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