Package com.google.common.util.concurrent

Class AbstractService

    • Constructor Detail

      • AbstractService

        protected AbstractService()
        Constructor for use by subclasses.

    • Method Detail

      • doStart

        @ForOverride
protected abstract void doStart()
        This method is called by startAsync() to initiate service startup. The invocation of this method should cause a call to notifyStarted(), either during this method's run, or after it has returned. If startup fails, the invocation should cause a call to notifyFailed(Throwable) instead.

        This method should return promptly; prefer to do work on a different thread where it is convenient. It is invoked exactly once on service startup, even when startAsync() is called multiple times.

      • doStop

        @ForOverride
protected abstract void doStop()
        This method should be used to initiate service shutdown. The invocation of this method should cause a call to notifyStopped(), either during this method's run, or after it has returned. If shutdown fails, the invocation should cause a call to notifyFailed(Throwable) instead.

        This method should return promptly; prefer to do work on a different thread where it is convenient. It is invoked exactly once on service shutdown, even when stopAsync() is called multiple times.

        If stopAsync() is called on a Service.State.STARTING service, this method is not invoked immediately. Instead, it will be deferred until after the service is Service.State.RUNNING. Services that need to cancel startup work can override doCancelStart().

      • doCancelStart

        @ForOverride
protected void doCancelStart()
        This method is called by stopAsync() when the service is still starting (i.e. startAsync() has been called but notifyStarted() has not). Subclasses can override the method to cancel pending work and then call notifyStopped() to stop the service.

        This method should return promptly; prefer to do work on a different thread where it is convenient. It is invoked exactly once on service shutdown, even when stopAsync() is called multiple times.

        When this method is called state() will return Service.State.STOPPING, which is the external state observable by the caller of stopAsync().

        Since:
        27.0

      • 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

      • awaitRunning

        public final void awaitRunning​(long timeout,
                               java.util.concurrent.TimeUnit unit)
                        throws java.util.concurrent.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:
        java.util.concurrent.TimeoutException - if the service has not reached the given state within the deadline

      • awaitTerminated

        public final void awaitTerminated​(long timeout,
                                  java.util.concurrent.TimeUnit unit)
                           throws java.util.concurrent.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:
        java.util.concurrent.TimeoutException - if the service has not reached the given state within the deadline

      • notifyFailed

        protected final void notifyFailed​(java.lang.Throwable cause)
        Invoke this method to transition the service to the Service.State.FAILED. The service will not be stopped if it is running. Invoke this method when a service has failed critically or otherwise cannot be started nor stopped.

      • failureCause

        public final java.lang.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

      • addListener

        public final void addListener​(Service.Listener listener,
                              java.util.concurrent.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

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object