1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.lang3.concurrent;
18
19 import org.apache.commons.lang3.function.FailableSupplier;
20
21 /**
22 * Defines the thread-safe initialization of objects.
23 * <p>
24 * 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
25 * which can all access the object produced by the initializer. Through the {@link #get()} method the object can be queried.
26 * </p>
27 * <p>
28 * Concrete implementations of this interface will use different strategies for the creation of the managed object, e.g. lazy initialization or initialization
29 * in a background thread. This is completely transparent to client code, so it is possible to change the initialization strategy without affecting clients.
30 * </p>
31 * <p>
32 * An implementation of {@link #get()} returns the fully initialized object produced by this {@code
33 * ConcurrentInitializer}. A concrete implementation here returns the results of the initialization process. This method may block until results are available.
34 * Typically, once created the result object is always the same.
35 * </p>
36 * <p>
37 * An implementation throws {@link ConcurrentException} if an error occurred during initialization of the object.
38 * </p>
39 *
40 * @since 3.0
41 * @param <T> the type of the object managed by this initializer class.
42 */
43 public interface ConcurrentInitializer<T> extends FailableSupplier<T, ConcurrentException> {
44 // empty
45 }