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54 lines
1.0 KiB
C++
54 lines
1.0 KiB
C++
#pragma once
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#include <IO/WriteBufferFromFileBase.h>
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namespace DB
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{
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/** Use ready file descriptor. Does not open or close a file.
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*/
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class WriteBufferFromFileDescriptor : public WriteBufferFromFileBase
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{
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protected:
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int fd;
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void nextImpl() override;
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/// Name or some description of file.
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std::string getFileName() const override;
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public:
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WriteBufferFromFileDescriptor(
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int fd_ = -1,
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size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
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char * existing_memory = nullptr,
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size_t alignment = 0);
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/** Could be used before initialization if needed 'fd' was not passed to constructor.
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* It's not possible to change 'fd' during work.
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*/
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void setFD(int fd_)
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{
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fd = fd_;
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}
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~WriteBufferFromFileDescriptor() override;
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int getFD() const override
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{
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return fd;
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}
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off_t getPositionInFile() override;
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void sync() override;
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private:
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off_t doSeek(off_t offset, int whence) override;
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void doTruncate(off_t length) override;
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};
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}
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