arlut.csd.ganymede
Class serverClientProxy

java.lang.Object
  |
  +--arlut.csd.ganymede.serverClientProxy

All Implemented Interfaces:

java.lang.Runnable

public class serverClientProxy

extends java.lang.Object

implements java.lang.Runnable

serverClientProxy is a partial server-side Client proxy object which buffers async client updates, coalescing update events as needed to maximize server efficiency. Each serverClientProxy object has a background thread which communicates with a remote Client in the background, allowing the Ganymede server's operations to be asynchronous with respect to Client messages.

See Also:

clientEvent

Field Summary

private static int	classCounter Used to generate a unique name for our background thread.
private arlut.csd.ganymede.Client	client Our remote reference to the Client
private java.lang.Thread	commThread Our background communications thread, which is responsible for calling the remote Client via RMI.
private int	dequeuePtr Index pointer to the slot for the next item to be pulled from
private boolean	done If true, we have been told to shut down, and our background commThread will exit as soon as it can clear its event queue.
private int	ebSz Current counter for how many events we have queued
private int	enqueuePtr Index pointer to the slot for the next item to be place in
private java.lang.String	errorCondition If our commThread receives a remote exception when communicating with a remote Client, this field will become non-null, and no more communications will be attempted with that client.
private arlut.csd.ganymede.clientEvent[]	eventBuffer Our queue of clientEvent objects.
private arlut.csd.ganymede.clientEvent[]	lookUp Handy direct look-up table for events in eventBuffer
private int	maxBufferSize How many events we'll queue up before deciding that the Client isn't responding.

Constructor Summary

serverClientProxy(arlut.csd.ganymede.Client client)

Method Summary

private void	addEvent(arlut.csd.ganymede.clientEvent newEvent) private helper method in serverClientProxy, used to add an event to the proxy's event buffer.
private arlut.csd.ganymede.clientEvent	dequeue() private dequeue method.
private void	enqueue(arlut.csd.ganymede.clientEvent item) private enqueue method.
boolean	isAlive() Returns true if we are successfully in communications with the attached Client.
private void	replaceEvent(arlut.csd.ganymede.clientEvent newEvent) private helper method in serverClientProxy, used to add an event to the proxy's event buffer.
void	run() The serverClientProxy's background thread's run() method.
void	sendMessage(int type, java.lang.String message) This method is used to submit a message to be sent to the client.
void	shutdown() This method shuts down the background thread.
private void	throwOverflow() This method throws a remoteException which describes the state of the event buffer.

Methods inherited from class java.lang.Object

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

Field Detail

classCounter

private static int classCounter

Used to generate a unique name for our background thread.

client

private arlut.csd.ganymede.Client client

Our remote reference to the Client

commThread

private java.lang.Thread commThread

Our background communications thread, which is responsible for calling the remote Client via RMI.

eventBuffer

private final arlut.csd.ganymede.clientEvent[] eventBuffer

Our queue of clientEvent objects.

enqueuePtr

private int enqueuePtr

Index pointer to the slot for the next item to be place in

dequeuePtr

private int dequeuePtr

Index pointer to the slot for the next item to be pulled from

ebSz

private int ebSz

Current counter for how many events we have queued

maxBufferSize

private final int maxBufferSize

How many events we'll queue up before deciding that the Client isn't responding.

See Also:

Constant Field Values

done

private volatile boolean done

If true, we have been told to shut down, and our background commThread will exit as soon as it can clear its event queue.

.

errorCondition

private java.lang.String errorCondition

If our commThread receives a remote exception when communicating with a remote Client, this field will become non-null, and no more communications will be attempted with that client.

lookUp

private arlut.csd.ganymede.clientEvent[] lookUp

Handy direct look-up table for events in eventBuffer

Constructor Detail

serverClientProxy

public serverClientProxy(arlut.csd.ganymede.Client client)

Method Detail

isAlive

public boolean isAlive()

Returns true if we are successfully in communications with the attached Client.

shutdown

public void shutdown()

This method shuts down the background thread.

sendMessage

public void sendMessage(int type,
                        java.lang.String message)
                 throws java.rmi.RemoteException

This method is used to submit a message to be sent to the client. If the serverClientProxy has already had its shutdown() method called, sendMessage() will silently fail, and the message will not be queued.

java.rmi.RemoteException

run

public void run()

The serverClientProxy's background thread's run() method. This method runs in the Client proxy thread to read events from this console's serverClientProxy eventBuffer and send them down to the Client.

Specified by:

run in interface java.lang.Runnable

addEvent

private void addEvent(arlut.csd.ganymede.clientEvent newEvent)
               throws java.rmi.RemoteException

private helper method in serverClientProxy, used to add an event to the proxy's event buffer. If the buffer already contains an event of the same type as newEvent, both events will be sent to the Client, in chronological order.

java.rmi.RemoteException

replaceEvent

private void replaceEvent(arlut.csd.ganymede.clientEvent newEvent)
                   throws java.rmi.RemoteException

private helper method in serverClientProxy, used to add an event to the proxy's event buffer. If the buffer already contains an event of the same type as newEvent, the old event's contents will be replaced with the new, and the remote client will never be notified of the old event's contents.

java.rmi.RemoteException

throwOverflow

private void throwOverflow()
                    throws java.rmi.RemoteException

This method throws a remoteException which describes the state of the event buffer. This is called from addEvent and replaceEvent.

java.rmi.RemoteException

enqueue

private void enqueue(arlut.csd.ganymede.clientEvent item)

private enqueue method.

dequeue

private arlut.csd.ganymede.clientEvent dequeue()

private dequeue method. assumes that the calling code will check bounds.