code: /*
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed 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 io.reactivex.rxjava3.internal.operators.flowable;
  
  import java.util.concurrent.atomic.AtomicBoolean;
  
  import org.reactivestreams.Subscriber;
  
  import io.reactivex.rxjava3.core.Flowable;
  import io.reactivex.rxjava3.processors.FlowableProcessor;
  
  /**
   * Wrapper for a FlowableProcessor that detects an incoming subscriber.
   * @param <T> the element type of the flow.
   * @since 3.0.0
   */
  final class FlowableWindowSubscribeIntercept<T> extends Flowable<T> {
  
      final FlowableProcessor<T> window;
  
      final AtomicBoolean once;
  
      FlowableWindowSubscribeIntercept(FlowableProcessor<T> source) {
          this.window = source;
          this.once = new AtomicBoolean();
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super T> s) {
          window.subscribe(s);
          once.set(true);
      }
  
      boolean tryAbandon() {
          return !once.get() && once.compareAndSet(false, true);
      }
  }
  