Lock.java

/*
 * Copyright (c) 2010-2017. Axon Framework
 * 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 org.axonframework.common.lock;

/**
 * Interface of a lock acquired to gain (exclusive) access to a shared resource, with a mechanism to release it again.
 * <p/>
 * This lock is a {@link AutoCloseable} resource, so will be released automatically if declared in a {@code
 * try}-with-resources block.
 *
 * @author Rene de Waele
 * @since 3.0
 */
public interface Lock extends AutoCloseable {

    /**
     * Releases this lock. By default this simply calls {@link #release()}.
     * <p/>
     * {@inheritDoc}
     */
    @Override
    default void close() {
        release();
    }

    /**
     * Releases this lock. If this lock is already released or no longer valid, the behavior of this method is
     * undefined.
     */
    void release();

    /**
     * Indicates whether the lock is still owned {@code true}, or whether it has been released {@code false}.
     *
     * @return true if the lock is still valid, or false if it has been released
     */
    boolean isHeld();
}