ratpack.service.ServiceDependenciesSpec Maven / Gradle / Ivy
/*
* Copyright 2016 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package ratpack.service;
import ratpack.func.Predicate;
import static ratpack.service.internal.ServicesGraph.isOfType;
import static ratpack.service.internal.ServicesGraph.unpackIfLegacy;
/**
* Allows declaring which services depend on which services.
*
* @see ServiceDependencies
* @see DependsOn
* @since 1.3
*/
public interface ServiceDependenciesSpec {
/**
* Specifies that all services that match the {@code dependents} predicate are dependent on all services that match the {@code dependencies} predicate.
*
* Note that legacy {@link ratpack.server.Service} will be wrapped in a {@link LegacyServiceAdapter} when supplied to the given predicates.
*
* @param dependents the criteria for dependent services
* @param dependencies the criteria for services they depend on
* @return {@code this}
* @throws Exception any thrown by either predicate
*/
ServiceDependenciesSpec dependsOn(Predicate dependents, Predicate dependencies) throws Exception;
/**
* Specifies that all services that are of the given {@code dependentsType} that match the {@code dependents} predicate are dependent on all services that are of the {@code dependenciesType} that match the {@code dependencies} predicate.
*
* Note that this method is {@link LegacyServiceAdapter} aware.
* Adapted services are unpacked, and their real type (i.e. {@link ratpack.server.Service} implementation type) is used.
*
* @param dependents the criteria for dependent services
* @param dependencies the criteria for services they depend on
* @param the type of dependent services
* @param the type of services they depend on
* @return {@code this}
* @throws Exception any thrown by either predicate
*/
default ServiceDependenciesSpec dependsOn(Class dependentsType, Predicate dependents, Class dependenciesType, Predicate dependencies) throws Exception {
return dependsOn(
s -> isOfType(s, dependentsType) && dependents.apply(dependentsType.cast(unpackIfLegacy(s))),
s -> isOfType(s, dependenciesType) && dependencies.apply(dependenciesType.cast(unpackIfLegacy(s)))
);
}
/**
* A convenience form of {@link #dependsOn(Predicate, Predicate)} where the predicates are based on compatibility with the given types.
*
* All services that are type compatible with the {@code dependents} type,
* will be considered dependents of all services that are type compatible with the {@code dependencies} type.
*
* Note that this method is {@link LegacyServiceAdapter} aware.
* Adapted services are unpacked, and their real type (i.e. {@link ratpack.server.Service} implementation type) is used.
*
* Use of this method is equivalent to annotating {@code dependents} with {@link DependsOn} with a value of {@code dependencies}.
* It can be useful in situations however where you are unable to modify the {@code dependents} class.
*
* @param dependents the type of dependent services
* @param dependencies the type of the services they depend on
* @return {@code this}
* @throws Exception any
* @see DependsOn
*/
default ServiceDependenciesSpec dependsOn(Class dependents, Class dependencies) throws Exception {
return dependsOn(dependents, Predicate.TRUE, dependencies, Predicate.TRUE);
}
}