Differential D4004 Diff 11103 src/leveldb/include/leveldb/env.h

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src/leveldb/include/leveldb/env.h

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// slower that reading the same data, but may be faster.		// slower that reading the same data, but may be faster.
//		//
// If end of file is reached, skipping will stop at the end of the		// If end of file is reached, skipping will stop at the end of the
// file, and Skip will return OK.		// file, and Skip will return OK.
//		//
// REQUIRES: External synchronization		// REQUIRES: External synchronization
virtual Status Skip(uint64_t n) = 0;		virtual Status Skip(uint64_t n) = 0;

		// Get a name for the file, only for error reporting
		virtual std::string GetName() const = 0;

private:		private:
// No copying allowed		// No copying allowed
SequentialFile(const SequentialFile&);		SequentialFile(const SequentialFile&);
void operator=(const SequentialFile&);		void operator=(const SequentialFile&);
};		};

// A file abstraction for randomly reading the contents of a file.		// A file abstraction for randomly reading the contents of a file.
class RandomAccessFile {		class RandomAccessFile {
public:		public:
RandomAccessFile() { }		RandomAccessFile() { }
virtual ~RandomAccessFile();		virtual ~RandomAccessFile();

// Read up to "n" bytes from the file starting at "offset".		// Read up to "n" bytes from the file starting at "offset".
// "scratch[0..n-1]" may be written by this routine. Sets "*result"		// "scratch[0..n-1]" may be written by this routine. Sets "*result"
// to the data that was read (including if fewer than "n" bytes were		// to the data that was read (including if fewer than "n" bytes were
// successfully read). May set "*result" to point at data in		// successfully read). May set "*result" to point at data in
// "scratch[0..n-1]", so "scratch[0..n-1]" must be live when		// "scratch[0..n-1]", so "scratch[0..n-1]" must be live when
// "*result" is used. If an error was encountered, returns a non-OK		// "*result" is used. If an error was encountered, returns a non-OK
// status.		// status.
//		//
// Safe for concurrent use by multiple threads.		// Safe for concurrent use by multiple threads.
virtual Status Read(uint64_t offset, size_t n, Slice* result,		virtual Status Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const = 0;		char* scratch) const = 0;

		// Get a name for the file, only for error reporting
		virtual std::string GetName() const = 0;

private:		private:
// No copying allowed		// No copying allowed
RandomAccessFile(const RandomAccessFile&);		RandomAccessFile(const RandomAccessFile&);
void operator=(const RandomAccessFile&);		void operator=(const RandomAccessFile&);
};		};

// A file abstraction for sequential writing. The implementation		// A file abstraction for sequential writing. The implementation
// must provide buffering since callers may append small fragments		// must provide buffering since callers may append small fragments
// at a time to the file.		// at a time to the file.
class WritableFile {		class WritableFile {
public:		public:
WritableFile() { }		WritableFile() { }
virtual ~WritableFile();		virtual ~WritableFile();

virtual Status Append(const Slice& data) = 0;		virtual Status Append(const Slice& data) = 0;
virtual Status Close() = 0;		virtual Status Close() = 0;
virtual Status Flush() = 0;		virtual Status Flush() = 0;
virtual Status Sync() = 0;		virtual Status Sync() = 0;

		// Get a name for the file, only for error reporting
		virtual std::string GetName() const = 0;

private:		private:
// No copying allowed		// No copying allowed
WritableFile(const WritableFile&);		WritableFile(const WritableFile&);
void operator=(const WritableFile&);		void operator=(const WritableFile&);
};		};

// An interface for writing log messages.		// An interface for writing log messages.
class Logger {		class Logger {
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