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Common code shared by multiple Tomcat components
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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.tomcat.util.threads;

import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.tomcat.util.security.PrivilegedSetAccessControlContext;
import org.apache.tomcat.util.security.PrivilegedSetTccl;

/**
 * Simple task thread factory to use to create threads for an executor
 * implementation.
 */
public class TaskThreadFactory implements ThreadFactory {

    private final ThreadGroup group;
    private final AtomicInteger threadNumber = new AtomicInteger(1);
    private final String namePrefix;
    private final boolean daemon;
    private final int threadPriority;

    public TaskThreadFactory(String namePrefix, boolean daemon, int priority) {
        SecurityManager s = System.getSecurityManager();
        group = (s != null) ? s.getThreadGroup() : Thread.currentThread().getThreadGroup();
        this.namePrefix = namePrefix;
        this.daemon = daemon;
        this.threadPriority = priority;
    }

    @Override
    public Thread newThread(Runnable r) {
        TaskThread t = new TaskThread(group, r, namePrefix + threadNumber.getAndIncrement());
        t.setDaemon(daemon);
        t.setPriority(threadPriority);

        if (Constants.IS_SECURITY_ENABLED) {
            // Set the context class loader of newly created threads to be the
            // class loader that loaded this factory. This avoids retaining
            // references to web application class loaders and similar.
            PrivilegedAction pa = new PrivilegedSetTccl(
                    t, getClass().getClassLoader());
            AccessController.doPrivileged(pa);

            // This method may be triggered from an InnocuousThread. Ensure that
            // the thread inherits an appropriate AccessControlContext
            pa = new PrivilegedSetAccessControlContext(t);
            AccessController.doPrivileged(pa);
        } else {
            t.setContextClassLoader(getClass().getClassLoader());
        }

        return t;
    }
}