1 /*
2 * The contents of this file are subject to the terms of the Common Development and
3 * Distribution License (the License). You may not use this file except in compliance with the
4 * License.
5 *
6 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
7 * specific language governing permission and limitations under the License.
8 *
9 * When distributing Covered Software, include this CDDL Header Notice in each file and include
10 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
11 * Header, with the fields enclosed by brackets [] replaced by your own identifying
12 * information: "Portions copyright [year] [name of copyright owner]".
13 *
14 * Copyright 2016 ForgeRock AS.
15 */
16
17 package org.forgerock.util;
18
19 import static org.forgerock.util.Reject.checkNotNull;
20
21 import java.io.Closeable;
22
23 /**
24 * {@link Function} that silently closes an input-parameter after a delegate-function's {@link Function#apply(Object)}
25 * is invoked. The static {@link #closeSilently(Function)} method is provided for convenience.
26 *
27 * @param <VIN>
28 * The type of the function input-parameter, which implements {@code Closeable}.
29 * @param <VOUT>
30 * The type of the function result, or {@link Void} if the function
31 * does not return anything (i.e. it only has side-effects).
32 * @param <E>
33 * The type of the exception thrown by the function, or
34 * {@link org.forgerock.util.promise.NeverThrowsException} if no exception is thrown by the
35 * function.
36 */
37 public class CloseSilentlyFunction<VIN extends Closeable, VOUT, E extends Exception> implements Function<VIN, VOUT, E> {
38
39 private final Function<VIN, VOUT, E> delegate;
40
41 /**
42 * Creates a new {@code CloseSilentlyFunction} instance.
43 *
44 * @param delegate Delegate function.
45 */
46 public CloseSilentlyFunction(final Function<VIN, VOUT, E> delegate) {
47 this.delegate = checkNotNull(delegate);
48 }
49
50 /**
51 * Invokes the delegate function's {@link Function#apply(Object)} with the input parameter {@code value}, closes it,
52 * and returns the result.
53 *
54 * @param value {@code Closeable} input parameter.
55 * @return The result of applying delegate function to {@code value}.
56 * @throws E Propagates {@code Exception} thrown by delegate {@link Function}.
57 */
58 @Override
59 public VOUT apply(final VIN value) throws E {
60 try {
61 return delegate.apply(value);
62 } finally {
63 Utils.closeSilently(value);
64 }
65 }
66
67 /**
68 * Wraps a delegate function in a {@code CloseSilentlyFunction}.
69 *
70 * @param delegate Delegate function.
71 * @param <IN>
72 * The type of the function input-parameter, which implements {@code Closeable}.
73 * @param <OUT>
74 * The type of the function result, or {@link Void} if the function does not return anything
75 * (i.e. it only has side-effects).
76 * @param <EX> The type of the exception thrown by the function, or
77 * {@link org.forgerock.util.promise.NeverThrowsException} if no exception is thrown by the function.
78 * @return New {@code CloseSilentlyFunction} instance.
79 */
80 public static <IN extends Closeable, OUT, EX extends Exception> Function<IN, OUT, EX> closeSilently(
81 final Function<IN, OUT, EX> delegate) {
82 return new CloseSilentlyFunction<>(delegate);
83 }
84
85 }