Module dev.mccue.guava.concurrent
Package dev.mccue.guava.concurrent

Class AbstractService

java.lang.Object
dev.mccue.guava.concurrent.AbstractService
All Implemented Interfaces:
Service
public abstract class AbstractService extends Object implements Service
Base class for implementing services that can handle #doStart and #doStop requests, responding to them with #notifyStarted() and #notifyStopped() callbacks. Its subclasses must manage threads manually; consider AbstractExecutionThreadService if you need only a single execution thread.
Since:
1.0
Author:
Jesse Wilson, Luke Sandberg

  • Nested Class Summary

    Nested classes/interfaces inherited from interface dev.mccue.guava.concurrent.Service

    Service.Listener, Service.State

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    AbstractService()
    Constructor for use by subclasses.

  • Method Summary

    Modifier and Type
    Method
    Description
    final void
    addListener(Service.Listener listener, Executor executor)
    Registers a Listener to be Executor#execute executed on the given executor.
    final void
    awaitRunning()
    Waits for the Service to reach the State#RUNNING running state.
    final void
    awaitRunning(long timeout, TimeUnit unit)
    Waits for the Service to reach the State#RUNNING running state for no more than the given time.
    final void
    awaitRunning(Duration timeout)
    Waits for the Service to reach the State#RUNNING running state for no more than the given time.
    final void
    awaitTerminated()
    Waits for the Service to reach the State#TERMINATED terminated state.
    final void
    awaitTerminated(long timeout, TimeUnit unit)
    Waits for the Service to reach a terminal state (either Service.State#TERMINATED terminated or Service.State#FAILED failed) for no more than the given time.
    final void
    awaitTerminated(Duration timeout)
    Waits for the Service to reach a terminal state (either Service.State#TERMINATED terminated or Service.State#FAILED failed) for no more than the given time.
    protected void
    doCancelStart()
    This method is called by #stopAsync when the service is still starting (i.e.
    protected abstract void
    doStart()
    This method is called by #startAsync to initiate service startup.
    protected abstract void
    doStop()
    This method should be used to initiate service shutdown.
    final Throwable
    failureCause()
    Returns the Throwable that caused this service to fail.
    final boolean
    isRunning()
    Returns true if this service is State#RUNNING running.
    protected final void
    notifyFailed(Throwable cause)
    Invoke this method to transition the service to the State#FAILED.
    protected final void
    notifyStarted()
    Implementing classes should invoke this method once their service has started.
    protected final void
    notifyStopped()
    Implementing classes should invoke this method once their service has stopped.
    final Service
    startAsync()
    If the service state is State#NEW, this initiates service startup and returns immediately.
    final Service.State
    state()
    Returns the lifecycle state of the service.
    final Service
    stopAsync()
    If the service is State#STARTING starting or State#RUNNING running, this initiates service shutdown and returns immediately.
    String
    toString()
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

  • Constructor Details

    • AbstractService

      protected AbstractService()
      Constructor for use by subclasses.

  • Method Details

    • 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 State#STARTING service, this method is not invoked immediately. Instead, it will be deferred until after the service is 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 State#STOPPING, which is the external state observable by the caller of #stopAsync.

      Since:
      27.0

    • startAsync

      @CanIgnoreReturnValue public final Service startAsync()
      Description copied from interface: Service
      If the service state is State#NEW, this initiates service startup and returns immediately. A stopped service may not be restarted.
      Specified by:
      startAsync in interface Service
      Returns:
      this

    • stopAsync

      @CanIgnoreReturnValue public final Service stopAsync()
      Description copied from interface: Service
      If the service is State#STARTING starting or State#RUNNING running, this initiates service shutdown and returns immediately. If the service is State#NEW new, it is State#TERMINATED 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()
      Description copied from interface: Service
      Waits for the Service to reach the State#RUNNING running state.
      Specified by:
      awaitRunning in interface Service

    • awaitRunning

      public final void awaitRunning(Duration timeout) throws TimeoutException
      Description copied from interface: Service
      Waits for the Service to reach the State#RUNNING running state for no more than the given time.
      Specified by:
      awaitRunning in interface Service
      Parameters:
      timeout - the maximum time to wait
      Throws:
      TimeoutException - if the service has not reached the given state within the deadline
      Since:
      28.0

    • awaitRunning

      public final void awaitRunning(long timeout, TimeUnit unit) throws TimeoutException
      Description copied from interface: Service
      Waits for the Service to reach the State#RUNNING 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

    • awaitTerminated

      public final void awaitTerminated()
      Description copied from interface: Service
      Waits for the Service to reach the State#TERMINATED terminated state.
      Specified by:
      awaitTerminated in interface Service

    • awaitTerminated

      public final void awaitTerminated(Duration timeout) throws TimeoutException
      Description copied from interface: Service
      Waits for the Service to reach a terminal state (either Service.State#TERMINATED terminated or Service.State#FAILED failed) for no more than the given time.
      Specified by:
      awaitTerminated in interface Service
      Parameters:
      timeout - the maximum time to wait
      Throws:
      TimeoutException - if the service has not reached the given state within the deadline
      Since:
      28.0

    • 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 Service.State#TERMINATED terminated or Service.State#FAILED 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

    • notifyStarted

      protected final void notifyStarted()
      Implementing classes should invoke this method once their service has started. It will cause the service to transition from State#STARTING to State#RUNNING.
      Throws:
      IllegalStateException - if the service is not State#STARTING.

    • notifyStopped

      protected final void notifyStopped()
      Implementing classes should invoke this method once their service has stopped. It will cause the service to transition from State#STARTING or State#STOPPING to State#TERMINATED.
      Throws:
      IllegalStateException - if the service is not one of State#STOPPING, State#STARTING, or State#RUNNING.

    • notifyFailed

      protected final void notifyFailed(Throwable cause)
      Invoke this method to transition the service to the 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.

    • isRunning

      public final boolean isRunning()
      Description copied from interface: Service
      Returns true if this service is State#RUNNING 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

    • 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

    • addListener

      public final void addListener(Service.Listener listener, Executor executor)
      Description copied from interface: Service
      Registers a Listener to be Executor#execute 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 String toString()
      Overrides:
      toString in class Object