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56 lines
1.3 KiB
C++
56 lines
1.3 KiB
C++
#pragma once
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#include <IO/WriteBuffer.h>
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#include <IO/BufferWithOwnMemory.h>
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#include <utility>
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#include <memory>
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namespace DB
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{
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class WriteBuffer;
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/// WriteBuffer that decorates data and delegates it to underlying buffer.
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/// It's used for writing compressed and encrypted data
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template <class Base>
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class WriteBufferDecorator : public Base
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{
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public:
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template <class ... BaseArgs>
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explicit WriteBufferDecorator(std::unique_ptr<WriteBuffer> out_, BaseArgs && ... args)
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: Base(std::forward<BaseArgs>(args)...), out(std::move(out_))
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{
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}
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void finalizeImpl() override
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{
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try
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{
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finalizeBefore();
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out->finalize();
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finalizeAfter();
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}
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catch (...)
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{
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/// Do not try to flush next time after exception.
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out->position() = out->buffer().begin();
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throw;
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}
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}
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WriteBuffer * getNestedBuffer() { return out.get(); }
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protected:
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/// Do some finalization before finalization of underlying buffer.
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virtual void finalizeBefore() {}
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/// Do some finalization after finalization of underlying buffer.
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virtual void finalizeAfter() {}
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std::unique_ptr<WriteBuffer> out;
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};
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using WriteBufferWithOwnMemoryDecorator = WriteBufferDecorator<BufferWithOwnMemory<WriteBuffer>>;
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}
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