Package org.graylog2.system.shutdown

Interface GracefulShutdownHook

All Known Implementing Classes:

JobWorkerPool

public interface GracefulShutdownHook

Services can implement this to participate in a graceful shutdown of the server.

A service can register itself with the GracefulShutdownService like this:

 
 class MyService implements GracefulShutdownHook {
     private final GracefulShutdownService shutdownService;

     @Inject
     public MyService(GracefulShutdownService shutdownService) {
         this.shutdownService = shutdownService;
     }

     // This will be executed by the GracefulShutdownService on server shutdown
     @Override
     void doGracefulShutdown() throws Exception {
         runShutdownTasks();
     }

     public void start() {
         // Let the GracefulShutdownService know about this service
         this.shutdownService.register(this);
     }

     // This will be executed by some service manager when this service is stopped
     public void stop() {
         // Remove this service from the GracefulShutdownService because it's stopped before server shutdown and
         // we don't need any graceful shutdown for it anymore
         this.shutdownService.unregister(this);
         runShutdownTasks();
     }

     private void runShutdownTasks() {
         // Run the actual shutdown tasks for the service here
     }
 }
 

Method Summary

Modifier and Type	Method	Description
void	doGracefulShutdown()	Execute shutdown tasks for the service that implements this interface.

Method Details

doGracefulShutdown

void doGracefulShutdown()
                 throws Exception

Execute shutdown tasks for the service that implements this interface.

Warning:

• This method is called from another thread so the class that implements GracefulShutdownHook must be thread-safe.
• The server shutdown is waiting for this method call to complete. Blocking this method will block the server shutdown!

Throws:

Exception