groovyx.gpars.dataflow.operator.component
[Java] Class GracefulShutdownMonitor

java.lang.Object
  groovyx.gpars.dataflow.operator.component.GracefulShutdownMonitor

All Implemented Interfaces:

OperatorStateMonitor

public final class GracefulShutdownMonitor

The monitor will orchestrate a graceful shutdown, when its shutdownNetwork() method is called. For this mechanism to work, all selectors/operators in the network have to have their own instance of GracefulShutdownListener added and these listeners have to share the same GracefulShutdownMonitor instance. Each listener observes the activity in the input channels of its corresponding operator/selector. Upon graceful shutdown initialization, the listeners also start watching the state of their operators/selectors. The GracefulShutdownMonitor then repeatedly watches, whether listeners report activity in the operators. When the activity ceases, the monitor will poll all listeners about the state of their operator/selector and its input channels. If all listeners report no activity and no incoming messages, the monitor can safely terminate all operators.

Authors:

Vaclav Pech

DEFAULT_DELAY

private static final long DEFAULT_DELAY

delay

private final long delay

listeners

private final java.util.Collection listeners

notificationArrivedFlag

private final java.util.concurrent.atomic.AtomicBoolean notificationArrivedFlag

Uses the default timer delay

result

private final DataflowVariable result

shutdownFlag

private boolean shutdownFlag

All listeners that watch the operators/selectors in the network

GracefulShutdownMonitor

public GracefulShutdownMonitor()

GracefulShutdownMonitor

public GracefulShutdownMonitor(long delay)

Invoked whenever a processor changes state

checkWhetherAnyEventsHaveArrived

private boolean checkWhetherAnyEventsHaveArrived()

Checks the notification flag whether there has been some activity since last timer run.

Returns:

True, if events have been registered since last time, false otherwise.

onTimer

void onTimer()

registerProcessorListener

@java.lang.Overrideif (!shutdownFlag) {
public void registerProcessorListener(GracefulShutdownListener listener)

Initializes the shutdown process. New listeners cannot be registered after this point. New messages should not enter the dataflow network from the outside, since this may prevent the network from terminating.

Returns:

A Promise, which may be used to wait for or get notified about the shutdown success.

schedule

private void schedule()

shutdownNetwork

public Promise shutdownNetwork()

Checks, whether the network is no longer active. To reduce effect on system performance, cheap criteria are being checked first.

stateChanged

@java.lang.Overridelisteners.add(listener);
public void stateChanged()

Copyright © 2008–2013 Václav Pech. All Rights Reserved.