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
   *
   *     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 org.apache.beam.sdk.util;
  
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertFalse;
  import static org.junit.Assert.assertTrue;
  
  import org.apache.beam.sdk.transforms.Combine;
  import org.junit.Test;
  import org.junit.runner.RunWith;
  import org.junit.runners.JUnit4;
  
  /** Tests {@link MovingFunction}. */
  @RunWith(JUnit4.class)
  public class MovingFunctionTest {
  
    private static final long SAMPLE_PERIOD = 100;
    private static final int SAMPLE_UPDATE = 10;
    private static final int SIGNIFICANT_BUCKETS = 2;
    private static final int SIGNIFICANT_SAMPLES = 10;
  
    private static final Combine.BinaryCombineLongFn SUM =
        new Combine.BinaryCombineLongFn() {
          @Override
          public long apply(long left, long right) {
            return left + right;
          }
  
          @Override
          public long identity() {
            return 0;
          }
        };
  
    private MovingFunction newFunc() {
      return new MovingFunction(
          SAMPLE_PERIOD, SAMPLE_UPDATE, SIGNIFICANT_BUCKETS, SIGNIFICANT_SAMPLES, SUM);
    }
  
    @Test
    public void significantSamples() {
      MovingFunction f = newFunc();
      assertFalse(f.isSignificant());
      for (int i = 0; i < SIGNIFICANT_SAMPLES - 1; i++) {
        f.add(0, 0);
        assertFalse(f.isSignificant());
      }
      f.add(0, 0);
      assertTrue(f.isSignificant());
    }
  
    @Test
    public void significantBuckets() {
      MovingFunction f = newFunc();
      assertFalse(f.isSignificant());
      f.add(0, 0);
      assertFalse(f.isSignificant());
      f.add(SAMPLE_UPDATE, 0);
      assertTrue(f.isSignificant());
    }
  
    @Test
    public void sum() {
      MovingFunction f = newFunc();
      for (int i = 0; i < SAMPLE_PERIOD; i++) {
        f.add(i, i);
        assertEquals(((i + 1) * i) / 2, f.get(i));
      }
    }
  
    @Test
    public void movingSum() {
      MovingFunction f = newFunc();
      int lost = 0;
      for (int i = 0; i < SAMPLE_PERIOD * 2; i++) {
        f.add(i, 1);
        if (i >= SAMPLE_PERIOD && i % SAMPLE_UPDATE == 0) {
          lost += SAMPLE_UPDATE;
        }
        assertEquals(i + 1 - lost, f.get(i));
      }
    }
  
    @Test
    public void jumpingSum() {
      MovingFunction f = newFunc();
      f.add(0, 1);
      f.add(SAMPLE_PERIOD - 1, 1);
      assertEquals(2, f.get(SAMPLE_PERIOD - 1));
      assertEquals(1, f.get(SAMPLE_PERIOD + 3 * SAMPLE_UPDATE));
      assertEquals(0, f.get(SAMPLE_PERIOD * 2));
    }
  
    @Test
    public void properlyFlushStaleValues() {
      MovingFunction f = newFunc();
      f.add(0, 1);
      f.add(SAMPLE_PERIOD * 3, 1);
      assertEquals(1, f.get(SAMPLE_PERIOD * 3));
    }
  }
  