1 /*
2 * Copyright (c) 2012-2024, jcabi.com
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met: 1) Redistributions of source code must retain the above
8 * copyright notice, this list of conditions and the following
9 * disclaimer. 2) Redistributions in binary form must reproduce the above
10 * copyright notice, this list of conditions and the following
11 * disclaimer in the documentation and/or other materials provided
12 * with the distribution. 3) Neither the name of the jcabi.com nor
13 * the names of its contributors may be used to endorse or promote
14 * products derived from this software without specific prior written
15 * permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
19 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
21 * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
22 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
24 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
26 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
28 * OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30 package com.jcabi.aspects;
31
32 import java.lang.annotation.Documented;
33 import java.lang.annotation.ElementType;
34 import java.lang.annotation.Retention;
35 import java.lang.annotation.RetentionPolicy;
36 import java.lang.annotation.Target;
37 import java.util.concurrent.TimeUnit;
38
39 /**
40 * Makes a method time constrained.
41 *
42 * <p>For example, this {@code load()} method should not take more than
43 * a second, and should be interrupted if it takes more:
44 *
45 * <pre> @Timeable(limit = 1, unit = TimeUnit.SECONDS)
46 * String load(String resource) {
47 * // something that runs potentially long
48 * }</pre>
49 *
50 * <p>Important to note that in Java 1.5+ it is impossible to force thread
51 * termination, for many reasons. Thus, we can't
52 * just call {@code Thread.stop()},
53 * when a thread is over a specified time limit. The best thing we can do is to
54 * call {@link Thread#interrupt()} and hope that the thread itself
55 * is checking its
56 * {@link Thread#isInterrupted()} status. If you want to design your long
57 * running methods in a way that {@link Timeable} can terminate them, embed
58 * a checker into your most intessively used place, for example:
59 *
60 * <pre> @Timeable(limit = 1, unit = TimeUnit.SECONDS)
61 * String load(String resource) {
62 * while (true) {
63 * if (Thread.currentThread.isInterrupted()) {
64 * throw new IllegalStateException("time out");
65 * }
66 * // execution as usual
67 * }
68 * }</pre>
69 *
70 * @since 0.7.16
71 * @see <a href="http://aspects.jcabi.com">http://aspects.jcabi.com/</a>
72 * @see <a href="http://docs.oracle.com/javase/1.5.0/docs/guide/misc/threadPrimitiveDeprecation.html">Why Are Thread.stop, Thread.suspend, Thread.resume and Runtime.runFinalizersOnExit Deprecated?</a>
73 * @see <a href="http://www.yegor256.com/2014/06/20/limit-method-execution-time.html">Limit Java Method Execution Time, by Yegor Bugayenko</a>
74 */
75 @Documented
76 @Retention(RetentionPolicy.RUNTIME)
77 @Target(ElementType.METHOD)
78 public @interface Timeable {
79
80 /**
81 * The default maximum amount (of seconds).
82 */
83 int DEFAULT_LIMIT = 15;
84
85 /**
86 * Maximum amount allowed for this method.
87 * @return The limit
88 */
89 int limit() default Timeable.DEFAULT_LIMIT;
90
91 /**
92 * Time unit for the limit.
93 *
94 * <p>The minimum unit you can use is a second. We simply can't monitor with
95 * a frequency higher than a second.
96 * @return The time unit
97 */
98 TimeUnit unit() default TimeUnit.SECONDS;
99
100 }