@Beta @GwtIncompatible 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. |
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.
|
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.
|
Service |
stopAsync()
|
String |
toString()
Returns a string representation of the object.
|
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 String toString()
java.lang.ObjecttoString 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())
public final boolean isRunning()
Servicetrue if this service is running.public final Service.State state()
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.
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 Servicelistener - the listener to run when the service changes state is completeexecutor - 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 Throwable failureCause()
ServiceThrowable that caused this service to fail.failureCause in interface Service@CanIgnoreReturnValue public final Service startAsync()
ServiceService.State.NEW, this initiates service startup and returns
immediately. A stopped service may not be restarted.startAsync in interface Service@CanIgnoreReturnValue public final Service stopAsync()
Servicepublic final void awaitRunning()
ServiceService to reach the running state.awaitRunning in interface Servicepublic final void awaitRunning(long timeout, TimeUnit unit) throws TimeoutException
ServiceService to reach the running state for no more
than the given time.awaitRunning in interface Servicetimeout - the maximum time to waitunit - the time unit of the timeout argumentTimeoutException - if the service has not reached the given state within the deadlinepublic final void awaitTerminated()
ServiceService to reach the terminated state.awaitTerminated in interface Servicepublic final void awaitTerminated(long timeout, TimeUnit unit) throws TimeoutException
ServiceService to reach a terminal state (either terminated or failed) for no more than the given time.awaitTerminated in interface Servicetimeout - the maximum time to waitunit - the time unit of the timeout argumentTimeoutException - if the service has not reached the given state within the deadlineprotected String serviceName()
AbstractExecutionThreadService may include the name
in debugging output.
Subclasses may override this method.
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