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.transforms.windowing;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.util.Collections;
  import java.util.List;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.coders.CoderException;
  import org.apache.beam.sdk.coders.DurationCoder;
  import org.apache.beam.sdk.coders.InstantCoder;
  import org.apache.beam.sdk.coders.StructuredCoder;
  import org.apache.beam.sdk.util.common.ElementByteSizeObserver;
  import org.checkerframework.checker.nullness.qual.Nullable;
  import org.joda.time.Duration;
  import org.joda.time.Instant;
  import org.joda.time.ReadableDuration;
  
  /**
   * An implementation of {@link BoundedWindow} that represents an interval from {@link #start}
   * (inclusive) to {@link #end} (exclusive).
   */
  public class IntervalWindow extends BoundedWindow implements Comparable<IntervalWindow> {
    /** Start of the interval, inclusive. */
    private final Instant start;
  
    /** End of the interval, exclusive. */
    private final Instant end;
  
    /** Creates a new IntervalWindow that represents the half-open time interval [start, end). */
    public IntervalWindow(Instant start, Instant end) {
      this.start = start;
      this.end = end;
    }
  
    public IntervalWindow(Instant start, ReadableDuration size) {
      this.start = start;
      this.end = start.plus(size);
    }
  
    /** Returns the start of this window, inclusive. */
    public Instant start() {
      return start;
    }
  
    /** Returns the end of this window, exclusive. */
    public Instant end() {
      return end;
    }
  
    /** Returns the largest timestamp that can be included in this window. */
    @Override
    public Instant maxTimestamp() {
      // end not inclusive
      return end.minus(Duration.millis(1));
    }
  
    /** Returns whether this window contains the given window. */
    public boolean contains(IntervalWindow other) {
      return !this.start.isAfter(other.start) && !this.end.isBefore(other.end);
    }
  
    /** Returns whether this window is disjoint from the given window. */
    public boolean isDisjoint(IntervalWindow other) {
      return !this.end.isAfter(other.start) || !other.end.isAfter(this.start);
    }
  
    /** Returns whether this window intersects the given window. */
    public boolean intersects(IntervalWindow other) {
      return !isDisjoint(other);
    }
  
    /** Returns the minimal window that includes both this window and the given window. */
    public IntervalWindow span(IntervalWindow other) {
      return new IntervalWindow(
          new Instant(Math.min(start.getMillis(), other.start.getMillis())),
          new Instant(Math.max(end.getMillis(), other.end.getMillis())));
    }
  
    @Override
    public boolean equals(@Nullable Object o) {
      return (o instanceof IntervalWindow)
          && ((IntervalWindow) o).end.isEqual(end)
          && ((IntervalWindow) o).start.isEqual(start);
    }
  
    @Override
    public int hashCode() {
      // The end values are themselves likely to be arithmetic sequence, which
      // is a poor distribution to use for a hashtable, so we
      // add a highly non-linear transformation.
      return (int) (start.getMillis() + modInverse((int) (end.getMillis() << 1) + 1));
    }
  
    /** Compute the inverse of (odd) x mod 2^32. */
    private int modInverse(int x) {
      // Cube gives inverse mod 2^4, as x^4 == 1 (mod 2^4) for all odd x.
      int inverse = x * x * x;
      // Newton iteration doubles correct bits at each step.
      inverse *= 2 - x * inverse;
      inverse *= 2 - x * inverse;
      inverse *= 2 - x * inverse;
      return inverse;
    }
  
    @Override
    public String toString() {
      return "[" + start + ".." + end + ")";
    }
  
    @Override
    public int compareTo(IntervalWindow o) {
      if (start.isEqual(o.start)) {
        return end.compareTo(o.end);
      }
      return start.compareTo(o.start);
    }
  
    /** Returns a {@link Coder} suitable for {@link IntervalWindow}. */
    public static Coder<IntervalWindow> getCoder() {
      return IntervalWindowCoder.of();
    }
  
    /** Encodes an {@link IntervalWindow} as a pair of its upper bound and duration. */
    public static class IntervalWindowCoder extends StructuredCoder<IntervalWindow> {
  
      private static final IntervalWindowCoder INSTANCE = new IntervalWindowCoder();
  
      private static final Coder<Instant> instantCoder = InstantCoder.of();
      private static final Coder<ReadableDuration> durationCoder = DurationCoder.of();
  
      public static IntervalWindowCoder of() {
        return INSTANCE;
      }
  
      @Override
      public void encode(IntervalWindow window, OutputStream outStream)
          throws IOException, CoderException {
        instantCoder.encode(window.end, outStream);
        durationCoder.encode(new Duration(window.start, window.end), outStream);
      }
  
      @Override
      public IntervalWindow decode(InputStream inStream) throws IOException, CoderException {
        Instant end = instantCoder.decode(inStream);
        ReadableDuration duration = durationCoder.decode(inStream);
        return new IntervalWindow(end.minus(duration), end);
      }
  
      @Override
      public void verifyDeterministic() throws NonDeterministicException {
        instantCoder.verifyDeterministic();
        durationCoder.verifyDeterministic();
      }
  
      @Override
      public boolean consistentWithEquals() {
        return instantCoder.consistentWithEquals() && durationCoder.consistentWithEquals();
      }
  
      @Override
      public boolean isRegisterByteSizeObserverCheap(IntervalWindow value) {
        return instantCoder.isRegisterByteSizeObserverCheap(value.end)
            && durationCoder.isRegisterByteSizeObserverCheap(new Duration(value.start, value.end));
      }
  
      @Override
      public void registerByteSizeObserver(IntervalWindow value, ElementByteSizeObserver observer)
          throws Exception {
        instantCoder.registerByteSizeObserver(value.end, observer);
        durationCoder.registerByteSizeObserver(new Duration(value.start, value.end), observer);
      }
  
      @Override
      public List<? extends Coder<?>> getCoderArguments() {
        return Collections.emptyList();
      }
    }
  }
  