@Beta public abstract class AbstractExecutionThreadService extends Objectimplements 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
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
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
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.
|
Service |
startAsync()
If the service state is
Service, this initiates service startup and returns immediately.
|
protected void |
startUp()
Start the service.
|
Service |
state()
Returns the lifecycle state of the service.
|
Service |
stopAsync()
|
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.
Exception
protected 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.
Exception
protected void shutDown()
throws Exception
By default this method does nothing.
Exception
protected void triggerShutdown()
By default this method does nothing.
protected Executorexecutor()
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 StringtoString()
public final boolean isRunning()
Service
true if this service is
running.
public final Service.State state()
Service
public final void addListener(Service.Listener listener, Executor executor)
Service
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.
addListener in interface
Service
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() .
public final ThrowablefailureCause()
Service
Throwable that caused this service to fail.
failureCause in interface
Service
public final ServicestartAsync()
Service
Service.State.NEW , this initiates service startup and returns immediately. A stopped service may not be restarted.
startAsync in interface
Service
public final ServicestopAsync()
Service
public final void awaitRunning()
Service
Service to reach the
running state.
awaitRunning in interface
Service
public final void awaitRunning(long timeout,
TimeUnit unit)
throws TimeoutException
Service
Service to reach the
running state for no more than the given time.
awaitRunning in interface
Service
timeout - the maximum time to wait
unit - the time unit of the timeout argument
TimeoutException - if the service has not reached the given state within the deadline
public final void awaitTerminated()
Service
Service to reach the
terminated state.
awaitTerminated in interface
Service
public final void awaitTerminated(long timeout,
TimeUnit unit)
throws TimeoutException
Service
Service to reach a terminal state (either
terminated or
failed) for no more than the given time.
awaitTerminated in interface
Service
timeout - the maximum time to wait
unit - the time unit of the timeout argument
TimeoutException - if the service has not reached the given state within the deadline
protected StringserviceName()
AbstractExecutionThreadService may include the name in debugging output.
Subclasses may override this method.