org.xerial.db.storage
Interface DBFile

All Known Implementing Classes:

DiskFile, MemoryFile

public interface DBFile

An interface to access disk files, or main memory buffers. Accesses to the DBFile are not guaranteed to be thread-safe, that is, concurrent accesses to the DBFile may cause undesired effects; for example, contiguous write requests may overwrite the previous write results because the second write request can be performed before the file cursor is properly updated.

Author:

leo

Method Summary

void	close() Closes the file.
void	read(byte[] buffer, int offset, int byteSize) Reads data from the file, and writes the read data to the specified buffer
void	seek(long fileBytePos) Sets the file pointer offset, measured from the beginning of the file, at which the next read/write request occurs.
void	write(byte[] buffer, int offset, int byteSize) Writes the given data into the file

Method Detail

read

void read(byte[] buffer,
          int offset,
          int byteSize)
          throws DBException

Reads data from the file, and writes the read data to the specified buffer

Parameters:

buffer - the buffer into which the data is read

offset - the start offset in the buffer at which the data is written

byteSize - the bytes to read

Throws:

DBFileException - when failed to read the data

DBException

write

void write(byte[] buffer,
           int offset,
           int byteSize)
           throws DBException

Writes the given data into the file

Parameters:

buffer - the data

offset - the start offset in the data

byteSize - the bytes to write

Throws:

DBFileException - when failed to write the data

DBException

seek

void seek(long fileBytePos)
          throws DBException

Sets the file pointer offset, measured from the beginning of the file, at which the next read/write request occurs. The fileBytePos can exceed the end of the file. Setting the fileBytePos higher than the end of the file does not expand the file size. The size will change by writing after the offset has been set beyond the end of the file.

Parameters:

fileBytePos -

Throws:

DBFileException

DBException

close

void close()
           throws DBException

Closes the file.

Throws:

DBFileException

DBException