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java.lang.Object com.google.common.util.concurrent.AbstractExecutionThreadService
@Beta public abstract class AbstractExecutionThreadService
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.
Nested Class Summary |
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Nested classes/interfaces inherited from interface com.google.common.util.concurrent.Service |
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Service.State |
Constructor Summary | |
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AbstractExecutionThreadService()
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Method Summary | |
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protected Executor |
executor()
Returns the Executor that will be used to run this service. |
boolean |
isRunning()
Returns true if this service is running. |
protected abstract void |
run()
Run the 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()
If the service is starting or running, this initiates service shutdown and returns immediately. |
Service.State |
stopAndWait()
Initiates service shutdown (if necessary), returning once the service has finished stopping. |
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 |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
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public AbstractExecutionThreadService()
Method Detail |
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protected void startUp() throws Exception
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
Exception
protected void triggerShutdown()
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.
public String toString()
java.lang.Object
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())
toString
in class Object
public final ListenableFuture<Service.State> start()
Service
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.
start
in interface Service
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 the returned
future is unsupported and always returns false
.public final Service.State startAndWait()
Service
start().get()
, this method throws
no checked exceptions, and it cannot be interrupted.
startAndWait
in interface Service
public final boolean isRunning()
Service
true
if this service is running.
isRunning
in interface Service
public final Service.State state()
Service
state
in interface Service
public final ListenableFuture<Service.State> stop()
Service
stop
in interface Service
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 is unsupported and always returns
false
.public final Service.State stopAndWait()
Service
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.
stopAndWait
in interface Service
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