/*
* Copyright 2013 Stephen Connolly.
*
* 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 net.jcip.annotations;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
/**
* The presence of this annotation indicates that the field or method must only
* be accessed when holding the specified lock.
*/
@Documented
@Target(value = { FIELD, METHOD })
@Retention(RUNTIME)
public @interface GuardedBy {
/**
* The specified lock that guards the annotated field or method. Valid
* values are:
* <ul>
* <li>{@code this} indicates the intrinsic lock of the instance containing
* the field or method.</li>
* <li><code><i>class-name</i>.this</code> which allows for disambiguation
* of which {@code this} when dealing with inner classes</li>
* <li>{@code itself} which is valid for reference fields only, and
* indicates that the referenced instance's own intrinsic lock should be
* used as the guard</li>
* <li><code><i>field-name</i></code> indicates the named instance or static
* field is to be used as the guard. If the field type is not a sub-type of
* {@link java.util.concurrent.locks.Lock} then the intrinsic lock of the
* referenced instance is to be used</li>
* <li><code><i>class-name</i>.<i>field-name</i></code> indicates the named
* static field is to be used as the guard. If the field type is not a
* sub-type of {@link java.util.concurrent.locks.Lock} then the intrinsic
* lock of the referenced instance is to be used</li>
* <li><code><i>method-name</i>()</code> indicates that the zero-argument
* method should be called to obtain the lock object. If the return type is
* not a sub-type of {@link java.util.concurrent.locks.Lock} then the
* intrinsic lock of the returned instance is to be used</li>
* <li><code><i>class-name</i>.class</code> indicates that the intrinsic
* lock of the specified class should be used as the guard</li>
* </ul>
*
* @return The specified lock that guards the annotated field or method
*/
String value();
}