/*
 * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package com.amazonaws.samples.kinesis.replay.utils;

import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.MoreExecutors;

import java.util.concurrent.Semaphore;

public class BackpressureSemaphore<T> implements FutureCallback<T> {

  private final Semaphore semaphore;

  public BackpressureSemaphore(int maxOutstandingRecordCount) {
    semaphore = new Semaphore(maxOutstandingRecordCount, true);
  }

  @Override
  public void onSuccess(T result) {
    semaphore.release();
  }

  @Override
  public void onFailure(Throwable t) {
    semaphore.release();
  }

  public void acquire(ListenableFuture<T> f) {
    try {
      semaphore.acquire();

      Futures.addCallback(f, this, MoreExecutors.directExecutor());
    } catch (InterruptedException e) {
      semaphore.release();
    }
  }
}