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.core;
  
  import java.util.Collection;
  import java.util.Set;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.transforms.windowing.WindowFn;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.annotations.VisibleForTesting;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableSet;
  
  /**
   * Implementation of {@link ActiveWindowSet} used with {@link WindowFn WindowFns} that don't support
   * merging.
   *
   * @param <W> the types of windows being managed
   */
  public class NonMergingActiveWindowSet<W extends BoundedWindow> implements ActiveWindowSet<W> {
    @Override
    public void cleanupTemporaryWindows() {}
  
    @Override
    public void persist() {}
  
    @Override
    public Set<W> getActiveAndNewWindows() {
      // Only supported when merging.
      throw new java.lang.UnsupportedOperationException();
    }
  
    @Override
    public boolean isActive(W window) {
      // Windows should never disappear, since we don't support merging.
      return true;
    }
  
    @Override
    public boolean isActiveOrNew(W window) {
      return true;
    }
  
    @Override
    public void ensureWindowExists(W window) {}
  
    @Override
    public void ensureWindowIsActive(W window) {}
  
    @Override
    @VisibleForTesting
    public void addActiveForTesting(W window) {}
  
    @Override
    public void remove(W window) {}
  
    @Override
    public void merge(MergeCallback<W> mergeCallback) throws Exception {}
  
    @Override
    public void merged(W window) {}
  
    @Override
    public Set<W> readStateAddresses(W window) {
      return ImmutableSet.of(window);
    }
  
    @Override
    public W writeStateAddress(W window) {
      return window;
    }
  
    @Override
    public W mergedWriteStateAddress(Collection<W> toBeMerged, W mergeResult) {
      return mergeResult;
    }
  }
  