@Beta public abstract class AbstractExecutionThreadService extends Object implements Service
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.Service.Listener, Service.State| Modifier | Constructor and Description |
|---|---|
protected |
AbstractExecutionThreadService()
Constructor for use by subclasses.
|
| Modifier and Type | Method and Description |
|---|---|
void |
addListener(Service.Listener listener,
Executor executor)
Registers a
Service.Listener to be executed on the given
executor. |
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()
If the service state is
Service.State.NEW, this initiates service startup and returns
immediately. |
Service.State |
startAndWait()
Initiates service startup (if necessary), returning once the service has finished starting.
|
protected void |
startUp()
Start the service.
|
Service.State |
state()
Returns the lifecycle state of the service.
|
ListenableFuture<Service.State> |
stop()
|
Service.State |
stopAndWait()
Initiates service shutdown (if necessary), returning once the service has finished stopping.
|
String |
toString() |
protected void |
triggerShutdown()
Invoked to request the service to stop.
|
protected AbstractExecutionThreadService()
protected void startUp() throws Exception
By default this method does nothing.
Exceptionprotected abstract void run() throws Exception
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.Exceptionprotected void shutDown() throws Exception
By default this method does nothing.
Exceptionprotected void triggerShutdown()
By default this method does nothing.
protected Executor executor()
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()
public final ListenableFuture<Service.State> start()
ServiceService.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.start in interface ServiceFuture.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.public final Service.State startAndWait()
Servicestart().get(), this method throws no checked exceptions, and it cannot
be interrupted.startAndWait in interface Servicepublic final boolean isRunning()
Servicetrue if this service is running.public final Service.State state()
Servicepublic final ListenableFuture<Service.State> stop()
Servicestop in interface ServiceFuture.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.public final Service.State stopAndWait()
ServiceService.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.stopAndWait in interface Servicepublic final void addListener(Service.Listener listener, Executor executor)
ServiceService.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.
addListener in interface Servicelistener - the listener to run when the service changes state is completeexecutor - the executor in which the the listeners callback methods will be run. For fast,
lightweight listeners that would be safe to execute in any thread, consider
MoreExecutors.sameThreadExecutor().public final Throwable failureCause()
ServiceThrowable that caused this service to fail.failureCause in interface Serviceprotected String serviceName()
AbstractExecutionThreadService
may include the name in debugging output.
Subclasses may override this method.
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