ClickHouse/dbms/include/DB/IO/ReadBufferFromFile.h

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#pragma once
#include <DB/IO/ReadBufferFromFileDescriptor.h>
#include <DB/Common/CurrentMetrics.h>
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#ifndef O_DIRECT
#define O_DIRECT 00040000
#endif
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namespace CurrentMetrics
{
extern const Metric OpenFileForRead;
}
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namespace DB
{
/** Accepts path to file and opens it, or pre-opened file descriptor.
* Closes file by himself (thus "owns" a file descriptor).
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*/
class ReadBufferFromFile : public ReadBufferFromFileDescriptor
{
protected:
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std::string file_name;
CurrentMetrics::Increment metric_increment{CurrentMetrics::OpenFileForRead};
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public:
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ReadBufferFromFile(const std::string & file_name_, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE, int flags = -1,
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char * existing_memory = nullptr, size_t alignment = 0);
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/// Use pre-opened file descriptor.
ReadBufferFromFile(int fd, const std::string & original_file_name = {}, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE, int flags = -1,
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char * existing_memory = nullptr, size_t alignment = 0);
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~ReadBufferFromFile() override;
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/// Close file before destruction of object.
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void close();
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std::string getFileName() const override
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{
return file_name;
}
};
}