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.*;
  import java.util.concurrent.atomic.AtomicReference;
  import java.util.concurrent.locks.*;
  
  import org.reactivestreams.Subscription;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.Disposable;
  import io.reactivex.rxjava3.exceptions.*;
  import io.reactivex.rxjava3.internal.subscriptions.SubscriptionHelper;
  import io.reactivex.rxjava3.internal.util.*;
  import io.reactivex.rxjava3.operators.SpscArrayQueue;
  
  public final class BlockingFlowableIterable<T> implements Iterable<T> {
      final Flowable<T> source;
  
      final int bufferSize;
  
      public BlockingFlowableIterable(Flowable<T> source, int bufferSize) {
          this.source = source;
          this.bufferSize = bufferSize;
      }
  
      @Override
      public Iterator<T> iterator() {
          BlockingFlowableIterator<T> it = new BlockingFlowableIterator<>(bufferSize);
          source.subscribe(it);
          return it;
      }
  
      static final class BlockingFlowableIterator<T>
      extends AtomicReference<Subscription>
      implements FlowableSubscriber<T>, Iterator<T>, Runnable, Disposable {
  
          private static final long serialVersionUID = 6695226475494099826L;
  
          final SpscArrayQueue<T> queue;
  
          final long batchSize;
  
          final long limit;
  
          final Lock lock;
  
          final Condition condition;
  
          long produced;
  
          volatile boolean done;
          volatile Throwable error;
  
          BlockingFlowableIterator(int batchSize) {
              this.queue = new SpscArrayQueue<>(batchSize);
              this.batchSize = batchSize;
              this.limit = batchSize - (batchSize >> 2);
              this.lock = new ReentrantLock();
              this.condition = lock.newCondition();
          }
  
          @Override
          public boolean hasNext() {
              for (;;) {
                  if (isDisposed()) {
                      Throwable e = error;
                      if (e != null) {
                          throw ExceptionHelper.wrapOrThrow(e);
                      }
                      return false;
                  }
                  boolean d = done;
                  boolean empty = queue.isEmpty();
                  if (d) {
                      Throwable e = error;
                      if (e != null) {
                          throw ExceptionHelper.wrapOrThrow(e);
                      } else
                      if (empty) {
                          return false;
                      }
                  }
                  if (empty) {
                      BlockingHelper.verifyNonBlocking();
                      lock.lock();
                      try {
                          while (!done && queue.isEmpty() && !isDisposed()) {
                              condition.await();
                          }
                      } catch (InterruptedException ex) {
                          run();
                          throw ExceptionHelper.wrapOrThrow(ex);
                      } finally {
                          lock.unlock();
                      }
                  } else {
                      return true;
                  }
              }
          }
  
          @Override
          public T next() {
              if (hasNext()) {
                  T v = queue.poll();
  
                  long p = produced + 1;
                  if (p == limit) {
                      produced = 0;
                      get().request(p);
                  } else {
                      produced = p;
                  }
  
                  return v;
              }
              throw new NoSuchElementException();
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              SubscriptionHelper.setOnce(this, s, batchSize);
          }
  
          @Override
          public void onNext(T t) {
              if (!queue.offer(t)) {
                  SubscriptionHelper.cancel(this);
  
                  onError(new QueueOverflowException());
              } else {
                  signalConsumer();
              }
          }
  
          @Override
          public void onError(Throwable t) {
              error = t;
              done = true;
              signalConsumer();
          }
  
          @Override
          public void onComplete() {
              done = true;
              signalConsumer();
          }
  
          void signalConsumer() {
              lock.lock();
              try {
                  condition.signalAll();
              } finally {
                  lock.unlock();
              }
          }
  
          @Override
          public void run() {
              SubscriptionHelper.cancel(this);
              signalConsumer();
          }
  
          @Override // otherwise default method which isn't available in Java 7
          public void remove() {
              throw new UnsupportedOperationException("remove");
          }
  
          @Override
          public void dispose() {
              SubscriptionHelper.cancel(this);
              signalConsumer(); // Just in case it is currently blocking in hasNext.
          }
  
          @Override
          public boolean isDisposed() {
              return get() == SubscriptionHelper.CANCELLED;
          }
      }
  }
  