Interface ApiService (2.4.0)

  public 
  
 interface 
 ApiService 
 

An object with an operational state, plus asynchronous #startAsync() and #stopAsync() lifecycle methods to transition between states. Example services include webservers, RPC servers and timers.

The normal lifecycle of a service is:

• NEW ->
• STARTING ->
• RUNNING ->
• STOPPING ->
• TERMINATED

There are deviations from this if there are failures or if ApiService#stopAsync is called before the ApiService reaches the RUNNING state. The set of legal transitions form a DAG , therefore every method of the listener will be called at most once. N.B. The State#FAILED and State#TERMINATED states are terminal states, once a service enters either of these states it cannot ever leave them.

Implementors of this interface are strongly encouraged to extend AbstractApiService which implement this interface and make the threading and state management easier.

Similar to Guava's Service , but redeclared so that Guava could be shaded.

  public 
  
 abstract 
  
 void 
  
 addListener 
 ( 
 ApiService 
 . 
 Listener 
  
 listener 
 , 
  
 Executor 
  
 executor 
 ) 
 

Registers a 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.

  public 
  
 abstract 
  
 void 
  
 awaitRunning 
 () 
 

Waits for the ApiService to reach the running state .

  public 
  
 abstract 
  
 void 
  
 awaitRunning 
 ( 
 long 
  
 timeout 
 , 
  
 TimeUnit 
  
 unit 
 ) 
 

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

  public 
  
 abstract 
  
 void 
  
 awaitTerminated 
 () 
 

Waits for the ApiService to reach the terminated state .

  public 
  
 abstract 
  
 void 
  
 awaitTerminated 
 ( 
 long 
  
 timeout 
 , 
  
 TimeUnit 
  
 unit 
 ) 
 

Waits for the ApiService to reach a terminal state (either terminated or failed ) for no more than the given time.

  public 
  
 abstract 
  
 Throwable 
  
 failureCause 
 () 
 

Returns the Throwable that caused this service to fail.

  public 
  
 abstract 
  
 boolean 
  
 isRunning 
 () 
 

Returns true if this service is running .

  public 
  
 abstract 
  
 ApiService 
  
 startAsync 
 () 
 

If the service state is State#NEW , this initiates service startup and returns immediately. A stopped service may not be restarted.

  public 
  
 abstract 
  
 ApiService 
 . 
 State 
  
 state 
 () 
 

Returns the lifecycle state of the service.

  public 
  
 abstract 
  
 ApiService 
  
 stopAsync 
 () 
 

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.