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.Arrays;
  import java.util.Objects;
  import java.util.concurrent.atomic.*;
  
  import org.reactivestreams.*;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.exceptions.Exceptions;
  import io.reactivex.rxjava3.functions.Function;
  import io.reactivex.rxjava3.internal.subscriptions.*;
  import io.reactivex.rxjava3.internal.util.*;
  import io.reactivex.rxjava3.operators.QueueSubscription;
  import io.reactivex.rxjava3.operators.SimpleQueue;
  import io.reactivex.rxjava3.operators.SpscArrayQueue;
  
  public final class FlowableZip<T, R> extends Flowable<R> {
  
      final Publisher<? extends T>[] sources;
      final Iterable<? extends Publisher<? extends T>> sourcesIterable;
      final Function<? super Object[], ? extends R> zipper;
      final int bufferSize;
      final boolean delayError;
  
      public FlowableZip(Publisher<? extends T>[] sources,
              Iterable<? extends Publisher<? extends T>> sourcesIterable,
                      Function<? super Object[], ? extends R> zipper,
                      int bufferSize,
                      boolean delayError) {
          this.sources = sources;
          this.sourcesIterable = sourcesIterable;
          this.zipper = zipper;
          this.bufferSize = bufferSize;
          this.delayError = delayError;
      }
  
      @Override
      @SuppressWarnings("unchecked")
      public void subscribeActual(Subscriber<? super R> s) {
          Publisher<? extends T>[] sources = this.sources;
          int count = 0;
          if (sources == null) {
              sources = new Publisher[8];
              for (Publisher<? extends T> p : sourcesIterable) {
                  if (count == sources.length) {
                      Publisher<? extends T>[] b = new Publisher[count + (count >> 2)];
                      System.arraycopy(sources, 0, b, 0, count);
                      sources = b;
                  }
                  sources[count++] = p;
              }
          } else {
              count = sources.length;
          }
  
          if (count == 0) {
              EmptySubscription.complete(s);
              return;
          }
  
          ZipCoordinator<T, R> coordinator = new ZipCoordinator<>(s, zipper, count, bufferSize, delayError);
  
          s.onSubscribe(coordinator);
  
          coordinator.subscribe(sources, count);
      }
  
      static final class ZipCoordinator<T, R>
      extends AtomicInteger
      implements Subscription {
  
          private static final long serialVersionUID = -2434867452883857743L;
  
          final Subscriber<? super R> downstream;
  
          final ZipSubscriber<T, R>[] subscribers;
  
          final Function<? super Object[], ? extends R> zipper;
  
          final AtomicLong requested;
  
          final AtomicThrowable errors;
  
          final boolean delayErrors;
  
          volatile boolean cancelled;
  
          final Object[] current;
  
          ZipCoordinator(Subscriber<? super R> actual,
                  Function<? super Object[], ? extends R> zipper, int n, int prefetch, boolean delayErrors) {
              this.downstream = actual;
              this.zipper = zipper;
              this.delayErrors = delayErrors;
              @SuppressWarnings("unchecked")
              ZipSubscriber<T, R>[] a = new ZipSubscriber[n];
              for (int i = 0; i < n; i++) {
                  a[i] = new ZipSubscriber<>(this, prefetch);
              }
              this.current = new Object[n];
              this.subscribers = a;
              this.requested = new AtomicLong();
              this.errors = new AtomicThrowable();
          }
  
          void subscribe(Publisher<? extends T>[] sources, int n) {
              ZipSubscriber<T, R>[] a = subscribers;
              for (int i = 0; i < n; i++) {
                  if (cancelled || (!delayErrors && errors.get() != null)) {
                      return;
                  }
                  sources[i].subscribe(a[i]);
              }
          }
  
          @Override
          public void request(long n) {
              if (SubscriptionHelper.validate(n)) {
                  BackpressureHelper.add(requested, n);
                  drain();
              }
          }
  
          @Override
          public void cancel() {
              if (!cancelled) {
                  cancelled = true;
  
                  cancelAll();
              }
          }
  
          void error(ZipSubscriber<T, R> inner, Throwable e) {
              if (errors.tryAddThrowableOrReport(e)) {
                  inner.done = true;
                  drain();
              }
          }
  
          void cancelAll() {
              for (ZipSubscriber<T, R> s : subscribers) {
                  s.cancel();
              }
          }
  
          void drain() {
  
              if (getAndIncrement() != 0) {
                  return;
              }
  
              final Subscriber<? super R> a = downstream;
              final ZipSubscriber<T, R>[] qs = subscribers;
              final int n = qs.length;
              Object[] values = current;
  
              int missed = 1;
  
              for (;;) {
  
                  long r = requested.get();
                  long e = 0L;
  
                  while (r != e) {
  
                      if (cancelled) {
                          return;
                      }
  
                      if (!delayErrors && errors.get() != null) {
                          cancelAll();
                          errors.tryTerminateConsumer(a);
                          return;
                      }
  
                      boolean empty = false;
  
                      for (int j = 0; j < n; j++) {
                          ZipSubscriber<T, R> inner = qs[j];
                          if (values[j] == null) {
                              boolean d = inner.done;
                              SimpleQueue<T> q = inner.queue;
                              T v = null;
                              try {
  
                                  v = q != null ? q.poll() : null;
                              } catch (Throwable ex) {
                                  Exceptions.throwIfFatal(ex);
  
                                  errors.tryAddThrowableOrReport(ex);
                                  if (!delayErrors) {
                                      cancelAll();
                                      errors.tryTerminateConsumer(a);
                                      return;
                                  }
                                  d = true;
                              }
  
                              boolean sourceEmpty = v == null;
                              if (d && sourceEmpty) {
                                  cancelAll();
                                  errors.tryTerminateConsumer(a);
                                  return;
                              }
                              if (!sourceEmpty) {
                                  values[j] = v;
                              } else {
                                  empty = true;
                              }
                          }
                      }
  
                      if (empty) {
                          break;
                      }
  
                      R v;
  
                      try {
                          v = Objects.requireNonNull(zipper.apply(values.clone()), "The zipper returned a null value");
                      } catch (Throwable ex) {
                          Exceptions.throwIfFatal(ex);
                          cancelAll();
                          errors.tryAddThrowableOrReport(ex);
                          errors.tryTerminateConsumer(a);
                          return;
                      }
  
                      a.onNext(v);
  
                      e++;
  
                      Arrays.fill(values, null);
                  }
  
                  if (r == e) {
                      if (cancelled) {
                          return;
                      }
  
                      if (!delayErrors && errors.get() != null) {
                          cancelAll();
                          errors.tryTerminateConsumer(a);
                          return;
                      }
  
                      for (int j = 0; j < n; j++) {
                          ZipSubscriber<T, R> inner = qs[j];
                          if (values[j] == null) {
                              boolean d = inner.done;
                              SimpleQueue<T> q = inner.queue;
                              T v = null;
                              try {
                                  v = q != null ? q.poll() : null;
                              } catch (Throwable ex) {
                                  Exceptions.throwIfFatal(ex);
                                  errors.tryAddThrowableOrReport(ex);
                                  if (!delayErrors) {
                                      cancelAll();
                                      errors.tryTerminateConsumer(a);
                                      return;
                                  }
                                  d = true;
                              }
                              boolean empty = v == null;
                              if (d && empty) {
                                  cancelAll();
                                  errors.tryTerminateConsumer(a);
                                  return;
                              }
                              if (!empty) {
                                  values[j] = v;
                              }
                          }
                      }
  
                  }
  
                  if (e != 0L) {
  
                      for (ZipSubscriber<T, R> inner : qs) {
                          inner.request(e);
                      }
  
                      if (r != Long.MAX_VALUE) {
                          requested.addAndGet(-e);
                      }
                  }
  
                  missed = addAndGet(-missed);
                  if (missed == 0) {
                      break;
                  }
              }
          }
      }
  
      static final class ZipSubscriber<T, R> extends AtomicReference<Subscription> implements FlowableSubscriber<T>, Subscription {
  
          private static final long serialVersionUID = -4627193790118206028L;
  
          final ZipCoordinator<T, R> parent;
  
          final int prefetch;
  
          final int limit;
  
          SimpleQueue<T> queue;
  
          long produced;
  
          volatile boolean done;
  
          int sourceMode;
  
          ZipSubscriber(ZipCoordinator<T, R> parent, int prefetch) {
              this.parent = parent;
              this.prefetch = prefetch;
              this.limit = prefetch - (prefetch >> 2);
          }
  
          @SuppressWarnings("unchecked")
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.setOnce(this, s)) {
                  if (s instanceof QueueSubscription) {
                      QueueSubscription<T> f = (QueueSubscription<T>) s;
  
                      int m = f.requestFusion(QueueSubscription.ANY | QueueSubscription.BOUNDARY);
  
                      if (m == QueueSubscription.SYNC) {
                          sourceMode = m;
                          queue = f;
                          done = true;
                          parent.drain();
                          return;
                      }
                      if (m == QueueSubscription.ASYNC) {
                          sourceMode = m;
                          queue = f;
                          s.request(prefetch);
                          return;
                      }
                  }
  
                  queue = new SpscArrayQueue<>(prefetch);
  
                  s.request(prefetch);
              }
          }
  
          @Override
          public void onNext(T t) {
              if (sourceMode != QueueSubscription.ASYNC) {
                  queue.offer(t);
              }
              parent.drain();
          }
  
          @Override
          public void onError(Throwable t) {
              parent.error(this, t);
          }
  
          @Override
          public void onComplete() {
              done = true;
              parent.drain();
          }
  
          @Override
          public void cancel() {
              SubscriptionHelper.cancel(this);
          }
  
          @Override
          public void request(long n) {
              if (sourceMode != QueueSubscription.SYNC) {
                  long p = produced + n;
                  if (p >= limit) {
                      produced = 0L;
                      get().request(p);
                  } else {
                      produced = p;
                  }
              }
          }
      }
  }
  