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/*
 * Licensed to Elasticsearch B.V. under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch B.V. 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 co.elastic.otel.profiler.pooling;

import java.util.Queue;
import javax.annotation.Nullable;

public class QueueBasedObjectPool extends AbstractObjectPool {

  private final Queue queue;

  /**
   * Creates a queue based pooled for types that implement {@link Recyclable}, use {@link #of(Queue,
   * boolean, Allocator, Resetter)} for other pooled object types.
   *
   * @param queue the underlying queue
   * @param preAllocate when set to true, queue will be be pre-allocated with object instance.
   * @param allocator a factory used to create new instances of the recyclable object. This factory
   *     is used when there are no objects in the queue and to preallocate the queue
   */
  public static  QueueBasedObjectPool ofRecyclable(
      Queue queue, boolean preAllocate, Allocator allocator) {
    return new QueueBasedObjectPool<>(
        queue, preAllocate, allocator, Resetter.ForRecyclable.get());
  }

  /**
   * Creates a queue based pooled for types that do not implement {@link Recyclable}, use {@link
   * #ofRecyclable(Queue, boolean, Allocator)} for types that implement {@link Recyclable}.
   *
   * @param queue the underlying queue
   * @param preAllocate when set to true, queue will be be pre-allocated with object instances
   *     fitting queue size
   * @param allocator a factory used to create new instances of the recyclable object. This factory
   *     is used when there are no objects in the queue and to preallocate the queue
   * @param resetter a reset strategy class
   */
  public static  QueueBasedObjectPool of(
      Queue queue,
      boolean preAllocate,
      Allocator allocator,
      Resetter resetter) {
    return new QueueBasedObjectPool<>(queue, preAllocate, allocator, resetter);
  }

  private QueueBasedObjectPool(
      Queue queue,
      boolean preAllocate,
      Allocator allocator,
      Resetter resetter) {
    super(allocator, resetter);
    this.queue = queue;
    if (preAllocate) {
      boolean addMore;
      do {
        addMore = queue.offer(allocator.createInstance());
      } while (addMore);
    }
  }

  @Nullable
  @Override
  public T tryCreateInstance() {
    return queue.poll();
  }

  @Override
  protected boolean returnToPool(T obj) {
    return queue.offer(obj);
  }

  public int getObjectsInPool() {
    // as the size of the ring buffer is an int, this can never overflow
    return queue.size();
  }

  @Override
  public void clear() {
    queue.clear();
  }
}