1 package org.apache.maven.surefire.junitcore.pc;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import org.junit.runners.model.RunnerScheduler;
23
24 import java.util.concurrent.RejectedExecutionException;
25
26 /**
27 * Specifies the strategy of scheduling whether sequential, or parallel.
28 * The strategy may use a thread pool <em>shared</em> with other strategies.
29 * <p/>
30 * One instance of strategy can be used just by one {@link Scheduler}.
31 * <p/>
32 * The strategy is scheduling tasks in {@link #schedule(Runnable)} and awaiting them
33 * completed in {@link #finished()}. Both methods should be used in one thread.
34 *
35 * @author Tibor Digana (tibor17)
36 * @since 2.16
37 */
38 public abstract class SchedulingStrategy
39 {
40
41 /**
42 * Schedules tasks if {@link #canSchedule()}.
43 *
44 * @param task runnable to schedule in a thread pool or invoke
45 * @throws RejectedExecutionException if <tt>task</tt>
46 * cannot be scheduled for execution
47 * @throws NullPointerException if <tt>task</tt> is <tt>null</tt>
48 * @see RunnerScheduler#schedule(Runnable)
49 * @see java.util.concurrent.Executor#execute(Runnable)
50 */
51 protected abstract void schedule( Runnable task );
52
53 /**
54 * Waiting for scheduled tasks to finish.
55 * New tasks will not be scheduled by calling this method.
56 *
57 * @return <tt>true</tt> if successfully stopped the scheduler, else
58 * <tt>false</tt> if already stopped (a <em>shared</em> thread
59 * pool was shutdown externally).
60 * @throws InterruptedException if interrupted while waiting
61 * for scheduled tasks to finish
62 * @see RunnerScheduler#finished()
63 */
64 protected abstract boolean finished()
65 throws InterruptedException;
66
67 /**
68 * Stops scheduling new tasks (e.g. by {@link java.util.concurrent.ExecutorService#shutdown()}
69 * on a private thread pool which cannot be <em>shared</em> with other strategy).
70 *
71 * @return <tt>true</tt> if successfully stopped the scheduler, else
72 * <tt>false</tt> if already stopped (a <em>shared</em> thread
73 * pool was shutdown externally).
74 * @see java.util.concurrent.ExecutorService#shutdown()
75 */
76 protected abstract boolean stop();
77
78 /**
79 * Stops scheduling new tasks and <em>interrupts</em> running tasks
80 * (e.g. by {@link java.util.concurrent.ExecutorService#shutdownNow()} on a private thread pool
81 * which cannot be <em>shared</em> with other strategy).
82 * <p/>
83 * This method calls {@link #stop()} by default.
84 *
85 * @return <tt>true</tt> if successfully stopped the scheduler, else
86 * <tt>false</tt> if already stopped (a <em>shared</em> thread
87 * pool was shutdown externally).
88 * @see java.util.concurrent.ExecutorService#shutdownNow()
89 */
90 protected boolean stopNow()
91 {
92 return stop();
93 }
94
95 protected void setDefaultShutdownHandler( Scheduler.ShutdownHandler handler )
96 {
97 }
98
99 /**
100 * @return <tt>true</tt> if a thread pool associated with this strategy
101 * can be shared with other strategies.
102 */
103 protected abstract boolean hasSharedThreadPool();
104
105 /**
106 * @return <tt>true</tt> unless stopped or finished.
107 */
108 protected abstract boolean canSchedule();
109 }