content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.util;
  
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertFalse;
  import static org.junit.Assert.assertTrue;
  
  import com.google.common.base.Ticker;
  import org.junit.Before;
  import org.junit.Test;
  
  import java.time.Duration;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Optional;
  
  public class RateLimiterTest {
  
    private final Ticker mTicker = new Ticker() {
      @Override
      public long read() {
        return mTime;
      }
    };
  
    private long mTime;
  
    @Before
    public void before() {
      mTime = 0;
    }
  
    @Test
    public void testFastRequests() {
      long permitsPerSecond = 10;
      long timePerPermit = Duration.ofSeconds(1).toNanos() / permitsPerSecond;
      SimpleRateLimiter rateLimiter = new SimpleRateLimiter(permitsPerSecond, mTicker);
  
      // if the timer is moving as fast as the permits then there should be no waiting
      for (int i = 0; i < 10; i++) {
        mTime += timePerPermit;
        assertFalse(rateLimiter.acquire().isPresent());
      }
      // if we move forward a large amount, we should still only get 1 new permit
      mTime += timePerPermit * 100;
      assertFalse(rateLimiter.acquire().isPresent());
      assertTrue(rateLimiter.acquire().isPresent());
  
      mTime += timePerPermit;
      assertTrue(rateLimiter.acquire().isPresent());
  
      mTime += timePerPermit * 2;
      assertFalse(rateLimiter.acquire().isPresent());
  
      Optional<Long> permit = rateLimiter.acquire();
      assertTrue(permit.isPresent());
      mTime += timePerPermit;
      assertEquals(mTime, (long) permit.get());
    }
  
    @Test
    public void testSlowRequests() {
      long permitsPerSecond = 10;
      long timePerPermit = Duration.ofSeconds(1).toNanos() / permitsPerSecond;
      SimpleRateLimiter rateLimiter = new SimpleRateLimiter(permitsPerSecond, mTicker);
      List<Long> permits = new ArrayList<>();
      for (int i = 0; i < permitsPerSecond; i++) {
        Optional<Long> permit = rateLimiter.acquire();
        assertTrue(permit.isPresent());
        permits.add(permit.get());
      }
      assertEquals(Duration.ofSeconds(1).toNanos(), (long) permits.get(permits.size() - 1));
      for (int i = 0; i < permitsPerSecond; i++) {
        mTime += timePerPermit;
        assertEquals(0, rateLimiter.getWaitTimeNanos(permits.get(i)));
      }
    }
  }
  