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.runners.direct;
  
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicBoolean;
  import org.apache.beam.runners.local.StructuralKey;
  import org.apache.beam.sdk.coders.ByteArrayCoder;
  import org.apache.beam.sdk.transforms.PTransform;
  import org.apache.beam.sdk.util.construction.SplittableParDo.PrimitiveUnboundedRead;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.CacheBuilder;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.CacheLoader;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.LoadingCache;
  import org.joda.time.Duration;
  
  /**
   * Provides methods to determine if a record is a duplicate within the evaluation of a {@link
   * PrimitiveUnboundedRead SplittableParDo.PrimitiveUnboundedRead} {@link PTransform}.
   */
  interface UnboundedReadDeduplicator {
    /**
     * Returns true if the record with the provided ID should be output, and false if it should not be
     * because it is a duplicate.
     */
    boolean shouldOutput(byte[] recordId);
  
    /**
     * An {@link UnboundedReadDeduplicator} that always returns true. For use with sources do not
     * require deduplication.
     */
    class NeverDeduplicator implements UnboundedReadDeduplicator {
      /** Create a new {@link NeverDeduplicator}. */
      public static UnboundedReadDeduplicator create() {
        return new NeverDeduplicator();
      }
  
      @Override
      public boolean shouldOutput(byte[] recordId) {
        return true;
      }
    }
  
    /**
     * An {@link UnboundedReadDeduplicator} that returns true if the record ID has not been seen
     * within 10 minutes.
     */
    class CachedIdDeduplicator implements UnboundedReadDeduplicator {
      private static final ByteArrayCoder RECORD_ID_CODER = ByteArrayCoder.of();
      private static final long MAX_RETENTION_SINCE_ACCESS =
          Duration.standardMinutes(10L).getMillis();
  
      private final LoadingCache<StructuralKey<byte[]>, AtomicBoolean> ids;
  
      /** Create a new {@link CachedIdDeduplicator}. */
      public static UnboundedReadDeduplicator create() {
        return new CachedIdDeduplicator();
      }
  
      private CachedIdDeduplicator() {
        ids =
            CacheBuilder.newBuilder()
                .expireAfterAccess(MAX_RETENTION_SINCE_ACCESS, TimeUnit.MILLISECONDS)
                .maximumSize(100_000L)
                .build(new TrueBooleanLoader());
      }
  
      @Override
      public boolean shouldOutput(byte[] recordId) {
        return ids.getUnchecked(StructuralKey.of(recordId, RECORD_ID_CODER)).getAndSet(false);
      }
  
      private static class TrueBooleanLoader
          extends CacheLoader<StructuralKey<byte[]>, AtomicBoolean> {
        @Override
        public AtomicBoolean load(StructuralKey<byte[]> key) throws Exception {
          return new AtomicBoolean(true);
        }
      }
    }
  }
  