001 /*
002 * Copyright (C) 2010 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017 package com.google.common.util.concurrent;
018
019 import static com.google.common.base.Preconditions.checkArgument;
020 import static com.google.common.base.Preconditions.checkNotNull;
021
022 import java.lang.Thread.UncaughtExceptionHandler;
023 import java.util.concurrent.Executors;
024 import java.util.concurrent.ThreadFactory;
025 import java.util.concurrent.atomic.AtomicLong;
026
027 /**
028 * A ThreadFactory builder, providing any combination of these features:
029 * <ul>
030 * <li> whether threads should be marked as {@linkplain Thread#setDaemon daemon}
031 * threads
032 * <li> a {@linkplain ThreadFactoryBuilder#setNameFormat naming format}
033 * <li> a {@linkplain Thread#setPriority thread priority}
034 * <li> an {@linkplain Thread#setUncaughtExceptionHandler uncaught exception
035 * handler}
036 * <li> a {@linkplain ThreadFactory#newThread backing thread factory}
037 * </ul>
038 * If no backing thread factory is provided, a default backing thread factory is
039 * used as if by calling {@code setThreadFactory(}{@link
040 * Executors#defaultThreadFactory()}{@code )}.
041 *
042 * @author Kurt Alfred Kluever
043 * @since 4.0
044 */
045 public final class ThreadFactoryBuilder {
046 private String nameFormat = null;
047 private Boolean daemon = null;
048 private Integer priority = null;
049 private UncaughtExceptionHandler uncaughtExceptionHandler = null;
050 private ThreadFactory backingThreadFactory = null;
051
052 /**
053 * Creates a new {@link ThreadFactory} builder.
054 */
055 public ThreadFactoryBuilder() {}
056
057 /**
058 * Sets the naming format to use when naming threads ({@link Thread#setName})
059 * which are created with this ThreadFactory.
060 *
061 * @param nameFormat a {@link String#format(String, Object...)}-compatible
062 * format String, to which a unique integer (0, 1, etc.) will be supplied
063 * as the single parameter. This integer will be unique to the built
064 * instance of the ThreadFactory and will be assigned sequentially.
065 * @return this for the builder pattern
066 */
067 public ThreadFactoryBuilder setNameFormat(String nameFormat) {
068 String.format(nameFormat, 0); // fail fast if the format is bad or null
069 this.nameFormat = nameFormat;
070 return this;
071 }
072
073 /**
074 * Sets daemon or not for new threads created with this ThreadFactory.
075 *
076 * @param daemon whether or not new Threads created with this ThreadFactory
077 * will be daemon threads
078 * @return this for the builder pattern
079 */
080 public ThreadFactoryBuilder setDaemon(boolean daemon) {
081 this.daemon = daemon;
082 return this;
083 }
084
085 /**
086 * Sets the priority for new threads created with this ThreadFactory.
087 *
088 * @param priority the priority for new Threads created with this
089 * ThreadFactory
090 * @return this for the builder pattern
091 */
092 public ThreadFactoryBuilder setPriority(int priority) {
093 // Thread#setPriority() already checks for validity. These error messages
094 // are nicer though and will fail-fast.
095 checkArgument(priority >= Thread.MIN_PRIORITY,
096 "Thread priority (%s) must be >= %s", priority, Thread.MIN_PRIORITY);
097 checkArgument(priority <= Thread.MAX_PRIORITY,
098 "Thread priority (%s) must be <= %s", priority, Thread.MAX_PRIORITY);
099 this.priority = priority;
100 return this;
101 }
102
103 /**
104 * Sets the {@link UncaughtExceptionHandler} for new threads created with this
105 * ThreadFactory.
106 *
107 * @param uncaughtExceptionHandler the uncaught exception handler for new
108 * Threads created with this ThreadFactory
109 * @return this for the builder pattern
110 */
111 public ThreadFactoryBuilder setUncaughtExceptionHandler(
112 UncaughtExceptionHandler uncaughtExceptionHandler) {
113 this.uncaughtExceptionHandler = checkNotNull(uncaughtExceptionHandler);
114 return this;
115 }
116
117 /**
118 * Sets the backing {@link ThreadFactory} for new threads created with this
119 * ThreadFactory. Threads will be created by invoking #newThread(Runnable) on
120 * this backing {@link ThreadFactory}.
121 *
122 * @param backingThreadFactory the backing {@link ThreadFactory} which will
123 * be delegated to during thread creation.
124 * @return this for the builder pattern
125 *
126 * @see MoreExecutors
127 */
128 public ThreadFactoryBuilder setThreadFactory(
129 ThreadFactory backingThreadFactory) {
130 this.backingThreadFactory = checkNotNull(backingThreadFactory);
131 return this;
132 }
133
134 /**
135 * Returns a new thread factory using the options supplied during the building
136 * process. After building, it is still possible to change the options used to
137 * build the ThreadFactory and/or build again. State is not shared amongst
138 * built instances.
139 *
140 * @return the fully constructed {@link ThreadFactory}
141 */
142 public ThreadFactory build() {
143 return build(this);
144 }
145
146 private static ThreadFactory build(ThreadFactoryBuilder builder) {
147 final String nameFormat = builder.nameFormat;
148 final Boolean daemon = builder.daemon;
149 final Integer priority = builder.priority;
150 final UncaughtExceptionHandler uncaughtExceptionHandler =
151 builder.uncaughtExceptionHandler;
152 final ThreadFactory backingThreadFactory =
153 (builder.backingThreadFactory != null)
154 ? builder.backingThreadFactory
155 : Executors.defaultThreadFactory();
156 final AtomicLong count = (nameFormat != null) ? new AtomicLong(0) : null;
157 return new ThreadFactory() {
158 @Override public Thread newThread(Runnable runnable) {
159 Thread thread = backingThreadFactory.newThread(runnable);
160 if (nameFormat != null) {
161 thread.setName(String.format(nameFormat, count.getAndIncrement()));
162 }
163 if (daemon != null) {
164 thread.setDaemon(daemon);
165 }
166 if (priority != null) {
167 thread.setPriority(priority);
168 }
169 if (uncaughtExceptionHandler != null) {
170 thread.setUncaughtExceptionHandler(uncaughtExceptionHandler);
171 }
172 return thread;
173 }
174 };
175 }
176 }