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package org.zodiac.sdk.shutdown.hooks;
import java.util.Timer;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import org.zodiac.sdk.toolkit.function.throwing.ThrowingRunnable;
/**
* A registry of shutdown hooks which run in LIFO order on shutdown; for cases
* where the order cannot be determined by instantiaton/addition order, first,
* last and middle (default) batches of hooks are provided.
*
* Hooks are guaranteed to be run regardless of any other hook aborting or
* throwing an exception.
*
* Hooks may be added such that they are weakly referenced, and will be omitted
* if garbage-collected.
*
* Additions during shutdown are guaranteed to be run.
*
* Executor services will have termination waited for for a settable timeout;
* the timeout is collective and is how long all executors will be waited
* for in aggregate. The default is three minutes.
*
*
*/
public interface ShutdownHooks {
/**
* Returns true if shutdown hooks are currently being run.
*
* @return True if hooks are running
*/
boolean isRunningShutdownHooks();
/**
* Add a Runnable to the default batch.
*
* @param toRun A runnable
*/
void add(Runnable toRun);
/**
* Add a Runnable to the batch which runs last.
*
* @param toRun A runnable
* @return This.
*/
ShutdownHooks addLast(Runnable toRun);
/**
* Add a Runnable to the batch which runs first.
*
* @param toRun A runnable
* @return This.
*/
ShutdownHooks addFirst(Runnable toRun);
/**
* Add a Runnable to the default batch, without keeping it strongly
* referenced.
*
* @param toRun A runnable
* @return This.
*/
ShutdownHooks addWeak(Runnable toRun);
/**
* Add a Runnable to the batch which runs first, without keeping it strongly
* referenced.
*
* @param toRun A runnable
* @return This.
*/
ShutdownHooks addFirstWeak(Runnable toRun);
/**
* Add a Runnable to the batch which runs first, without keeping it strongly
* referenced.
*
* @param toRun A runnable
* @return This.
*/
ShutdownHooks addLastWeak(Runnable toRun);
/**
* Add an executor service to the default batch; the executor service will
* be strongly referenced; when hooks are run, all executors are first shut
* down, and then in a separate pass, awaited for termination en-banc up to
* the expiration of a timeout.
*
* @param toShutdown An ExecutorService
* @return This.
*/
ShutdownHooks add(ExecutorService toShutdown);
/**
* Add an executor service to the batch which runs first; the executor
* service will be strongly referenced; when hooks are run, all executors
* are first shut down, and then in a separate pass, awaited for termination
* en-banc up to the expiration of a timeout.
*
* @param toShutdown An ExecutorService
* @return This.
*/
ShutdownHooks addFirst(ExecutorService toShutdown);
/**
* Add an executor service to the batch which runs last; the executor
* service will be strongly referenced; when hooks are run, all executors
* are first shut down, and then in a separate pass, awaited for termination
* en-banc up to the expiration of a timeout.
*
* @param toShutdown An ExecutorService
* @return This.
*/
ShutdownHooks addLast(ExecutorService toShutdown);
/**
* Add a timer to be cancelled to the default batch; the timer will be
* weakly referenced.
*
* @param toCancel A timer
* @return This.
*/
ShutdownHooks add(Timer toCancel);
/**
* Add a timer to be cancelled to the batch which runs first; the timer will
* be weakly referenced.
*
* @param toCancel A timer
* @return This.
*/
ShutdownHooks addFirst(Timer toCancel);
/**
* Add a timer to be cancelled to the batch which runs last; the timer will
* be weakly referenced.
*
* @param toCancel A timer
* @return This.
*/
ShutdownHooks addLast(Timer toCancel);
/**
* Add an AutoCloseable to be cancelled to the default batch; the
* AutoCloseable will be weakly referenced.
*
* @param toClose A resource to be closed
* @return This.
*/
ShutdownHooks addResource(AutoCloseable toClose);
/**
* Add an AutoCloseable to be cancelled to the batch which runs first; the
* AutoCloseable will be weakly referenced.
*
* @param toClose A resource to be closed
* @return This.
*/
ShutdownHooks addResourceFirst(AutoCloseable toClose);
/**
* Add an AutoCloseable to be cancelled to the batch which runs last; the
* AutoCloseable will be weakly referenced.
*
* @param toClose A resource to be closed
* @return This.
*/
ShutdownHooks addResourceLast(AutoCloseable toClose);
ShutdownHooks add(Callable toRun);
ShutdownHooks addFirst(Callable toRun);
ShutdownHooks addLast(Callable toRun);
ShutdownHooks addFirstWeak(Callable toRun);
ShutdownHooks addLastWeak(Callable toRun);
ShutdownHooks addWeak(Callable toRun);
ShutdownHooks addThrowing(ThrowingRunnable toRun);
ShutdownHooks addFirstThrowing(ThrowingRunnable toRun);
ShutdownHooks addLastThrowing(ThrowingRunnable toRun);
default ShutdownHooks addWeakThrowing(ThrowingRunnable toRun) {
return addThrowing(ThrowingRunnable.weak(toRun));
}
default ShutdownHooks addFirstWeakThrowing(ThrowingRunnable toRun) {
return addFirstThrowing(ThrowingRunnable.weak(toRun));
}
default ShutdownHooks addLastWeakThrowing(ThrowingRunnable toRun) {
return addLastThrowing(ThrowingRunnable.weak(toRun));
}
/**
* Imperatively run shutdown tasks, clearing the set of tasks and
* deregistering the ShutdownHooks as a VM shutdown hook if it has been
* registered.
*
* In general this should only be called by test frameworks and a few
* rare cases of applications that cleanly shut down all their state and
* reload themselves, or things run inside an isolating classloader whose
* shutdown tasks must run before the classloader is closed.
*
*
* @return The count of tasks run during shutdown
*/
int shutdown();
}