Package org.cometd.oort

Class OortLong

java.lang.Object

org.eclipse.jetty.util.component.AbstractLifeCycle

org.cometd.oort.OortLong

All Implemented Interfaces:

org.eclipse.jetty.util.component.LifeCycle

public class OortLong
extends org.eclipse.jetty.util.component.AbstractLifeCycle

A shared atomic long made of an internal AtomicLong and of an internal OortObject<Long>.

This class exposes an API similar to that of AtomicLong, and for every successful update of the local value of the internal AtomicLong, it broadcast the local value via the internal OortObject to other nodes.

This class can be seen as the counterpart of OortPrimaryLong.

Where the OortPrimaryLong instance in each node has an internal AtomicLong, but only the one in the "primary" node has a non-zero value, the instance of this class in each node has an internal AtomicLong that has its own value.

Where in OortPrimaryLong updates are always sent to the "primary" node, in this class updates are always local, and then broadcast to the other nodes in the cluster.

Where in OortPrimaryLong each node has to send a message to the "primary" node to retrieve the total value, in this class the total value can be obtained from the internal OortObject without network communication with other nodes.

Where OortPrimaryLong trades less memory (one long per node) for larger latencies (every operation on non-primary nodes requires sending a message to the primary node), this class trades more memory (N longs per node - where N is the number of nodes) for smaller latencies (operations do not require messaging).

See Also:

OortPrimaryLong

Nested Class Summary

Nested classes/interfaces inherited from class org.eclipse.jetty.util.component.AbstractLifeCycle

org.eclipse.jetty.util.component.AbstractLifeCycle.AbstractLifeCycleListener, org.eclipse.jetty.util.component.AbstractLifeCycle.StopException

Nested classes/interfaces inherited from interface org.eclipse.jetty.util.component.LifeCycle

org.eclipse.jetty.util.component.LifeCycle.Listener

Field Summary

Fields inherited from class org.eclipse.jetty.util.component.AbstractLifeCycle

FAILED, STARTED, STARTING, STOPPED, STOPPING

Constructor Summary

Constructors

Constructor	Description
OortLong(Oort oort, java.lang.String name)
OortLong(Oort oort, java.lang.String name, long initial)

Method Summary

Modifier and Type	Method	Description
long	addAndGet(long delta)
void	addListener(OortObject.Listener<java.lang.Long> listener)
boolean	compareAndSet(long expected, long newValue)
protected void	doStart()
protected void	doStop()
long	get()
long	getAndAdd(long delta)
long	getAndSet(long newValue)
LocalSession	getLocalSession()
Oort	getOort()
void	removeListener(OortObject.Listener<java.lang.Long> listener)
void	removeListeners()	Removes all listeners.
long	sum()

Methods inherited from class org.eclipse.jetty.util.component.AbstractLifeCycle

addEventListener, getEventListeners, getState, getState, isFailed, isRunning, isStarted, isStarting, isStopped, isStopping, removeEventListener, setEventListeners, start, stop, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

OortLong

public OortLong(Oort oort,
                java.lang.String name)

OortLong

public OortLong(Oort oort,
                java.lang.String name,
                long initial)

Parameters:

oort - the oort this instance is associated to

name - the name of this service

initial - the initial local value

Method Detail

doStart

protected void doStart()
                throws java.lang.Exception

Overrides:

doStart in class org.eclipse.jetty.util.component.AbstractLifeCycle

Throws:

java.lang.Exception

doStop

protected void doStop()
               throws java.lang.Exception

Overrides:

doStop in class org.eclipse.jetty.util.component.AbstractLifeCycle

Throws:

java.lang.Exception

getOort

public Oort getOort()

Returns:

the Oort instance associated with this oort long

getLocalSession

public LocalSession getLocalSession()

Returns:

the local session that sends messages to other nodes

addListener

public void addListener(OortObject.Listener<java.lang.Long> listener)

Parameters:

listener - the listener to add that is notified of updates of the value in a node

See Also:

removeListener(OortObject.Listener)

removeListener

public void removeListener(OortObject.Listener<java.lang.Long> listener)

Parameters:

listener - the listener to remove

See Also:

addListener(OortObject.Listener)

removeListeners

public void removeListeners()

Removes all listeners.

See Also:

addListener(OortObject.Listener), removeListener(OortObject.Listener)

get

public long get()

Returns:

the local value

addAndGet

public long addAndGet(long delta)

Parameters:

delta - the delta to add to the local value (may be negative)

Returns:

the new local value

getAndAdd

public long getAndAdd(long delta)

Parameters:

delta - the delta to add to the local value (may be negative)

Returns:

the old local value

getAndSet

public long getAndSet(long newValue)

Parameters:

newValue - the new local value to set

Returns:

the old local value

compareAndSet

public boolean compareAndSet(long expected,
                             long newValue)

Parameters:

expected - the expected local value

newValue - the new local value

Returns:

whether the operation was successful

sum

public long sum()

Returns:

the sum of local values of each node