ratpack.exec.ExecutionRef Maven / Gradle / Ivy
/*
* Copyright 2018 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.exec;
import ratpack.registry.Registry;
import java.util.Optional;
/**
* A reference to an {@link Execution} that is usable from outside of it.
*
* An execution ref is-a registry.
* It is a read only view of the actual execution registry, while the execution is active.
* Once the execution has completed, the registry is effectively empty.
* Note that there are no guarantees that the registry is immutable.
* The execution may mutate the registry or its entries.
* Concurrent access via this reference is however safe.
*
* A ref avoids holding a long lived reference to the actual execution and its registry.
* Therefore, holding a reference to an execution-ref in memory does not prevent the execution's
* registry from being garbage collected.
*
* @see Execution#getParent()
* @since 1.6
*/
public interface ExecutionRef extends Registry {
/**
* A ref to the execution that forked this execution.
*
* @throws IllegalStateException if this is a top level exception with no parent
* @return a ref to the execution that forked this execution
* @see #maybeParent()
*/
ExecutionRef getParent() throws IllegalStateException;
/**
* A ref to the execution that forked this execution, if it has a parent.
*
* @return a ref to the execution that forked this execution
*/
Optional maybeParent();
/**
* Whether the execution this refers to is complete.
*
* This method is equivalent to {@link Execution#isComplete()}.
*
* @return whether the execution this refers to is complete
*/
boolean isComplete();
}