org.apache.cassandra.diag

Class DiagnosticEventService

java.lang.Object

org.apache.cassandra.diag.DiagnosticEventService

All Implemented Interfaces:

DiagnosticEventServiceMBean

public final class DiagnosticEventService
extends java.lang.Object
implements DiagnosticEventServiceMBean

Service for publishing and consuming DiagnosticEvents.

Method Summary

Modifier and Type	Method and Description
void	cleanup() Removes all active subscribers.
void	disableDiagnostics() Kill switch for disabling all events immediately, without restarting the node.
void	disableEventPersistence(java.lang.String eventClazz) Stop storing events.
void	enableEventPersistence(java.lang.String eventClazz) Start storing events to make them available via DiagnosticEventServiceMBean.readEvents(String, Long, int).
<E extends DiagnosticEvent> boolean	hasSubscribers(java.lang.Class<E> event) Indicates if any Consumer has been registered for the specified class of events.
<E extends DiagnosticEvent,T extends java.lang.Enum<T>> boolean	hasSubscribers(java.lang.Class<E> event, T eventType) Indicates if any Consumer has been registered for the specified class of events.
static DiagnosticEventService	instance()
boolean	isDiagnosticsEnabled()
<E extends DiagnosticEvent> boolean	isEnabled(java.lang.Class<E> event) Indicates if events are enabled for specified event class based on DatabaseDescriptor.diagnosticEventsEnabled() and hasSubscribers(Class).
<E extends DiagnosticEvent,T extends java.lang.Enum<T>> boolean	isEnabled(java.lang.Class<E> event, T eventType) Indicates if events are enabled for specified event class based on DatabaseDescriptor.diagnosticEventsEnabled() and hasSubscribers(Class, Enum).
void	publish(DiagnosticEvent event) Makes provided event available to all subscribers.
java.util.SortedMap<java.lang.Long,java.util.Map<java.lang.String,java.io.Serializable>>	readEvents(java.lang.String eventClazz, java.lang.Long lastKey, int limit) Retrieved all events of specified type starting with provided key.
<E extends DiagnosticEvent> void	subscribe(java.lang.Class<E> event, java.util.function.Consumer<E> consumer) Registers event handler for specified class of events.
<E extends DiagnosticEvent,T extends java.lang.Enum<T>> void	subscribe(java.lang.Class<E> event, T eventType, java.util.function.Consumer<E> consumer) Registers event handler for specified class of events.
void	subscribeAll(java.util.function.Consumer<DiagnosticEvent> consumer) Registers event handler for all DiagnosticEvents published from this point.
<E extends DiagnosticEvent> void	unsubscribe(java.lang.Class<E> event, java.util.function.Consumer<E> consumer) De-registers event handler from receiving any further events.
<E extends DiagnosticEvent> void	unsubscribe(java.util.function.Consumer<E> consumer) De-registers event handler from receiving any further events.

Methods inherited from class java.lang.Object

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

Method Detail

publish

public void publish(DiagnosticEvent event)

Makes provided event available to all subscribers.

subscribe

public <E extends DiagnosticEvent> void subscribe(java.lang.Class<E> event,
                                                  java.util.function.Consumer<E> consumer)

Registers event handler for specified class of events.

Parameters:

event - DiagnosticEvent class implementation

consumer - Consumer for received events

subscribe

public <E extends DiagnosticEvent,T extends java.lang.Enum<T>> void subscribe(java.lang.Class<E> event,
                                                                              T eventType,
                                                                              java.util.function.Consumer<E> consumer)

Registers event handler for specified class of events.

Parameters:

event - DiagnosticEvent class implementation

consumer - Consumer for received events

subscribeAll

public void subscribeAll(java.util.function.Consumer<DiagnosticEvent> consumer)

Registers event handler for all DiagnosticEvents published from this point.

Parameters:

consumer - Consumer for received events

unsubscribe

public <E extends DiagnosticEvent> void unsubscribe(java.util.function.Consumer<E> consumer)

De-registers event handler from receiving any further events.

Parameters:

consumer - Consumer registered for receiving events

unsubscribe

public <E extends DiagnosticEvent> void unsubscribe(@Nullable
                                                    java.lang.Class<E> event,
                                                    java.util.function.Consumer<E> consumer)

De-registers event handler from receiving any further events.

Parameters:

event - DiagnosticEvent class to unsubscribe from

consumer - Consumer registered for receiving events

hasSubscribers

public <E extends DiagnosticEvent> boolean hasSubscribers(java.lang.Class<E> event)

Indicates if any Consumer has been registered for the specified class of events.

Parameters:

event - DiagnosticEvent class implementation

hasSubscribers

public <E extends DiagnosticEvent,T extends java.lang.Enum<T>> boolean hasSubscribers(java.lang.Class<E> event,
                                                                                      T eventType)

Indicates if any Consumer has been registered for the specified class of events.

Parameters:

event - DiagnosticEvent class implementation

eventType - Subscribed event type matched against DiagnosticEvent.getType()

isEnabled

public <E extends DiagnosticEvent> boolean isEnabled(java.lang.Class<E> event)

Indicates if events are enabled for specified event class based on DatabaseDescriptor.diagnosticEventsEnabled() and hasSubscribers(Class).

Parameters:

event - DiagnosticEvent class implementation

isEnabled

public <E extends DiagnosticEvent,T extends java.lang.Enum<T>> boolean isEnabled(java.lang.Class<E> event,
                                                                                 T eventType)

Indicates if events are enabled for specified event class based on DatabaseDescriptor.diagnosticEventsEnabled() and hasSubscribers(Class, Enum).

Parameters:

event - DiagnosticEvent class implementation

eventType - Subscribed event type matched against DiagnosticEvent.getType()

instance

public static DiagnosticEventService instance()

cleanup

public void cleanup()

Removes all active subscribers. Should only be called from testing.

isDiagnosticsEnabled

public boolean isDiagnosticsEnabled()

Specified by:

isDiagnosticsEnabled in interface DiagnosticEventServiceMBean

disableDiagnostics

public void disableDiagnostics()

Description copied from interface: DiagnosticEventServiceMBean

Kill switch for disabling all events immediately, without restarting the node. Please edit cassandra.yaml for making this permanent.

Specified by:

disableDiagnostics in interface DiagnosticEventServiceMBean

readEvents

public java.util.SortedMap<java.lang.Long,java.util.Map<java.lang.String,java.io.Serializable>> readEvents(java.lang.String eventClazz,
                                                                                                           java.lang.Long lastKey,
                                                                                                           int limit)

Description copied from interface: DiagnosticEventServiceMBean

Retrieved all events of specified type starting with provided key. Result will be sorted chronologically.

Specified by:

readEvents in interface DiagnosticEventServiceMBean

Parameters:

eventClazz - fqn of event class

lastKey - ID of first event to retrieve

limit - number of results to return

enableEventPersistence

public void enableEventPersistence(java.lang.String eventClazz)

Description copied from interface: DiagnosticEventServiceMBean

Start storing events to make them available via DiagnosticEventServiceMBean.readEvents(String, Long, int).

Specified by:

enableEventPersistence in interface DiagnosticEventServiceMBean

disableEventPersistence

public void disableEventPersistence(java.lang.String eventClazz)

Description copied from interface: DiagnosticEventServiceMBean

Stop storing events.

Specified by:

disableEventPersistence in interface DiagnosticEventServiceMBean