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.dataflow.worker.windmill.state;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.Future;
  import org.apache.beam.runners.core.StateNamespace;
  import org.apache.beam.runners.core.StateTag;
  import org.apache.beam.runners.dataflow.worker.windmill.Windmill;
  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.util.ByteStringOutputStream;
  import org.apache.beam.sdk.util.Weighted;
  import org.apache.beam.vendor.grpc.v1p69p0.com.google.protobuf.ByteString;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
  
  @SuppressWarnings({
    "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public class WindmillBag<T> extends SimpleWindmillState implements BagState<T> {
  
    private final StateNamespace namespace;
    private final StateTag<BagState<T>> address;
    private final ByteString stateKey;
    private final String stateFamily;
    private final Coder<T> elemCoder;
  
    private boolean cleared = false;
    /**
     * If non-{@literal null}, this contains the complete contents of the bag, except for any local
     * additions. If {@literal null} then we don't know if Windmill contains additional values which
     * should be part of the bag. We'll need to read them if the work item actually wants the bag
     * contents.
     */
    private ConcatIterables<T> cachedValues = null;
  
    private List<T> localAdditions = new ArrayList<>();
    private long encodedSize = 0;
  
    WindmillBag(
        StateNamespace namespace,
        StateTag<BagState<T>> address,
        String stateFamily,
        Coder<T> elemCoder,
        boolean isNewKey,
        WindmillStateTagUtil windmillStateTagUtil) {
      this.namespace = namespace;
      this.address = address;
      this.stateKey = windmillStateTagUtil.encodeKey(namespace, address);
      this.stateFamily = stateFamily;
      this.elemCoder = elemCoder;
      if (isNewKey) {
        this.cachedValues = new ConcatIterables<>();
      }
    }
  
    @Override
    public void clear() {
      cleared = true;
      cachedValues = new ConcatIterables<>();
      localAdditions = new ArrayList<>();
      encodedSize = 0;
    }
  
    /**
     * Return iterable over all bag values in Windmill which should contribute to overall bag
     * contents.
     */
    private Iterable<T> fetchData(Future<Iterable<T>> persistedData) {
      try (Closeable scope = scopedReadState()) {
        if (cachedValues != null) {
          return cachedValues.snapshot();
        }
        Iterable<T> data = persistedData.get();
        if (data instanceof Weighted) {
          // We have a known bounded amount of data; cache it.
          cachedValues = new ConcatIterables<>();
          cachedValues.extendWith(data);
          encodedSize = ((Weighted) data).getWeight();
          return cachedValues.snapshot();
        } else {
          // This is an iterable that may not fit in memory at once; don't cache it.
          return data;
        }
      } catch (InterruptedException | ExecutionException | IOException e) {
        if (e instanceof InterruptedException) {
          Thread.currentThread().interrupt();
        }
        throw new RuntimeException("Unable to read state", e);
      }
    }
  
    public boolean valuesAreCached() {
      return cachedValues != null;
    }
  
    @Override
    @SuppressWarnings("FutureReturnValueIgnored")
    public WindmillBag<T> readLater() {
      getFuture();
      return this;
    }
  
    @Override
    public Iterable<T> read() {
      return Iterables.concat(
          fetchData(getFuture()), Iterables.limit(localAdditions, localAdditions.size()));
    }
  
    @Override
    public ReadableState<Boolean> isEmpty() {
      return new ReadableState<Boolean>() {
        @Override
        public ReadableState<Boolean> readLater() {
          WindmillBag.this.readLater();
          return this;
        }
  
        @Override
        public Boolean read() {
          return Iterables.isEmpty(fetchData(getFuture())) && localAdditions.isEmpty();
        }
      };
    }
  
    @Override
    public void add(T input) {
      localAdditions.add(input);
    }
  
    @Override
    public Windmill.WorkItemCommitRequest persistDirectly(WindmillStateCache.ForKeyAndFamily cache)
        throws IOException {
      Windmill.WorkItemCommitRequest.Builder commitBuilder =
          Windmill.WorkItemCommitRequest.newBuilder();
  
      Windmill.TagBag.Builder bagUpdatesBuilder = null;
  
      if (cleared) {
        bagUpdatesBuilder = commitBuilder.addBagUpdatesBuilder();
        bagUpdatesBuilder.setDeleteAll(true);
        cleared = false;
      }
  
      if (!localAdditions.isEmpty()) {
        // Tell Windmill to capture the local additions.
        if (bagUpdatesBuilder == null) {
          bagUpdatesBuilder = commitBuilder.addBagUpdatesBuilder();
        }
        for (T value : localAdditions) {
          ByteStringOutputStream stream = new ByteStringOutputStream();
          // Encode the value
          elemCoder.encode(value, stream, Coder.Context.OUTER);
          ByteString encoded = stream.toByteString();
          if (cachedValues != null) {
            // We'll capture this value in the cache below.
            // Capture the value's size now since we have it.
            encodedSize += encoded.size();
          }
          bagUpdatesBuilder.addValues(encoded);
        }
      }
  
      if (bagUpdatesBuilder != null) {
        bagUpdatesBuilder.setTag(stateKey).setStateFamily(stateFamily);
      }
  
      if (cachedValues != null) {
        if (!localAdditions.isEmpty()) {
          // Capture the local additions in the cached value since we and
          // Windmill are now in agreement.
          cachedValues.extendWith(localAdditions);
        }
        // We now know the complete bag contents, and any read on it will yield a
        // cached value, so cache it for future reads.
        cache.put(namespace, address, this, encodedSize + stateKey.size());
      }
  
      // Don't reuse the localAdditions object; we don't want future changes to it to
      // modify the value of cachedValues.
      localAdditions = new ArrayList<>();
  
      return commitBuilder.buildPartial();
    }
  
    private Future<Iterable<T>> getFuture() {
      return cachedValues != null ? null : reader.bagFuture(stateKey, stateFamily, elemCoder);
    }
  }
  