com.google.common.util.concurrent

Class AbstractExecutionThreadService

java.lang.Object

com.google.common.util.concurrent.AbstractExecutionThreadService

All Implemented Interfaces:

Service

@Beta
public abstract class AbstractExecutionThreadService
extends Object
implements Service

Base class for services that can implement startUp(), run() and shutDown() methods. This class uses a single thread to execute the service; consider AbstractService if you would like to manage any threading manually.

Since:

1.0

Author:

Jesse Wilson

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	AbstractExecutionThreadService() Constructor for use by subclasses.

Method Summary

Methods

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 abstract void	run() Run the service.
protected String	serviceName() Returns the name of this service.
protected void	shutDown() Stop the service.
ListenableFuture<Service.State>	start() Deprecated.
Service.State	startAndWait() Deprecated.
Service	startAsync() If the service state is Service.State.NEW, this initiates service startup and returns immediately.
protected void	startUp() Start the service.
Service.State	state() Returns the lifecycle state of the service.
ListenableFuture<Service.State>	stop() Deprecated.
Service.State	stopAndWait() Deprecated.
Service	stopAsync() If the service is starting or running, this initiates service shutdown and returns immediately.
String	toString() Returns a string representation of the object.
protected void	triggerShutdown() Invoked to request the service to stop.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractExecutionThreadService

protected AbstractExecutionThreadService()

Constructor for use by subclasses.

Method Detail

startUp

protected void startUp()
                throws Exception

Start the service. This method is invoked on the execution thread.

By default this method does nothing.

Throws:

Exception

run

protected abstract void run()
                     throws Exception

Run the service. This method is invoked on the execution thread. Implementations must respond to stop requests. You could poll for lifecycle changes in a work loop:

   public void run() {
     while (isRunning()) {
       // perform a unit of work
     }
   }
 

...or you could respond to stop requests by implementing triggerShutdown(), which should cause run() to return.

Throws:

Exception

shutDown

protected void shutDown()
                 throws Exception

Stop the service. This method is invoked on the execution thread.

By default this method does nothing.

Throws:

Exception

triggerShutdown

protected void triggerShutdown()

Invoked to request the service to stop.

By default this method does nothing.

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 should return promptly.

The default implementation returns a new Executor that sets the name of its threads to the string returned by serviceName()

toString

public String toString()

Description copied from class: java.lang.Object

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())
 

Overrides:

toString in class Object

Returns:

a string representation of the object.

start

@Deprecated
public final ListenableFuture<Service.State> start()

Deprecated.

Description copied from interface: Service

If the service state is Service.State.NEW, this initiates service startup and returns immediately. If the service has already been started, this method returns immediately without taking action. A stopped service may not be restarted.

Specified by:

start in interface Service

Returns:

a future for the startup result, regardless of whether this call initiated startup. Calling Future.get() will block until the service has finished starting, and returns one of Service.State.RUNNING, Service.State.STOPPING or Service.State.TERMINATED. If the service fails to start, Future.get() will throw an ExecutionException, and the service's state will be Service.State.FAILED. If it has already finished starting, Future.get() returns immediately. Cancelling this future has no effect on the service.

startAndWait

@Deprecated
public final Service.State startAndWait()

Deprecated.

Description copied from interface: Service

Initiates service startup (if necessary), returning once the service has finished starting. Unlike calling start().get(), this method throws no checked exceptions, and it cannot be interrupted.

Specified by:

startAndWait in interface Service

Returns:

the state of the service when startup finished.

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

stop

@Deprecated
public final ListenableFuture<Service.State> stop()

Deprecated.

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:

stop in interface Service

Returns:

a future for the shutdown result, regardless of whether this call initiated shutdown. Calling Future.get() will block until the service has finished shutting down, and either returns Service.State.TERMINATED or throws an ExecutionException. If it has already finished stopping, Future.get() returns immediately. Cancelling this future has no effect on the service.

stopAndWait

@Deprecated
public final Service.State stopAndWait()

Deprecated.

Description copied from interface: Service

Initiates service shutdown (if necessary), returning once the service has finished stopping. If this is Service.State.STARTING, startup will be cancelled. If this is Service.State.NEW, it is terminated without having been started nor stopped. Unlike calling stop().get(), this method throws no checked exceptions.

Specified by:

stopAndWait in interface Service

Returns:

the state of the service when shutdown finished.

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.

There is no guaranteed ordering of execution of listeners, but any listener added through this method is guaranteed to be called whenever there is a state change.

Exceptions thrown by a listener will be propagated up to the executor. Any exception thrown during Executor.execute (e.g., a RejectedExecutionException or an exception thrown by inline execution) 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.sameThreadExecutor().

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. AbstractExecutionThreadService may include the name in debugging output.

Subclasses may override this method.

Since:

14.0 (present in 10.0 as getServiceName)