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.observers;
  
  import java.util.concurrent.*;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.Disposable;
  import io.reactivex.rxjava3.exceptions.Exceptions;
  import io.reactivex.rxjava3.functions.*;
  import io.reactivex.rxjava3.internal.util.*;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  
  /**
   * A combined Observer that awaits the success or error signal via a CountDownLatch.
   * @param <T> the value type
   */
  public final class BlockingMultiObserver<T>
  extends CountDownLatch
  implements SingleObserver<T>, CompletableObserver, MaybeObserver<T> {
  
      T value;
      Throwable error;
  
      Disposable upstream;
  
      volatile boolean cancelled;
  
      public BlockingMultiObserver() {
          super(1);
      }
  
      void dispose() {
          cancelled = true;
          Disposable d = this.upstream;
          if (d != null) {
              d.dispose();
          }
      }
  
      @Override
      public void onSubscribe(Disposable d) {
          this.upstream = d;
          if (cancelled) {
              d.dispose();
          }
      }
  
      @Override
      public void onSuccess(T value) {
          this.value = value;
          countDown();
      }
  
      @Override
      public void onError(Throwable e) {
          error = e;
          countDown();
      }
  
      @Override
      public void onComplete() {
          countDown();
      }
  
      /**
       * Block until the latch is counted down then rethrow any exception received (wrapped if checked)
       * or return the received value (null if none).
       * @return the value received or null if no value received
       */
      public T blockingGet() {
          if (getCount() != 0) {
              try {
                  BlockingHelper.verifyNonBlocking();
                  await();
              } catch (InterruptedException ex) {
                  dispose();
                  throw ExceptionHelper.wrapOrThrow(ex);
              }
          }
          Throwable ex = error;
          if (ex != null) {
              throw ExceptionHelper.wrapOrThrow(ex);
          }
          return value;
      }
  
      /**
       * Block until the latch is counted down then rethrow any exception received (wrapped if checked)
       * or return the received value (the defaultValue if none).
       * @param defaultValue the default value to return if no value was received
       * @return the value received or defaultValue if no value received
       */
      public T blockingGet(T defaultValue) {
          if (getCount() != 0) {
              try {
                  BlockingHelper.verifyNonBlocking();
                  await();
              } catch (InterruptedException ex) {
                  dispose();
                  throw ExceptionHelper.wrapOrThrow(ex);
              }
          }
          Throwable ex = error;
          if (ex != null) {
              throw ExceptionHelper.wrapOrThrow(ex);
          }
          T v = value;
          return v != null ? v : defaultValue;
      }
  
      /**
       * Block until the observer terminates and return true; return false if
       * the wait times out.
       * @param timeout the timeout value
       * @param unit the time unit
       * @return true if the observer terminated in time, false otherwise
       */
      public boolean blockingAwait(long timeout, TimeUnit unit) {
          if (getCount() != 0) {
              try {
                  BlockingHelper.verifyNonBlocking();
                  if (!await(timeout, unit)) {
                      dispose();
                      return false;
                  }
              } catch (InterruptedException ex) {
                  dispose();
                  throw ExceptionHelper.wrapOrThrow(ex);
              }
          }
          Throwable ex = error;
          if (ex != null) {
              throw ExceptionHelper.wrapOrThrow(ex);
          }
          return true;
      }
  
      /**
       * Blocks until the source completes and calls the appropriate callback.
       * @param onSuccess for a succeeding source
       * @param onError for a failing source
       * @param onComplete for an empty source
       */
      public void blockingConsume(Consumer<? super T> onSuccess, Consumer<? super Throwable> onError, Action onComplete) {
          try {
              if (getCount() != 0) {
                  try {
                      BlockingHelper.verifyNonBlocking();
                      await();
                  } catch (InterruptedException ex) {
                      dispose();
                      onError.accept(ex);
                      return;
                  }
              }
              Throwable ex = error;
              if (ex != null) {
                  onError.accept(ex);
                  return;
              }
              T v = value;
              if (v != null) {
                  onSuccess.accept(v);
              } else {
                  onComplete.run();
              }
          } catch (Throwable t) {
              Exceptions.throwIfFatal(t);
              RxJavaPlugins.onError(t);
          }
      }
  }
  