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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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/**
 * 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.activemq.artemis.jlibaio.util;

import org.apache.activemq.artemis.jlibaio.SubmitInfo;

/**
 * this is an utility class where you can reuse Callbackk objects for your LibaioContext usage.
 */
public class CallbackCache {

   private final SubmitInfo[] pool;

   private int put = 0;
   private int get = 0;
   private int available = 0;
   private final int size;

   private final Object lock = new Object();

   public CallbackCache(int size) {
      this.pool = new SubmitInfo[size];
      this.size = size;
   }

   public Callback get() {
      synchronized (lock) {
         if (available <= 0) {
            return null;
         }
         else {
            Callback retValue = (Callback) pool[get];
            pool[get] = null;
            if (retValue == null) {
               throw new NullPointerException("You should initialize the pool before using it");
            }
            if (retValue != null) {
               available--;
               get++;
               if (get >= size) {
                  get = 0;
               }
            }
            return retValue;
         }
      }
   }

   public CallbackCache put(Callback callback) {
      if (callback == null) {
         return null;
      }
      synchronized (lock) {
         if (available < size) {
            available++;
            pool[put++] = callback;
            if (put >= size) {
               put = 0;
            }
         }
      }
      return this;
   }
}