org.apache.hadoop.yarn.server.nodemanager.containermanager

Class AuxServices

java.lang.Object

org.apache.hadoop.service.AbstractService

org.apache.hadoop.yarn.server.nodemanager.containermanager.AuxServices

All Implemented Interfaces:

Closeable, AutoCloseable, Service, ServiceStateChangeListener, EventHandler<AuxServicesEvent>

public class AuxServices
extends AbstractService
implements ServiceStateChangeListener, EventHandler<AuxServicesEvent>

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.hadoop.service.Service

Service.STATE

Field Summary

Fields

Modifier and Type	Field and Description
protected Map<String,AuxiliaryService>	serviceMap
protected Map<String,ByteBuffer>	serviceMetaData

Constructor Summary

Constructors

Constructor and Description
AuxServices()

Method Summary

Methods

Modifier and Type	Method and Description
protected void	addService(String name, AuxiliaryService service)
Map<String,ByteBuffer>	getMetaData()
void	handle(AuxServicesEvent event)
void	serviceInit(Configuration conf) All initialization code needed by a service.
void	serviceStart() Actions called during the INITED to STARTED transition.
void	serviceStop() Actions called during the transition to the STOPPED state.
void	stateChanged(Service service) Callback to notify of a state change.

Methods inherited from class org.apache.hadoop.service.AbstractService

close, getBlockers, getConfig, getFailureCause, getFailureState, getLifecycleHistory, getName, getServiceState, getStartTime, init, isInState, noteFailure, putBlocker, registerGlobalListener, registerServiceListener, removeBlocker, setConfig, start, stop, toString, unregisterGlobalListener, unregisterServiceListener, waitForServiceToStop

Methods inherited from class java.lang.Object

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

Field Detail

serviceMap

protected final Map<String,AuxiliaryService> serviceMap

serviceMetaData

protected final Map<String,ByteBuffer> serviceMetaData

Constructor Detail

AuxServices

public AuxServices()

Method Detail

addService

protected final void addService(String name,
              AuxiliaryService service)

getMetaData

public Map<String,ByteBuffer> getMetaData()

Returns:

the meta data for all registered services, that have been started. If a service has not been started no metadata will be available. The key is the name of the service as defined in the configuration.

serviceInit

public void serviceInit(Configuration conf)
                 throws Exception

Description copied from class: AbstractService

All initialization code needed by a service. This method will only ever be called once during the lifecycle of a specific service instance. Implementations do not need to be synchronized as the logic in AbstractService.init(Configuration) prevents re-entrancy. The base implementation checks to see if the subclass has created a new configuration instance, and if so, updates the base class value

Overrides:

serviceInit in class AbstractService

Parameters:

conf - configuration

Throws:

Exception - on a failure -these will be caught, possibly wrapped, and wil; trigger a service stop

serviceStart

public void serviceStart()
                  throws Exception

Description copied from class: AbstractService

Actions called during the INITED to STARTED transition. This method will only ever be called once during the lifecycle of a specific service instance. Implementations do not need to be synchronized as the logic in AbstractService.start() prevents re-entrancy.

Overrides:

serviceStart in class AbstractService

Throws:

Exception - if needed -these will be caught, wrapped, and trigger a service stop

serviceStop

public void serviceStop()
                 throws Exception

Description copied from class: AbstractService

Actions called during the transition to the STOPPED state. This method will only ever be called once during the lifecycle of a specific service instance. Implementations do not need to be synchronized as the logic in AbstractService.stop() prevents re-entrancy. Implementations MUST write this to be robust against failures, including checks for null references -and for the first failure to not stop other attempts to shut down parts of the service.

Overrides:

serviceStop in class AbstractService

Throws:

Exception - if needed -these will be caught and logged.

stateChanged

public void stateChanged(Service service)

Description copied from interface: ServiceStateChangeListener

Callback to notify of a state change. The service will already have changed state before this callback is invoked. This operation is invoked on the thread that initiated the state change, while the service itself in in a sychronized section.

1. Any long-lived operation here will prevent the service state change from completing in a timely manner.
2. If another thread is somehow invoked from the listener, and that thread invokes the methods of the service (including subclass-specific methods), there is a risk of a deadlock.

Specified by:

stateChanged in interface ServiceStateChangeListener

Parameters:

service - the service that has changed.

handle

public void handle(AuxServicesEvent event)

Specified by:

handle in interface EventHandler<AuxServicesEvent>