1 /*
2 * Copyright (C) 2010 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package com.google.common.util.concurrent;
18
19 import static com.google.common.base.Preconditions.checkArgument;
20 import static com.google.common.base.Preconditions.checkNotNull;
21
22 import java.lang.Thread.UncaughtExceptionHandler;
23 import java.util.concurrent.Executors;
24 import java.util.concurrent.ThreadFactory;
25 import java.util.concurrent.atomic.AtomicLong;
26
27 /**
28 * A ThreadFactory builder, providing any combination of these features:
29 * <ul>
30 * <li> whether threads should be marked as {@linkplain Thread#setDaemon daemon}
31 * threads
32 * <li> a {@linkplain ThreadFactoryBuilder#setNameFormat naming format}
33 * <li> a {@linkplain Thread#setPriority thread priority}
34 * <li> an {@linkplain Thread#setUncaughtExceptionHandler uncaught exception
35 * handler}
36 * <li> a {@linkplain ThreadFactory#newThread backing thread factory}
37 * </ul>
38 * <p>If no backing thread factory is provided, a default backing thread factory is
39 * used as if by calling {@code setThreadFactory(}{@link
40 * Executors#defaultThreadFactory()}{@code )}.
41 *
42 * @author Kurt Alfred Kluever
43 * @since 4.0
44 */
45 public final class ThreadFactoryBuilder {
46 private String nameFormat = null;
47 private Boolean daemon = null;
48 private Integer priority = null;
49 private UncaughtExceptionHandler uncaughtExceptionHandler = null;
50 private ThreadFactory backingThreadFactory = null;
51
52 /**
53 * Creates a new {@link ThreadFactory} builder.
54 */
55 public ThreadFactoryBuilder() {}
56
57 /**
58 * Sets the naming format to use when naming threads ({@link Thread#setName})
59 * which are created with this ThreadFactory.
60 *
61 * @param nameFormat a {@link String#format(String, Object...)}-compatible
62 * format String, to which a unique integer (0, 1, etc.) will be supplied
63 * as the single parameter. This integer will be unique to the built
64 * instance of the ThreadFactory and will be assigned sequentially. For
65 * example, {@code "rpc-pool-%d"} will generate thread names like
66 * {@code "rpc-pool-0"}, {@code "rpc-pool-1"}, {@code "rpc-pool-2"}, etc.
67 * @return this for the builder pattern
68 */
69 @SuppressWarnings("ReturnValueIgnored")
70 public ThreadFactoryBuilder setNameFormat(String nameFormat) {
71 String.format(nameFormat, 0); // fail fast if the format is bad or null
72 this.nameFormat = nameFormat;
73 return this;
74 }
75
76 /**
77 * Sets daemon or not for new threads created with this ThreadFactory.
78 *
79 * @param daemon whether or not new Threads created with this ThreadFactory
80 * will be daemon threads
81 * @return this for the builder pattern
82 */
83 public ThreadFactoryBuilder setDaemon(boolean daemon) {
84 this.daemon = daemon;
85 return this;
86 }
87
88 /**
89 * Sets the priority for new threads created with this ThreadFactory.
90 *
91 * @param priority the priority for new Threads created with this
92 * ThreadFactory
93 * @return this for the builder pattern
94 */
95 public ThreadFactoryBuilder setPriority(int priority) {
96 // Thread#setPriority() already checks for validity. These error messages
97 // are nicer though and will fail-fast.
98 checkArgument(priority >= Thread.MIN_PRIORITY,
99 "Thread priority (%s) must be >= %s", priority, Thread.MIN_PRIORITY);
100 checkArgument(priority <= Thread.MAX_PRIORITY,
101 "Thread priority (%s) must be <= %s", priority, Thread.MAX_PRIORITY);
102 this.priority = priority;
103 return this;
104 }
105
106 /**
107 * Sets the {@link UncaughtExceptionHandler} for new threads created with this
108 * ThreadFactory.
109 *
110 * @param uncaughtExceptionHandler the uncaught exception handler for new
111 * Threads created with this ThreadFactory
112 * @return this for the builder pattern
113 */
114 public ThreadFactoryBuilder setUncaughtExceptionHandler(
115 UncaughtExceptionHandler uncaughtExceptionHandler) {
116 this.uncaughtExceptionHandler = checkNotNull(uncaughtExceptionHandler);
117 return this;
118 }
119
120 /**
121 * Sets the backing {@link ThreadFactory} for new threads created with this
122 * ThreadFactory. Threads will be created by invoking #newThread(Runnable) on
123 * this backing {@link ThreadFactory}.
124 *
125 * @param backingThreadFactory the backing {@link ThreadFactory} which will
126 * be delegated to during thread creation.
127 * @return this for the builder pattern
128 *
129 * @see MoreExecutors
130 */
131 public ThreadFactoryBuilder setThreadFactory(
132 ThreadFactory backingThreadFactory) {
133 this.backingThreadFactory = checkNotNull(backingThreadFactory);
134 return this;
135 }
136
137 /**
138 * Returns a new thread factory using the options supplied during the building
139 * process. After building, it is still possible to change the options used to
140 * build the ThreadFactory and/or build again. State is not shared amongst
141 * built instances.
142 *
143 * @return the fully constructed {@link ThreadFactory}
144 */
145 public ThreadFactory build() {
146 return build(this);
147 }
148
149 private static ThreadFactory build(ThreadFactoryBuilder builder) {
150 final String nameFormat = builder.nameFormat;
151 final Boolean daemon = builder.daemon;
152 final Integer priority = builder.priority;
153 final UncaughtExceptionHandler uncaughtExceptionHandler =
154 builder.uncaughtExceptionHandler;
155 final ThreadFactory backingThreadFactory =
156 (builder.backingThreadFactory != null)
157 ? builder.backingThreadFactory
158 : Executors.defaultThreadFactory();
159 final AtomicLong count = (nameFormat != null) ? new AtomicLong(0) : null;
160 return new ThreadFactory() {
161 @Override public Thread newThread(Runnable runnable) {
162 Thread thread = backingThreadFactory.newThread(runnable);
163 if (nameFormat != null) {
164 thread.setName(String.format(nameFormat, count.getAndIncrement()));
165 }
166 if (daemon != null) {
167 thread.setDaemon(daemon);
168 }
169 if (priority != null) {
170 thread.setPriority(priority);
171 }
172 if (uncaughtExceptionHandler != null) {
173 thread.setUncaughtExceptionHandler(uncaughtExceptionHandler);
174 }
175 return thread;
176 }
177 };
178 }
179 }