code: /**
   * 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 edu.utexas.cs.utopia.cortado.githubbenchmarks.org.apache.hadoop.metrics2.impl;
  
  import edu.utexas.cs.utopia.cortado.mockclasses.Atomic;
  
  /**
   * A half-blocking (nonblocking for producers, blocking for consumers) queue
   * for metrics sinks.
   *
   * New elements are dropped when the queue is full to preserve "interesting"
   * elements at the onset of queue filling events
   */
  class ImplicitSinkQueue<T> implements SinkQueueInterface<T>{
  
      interface Consumer<T> {
          void consume(T object) throws InterruptedException;
      }
  
      // A fixed size circular buffer to minimize garbage
      private final T[] data;
      private int head; // head position
      private int tail; // tail position
      private int size; // number of elements
      private int capacity; // data.length
  
      @SuppressWarnings("unchecked")
      public ImplicitSinkQueue(int capacity) {
          // TODO: fix issue with Math.max
          if (capacity < 1)
              capacity = 1;
          this.data = (T[]) new Object[capacity];
          head = tail = size = 0;
          this.capacity = capacity;
      }
  
      @Atomic
      public boolean enqueue(T e) {
          if (capacity == size) {
              return false;
          }
          tail = (tail + 1) % capacity;
          data[tail] = e;
  
          ++size;
          return true;
      }
  
      /**
       * Dequeue one element from head of the queue, will block if queue is empty
       * @return  the first element
       * @throws InterruptedException
       */
      @Atomic(waituntil="isNotEmpty")
      public T dequeue() throws InterruptedException {
          isNotEmpty();
  
          if (0 == size) {
              throw new IllegalStateException("Size must > 0 here.");
          }
          head = (head + 1) % capacity;
          T ret = data[head];
          data[head] = null;  // hint to gc
  
          --size;
          return ret;
      }
  
      private boolean isNotEmpty() {
          return 0 != size;
      }
  
      @Atomic
      public void clear() {
          for (int i = capacity; i-- > 0; ) {
              data[i] = null;
          }
          size = 0;
      }
  
      @Atomic
      public int size() {
          return size;
      }
  
      int capacity() {
          return capacity;
      }
  
  
      // dummy consumer for use in main method
      public static class DummyConsumer<T> implements Consumer<T> {
          public void consume(T object) throws InterruptedException {
              object.getClass();
          }
      }
  
      /**
       * Add main method so that CCR methods are reachable from soot pointer analysis
       */
      public static void main(String[] args) throws InterruptedException {
          final ImplicitSinkQueue sinkQueue = new ImplicitSinkQueue<String>(10);
          sinkQueue.enqueue("String1");
          sinkQueue.enqueue("String2");
          sinkQueue.enqueue("String3");
          sinkQueue.enqueue("String4");
          sinkQueue.dequeue();
          sinkQueue.size();
          sinkQueue.clear();
          sinkQueue.capacity();
      }
  }
  