gov.nist.nlpir.irf.proxy
Class HandlesByOid

java.lang.Object
  |
  +--gov.nist.nlpir.irf.proxy.HandlesByOid

Direct Known Subclasses:

AnySizeHandlesByOid, OneSizeHandlesByOid

public abstract class HandlesByOid

extends java.lang.Object

implements java.io.Serializable

The HandlesByOid table is responsible for keeping track of the handle of each persistent object by its object identifier (Oid). Oids are assigned by IRF and handles may vary according to the persistence mechanism used.

This class is abstract. Thus, there may be several implementations, matching different families of handles. If all handles have the same size when they're written to disk, then the OneSizeHandlesByOid class can be used to get an actual instance of HandlesByOid. If they can be different, then AnySizeHandlesByOid will work, as it uses a more generic mechanism to match Handles to Oids.

Version:

$Revision: 1.6 $

Author:

This software was produced by NIST, an agency of the U.S. government, and by statute is not subject to copyright in the United States. Recipients of this software assume all responsibilities associated with its operation, modification and maintenance.

See Also:

Oid, Handle, Serialized Form

Field Summary

protected static java.lang.String	fileSeparator Local copy of System file separator
private static long	handlesByOidAdds Statistics on handlesByOid table and cache.
private static HashingCache	handlesByOidCache Cache for handles by Oid
protected static BufferedRandomAccessFile	handlesByOidDataFile The file used to keep track of handles by Oid.
private static java.lang.String	handlesByOidDataFileLocation Used to find the file associating Handles to Oids.
private static long	handlesByOidGets
private static long	handlesByOidGetsFromCache
private static long	handlesByOidRemoves
private static long	handlesByOidUpdates
private static int	maxHandlesByOidCacheEntries Initial size of the cache used to match handles to Oids.
(package private) static long	serialVersionUID serial version universal id - put here so Java does not insert one which may change due to revisions and make it impossible to deserialize earlier versions of serialized objects

Constructor Summary

HandlesByOid()

Method Summary

void	addHandleByOid(Oid oid, Handle handle) Adds a handle to the table of handles by Oid
Handle	getHandleByOid(Oid oid) Gets a handle from the table of handles by Oid
java.lang.String	getHandlesByOidDataFileLocation() Gets the location of the handlesByOidDataFile;
abstract long	getHandlesByOidSize() Gets the size of the table
int	getMaxHandlesByOidCacheEntries() Returns the maximum number of entries in the cache
java.lang.String	getStatistics() Returns a String that contains statistics about this table and the cache it embeds.
void	openHandlesByOid(java.lang.String directory) Opens the handles-by-oid files
protected abstract Handle	readHandleForOid(Oid oid) Reads the handle from the disk.
void	replaceHandleByOid(Oid oid, Handle newHandle) Replaces the entry in table of handles by Oid for the specified Oid with a new one using the same Oid the new handle passed.
void	setHandlesByOidDataFileLocation(java.lang.String location) Sets the location of the handlesByOidDataFile
void	setMaxHandlesByOidCacheEntries(int maxHandlesByOidCacheEntries) Changes the size of the cache used to match Handles to Oids
void	shutdown() Makes sure modifications to cache entries are reflected in their persistent analogues.
protected abstract void	writeHandleForOid(Oid oid, Handle handle) Associates the given Handle to the given Oid in the file pointed by handlesByOidDataFile.

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

static final long serialVersionUID

serial version universal id - put here so Java does not insert one which may change due to revisions and make it impossible to deserialize earlier versions of serialized objects

handlesByOidDataFile

protected static BufferedRandomAccessFile handlesByOidDataFile

The file used to keep track of handles by Oid.

handlesByOidDataFileLocation

private static java.lang.String handlesByOidDataFileLocation

Used to find the file associating Handles to Oids.

maxHandlesByOidCacheEntries

private static int maxHandlesByOidCacheEntries

Initial size of the cache used to match handles to Oids.

handlesByOidCache

private static HashingCache handlesByOidCache

Cache for handles by Oid

fileSeparator

protected static final java.lang.String fileSeparator

Local copy of System file separator

handlesByOidAdds

private static transient long handlesByOidAdds

Statistics on handlesByOid table and cache.

handlesByOidRemoves

private static transient long handlesByOidRemoves

handlesByOidUpdates

private static transient long handlesByOidUpdates

handlesByOidGets

private static transient long handlesByOidGets

handlesByOidGetsFromCache

private static transient long handlesByOidGetsFromCache

Constructor Detail

HandlesByOid

public HandlesByOid()

Method Detail

openHandlesByOid

public void openHandlesByOid(java.lang.String directory)

Opens the handles-by-oid files

Parameters:

directory - directory in which to open the files

setHandlesByOidDataFileLocation

public final void setHandlesByOidDataFileLocation(java.lang.String location)

Sets the location of the handlesByOidDataFile

Parameters:

location - location of the handlesByOidDataFile

getMaxHandlesByOidCacheEntries

public final int getMaxHandlesByOidCacheEntries()

Returns the maximum number of entries in the cache

Returns:

the maximum number of entries in the cache

getHandlesByOidDataFileLocation

public final java.lang.String getHandlesByOidDataFileLocation()

Gets the location of the handlesByOidDataFile;

Returns:

the location of the handlesByOidDataFile

getStatistics

public java.lang.String getStatistics()

Returns a String that contains statistics about this table and the cache it embeds.

addHandleByOid

public void addHandleByOid(Oid oid,
                           Handle handle)

Adds a handle to the table of handles by Oid

Parameters:

handle - handle to be saved

Oid - object identified to be associated with the handle

writeHandleForOid

protected abstract void writeHandleForOid(Oid oid,
                                          Handle handle)

Associates the given Handle to the given Oid in the file pointed by handlesByOidDataFile. It will allow this matching to live even after shutdown. For the cache mechanism, see the class below:

Parameters:

oid - Oid for which a handle is to be written

handle - Handle to be associated with the specified Oid

See Also:

HashingCache

replaceHandleByOid

public void replaceHandleByOid(Oid oid,
                               Handle newHandle)

Replaces the entry in table of handles by Oid for the specified Oid with a new one using the same Oid the new handle passed. If no entry to replace exists, write an error message, but add the new entry and continue.

Parameters:

Oid - for desired handle

newHandle - the new handle to replace the existing one

getHandleByOid

public Handle getHandleByOid(Oid oid)

Gets a handle from the table of handles by Oid

Parameters:

Oid - for desired object/handle

Returns:

the handle associated with the specified Oid

readHandleForOid

protected abstract Handle readHandleForOid(Oid oid)

Reads the handle from the disk. This method is gonna specify the way files are used for storing Handles (index, no index, ...)

getHandlesByOidSize

public abstract long getHandlesByOidSize()

Gets the size of the table

Returns:

the number of keys (Oids) in the table

setMaxHandlesByOidCacheEntries

public void setMaxHandlesByOidCacheEntries(int maxHandlesByOidCacheEntries)

Changes the size of the cache used to match Handles to Oids

Parameters:

maxHandlesByOidCacheEntries - maximum number of entries allowed in handles by Oid cache

shutdown

public void shutdown()

Makes sure modifications to cache entries are reflected in their persistent analogues.