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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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/*
 * 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:
 *
 *   https://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.buffer;

import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;

import io.netty.util.internal.ReferenceCountUpdater;

/**
 * Abstract base class for {@link ByteBuf} implementations that count references.
 */
public abstract class AbstractReferenceCountedByteBuf extends AbstractByteBuf {
    private static final long REFCNT_FIELD_OFFSET =
            ReferenceCountUpdater.getUnsafeOffset(AbstractReferenceCountedByteBuf.class, "refCnt");
    private static final AtomicIntegerFieldUpdater AIF_UPDATER =
            AtomicIntegerFieldUpdater.newUpdater(AbstractReferenceCountedByteBuf.class, "refCnt");

    private static final ReferenceCountUpdater updater =
            new ReferenceCountUpdater() {
        @Override
        protected AtomicIntegerFieldUpdater updater() {
            return AIF_UPDATER;
        }
        @Override
        protected long unsafeOffset() {
            return REFCNT_FIELD_OFFSET;
        }
    };

    // Value might not equal "real" reference count, all access should be via the updater
    @SuppressWarnings({"unused", "FieldMayBeFinal"})
    private volatile int refCnt;

    protected AbstractReferenceCountedByteBuf(int maxCapacity) {
        super(maxCapacity);
        updater.setInitialValue(this);
    }

    @Override
    boolean isAccessible() {
        // Try to do non-volatile read for performance as the ensureAccessible() is racy anyway and only provide
        // a best-effort guard.
        return updater.isLiveNonVolatile(this);
    }

    @Override
    public int refCnt() {
        return updater.refCnt(this);
    }

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

    /**
     * An unsafe operation intended for use by a subclass that resets the reference count of the buffer to 1
     */
    protected final void resetRefCnt() {
        updater.resetRefCnt(this);
    }

    @Override
    public ByteBuf retain() {
        return updater.retain(this);
    }

    @Override
    public ByteBuf retain(int increment) {
        return updater.retain(this, increment);
    }

    @Override
    public ByteBuf touch() {
        return this;
    }

    @Override
    public ByteBuf touch(Object hint) {
        return this;
    }

    @Override
    public boolean release() {
        return handleRelease(updater.release(this));
    }

    @Override
    public boolean release(int decrement) {
        return handleRelease(updater.release(this, decrement));
    }

    private boolean handleRelease(boolean result) {
        if (result) {
            deallocate();
        }
        return result;
    }

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