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41 lines
768 B
C++
41 lines
768 B
C++
#pragma once
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#include <Common/CurrentMetrics.h>
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#include <IO/MMappedFileDescriptor.h>
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#include <cstddef>
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namespace CurrentMetrics
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{
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extern const Metric OpenFileForRead;
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}
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namespace DB
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{
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/// Opens a file and mmaps a region in it (or a whole file) into memory. Unmaps and closes in destructor.
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class MMappedFile : public MMappedFileDescriptor
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{
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public:
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MMappedFile(const std::string & file_name_, size_t offset_, size_t length_);
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/// Map till end of file.
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MMappedFile(const std::string & file_name_, size_t offset_);
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~MMappedFile() override;
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void close();
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std::string getFileName() const;
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private:
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std::string file_name;
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CurrentMetrics::Increment metric_increment{CurrentMetrics::OpenFileForRead};
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void open();
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};
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}
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