Package org.eclipse.rdf4j.sail.nativerdf.datastore

Class IDFile

java.lang.Object

org.eclipse.rdf4j.sail.nativerdf.datastore.IDFile

All Implemented Interfaces:

Closeable, AutoCloseable

public class IDFile
extends Object
implements Closeable

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.

This class supports parallel reads but not parallel writes.

Author:

Arjohn Kampman

Constructor Summary

Constructors

Constructor	Description
IDFile(File file)
IDFile(File file, boolean forceSync)

Method Summary

Modifier and Type	Method	Description
void	clear()	Discards all stored data.
void	clearCache()
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.
void	sync(boolean force)

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

sync

public void sync(boolean force)
          throws IOException

Throws:

IOException

close

public void close()
           throws IOException

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

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException

clearCache

public void clearCache()