org.openrdf.sail.nativerdf.datastore
Class IDFile

java.lang.Object
  org.openrdf.sail.nativerdf.datastore.IDFile

public class IDFile
extends Object

Class supplying access to an ID file. An ID file maps IDs (integers >= 1) to file pointers (long integers). There is a direct correlation between IDs and the position at which the file pointers are stored; the file pointer for ID X is stored at position 8*X.

Author:

Arjohn Kampman

Constructor Summary

IDFile(File file)

IDFile(File file, boolean forceSync)

Method Summary

void	clear() Discards all stored data.
void	close() Closes the ID file, releasing any file locks that it might have.
File	getFile()
int	getMaxID() Gets the largest ID that is stored in this ID file.
long	getOffset(int id) Gets the offset of the data entry with the specified ID.
void	setOffset(int id, long offset) Sets or updates the stored offset for the specified ID.
int	storeOffset(long offset) Stores the offset of a new data entry, returning the ID under which is stored.
void	sync() Syncs any unstored data to the hash file.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

IDFile

public IDFile(File file)
       throws IOException

Throws:

IOException

IDFile

public IDFile(File file,
              boolean forceSync)
       throws IOException

Throws:

IOException

Method Detail

getFile

public final File getFile()

getMaxID

public int getMaxID()
             throws IOException

Gets the largest ID that is stored in this ID file.

Returns:

The largest ID, or 0 if the file does not contain any data.

Throws:

IOException - If an I/O error occurs.

storeOffset

public int storeOffset(long offset)
                throws IOException

Stores the offset of a new data entry, returning the ID under which is stored.

Throws:

IOException

setOffset

public void setOffset(int id,
                      long offset)
               throws IOException

Sets or updates the stored offset for the specified ID.

Parameters:

id - The ID to set the offset for, must be larger than 0.

offset - The (new) offset for the specified ID.

Throws:

IOException

getOffset

public long getOffset(int id)
               throws IOException

Gets the offset of the data entry with the specified ID.

Parameters:

id - The ID to get the offset for, must be larger than 0.

Returns:

The offset for the ID.

Throws:

IOException

clear

public void clear()
           throws IOException

Discards all stored data.

Throws:

IOException - If an I/O error occurred.

sync

public void sync()
          throws IOException

Syncs any unstored data to the hash file.

Throws:

IOException

close

public void close()
           throws IOException

Closes the ID file, releasing any file locks that it might have.

Throws:

IOException