edu.vub.at.actors.natives
Class ReceptionistsSet

java.lang.Object
  edu.vub.at.actors.natives.ReceptionistsSet

public class ReceptionistsSet

extends java.lang.Object

An NATActorMirror's ReceptionistsSet keeps a mapping between identifiers and local objects which allows resolving far objects to local ones. The ReceptionistsSet also stores which actors refer to an object, which is the basis for a distributed garbage collection algorithm.

Author:

smostinc

Field Summary

private java.util.HashMap	exportedObjectsTable_ object id (ATObjectID) -> local object (ATObject)
private java.util.Hashtable	farReferences_ a pool of far object references: ensures that each ATObjectID is paired with a unique far object reference
private MultiMap	objectToClients_ local object (ATObject) -> remote clients pointing to this object (Set of ATFarReference)
private ELActor	owner_
private java.util.Hashtable	remoteReferences_ a pool of remote object references: ensures that each ATObjectID is paired with a unique remote object reference (and corresponding outbox)

Constructor Summary

ReceptionistsSet(ELActor forActor)

Method Summary

void	addClient(ATObject service, ATFarReference client) Invoked whenever another actor is passed a reference to an object offering a service on this actor.
private NATLocalFarRef	createLocalFarRef(ELActor actor, ATObjectID objectId, ATStripe[] stripes)
private NATRemoteFarRef	createRemoteFarRef(ATObjectID objectId, ATStripe[] stripes)
NATLocalFarRef	exportObject(ATObject object) Export a local object such that it now has a unique global identifier which can be distributed to other actors.
void	removeClient(ATObject service, ATFarReference client) Called upon the collection of a service on a remote device, or possibly when the conditions negotiated for the use of the service (e.g. its lease period) have expired.
ATObject	resolveObject(ATObjectID objectId, ATStripe[] stripes) Try to resolve a remote object reference into a local (near) reference.

Methods inherited from class java.lang.Object

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

Field Detail

exportedObjectsTable_

private final java.util.HashMap exportedObjectsTable_

object id (ATObjectID) -> local object (ATObject)

objectToClients_

private final MultiMap objectToClients_

local object (ATObject) -> remote clients pointing to this object (Set of ATFarReference)

owner_

private final ELActor owner_

remoteReferences_

private final java.util.Hashtable remoteReferences_

a pool of remote object references: ensures that each ATObjectID is paired with a unique remote object reference (and corresponding outbox)

farReferences_

private final java.util.Hashtable farReferences_

a pool of far object references: ensures that each ATObjectID is paired with a unique far object reference

Constructor Detail

ReceptionistsSet

public ReceptionistsSet(ELActor forActor)

Method Detail

createRemoteFarRef

private NATRemoteFarRef createRemoteFarRef(ATObjectID objectId,
                                           ATStripe[] stripes)

createLocalFarRef

private NATLocalFarRef createLocalFarRef(ELActor actor,
                                         ATObjectID objectId,
                                         ATStripe[] stripes)

exportObject

public NATLocalFarRef exportObject(ATObject object)
                            throws InterpreterException

Export a local object such that it now has a unique global identifier which can be distributed to other actors. Only near references may be exported.

Parameters:

object - - the local object to export to the outside world

Returns:

a local remote reference denoting the local object

Throws:

XIllegalOperation - - if object is a far reference

InterpreterException

resolveObject

public ATObject resolveObject(ATObjectID objectId,
                              ATStripe[] stripes)

Try to resolve a remote object reference into a local (near) reference.

Parameters:

objectId - the identifier of the remote object

Returns:

either the local object corresponding to that identifier, or a far reference designating the id

Throws:

InterpreterException

addClient

public void addClient(ATObject service,
                      ATFarReference client)
               throws InterpreterException

Invoked whenever another actor is passed a reference to an object offering a service on this actor. This is automatically done when serialising a local object during parameter or result passing. Upon serialisation of a far reference pointing to a service, a command object should be sent at the lowest level to invoke this method as well. This method is related to a simple reference listing strategy which should be the basis for a distributed garbage collector.

Throws:

InterpreterException

removeClient

public void removeClient(ATObject service,
                         ATFarReference client)
                  throws InterpreterException

Called upon the collection of a service on a remote device, or possibly when the conditions negotiated for the use of the service (e.g. its lease period) have expired.

Throws:

InterpreterException