++
#pragma once
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#include <forward_list>
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#include <DB/IO/WriteBuffer.h>
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#include <DB/IO/IReadableWriteBuffer.h>
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#include <DB/Common/Allocator.h>
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#include <DB/Core/Defines.h>
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namespace DB
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{
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/// Stores data in memory chunks, size of cunks are exponentially increasing during write
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/// Written data could be reread after write
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class MemoryWriteBuffer : public WriteBuffer, public IReadableWriteBuffer, boost::noncopyable, private Allocator<false>
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{
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public:
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/// Use max_total_size_ = 0 for unlimited storage
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MemoryWriteBuffer(
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size_t max_total_size_ = 0,
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size_t initial_chunk_size_ = DBMS_DEFAULT_BUFFER_SIZE,
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double growth_rate_ = 2.0,
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size_t max_chunk_size_ = 128 * DBMS_DEFAULT_BUFFER_SIZE);
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void nextImpl() override;
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~MemoryWriteBuffer() override;
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protected:
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std::shared_ptr<ReadBuffer> getReadBufferImpl() override;
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const size_t max_total_size;
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const size_t initial_chunk_size;
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const size_t max_chunk_size;
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const double growth_rate;
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using Container = std::forward_list<BufferBase::Buffer>;
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Container chunk_list;
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Container::iterator chunk_tail;
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size_t total_chunks_size = 0;
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void addChunk();
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friend class ReadBufferFromMemoryWriteBuffer;
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};
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}
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