Class AbstractExecutionThreadService

java.lang.Object
com.google.common.util.concurrent.AbstractExecutionThreadService
All Implemented Interfaces:
Service
@GwtIncompatible 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

  • Constructor Details

    • AbstractExecutionThreadService

      protected AbstractExecutionThreadService()
      Constructor for use by subclasses.

  • Method Details

    • 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.

      Currently, this method is invoked while holding a lock. If an implementation of this method blocks, it can prevent this service from changing state. If you need to performing a blocking operation in order to trigger shutdown, consider instead registering a listener and implementing stopping. Note, however, that stopping does not run at exactly the same times as triggerShutdown.

    • 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()
      Overrides:
      toString in class Object

    • 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

    • 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.

      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.

      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.directExecutor().
      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

      @CanIgnoreReturnValue 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

      @CanIgnoreReturnValue 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)