content: /**
   * 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
   * <p>
   * http://www.apache.org/licenses/LICENSE-2.0
   * <p>
   * 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.atlas.utils;
  
  import org.apache.atlas.model.Clearable;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.ArrayList;
  import java.util.List;
  
  public class FixedBufferList<T extends Clearable> {
      private static final Logger LOG = LoggerFactory.getLogger(FixedBufferList.class);
  
      private final Class<T>     itemClass;
      private final ArrayList<T> buffer;
      private final int          incrementCapacityBy;
  
      private int length;
  
      public FixedBufferList(Class<T> clazz) {
          this(clazz, 1);
      }
  
      public FixedBufferList(Class<T> clazz, int incrementCapacityBy) {
          this.incrementCapacityBy = (incrementCapacityBy <= 0 ? 1 : incrementCapacityBy);
          this.itemClass           = clazz;
          this.buffer              = new ArrayList<>();
      }
  
      public T next() {
          request(length + 1);
  
          return buffer.get(length++);
      }
  
      public List<T> toList() {
          return this.buffer.subList(0, this.length);
      }
  
      public void reset() {
          for (T t : buffer) {
              t.clear();
          }
  
          this.length = 0;
      }
  
      private void request(int requestedCapacity) {
          if (requestedCapacity <= this.buffer.size()) {
              return;
          }
  
          int oldCapacity = this.buffer.size();
          int newCapacity = oldCapacity + this.incrementCapacityBy;
  
          this.buffer.ensureCapacity(newCapacity);
  
          instantiateItems(oldCapacity, newCapacity);
  
          LOG.debug("FixedBufferList: Requested: {} From: {} To:{}", requestedCapacity, oldCapacity, newCapacity);
      }
  
      private void instantiateItems(int startIndex, int maxSize) {
          for (int i = startIndex; i < maxSize; i++) {
              try {
                  this.buffer.add(itemClass.newInstance());
              } catch (InstantiationException e) {
                  LOG.error("FixedBufferList: InstantiationException: Instantiation failed!", e);
              } catch (IllegalAccessException e) {
                  LOG.error("FixedBufferList: IllegalAccessException: Instantiation failed!", e);
              }
          }
      }
  }
  