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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 static java.util.Objects.requireNonNull;
import com.google.common.annotations.GwtIncompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.CheckReturnValue;
import java.lang.Thread.UncaughtExceptionHandler;
import java.util.Locale;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicLong;
import javax.annotation.CheckForNull;
/**
* 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>
*
* <p>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
*/
@CanIgnoreReturnValue
@GwtIncompatible
@ElementTypesAreNonnullByDefault
public final class ThreadFactoryBuilder {
@CheckForNull private String nameFormat = null;
@CheckForNull private Boolean daemon = null;
@CheckForNull private Integer priority = null;
@CheckForNull private UncaughtExceptionHandler uncaughtExceptionHandler = null;
@CheckForNull 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. For
* example, {@code "rpc-pool-%d"} will generate thread names like {@code "rpc-pool-0"}, {@code
* "rpc-pool-1"}, {@code "rpc-pool-2"}, etc.
* @return this for the builder pattern
*/
public ThreadFactoryBuilder setNameFormat(String nameFormat) {
String unused = 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}
*/
@CheckReturnValue
public ThreadFactory build() {
return doBuild(this);
}
// Split out so that the anonymous ThreadFactory can't contain a reference back to the builder.
// At least, I assume that's why. TODO(cpovirk): Check, and maybe add a test for this.
private static ThreadFactory doBuild(ThreadFactoryBuilder builder) {
String nameFormat = builder.nameFormat;
Boolean daemon = builder.daemon;
Integer priority = builder.priority;
UncaughtExceptionHandler uncaughtExceptionHandler = builder.uncaughtExceptionHandler;
ThreadFactory backingThreadFactory =
(builder.backingThreadFactory != null)
? builder.backingThreadFactory
: Executors.defaultThreadFactory();
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) {
// requireNonNull is safe because we create `count` if (and only if) we have a nameFormat.
thread.setName(format(nameFormat, requireNonNull(count).getAndIncrement()));
}
if (daemon != null) {
thread.setDaemon(daemon);
}
if (priority != null) {
thread.setPriority(priority);
}
if (uncaughtExceptionHandler != null) {
thread.setUncaughtExceptionHandler(uncaughtExceptionHandler);
}
return thread;
}
};
}
private static String format(String format, Object... args) {
return String.format(Locale.ROOT, format, args);
}
}
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