com.athaydes.osgiaas.api.service.DynamicServiceHelper Maven / Gradle / Ivy
package com.athaydes.osgiaas.api.service;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Supplier;
/**
* Utility class to make it easy to handle dynamic services.
*
* All methods of this class are Thread-safe.
*/
public class DynamicServiceHelper {
/**
* Given a reference to a service, call the provided consumer if the service
* is present, or do nothing otherwise.
*
* @param reference to a service
* @param consumer consumer of the service
* @param type of the service
* @see #with(AtomicReference, Consumer, Runnable)
*/
public static void with( AtomicReference reference, Consumer consumer ) {
with( reference, consumer, () -> {
} );
}
/**
* Given a reference to a service, call the provided consumer if the service
* is present, or call the onUnavailable callback if the service is unavailable.
*
* @param reference to a service
* @param consumer consumer of the service
* @param onUnavailable callback to call if the service is unavailable
* @param type of the service
* @see #with(AtomicReference, Consumer)
*/
public static void with( AtomicReference reference,
Consumer consumer,
Runnable onUnavailable ) {
T instance = reference.get();
if ( instance != null ) {
consumer.accept( instance );
} else {
onUnavailable.run();
}
}
/**
* Given a reference to a service, call the provided consumer if the service
* is present, or call the onUnavailable callback if the service is unavailable.
*
* @param reference to a service
* @param consumer function used to provide a value given the service is present
* @param defaultSupplier supplier of a default value to return in case the service is unavailable
* @param type of the service
* @param type of the return value
* @return the result of calling the #consumer function in case the service is available,
* or of calling the provided #defaultSupplier in case the service is unavailable
*/
public static R let( AtomicReference reference,
Function consumer,
Supplier defaultSupplier ) {
AtomicReference resultRef = new AtomicReference<>();
with( reference,
( value ) -> resultRef.set( consumer.apply( value ) ),
() -> resultRef.set( defaultSupplier.get() ) );
return resultRef.get();
}
}