src/main/java/org/apache/commons/lang3/concurrent/ConcurrentInitializer.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.commons.lang3.concurrent;

import org.apache.commons.lang3.function.FailableSupplier;

/**
 * Defines the thread-safe initialization of objects.
 * <p>
 * The idea behind this interface is to provide access to an object in a thread-safe manner. A {@link ConcurrentInitializer} can be passed to multiple threads
 * which can all access the object produced by the initializer. Through the {@link #get()} method the object can be queried.
 * </p>
 * <p>
 * Concrete implementations of this interface will use different strategies for the creation of the managed object, e.g. lazy initialization or initialization
 * in a background thread. This is completely transparent to client code, so it is possible to change the initialization strategy without affecting clients.
 * </p>
 * <p>
 * An implementation of {@link #get()} returns the fully initialized object produced by this {@code
 * ConcurrentInitializer}. A concrete implementation here returns the results of the initialization process. This method may block until results are available.
 * Typically, once created the result object is always the same.
 * </p>
 * <p>
 * An implementation throws {@link ConcurrentException} if an error occurred during initialization of the object.
 * </p>
 *
 * @since 3.0
 * @param <T> the type of the object managed by this initializer class.
 */
public interface ConcurrentInitializer<T> extends FailableSupplier<T, ConcurrentException> {
    // empty
}