com.hazelcast.spi.impl.eventservice.impl

Class EventServiceImpl

java.lang.Object

com.hazelcast.spi.impl.eventservice.impl.EventServiceImpl

All Implemented Interfaces:

MetricsProvider, EventService, InternalEventService, PostJoinAwareService, PreJoinAwareService, Consumer<Packet>

public class EventServiceImpl
extends Object
implements InternalEventService, MetricsProvider

Service responsible for routing and dispatching local and remote events and keeping track of listener registrations. Local events are events published on a local subscriber (the subscriber is on this node) and remote events are published on a remote subscriber (the subscriber is on a different node and the event is sent to that node). The remote events are generally asnychronous meaning that we send the event and don't wait for the response. The exception to this is that every eventSyncFrequency remote event is sent as an operation and we wait for it to be submitted to the remote queue.

This implementation keeps registrations grouped into EventServiceSegments. Each segment is responsible for a single service (e.g. map service, cluster service, proxy service).

The events are processed on a StripedExecutor. The executor has a fixed queue and thread size and it is shared between all events meaning that it is important to configure it correctly. Inadequate thread count sizing can lead to wasted threads or low throughput. Inadequate queue size can lead to OutOfMemoryError or events being dropped when the queue is full. The events are ordered by order key which can be defined when publishing the event meaning that you can define your custom ordering. Events with the same order key will be processed by the same thread on the executor.

This order can still be broken in some cases. This is possible because remote events are asynchronous and we don't wait for the response before publishing the next event. The previously published event can be retransmitted causing it to be received by the target node at a later time.

Field Summary

Fields

Modifier and Type	Field and Description
static String	EVENT_SYNC_FREQUENCY_PROP Usually remote events are sent asynchronously.
static String	SERVICE_NAME

Constructor Summary

Constructors

Constructor and Description
EventServiceImpl(NodeEngineImpl nodeEngine)

Method Summary

Modifier and Type	Method and Description
void	accept(Packet packet) Performs this operation on the given argument.
void	close(EventRegistration eventRegistration) Closes an EventRegistration.
void	deregisterAllListeners(String serviceName, String topic) Deregisters all listeners belonging to the given service and topic.
boolean	deregisterListener(String serviceName, String topic, Object id) Deregisters a listener with the given registration ID.
void	executeEventCallback(Runnable callback) Executes an event callback on a random event thread.
StripedExecutor	getEventExecutor()
int	getEventQueueCapacity() Returns the queue capacity per event thread.
int	getEventQueueSize() Returns the current total event queue size.
int	getEventThreadCount() Returns the event thread count.
Operation	getPostJoinOperation() Post join operations must be lock free, meaning no locks at all: no partition locks, no key-based locks, no service level locks, no database interaction! The Operation.getPartitionId() method should return a negative value.
Operation	getPreJoinOperation() An operation to be executed on the joining member before it is set as joined.
Collection<EventRegistration>	getRegistrations(String serviceName, String topic) Returns all registrations belonging to the given service and topic.
EventRegistration[]	getRegistrationsAsArray(String serviceName, String topic) Returns all registrations belonging to the given service and topic as an array.
EventServiceSegment	getSegment(String service, boolean forceCreate) Returns the EventServiceSegment for the service.
boolean	handleRegistration(Registration reg)
boolean	hasEventRegistration(String serviceName, String topic) Returns true if a listener is registered with the specified service name and topic.
void	onMemberLeft(MemberImpl member)
void	provideMetrics(MetricsRegistry registry)
void	publishEvent(String serviceName, Collection<EventRegistration> registrations, Object event, int orderKey) Publishes an event for multiple event registrations.
void	publishEvent(String serviceName, EventRegistration registration, Object event, int orderKey) Publishes an event for a specific event registration.
void	publishEvent(String serviceName, String topic, Object event, int orderKey) Publishes an event for all event registrations belonging to the specified service name and topic.
void	publishRemoteEvent(String serviceName, Collection<EventRegistration> registrations, Object event, int orderKey) Publishes an event for multiple event registrations, excluding local ones.
EventRegistration	registerListener(String serviceName, String topic, EventFilter filter, Object listener) Registers a listener on all cluster nodes with an event filter.
EventRegistration	registerListener(String serviceName, String topic, Object listener) Registers a listener on all cluster nodes.
EventRegistration	registerLocalListener(String serviceName, String topic, EventFilter filter, Object listener) Registers a local only listener with an event filter.
EventRegistration	registerLocalListener(String serviceName, String topic, Object listener) Registers a local only listener.
void	shutdown()

Methods inherited from class java.lang.Object

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

Field Detail

SERVICE_NAME

public static final String SERVICE_NAME

See Also:

Constant Field Values

EVENT_SYNC_FREQUENCY_PROP

public static final String EVENT_SYNC_FREQUENCY_PROP

Usually remote events are sent asynchronously. This property dictates how often the event is sent synchronously. This means that the event will be sent as a SendEventOperation and we will wait for the response. The default value is .

See Also:

sendEvent(Address, EventEnvelope, int), Constant Field Values

Constructor Detail

EventServiceImpl

public EventServiceImpl(NodeEngineImpl nodeEngine)

Method Detail

provideMetrics

public void provideMetrics(MetricsRegistry registry)

Specified by:

provideMetrics in interface MetricsProvider

close

public void close(EventRegistration eventRegistration)

Description copied from interface: InternalEventService

Closes an EventRegistration.

If the EventRegistration has any closeable resource, e.g. a listener, than this listener is closed.

Specified by:

close in interface InternalEventService

Parameters:

eventRegistration - the EventRegistration to close.

getEventThreadCount

public int getEventThreadCount()

Description copied from interface: EventService

Returns the event thread count.

Specified by:

getEventThreadCount in interface EventService

Returns:

the event thread count

See Also:

GroupProperty.EVENT_THREAD_COUNT

getEventQueueCapacity

public int getEventQueueCapacity()

Description copied from interface: EventService

Returns the queue capacity per event thread.

Specified by:

getEventQueueCapacity in interface EventService

Returns:

the queue capacity per event thread

See Also:

GroupProperty.EVENT_QUEUE_CAPACITY

getEventQueueSize

public int getEventQueueSize()

Description copied from interface: EventService

Returns the current total event queue size.

Specified by:

getEventQueueSize in interface EventService

Returns:

the current total event queue size

registerLocalListener

public EventRegistration registerLocalListener(String serviceName,
                                               String topic,
                                               Object listener)

Description copied from interface: EventService

Registers a local only listener.

Specified by:

registerLocalListener in interface EventService

Parameters:

serviceName - service name

topic - topic name

listener - listener instance

Returns:

event registration

registerLocalListener

public EventRegistration registerLocalListener(String serviceName,
                                               String topic,
                                               EventFilter filter,
                                               Object listener)

Description copied from interface: EventService

Registers a local only listener with an event filter.

Specified by:

registerLocalListener in interface EventService

Parameters:

serviceName - service name

topic - topic name

filter - event filter

listener - listener instance

Returns:

event registration

registerListener

public EventRegistration registerListener(String serviceName,
                                          String topic,
                                          Object listener)

Description copied from interface: EventService

Registers a listener on all cluster nodes.

Specified by:

registerListener in interface EventService

Parameters:

serviceName - service name

topic - topic name

listener - listener instance

Returns:

event registration

registerListener

public EventRegistration registerListener(String serviceName,
                                          String topic,
                                          EventFilter filter,
                                          Object listener)

Description copied from interface: EventService

Registers a listener on all cluster nodes with an event filter.

Specified by:

registerListener in interface EventService

Parameters:

serviceName - service name

topic - topic name

filter - event filter

listener - listener instance

Returns:

event registration

handleRegistration

public boolean handleRegistration(Registration reg)

deregisterListener

public boolean deregisterListener(String serviceName,
                                  String topic,
                                  Object id)

Description copied from interface: EventService

Deregisters a listener with the given registration ID.

Specified by:

deregisterListener in interface EventService

Parameters:

serviceName - service name

topic - topic name

id - registration ID

Returns:

true if listener is deregistered successfully, false otherwise

See Also:

EventRegistration.getId(), EventService.registerListener(String, String, Object), EventService.registerLocalListener(String, String, Object)

deregisterAllListeners

public void deregisterAllListeners(String serviceName,
                                   String topic)

Description copied from interface: EventService

Deregisters all listeners belonging to the given service and topic.

Specified by:

deregisterAllListeners in interface EventService

Parameters:

serviceName - service name

topic - topic name

getEventExecutor

public StripedExecutor getEventExecutor()

getRegistrationsAsArray

public EventRegistration[] getRegistrationsAsArray(String serviceName,
                                                   String topic)

Description copied from interface: EventService

Returns all registrations belonging to the given service and topic as an array.

Specified by:

getRegistrationsAsArray in interface EventService

Parameters:

serviceName - service name

topic - topic name

Returns:

registrations array

getRegistrations

public Collection<EventRegistration> getRegistrations(String serviceName,
                                                      String topic)

Returns all registrations belonging to the given service and topic. The returned collection is unmodifiable and the method always returns a non-null collection.

Specified by:

getRegistrations in interface EventService

Parameters:

serviceName - service name

topic - topic name

Returns:

a non-null immutable collection of listener registrations

hasEventRegistration

public boolean hasEventRegistration(String serviceName,
                                    String topic)

Description copied from interface: EventService

Returns true if a listener is registered with the specified service name and topic.

Specified by:

hasEventRegistration in interface EventService

Parameters:

serviceName - service name

topic - topic name

Returns:

true if a listener is registered with specified service name and topic, false otherwise.

publishEvent

public void publishEvent(String serviceName,
                         String topic,
                         Object event,
                         int orderKey)

Description copied from interface: EventService

Publishes an event for all event registrations belonging to the specified service name and topic. All events with the same orderKey are ordered, otherwise the order is not preserved.

NOTE : The order may not be preserved in case the event needs to be republished (e.g. when the registration is not on this node and the event has to be retransmitted)

Specified by:

publishEvent in interface EventService

Parameters:

serviceName - service name

topic - topic name

event - event object

orderKey - the order key for this event. All events with the same order key are ordered.

publishEvent

public void publishEvent(String serviceName,
                         EventRegistration registration,
                         Object event,
                         int orderKey)

Description copied from interface: EventService

Publishes an event for a specific event registration. All events with the same orderKey are ordered, otherwise the order is not preserved.

NOTE : The order may not be preserved in case the event needs to be republished (e.g. when the registration is not on this node and the event has to be retransmitted)

Specified by:

publishEvent in interface EventService

Parameters:

serviceName - service name

registration - event registration

event - event object

orderKey - the order key for this event. All events with the same order key are ordered.

publishEvent

public void publishEvent(String serviceName,
                         Collection<EventRegistration> registrations,
                         Object event,
                         int orderKey)

Description copied from interface: EventService

Publishes an event for multiple event registrations. All events with the same orderKey are ordered, otherwise the order is not preserved.

NOTE : The order may not be preserved in case the event needs to be republished (e.g. when the registration is not on this node and the event has to be retransmitted)

Specified by:

publishEvent in interface EventService

Parameters:

serviceName - service name

registrations - multiple event registrations

event - event object

orderKey - the order key for this event. All events with the same order key are ordered.

publishRemoteEvent

public void publishRemoteEvent(String serviceName,
                               Collection<EventRegistration> registrations,
                               Object event,
                               int orderKey)

Publishes an event for multiple event registrations, excluding local ones. All events with the same orderKey are ordered, otherwise the order is not preserved.

NOTE : The order may not be preserved in case the event needs to be republished (e.g. when the registration is not on this node and the event has to be retransmitted)

Specified by:

publishRemoteEvent in interface EventService

Parameters:

serviceName - service name

registrations - multiple event registrations

event - event object

orderKey - order key

Throws:

IllegalArgumentException - if any registration is not an instance of Registration

getSegment

public EventServiceSegment getSegment(String service,
                                      boolean forceCreate)

Returns the EventServiceSegment for the service. If the segment is null and forceCreate is true, the segment is created and registered with the MetricsRegistry.

Parameters:

service - the service of the segment

forceCreate - whether the segment should be created in case there is no segment

Returns:

the segment for the service or null if there is no segment and forceCreate is false

executeEventCallback

public void executeEventCallback(Runnable callback)

Executes an event callback on a random event thread.

If callback is an instance of StripedRunnable, then StripedRunnable.getKey() will be used as order key to pick event thread.

If the execution is rejected, the rejection count is increased and a failure is logged. The event callback is not re-executed.

Specified by:

executeEventCallback in interface EventService

Parameters:

callback - the callback to execute on a random event thread

See Also:

StripedRunnable

accept

public void accept(Packet packet)

Performs this operation on the given argument. Handles an asynchronous remote event with a RemoteEventProcessor. The processor may determine the thread which will handle the event. If the execution is rejected, the rejection count is increased and a failure is logged. The event processing is not retried.

Specified by:

accept in interface Consumer<Packet>

Parameters:

packet - the response packet to handle

See Also:

sendEvent(Address, EventEnvelope, int)

getPreJoinOperation

public Operation getPreJoinOperation()

Description copied from interface: PreJoinAwareService

An operation to be executed on the joining member before it is set as joined. As is the case with PostJoinAwareService.getPostJoinOperation()s, no partition locks, no key-based locks, no service level locks, no database interaction are allowed. Additionally, a pre-join operation is executed while the cluster lock is being held on the joining member, so it is important that the operation finishes quickly and does not interact with other locks. The Operation.getPartitionId() method should return a negative value. This means that the operations should not implement PartitionAwareOperation.

Pre join operations should return response, which may also be a null response.

Specified by:

getPreJoinOperation in interface PreJoinAwareService

Returns:

an operation to be executed on joining member before it is set as joined. Can be null.

getPostJoinOperation

public Operation getPostJoinOperation()

Description copied from interface: PostJoinAwareService

Post join operations must be lock free, meaning no locks at all: no partition locks, no key-based locks, no service level locks, no database interaction! The Operation.getPartitionId() method should return a negative value. This means that the operations should not implement PartitionAwareOperation.

Post join operations should return response, at least a null response.

Specified by:

getPostJoinOperation in interface PostJoinAwareService

Returns:

a response from the post join operation. Can be null.

shutdown

public void shutdown()

onMemberLeft

public void onMemberLeft(MemberImpl member)