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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

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/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2014 Red Hat, Inc., and individual contributors
 * as indicated by the @author tags.
 *
 * 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 org.wildfly.common.ref;

import static java.security.AccessController.doPrivileged;

import java.lang.ref.ReferenceQueue;
import java.security.PrivilegedAction;
import java.util.concurrent.atomic.AtomicInteger;

import org.wildfly.common.Assert;

/**
 * A set of utility methods for reference types.
 */
public final class References {
    private References() {
    }

    private static final Reference NULL = new Reference() {
        public Object get() {
            return null;
        }

        public Object getAttachment() {
            return null;
        }

        public void clear() {
        }

        public Type getType() {
            return Type.NULL;
        }

        public String toString() {
            return "NULL reference";
        }
    };

    static final class ReaperThread extends Thread {
        static final ReferenceQueue REAPER_QUEUE = new ReferenceQueue();

        static {
            final AtomicInteger cnt = new AtomicInteger(1);
            final PrivilegedAction action = () -> {
                final ReaperThread thr = new ReaperThread();
                thr.setName("Reference Reaper #" + cnt.getAndIncrement());
                thr.setDaemon(true);
                thr.start();
                return null;
            };
            for (int i = 0; i < 3; i ++) {
                doPrivileged(action);
            }
        }

        public void run() {
            for (;;) try {
                final java.lang.ref.Reference ref = REAPER_QUEUE.remove();
                if (ref instanceof CleanerReference) {
                    ((CleanerReference) ref).clean();
                }
                if (ref instanceof Reapable) {
                    reap((Reapable) ref);
                }
            } catch (InterruptedException ignored) {
                // we consume interrupts.
            } catch (Throwable cause) {
                Log.log.reapFailed(cause);
            }
        }

        @SuppressWarnings({ "unchecked" })
        private static  void reap(final Reapable reapable) {
            reapable.getReaper().reap((Reference) reapable);
        }
    }

    /**
     * Create a reference of a given type with the provided value and attachment.  If the reference type is
     * {@link Reference.Type#STRONG} or {@link Reference.Type#NULL} then the reaper argument is ignored.  If
     * the reference type is {@link Reference.Type#NULL} then the value and attachment arguments are ignored.
     *
     * @param type the reference type
     * @param value the reference value
     * @param attachment the attachment value
     * @param reaper the reaper to use, if any
     * @param  the reference value type
     * @param  the reference attachment type
     * @return the reference
     */
    public static  Reference create(Reference.Type type, T value, A attachment, Reaper reaper) {
        Assert.checkNotNullParam("type", type);
        if (value == null) return getNullReference();
        switch (type) {
            case STRONG:
                return new StrongReference(value, attachment);
            case WEAK:
                return new WeakReference(value, attachment, reaper);
            case PHANTOM:
                return new PhantomReference(value, attachment, reaper);
            case SOFT:
                return new SoftReference(value, attachment, reaper);
            case NULL:
                return getNullReference();
            default:
                throw Assert.impossibleSwitchCase(type);
        }
    }

    /**
     * Create a reference of a given type with the provided value and attachment.  If the reference type is
     * {@link Reference.Type#STRONG} or {@link Reference.Type#NULL} then the reference queue argument is ignored.  If
     * the reference type is {@link Reference.Type#NULL} then the value and attachment arguments are ignored.
     *
     * @param type the reference type
     * @param value the reference value
     * @param attachment the attachment value
     * @param referenceQueue the reference queue to use, if any
     * @param  the reference value type
     * @param  the reference attachment type
     * @return the reference
     */
    public static  Reference create(Reference.Type type, T value, A attachment, ReferenceQueue referenceQueue) {
        Assert.checkNotNullParam("type", type);
        if (referenceQueue == null) return create(type, value, attachment);
        if (value == null) return getNullReference();
        switch (type) {
            case STRONG:
                return new StrongReference(value, attachment);
            case WEAK:
                return new WeakReference(value, attachment, referenceQueue);
            case PHANTOM:
                return new PhantomReference(value, attachment, referenceQueue);
            case SOFT:
                return new SoftReference(value, attachment, referenceQueue);
            case NULL:
                return getNullReference();
            default:
                throw Assert.impossibleSwitchCase(type);
        }
    }

    /**
     * Create a reference of a given type with the provided value and attachment.  If the reference type is
     * {@link Reference.Type#PHANTOM} then this method will return a {@code null} reference because
     * such references are not constructable without a queue or reaper.  If the reference type is
     * {@link Reference.Type#NULL} then the value and attachment arguments are ignored.
     *
     * @param type the reference type
     * @param value the reference value
     * @param attachment the attachment value
     * @param  the reference value type
     * @param  the reference attachment type
     * @return the reference
     */
    public static  Reference create(Reference.Type type, T value, A attachment) {
        Assert.checkNotNullParam("type", type);
        if (value == null) return getNullReference();
        switch (type) {
            case STRONG:
                return new StrongReference(value, attachment);
            case WEAK:
                return new WeakReference(value, attachment);
            case PHANTOM:
                return getNullReference();
            case SOFT:
                return new SoftReference(value, attachment);
            case NULL:
                return getNullReference();
            default:
                throw Assert.impossibleSwitchCase(type);
        }
    }

    /**
     * Get a null reference.  This reference type is always cleared and does not retain an attachment; as such
     * there is only one single instance of it.
     *
     * @param  the reference value type
     * @param  the attachment value type
     * @return the null reference
     */
    @SuppressWarnings({ "unchecked" })
    public static  Reference getNullReference() {
        return (Reference) NULL;
    }
}
    

    

    

            

    

            



    
    






    
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