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.io.range;
  
  import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkArgument;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.List;
  import org.apache.beam.sdk.coders.AtomicCoder;
  import org.apache.beam.sdk.coders.CoderException;
  import org.apache.beam.sdk.transforms.splittabledofn.HasDefaultTracker;
  import org.apache.beam.sdk.util.VarInt;
  import org.apache.beam.sdk.values.TypeDescriptor;
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /** A restriction represented by a range of integers [from, to). */
  public class OffsetRange
      implements Serializable,
          HasDefaultTracker<
              OffsetRange, org.apache.beam.sdk.transforms.splittabledofn.OffsetRangeTracker> {
    private final long from;
    private final long to;
  
    public OffsetRange(long from, long to) {
      checkArgument(from <= to, "Malformed range [%s, %s)", from, to);
      this.from = from;
      this.to = to;
    }
  
    public long getFrom() {
      return from;
    }
  
    public long getTo() {
      return to;
    }
  
    @Override
    public org.apache.beam.sdk.transforms.splittabledofn.OffsetRangeTracker newTracker() {
      return new org.apache.beam.sdk.transforms.splittabledofn.OffsetRangeTracker(this);
    }
  
    @Override
    public String toString() {
      return "[" + from + ", " + to + ')';
    }
  
    @Override
    public boolean equals(@Nullable Object o) {
      if (this == o) {
        return true;
      }
      if (o == null || getClass() != o.getClass()) {
        return false;
      }
  
      OffsetRange that = (OffsetRange) o;
  
      if (from != that.from) {
        return false;
      }
      return to == that.to;
    }
  
    @Override
    public int hashCode() {
      int result = (int) (from ^ (from >>> 32));
      result = 31 * result + (int) (to ^ (to >>> 32));
      return result;
    }
  
    public List<OffsetRange> split(long desiredNumOffsetsPerSplit, long minNumOffsetPerSplit) {
      List<OffsetRange> res = new ArrayList<>();
      long start = getFrom();
      long maxEnd = getTo();
  
      while (start < maxEnd) {
        long end = start + desiredNumOffsetsPerSplit;
        end = Math.min(end, maxEnd);
        // Avoid having a too small range at the end and ensure that we respect minNumOffsetPerSplit.
        long remaining = maxEnd - end;
        if ((remaining < desiredNumOffsetsPerSplit / 4) || (remaining < minNumOffsetPerSplit)) {
          end = maxEnd;
        }
        res.add(new OffsetRange(start, end));
        start = end;
      }
      return res;
    }
  
    /** A coder for {@link OffsetRange}s. */
    public static class Coder extends AtomicCoder<OffsetRange> {
      private static final Coder INSTANCE = new Coder();
      private static final TypeDescriptor<OffsetRange> TYPE_DESCRIPTOR =
          new TypeDescriptor<OffsetRange>() {};
  
      public static Coder of() {
        return INSTANCE;
      }
  
      @Override
      public void encode(OffsetRange value, OutputStream outStream)
          throws CoderException, IOException {
        VarInt.encode(value.from, outStream);
        VarInt.encode(value.to, outStream);
      }
  
      @Override
      public OffsetRange decode(InputStream inStream) throws CoderException, IOException {
        return new OffsetRange(VarInt.decodeLong(inStream), VarInt.decodeLong(inStream));
      }
  
      @Override
      public boolean isRegisterByteSizeObserverCheap(OffsetRange value) {
        return true;
      }
  
      @Override
      protected long getEncodedElementByteSize(OffsetRange value) throws Exception {
        return (long) VarInt.getLength(value.from) + VarInt.getLength(value.to);
      }
  
      @Override
      public boolean consistentWithEquals() {
        return true;
      }
  
      @Override
      public TypeDescriptor<OffsetRange> getEncodedTypeDescriptor() {
        return TYPE_DESCRIPTOR;
      }
    }
  }
  