com.google.common.util.concurrent

Class AbstractIdleService

java.lang.Object

com.google.common.util.concurrent.AbstractIdleService

All Implemented Interfaces:

Service

@Beta
 @GwtIncompatible
public abstract class AbstractIdleService
extends Object
implements Service

Base class for services that do not need a thread while "running" but may need one during startup and shutdown. Subclasses can implement startUp() and shutDown() methods, each which run in a executor which by default uses a separate thread for each method.

Since:

1.0

Author:

Chris Nokleberg

Nested Class Summary

Nested classes/interfaces inherited from interface com.google.common.util.concurrent.Service

Service.Listener, Service.State

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractIdleService() Constructor for use by subclasses.

Method Summary

Modifier and Type	Method and Description
void	addListener(Service.Listener listener, Executor executor) Registers a Service.Listener to be executed on the given executor.
void	awaitRunning() Waits for the Service to reach the running state.
void	awaitRunning(long timeout, TimeUnit unit) Waits for the Service to reach the running state for no more than the given time.
void	awaitTerminated() Waits for the Service to reach the terminated state.
void	awaitTerminated(long timeout, TimeUnit unit) Waits for the Service to reach a terminal state (either terminated or failed) for no more than the given time.
protected Executor	executor() Returns the Executor that will be used to run this service.
Throwable	failureCause() Returns the Throwable that caused this service to fail.
boolean	isRunning() Returns true if this service is running.
protected String	serviceName() Returns the name of this service.
protected abstract void	shutDown() Stop the service.
Service	startAsync() If the service state is Service.State.NEW, this initiates service startup and returns immediately.
protected abstract void	startUp() Start the service.
Service.State	state() Returns the lifecycle state of the service.
Service	stopAsync() If the service is starting or running, this initiates service shutdown and returns immediately.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractIdleService

protected AbstractIdleService()

Constructor for use by subclasses.

Method Detail

startUp

protected abstract void startUp()
                         throws Exception

Start the service.

Throws:

Exception

shutDown

protected abstract void shutDown()
                          throws Exception

Stop the service.

Throws:

Exception

executor

protected Executor executor()

Returns the Executor that will be used to run this service. Subclasses may override this method to use a custom Executor, which may configure its worker thread with a specific name, thread group or priority. The returned executor's execute() method is called when this service is started and stopped, and should return promptly.

toString

public String toString()

Overrides:

toString in class Object

isRunning

public final boolean isRunning()

Description copied from interface: Service

Returns true if this service is running.

Specified by:

isRunning in interface Service

state

public final Service.State state()

Description copied from interface: Service

Returns the lifecycle state of the service.

Specified by:

state in interface Service

addListener

public final void addListener(Service.Listener listener,
                              Executor executor)

Description copied from interface: Service

Registers a Service.Listener to be executed on the given executor. The listener will have the corresponding transition method called whenever the service changes state. The listener will not have previous state changes replayed, so it is suggested that listeners are added before the service starts.

addListener guarantees execution ordering across calls to a given listener but not across calls to multiple listeners. Specifically, a given listener will have its callbacks invoked in the same order as the underlying service enters those states. Additionally, at most one of the listener's callbacks will execute at once. However, multiple listeners' callbacks may execute concurrently, and listeners may execute in an order different from the one in which they were registered.

RuntimeExceptions thrown by a listener will be caught and logged. Any exception thrown during Executor.execute (e.g., a RejectedExecutionException) will be caught and logged.

Specified by:

addListener in interface Service

Parameters:

listener - the listener to run when the service changes state is complete

executor - the executor in which the listeners callback methods will be run. For fast, lightweight listeners that would be safe to execute in any thread, consider MoreExecutors.directExecutor().

Since:

13.0

failureCause

public final Throwable failureCause()

Description copied from interface: Service

Returns the Throwable that caused this service to fail.

Specified by:

failureCause in interface Service

Since:

14.0

startAsync

public final Service startAsync()

Description copied from interface: Service

If the service state is Service.State.NEW, this initiates service startup and returns immediately. A stopped service may not be restarted.

Specified by:

startAsync in interface Service

Returns:

this

Since:

15.0

stopAsync

public final Service stopAsync()

Description copied from interface: Service

If the service is starting or running, this initiates service shutdown and returns immediately. If the service is new, it is terminated without having been started nor stopped. If the service has already been stopped, this method returns immediately without taking action.

Specified by:

stopAsync in interface Service

Returns:

this

Since:

15.0

awaitRunning

public final void awaitRunning()

Description copied from interface: Service

Waits for the Service to reach the running state.

Specified by:

awaitRunning in interface Service

Since:

15.0

awaitRunning

public final void awaitRunning(long timeout,
                               TimeUnit unit)
                        throws TimeoutException

Description copied from interface: Service

Waits for the Service to reach the running state for no more than the given time.

Specified by:

awaitRunning in interface Service

Parameters:

timeout - the maximum time to wait

unit - the time unit of the timeout argument

Throws:

TimeoutException - if the service has not reached the given state within the deadline

Since:

15.0

awaitTerminated

public final void awaitTerminated()

Description copied from interface: Service

Waits for the Service to reach the terminated state.

Specified by:

awaitTerminated in interface Service

Since:

15.0

awaitTerminated

public final void awaitTerminated(long timeout,
                                  TimeUnit unit)
                           throws TimeoutException

Description copied from interface: Service

Waits for the Service to reach a terminal state (either terminated or failed) for no more than the given time.

Specified by:

awaitTerminated in interface Service

Parameters:

timeout - the maximum time to wait

unit - the time unit of the timeout argument

Throws:

TimeoutException - if the service has not reached the given state within the deadline

Since:

15.0

serviceName

protected String serviceName()

Returns the name of this service. AbstractIdleService may include the name in debugging output.

Since:

14.0