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.twister2.translators.functions.internal;
  
  import java.io.ObjectStreamException;
  import org.apache.beam.runners.core.MergingStateAccessor;
  import org.apache.beam.runners.core.StateAccessor;
  import org.apache.beam.runners.core.StateMerging;
  import org.apache.beam.runners.core.StateTag;
  import org.apache.beam.runners.core.StateTags;
  import org.apache.beam.runners.core.SystemReduceFn;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.state.BagState;
  import org.apache.beam.sdk.state.ReadableState;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.util.SerializableUtils;
  
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public class SystemReduceFnBuffering<K, T, W extends BoundedWindow>
      extends SystemReduceFn<K, T, Iterable<T>, Iterable<T>, W> {
    private static final String BUFFER_NAME = "buf";
    private transient StateTag<BagState<T>> bufferTagLocal;
    private transient Coder<T> inputCoder;
  
    private transient boolean isInitialized = false;
  
    private byte[] coderBytes;
  
    public SystemReduceFnBuffering() {
      super(null);
      this.isInitialized = false;
    }
  
    public SystemReduceFnBuffering(Coder<T> valueCoder) {
      super(null);
      bufferTagLocal = null;
      coderBytes = SerializableUtils.serializeToByteArray(valueCoder);
      ;
  
      inputCoder = valueCoder;
    }
  
    @Override
    public void onMerge(OnMergeContext context) throws Exception {
      initTransient();
      StateMerging.mergeBags(context.state(), bufferTagLocal);
    }
  
    @Override
    public void prefetchOnMerge(MergingStateAccessor<K, W> state) throws Exception {
      initTransient();
      StateMerging.prefetchBags(state, bufferTagLocal);
    }
  
    @Override
    public void processValue(ProcessValueContext c) throws Exception {
      initTransient();
      c.state().access(bufferTagLocal).add(c.value());
    }
  
    @Override
    public void prefetchOnTrigger(StateAccessor<K> state) {
      initTransient();
      state.access(bufferTagLocal).readLater();
    }
  
    @Override
    public void onTrigger(OnTriggerContext c) throws Exception {
      initTransient();
      c.output(c.state().access(bufferTagLocal).read());
    }
  
    @Override
    public void clearState(Context c) throws Exception {
      initTransient();
      c.state().access(bufferTagLocal).clear();
    }
  
    @Override
    public ReadableState<Boolean> isEmpty(StateAccessor<K> state) {
      initTransient();
      return state.access(bufferTagLocal).isEmpty();
    }
  
    /**
     * Method used to initialize the transient variables that were sent over as byte arrays or proto
     * buffers.
     */
    private void initTransient() {
      if (isInitialized) {
        return;
      }
      inputCoder =
          (Coder<T>) SerializableUtils.deserializeFromByteArray(coderBytes, "Custom Coder Bytes");
      bufferTagLocal = StateTags.makeSystemTagInternal(StateTags.bag(BUFFER_NAME, inputCoder));
      this.isInitialized = true;
    }
  
    protected Object readResolve() throws ObjectStreamException {
      return this;
    }
  }
  