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This artifact provides a single jar that contains all classes required to use remote Jakarta Enterprise Beans and Jakarta Messaging, including all dependencies. It is intended for use by those not using maven, maven users should just import the Jakarta Enterprise Beans and Jakarta Messaging 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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/*
 * Copyright 2013 The Netty Project
 *
 * The Netty Project 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 io.netty.util;

import io.netty.util.internal.PlatformDependent;

import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;

/**
 * Abstract base class for classes wants to implement {@link ReferenceCounted}.
 */
public abstract class AbstractReferenceCounted implements ReferenceCounted {

    private static final AtomicIntegerFieldUpdater refCntUpdater;

    static {
        AtomicIntegerFieldUpdater updater =
                PlatformDependent.newAtomicIntegerFieldUpdater(AbstractReferenceCounted.class, "refCnt");
        if (updater == null) {
            updater = AtomicIntegerFieldUpdater.newUpdater(AbstractReferenceCounted.class, "refCnt");
        }
        refCntUpdater = updater;
    }

    private volatile int refCnt = 1;

    @Override
    public final int refCnt() {
        return refCnt;
    }

    /**
     * An unsafe operation intended for use by a subclass that sets the reference count of the buffer directly
     */
    protected final void setRefCnt(int refCnt) {
        this.refCnt = refCnt;
    }

    @Override
    public ReferenceCounted retain() {
        for (;;) {
            int refCnt = this.refCnt;
            if (refCnt == 0) {
                throw new IllegalReferenceCountException(0, 1);
            }
            if (refCnt == Integer.MAX_VALUE) {
                throw new IllegalReferenceCountException(Integer.MAX_VALUE, 1);
            }
            if (refCntUpdater.compareAndSet(this, refCnt, refCnt + 1)) {
                break;
            }
        }
        return this;
    }

    @Override
    public ReferenceCounted retain(int increment) {
        if (increment <= 0) {
            throw new IllegalArgumentException("increment: " + increment + " (expected: > 0)");
        }

        for (;;) {
            int refCnt = this.refCnt;
            if (refCnt == 0) {
                throw new IllegalReferenceCountException(0, 1);
            }
            if (refCnt > Integer.MAX_VALUE - increment) {
                throw new IllegalReferenceCountException(refCnt, increment);
            }
            if (refCntUpdater.compareAndSet(this, refCnt, refCnt + increment)) {
                break;
            }
        }
        return this;
    }

    @Override
    public final boolean release() {
        for (;;) {
            int refCnt = this.refCnt;
            if (refCnt == 0) {
                throw new IllegalReferenceCountException(0, -1);
            }

            if (refCntUpdater.compareAndSet(this, refCnt, refCnt - 1)) {
                if (refCnt == 1) {
                    deallocate();
                    return true;
                }
                return false;
            }
        }
    }

    @Override
    public final boolean release(int decrement) {
        if (decrement <= 0) {
            throw new IllegalArgumentException("decrement: " + decrement + " (expected: > 0)");
        }

        for (;;) {
            int refCnt = this.refCnt;
            if (refCnt < decrement) {
                throw new IllegalReferenceCountException(refCnt, -decrement);
            }

            if (refCntUpdater.compareAndSet(this, refCnt, refCnt - decrement)) {
                if (refCnt == decrement) {
                    deallocate();
                    return true;
                }
                return false;
            }
        }
    }

    /**
     * Called once {@link #refCnt()} is equals 0.
     */
    protected abstract void deallocate();
}