org.gridgain.grid.events

Interface GridEvents

All Known Implementing Classes:

GridEventsImpl

public interface GridEvents

Provides functionality for local and remote event notifications on nodes defined by projection(). There are 2 ways to subscribe to event listening, local and remote. Instance of GridMessaging is obtained from grid projection as follows:

 GridEvents evts = GridGain.grid().events();
 

*

Local subscription, defined by localListen(GridPredicate, int...) method, will add a listener for specified events on local node only. This listener will be notified whenever any of subscribed events happen on local node regardless of whether local node belongs to underlying grid projection or not.

Remote subscription, defined by remoteListen(GridBiPredicate, GridPredicate, int...), will add an event listener for specified events on all nodes in the projection (possibly including local node if it belongs to the projection as well). All projection nodes will then be notified of the subscribed events. If the events pass the remote event filter, the events will be sent to local node for local listener notification.

Note that by default, all events in GridGain are disabled for performance reasons. You must only enable events that you need within your logic. You can enable/disable events either by calling enableLocal(int...) or disableLocal(int...) methods, or from XML configuration. For example, you can enable all cache events as follows:

 <property name="includeEventTypes">
     <util:constant static-field="org.gridgain.grid.events.GridEventType.EVTS_CACHE"/>
 </property>
 

Method Summary

Methods

Modifier and Type	Method and Description
void	disableLocal(int... types) Disables provided events.
int[]	enabledEvents() Gets types of enabled events.
void	enableLocal(int... types) Enables provided events.
boolean	isEnabled(int type) Check if event is enabled.
void	localListen(GridPredicate<? extends GridEvent> lsnr, int... types) Adds an event listener for local events.
<T extends GridEvent> Collection<T>	localQuery(GridPredicate<T> p, int... types) Queries local node for events using passed-in predicate filter for event selection.
GridProjection	projection() Gets grid projection to which this GridMessaging instance belongs.
void	recordLocal(GridEvent evt) Records customer user generated event.
<T extends GridEvent> GridFuture<UUID>	remoteListen(GridBiPredicate<UUID,T> locLsnr, GridPredicate<T> rmtFilter, int... types) Adds event listener for specified events to all nodes in the projection (possibly including local node if it belongs to the projection as well).
<T extends GridEvent> GridFuture<UUID>	remoteListen(int bufSize, long interval, boolean autoUnsubscribe, GridBiPredicate<UUID,T> locLsnr, GridPredicate<T> rmtFilter, int... types) Adds event listener for specified events to all nodes in the projection (possibly including local node if it belongs to the projection as well).
<T extends GridEvent> GridFuture<List<T>>	remoteQuery(GridPredicate<T> p, long timeout, int... types) Asynchronously queries nodes in this projection for events using passed in predicate filter for event selection.
boolean	stopLocalListen(GridPredicate<? extends GridEvent> lsnr, int... types) Removes local event listener.
GridFuture<?>	stopRemoteListen(UUID opId) Stops listening to remote events.
<T extends GridEvent> GridFuture<T>	waitForLocal(GridPredicate<T> filter, int... types) Gets event future that allows for asynchronous waiting for the specified events.

Method Detail

projection

GridProjection projection()

Gets grid projection to which this GridMessaging instance belongs.

Returns:

Grid projection to which this GridMessaging instance belongs.

remoteQuery

<T extends GridEvent> GridFuture<List<T>> remoteQuery(GridPredicate<T> p,
                                                    long timeout,
                                                    @Nullable
                                                    int... types)

Asynchronously queries nodes in this projection for events using passed in predicate filter for event selection.

Parameters:

p - Predicate filter used to query events on remote nodes.

timeout - Maximum time to wait for result, 0 to wait forever.

types - Event types to be queried.

Returns:

Collection of grid events returned from specified nodes.

remoteListen

<T extends GridEvent> GridFuture<UUID> remoteListen(@Nullable
                                                  GridBiPredicate<UUID,T> locLsnr,
                                                  @Nullable
                                                  GridPredicate<T> rmtFilter,
                                                  @Nullable
                                                  int... types)

Adds event listener for specified events to all nodes in the projection (possibly including local node if it belongs to the projection as well). This means that all events occurring on any node within this grid projection that pass remove filter will be sent to local node for local listener notification.

The listener can be unsubscribed automatically if local node stops, if locLsnr callback returns false or if stopRemoteListen(UUID) is called.

Type Parameters:

T - Type of the event.

Parameters:

locLsnr - Listener callback that is called on local node. If null, this events will be handled on remote nodes by passed in rmtFilter.

rmtFilter - Filter callback that is called on remote node. Only events that pass the remote filter will be sent to local node. If null, all events of specified types will be sent to local node. This remote filter can be used to pre-handle events remotely, before they are passed in to local callback. It will be auto-unsubsribed on the node where event occurred in case if it returns false.

types - Types of events to listen for. If not provided, all events that pass the provided remote filter will be sent to local node.

Returns:

Future that finishes when all listeners are registered. It returns operation ID that can be passed to stopRemoteListen(UUID) method to stop listening.

remoteListen

<T extends GridEvent> GridFuture<UUID> remoteListen(int bufSize,
                                                  long interval,
                                                  boolean autoUnsubscribe,
                                                  @Nullable
                                                  GridBiPredicate<UUID,T> locLsnr,
                                                  @Nullable
                                                  GridPredicate<T> rmtFilter,
                                                  @Nullable
                                                  int... types)

Adds event listener for specified events to all nodes in the projection (possibly including local node if it belongs to the projection as well). This means that all events occurring on any node within this grid projection that pass remove filter will be sent to local node for local listener notification.

Type Parameters:

T - Type of the event.

Parameters:

bufSize - Remote events buffer size. Events from remote nodes won't be sent until buffer is full or time interval is exceeded.

interval - Maximum time interval after which events from remote node will be sent. Events from remote nodes won't be sent until buffer is full or time interval is exceeded.

autoUnsubscribe - Flag indicating that event listeners on remote nodes should be automatically unregistered if master node (node that initiated event listening) leaves topology. If this flag is false, listeners will be unregistered only when stopRemoteListen(UUID) method is called, or the 'callback (locLsnr)' passed in returns false.

locLsnr - Callback that is called on local node. If this predicate returns true, the implementation will continue listening to events. Otherwise, events listening will be stopped and listeners will be unregistered on all nodes in the projection. If null, this events will be handled on remote nodes by passed in rmtFilter until local node stops (if 'autoUnsubscribe' is true) or until stopRemoteListen(UUID) is called.

rmtFilter - Filter callback that is called on remote node. Only events that pass the remote filter will be sent to local node. If null, all events of specified types will be sent to local node. This remote filter can be used to pre-handle events remotely, before they are passed in to local callback. It will be auto-unsubsribed on the node where event occurred in case if it returns false.

types - Types of events to listen for. If not provided, all events that pass the provided remote filter will be sent to local node.

Returns:

Future that finishes when all listeners are registered. It returns operation ID that can be passed to stopRemoteListen(UUID) method to stop listening.

See Also:

stopRemoteListen(UUID)

stopRemoteListen

GridFuture<?> stopRemoteListen(UUID opId)

Stops listening to remote events. This will unregister all listeners identified with provided operation ID on all nodes defined by projection().

Parameters:

opId - Operation ID that was returned from remoteListen(GridBiPredicate, GridPredicate, int...) method.

Returns:

Future that finishes when all listeners are unregistered.

See Also:

remoteListen(GridBiPredicate, GridPredicate, int...)

waitForLocal

<T extends GridEvent> GridFuture<T> waitForLocal(@Nullable
                                               GridPredicate<T> filter,
                                               @Nullable
                                               int... types)

Gets event future that allows for asynchronous waiting for the specified events. This method returns a future which by calling one of its get methods will block and wait for the specified event (either indefinitely or with provided timeout).

Parameters:

filter - Optional filtering predicate. Only if predicates evaluates to true will the event end the wait.

types - Types of the events to wait for. If not provided, all events will be passed to the filter.

Returns:

Grid event future.

localQuery

<T extends GridEvent> Collection<T> localQuery(GridPredicate<T> p,
                                             @Nullable
                                             int... types)

Queries local node for events using passed-in predicate filter for event selection.

Parameters:

p - Predicate to filter events. All predicates must be satisfied for the event to be returned.

types - Event types to be queried.

Returns:

Collection of grid events found on local node.

recordLocal

void recordLocal(GridEvent evt)

Records customer user generated event. All registered local listeners will be notified.

NOTE: all types in range from 1 to 1000 are reserved for internal GridGain events and should not be used by user-defined events. Attempt to record internal event with this method will cause IllegalArgumentException to be thrown.

Parameters:

evt - Locally generated event.

Throws:

IllegalArgumentException - If event type is within GridGain reserved range between 1 and 1000.

localListen

void localListen(GridPredicate<? extends GridEvent> lsnr,
               int... types)

Adds an event listener for local events. Note that listener will be added regardless of whether local node is in this projection or not.

Parameters:

lsnr - Predicate that is called on each received event. If predicate returns false, it will be unregistered and will stop receiving events.

types - Event types for which this listener will be notified.

Throws:

IllegalArgumentException - Thrown in case when passed in array of event types is empty.

stopLocalListen

boolean stopLocalListen(GridPredicate<? extends GridEvent> lsnr,
                      @Nullable
                      int... types)

Removes local event listener.

Parameters:

lsnr - Local event listener to remove.

types - Types of events for which to remove listener. If not specified, then listener will be removed for all types it was registered for.

Returns:

true if listener was removed, false otherwise.

enableLocal

void enableLocal(int... types)

Enables provided events. Allows to start recording events that were disabled before. Note that specified events will be enabled regardless of whether local node is in this projection or not.

Parameters:

types - Events to enable.

disableLocal

void disableLocal(int... types)

Disables provided events. Allows to stop recording events that were enabled before. Note that specified events will be disabled regardless of whether local node is in this projection or not.

Parameters:

types - Events to disable.

enabledEvents

int[] enabledEvents()

Gets types of enabled events.

Returns:

Types of enabled events.

isEnabled

boolean isEnabled(int type)

Check if event is enabled.

Parameters:

type - Event type.

Returns:

True if event of passed in type is enabled.