edu.ucdavis.rj

Class OpImpl

java.lang.Object

java.rmi.server.RemoteObject

java.rmi.server.RemoteServer

java.rmi.server.UnicastRemoteObject

edu.ucdavis.rj.OpImpl

All Implemented Interfaces:

Op, OpRemote, java.io.Serializable, java.rmi.Remote

Direct Known Subclasses:

OpInni, OpMethod

public abstract class OpImpl
extends java.rmi.server.UnicastRemoteObject
implements OpRemote

Basic operation abstraction. In general, an OpImpl shouldn't be passed as a parameter. Instead, use an OpProxy. E.g., if f is an OpImpl, then pass new OpProxy(f))

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface edu.ucdavis.rj.OpRemote

OpRemote.Helper

Field Summary

Fields

Modifier and Type	Field and Description
private java.lang.String	id
private static long	seqNum

Fields inherited from class java.rmi.server.RemoteObject

ref

Constructor Summary

Constructors

Constructor and Description
OpImpl() Create an instance of an OpImpl.

Method Summary

Modifier and Type	Method and Description
Invocation	call() Invoke this operation synchronously.
Invocation	call(Invocation originalInv) Invoke this operation synchronously.
boolean	equals(java.lang.Object other) Compares this OpImpl object with the specified object, which can be an OpRemote or an OpProxy.
java.lang.String	getId() Returns unique identifier for this operation.
int	hashCode() Returns a hash code for this OpImpl.
(package private) abstract void	internalSend(Invocation inv) Internal asynchronous invocation.
boolean	isNoop() Since have one noop per VM, need to know whether an OpImpl is a noop.
abstract int	length() Returns the number of Invocations pending for this operation.
private java.lang.String	makeId() An OpImpl's Id is formed from VM name and seqNum so it is unique across the entire program.
void	send() Invoke this operation asynchronously.
void	send(Invocation originalInv) Invoke this operation asynchronously.
void	V() A semaphore V (aka up) operation.

Methods inherited from class java.rmi.server.UnicastRemoteObject

clone, exportObject, exportObject, exportObject, unexportObject

Methods inherited from class java.rmi.server.RemoteServer

getClientHost, getLog, setLog

Methods inherited from class java.rmi.server.RemoteObject

getRef, toString, toStub

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface edu.ucdavis.rj.Op

canAppearInInni, deliverPendingMessages, elements, getFirstTime, getLock, isRemote, P, receive

Field Detail

seqNum

private static long seqNum

id

private java.lang.String id

Constructor Detail

OpImpl

public OpImpl()
       throws java.rmi.RemoteException

Create an instance of an OpImpl.

Throws:

java.rmi.RemoteException - if RMI fails.

Method Detail

makeId

private java.lang.String makeId()

An OpImpl's Id is formed from VM name and seqNum so it is unique across the entire program.

Returns:

The Id.

getId

public java.lang.String getId()

Description copied from interface: Op

Returns unique identifier for this operation.

Specified by:

getId in interface Op

Returns:

that id.

isNoop

public boolean isNoop()

Since have one noop per VM, need to know whether an OpImpl is a noop. (If c is an OpProxy, comparing noop == c c.equals(noop) won't work w/o something extra. default method. overriden for actual noop.

Specified by:

isNoop in interface Op

Returns:

true if and only if this operation is a noop.

send

public void send(Invocation originalInv)

Invoke this operation asynchronously.

Specified by:

send in interface Op

Parameters:

originalInv - The invocation to service.

send

public void send()

Invoke this operation asynchronously. Abbreviation for this.send (new Invocation(...)); See Op.send(edu.ucdavis.rj.Invocation).

Specified by:

send in interface Op

V

public void V()

Description copied from interface: Op

A semaphore V (aka up) operation. Intended for use on OpInni's semaphore operations.

Specified by:

V in interface Op

internalSend

abstract void internalSend(Invocation inv)

Internal asynchronous invocation. Note that both call and send come through here.

Parameters:

inv - The invocation to service. It is assumed to have already been cloned and its replyOp set properly (null for send; non-null for call).

call

public Invocation call(Invocation originalInv)

Invoke this operation synchronously.

Specified by:

call in interface Op

Parameters:

originalInv - The invocation to service.

Returns:

The invocation, from which the return value of the operation can be extracted.

N.B., (the reference for) the returned invocation might not be the same as inv. For example, do NOT use, e.g., Invocation inv = new Invocation(...); thefun.call(inv); System.out.println(inv.getReturnValue()); because inv's value after the call will be the same as its value before the call, and inv.getReturnValue() will likely be null. Instead, in this example, use inv = thefun.call(inv);.

call

public Invocation call()

Invoke this operation synchronously. Abbreviation for this.call (new Invocation(...)); See Op.call(edu.ucdavis.rj.Invocation).

Specified by:

call in interface Op

Returns:

The first pending invocation.

length

public abstract int length()

Returns the number of Invocations pending for this operation.

Specified by:

length in interface Op

Returns:

The number of pending Invocations.

equals

public boolean equals(java.lang.Object other)

Compares this OpImpl object with the specified object, which can be an OpRemote or an OpProxy.

Overrides:

equals in class java.rmi.server.RemoteObject

Parameters:

other - The other Object to compare.

Returns:

true if and only if the two objects are equal.

hashCode

public int hashCode()

Returns a hash code for this OpImpl. The hashCode for noop is same across all VMs. The hashCodes for non-noops are different on and across VMs.

Overrides:

hashCode in class java.rmi.server.RemoteObject

Returns:

a hash code value for this object.