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/*
* Copyright (C) 2010 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.util.concurrent;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import java.lang.Thread.UncaughtExceptionHandler;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicLong;
/**
* A ThreadFactory builder, providing any combination of these features:
* <ul>
* <li> whether threads should be marked as {@linkplain Thread#setDaemon daemon}
* threads
* <li> a {@linkplain ThreadFactoryBuilder#setNameFormat naming format}
* <li> a {@linkplain Thread#setPriority thread priority}
* <li> an {@linkplain Thread#setUncaughtExceptionHandler uncaught exception
* handler}
* <li> a {@linkplain ThreadFactory#newThread backing thread factory}
* </ul>
* If no backing thread factory is provided, a default backing thread factory is
* used as if by calling {@code setThreadFactory(}{@link
* Executors#defaultThreadFactory()}{@code )}.
*
* @author Kurt Alfred Kluever
* @since 4.0
*/
public final class ThreadFactoryBuilder {
private String nameFormat = null;
private Boolean daemon = null;
private Integer priority = null;
private UncaughtExceptionHandler uncaughtExceptionHandler = null;
private ThreadFactory backingThreadFactory = null;
/**
* Creates a new {@link ThreadFactory} builder.
*/
public ThreadFactoryBuilder() {}
/**
* Sets the naming format to use when naming threads ({@link Thread#setName})
* which are created with this ThreadFactory.
*
* @param nameFormat a {@link String#format(String, Object...)}-compatible
* format String, to which a unique integer (0, 1, etc.) will be supplied
* as the single parameter. This integer will be unique to the built
* instance of the ThreadFactory and will be assigned sequentially.
* @return this for the builder pattern
*/
public ThreadFactoryBuilder setNameFormat(String nameFormat) {
String.format(nameFormat, 0); // fail fast if the format is bad or null
this.nameFormat = nameFormat;
return this;
}
/**
* Sets daemon or not for new threads created with this ThreadFactory.
*
* @param daemon whether or not new Threads created with this ThreadFactory
* will be daemon threads
* @return this for the builder pattern
*/
public ThreadFactoryBuilder setDaemon(boolean daemon) {
this.daemon = daemon;
return this;
}
/**
* Sets the priority for new threads created with this ThreadFactory.
*
* @param priority the priority for new Threads created with this
* ThreadFactory
* @return this for the builder pattern
*/
public ThreadFactoryBuilder setPriority(int priority) {
// Thread#setPriority() already checks for validity. These error messages
// are nicer though and will fail-fast.
checkArgument(priority >= Thread.MIN_PRIORITY,
"Thread priority (%s) must be >= %s", priority, Thread.MIN_PRIORITY);
checkArgument(priority <= Thread.MAX_PRIORITY,
"Thread priority (%s) must be <= %s", priority, Thread.MAX_PRIORITY);
this.priority = priority;
return this;
}
/**
* Sets the {@link UncaughtExceptionHandler} for new threads created with this
* ThreadFactory.
*
* @param uncaughtExceptionHandler the uncaught exception handler for new
* Threads created with this ThreadFactory
* @return this for the builder pattern
*/
public ThreadFactoryBuilder setUncaughtExceptionHandler(
UncaughtExceptionHandler uncaughtExceptionHandler) {
this.uncaughtExceptionHandler = checkNotNull(uncaughtExceptionHandler);
return this;
}
/**
* Sets the backing {@link ThreadFactory} for new threads created with this
* ThreadFactory. Threads will be created by invoking #newThread(Runnable) on
* this backing {@link ThreadFactory}.
*
* @param backingThreadFactory the backing {@link ThreadFactory} which will
* be delegated to during thread creation.
* @return this for the builder pattern
*
* @see MoreExecutors
*/
public ThreadFactoryBuilder setThreadFactory(
ThreadFactory backingThreadFactory) {
this.backingThreadFactory = checkNotNull(backingThreadFactory);
return this;
}
/**
* Returns a new thread factory using the options supplied during the building
* process. After building, it is still possible to change the options used to
* build the ThreadFactory and/or build again. State is not shared amongst
* built instances.
*
* @return the fully constructed {@link ThreadFactory}
*/
public ThreadFactory build() {
return build(this);
}
private static ThreadFactory build(ThreadFactoryBuilder builder) {
final String nameFormat = builder.nameFormat;
final Boolean daemon = builder.daemon;
final Integer priority = builder.priority;
final UncaughtExceptionHandler uncaughtExceptionHandler =
builder.uncaughtExceptionHandler;
final ThreadFactory backingThreadFactory =
(builder.backingThreadFactory != null)
? builder.backingThreadFactory
: Executors.defaultThreadFactory();
final AtomicLong count = (nameFormat != null) ? new AtomicLong(0) : null;
return new ThreadFactory() {
@Override public Thread newThread(Runnable runnable) {
Thread thread = backingThreadFactory.newThread(runnable);
if (nameFormat != null) {
thread.setName(String.format(nameFormat, count.getAndIncrement()));
}
if (daemon != null) {
thread.setDaemon(daemon);
}
if (priority != null) {
thread.setPriority(priority);
}
if (uncaughtExceptionHandler != null) {
thread.setUncaughtExceptionHandler(uncaughtExceptionHandler);
}
return thread;
}
};
}
}
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