com.google.common.util.concurrent.AbstractService

All Implemented Interfaces:: Service

@GwtIncompatible 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 com.google.common.util.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 Service.Listener to be executed on the given executor.

final void

awaitRunning()

Waits for the Service to reach the running state.

final void

awaitRunning(long timeout, TimeUnit unit)

Waits for the Service to reach the running state for no more than the given time.

final void

awaitRunning(Duration timeout)

Waits for the Service to reach the running state for no more than the given time.

final void

awaitTerminated()

Waits for the Service to reach the terminated state.

final 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.

final void

awaitTerminated(Duration timeout)

Waits for the Service to reach a terminal state (either terminated or 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 running.

protected final void

notifyFailed(Throwable cause)

Invoke this method to transition the service to the Service.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 Service.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 starting or 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 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
- 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
- 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()
  
  Description copied from interface: Service
  
  Waits for the Service to reach the 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 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 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 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 terminated or 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 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
- notifyStarted
  
  protected final void notifyStarted()
  
  Implementing classes should invoke this method once their service has started. It will cause the service to transition from Service.State.STARTING to Service.State.RUNNING.
  
  Throws:
  
  IllegalStateException - if the service is not Service.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 Service.State.STARTING or Service.State.STOPPING to Service.State.TERMINATED.
  
  Throws:
  
  IllegalStateException - if the service is not one of Service.State.STOPPING, Service.State.STARTING, or Service.State.RUNNING.
- notifyFailed
  
  protected final void notifyFailed(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.
- 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
- 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 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 String toString()
  
  Overrides:
  
  toString in class Object

Class AbstractService

Nested Class Summary

Nested classes/interfaces inherited from interface com.google.common.util.concurrent.Service

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Details

AbstractService

Method Details

doStart

doStop

doCancelStart

startAsync

stopAsync

awaitRunning

awaitRunning

awaitRunning

awaitTerminated

awaitTerminated

awaitTerminated

notifyStarted

notifyStopped

notifyFailed

isRunning

state

failureCause

addListener

toString