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.observable;
  
  import static org.junit.Assert.*;
  
  import java.util.List;
  import java.util.concurrent.*;
  import java.util.concurrent.atomic.*;
  
  import org.junit.Test;
  
  import io.reactivex.rxjava3.annotations.NonNull;
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.*;
  import io.reactivex.rxjava3.exceptions.TestException;
  import io.reactivex.rxjava3.functions.Action;
  import io.reactivex.rxjava3.internal.schedulers.ImmediateThinScheduler;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  import io.reactivex.rxjava3.schedulers.Schedulers;
  import io.reactivex.rxjava3.testsupport.*;
  
  public class ObservableUnsubscribeOnTest extends RxJavaTest {
  
      @Test
      public void unsubscribeWhenSubscribeOnAndUnsubscribeOnAreOnSameThread() throws InterruptedException {
          UIEventLoopScheduler uiEventLoop = new UIEventLoopScheduler();
          try {
              final ThreadSubscription subscription = new ThreadSubscription();
              final AtomicReference<Thread> subscribeThread = new AtomicReference<>();
              Observable<Integer> w = Observable.unsafeCreate(new ObservableSource<Integer>() {
  
                  @Override
                  public void subscribe(Observer<? super Integer> t1) {
                      subscribeThread.set(Thread.currentThread());
                      t1.onSubscribe(subscription);
                      t1.onNext(1);
                      t1.onNext(2);
                      // observeOn will prevent canceling the upstream upon its termination now
                      // this call is racing for that state in this test
                      // not doing it will make sure the unsubscribeOn always gets through
                      // t1.onComplete();
                  }
              });
  
              TestObserverEx<Integer> observer = new TestObserverEx<>();
  
              w.subscribeOn(uiEventLoop).observeOn(Schedulers.computation())
              .unsubscribeOn(uiEventLoop)
              .take(2)
              .subscribe(observer);
  
              observer.awaitDone(5, TimeUnit.SECONDS);
  
              Thread unsubscribeThread = subscription.getThread();
  
              assertNotNull(unsubscribeThread);
              assertNotSame(Thread.currentThread(), unsubscribeThread);
  
              assertNotNull(subscribeThread.get());
              assertNotSame(Thread.currentThread(), subscribeThread.get());
              // True for Schedulers.newThread()
  
              System.out.println("unsubscribeThread: " + unsubscribeThread);
              System.out.println("subscribeThread.get(): " + subscribeThread.get());
              assertSame(unsubscribeThread.toString(), unsubscribeThread, uiEventLoop.getThread());
  
              observer.assertValues(1, 2);
              observer.assertTerminated();
          } finally {
              uiEventLoop.shutdown();
          }
      }
  
      @Test
      public void unsubscribeWhenSubscribeOnAndUnsubscribeOnAreOnDifferentThreads() throws InterruptedException {
          UIEventLoopScheduler uiEventLoop = new UIEventLoopScheduler();
          try {
              final ThreadSubscription subscription = new ThreadSubscription();
              final AtomicReference<Thread> subscribeThread = new AtomicReference<>();
              Observable<Integer> w = Observable.unsafeCreate(new ObservableSource<Integer>() {
  
                  @Override
                  public void subscribe(Observer<? super Integer> t1) {
                      subscribeThread.set(Thread.currentThread());
                      t1.onSubscribe(subscription);
                      t1.onNext(1);
                      t1.onNext(2);
                      // observeOn will prevent canceling the upstream upon its termination now
                      // this call is racing for that state in this test
                      // not doing it will make sure the unsubscribeOn always gets through
                      // t1.onComplete();
                  }
              });
  
              TestObserverEx<Integer> observer = new TestObserverEx<>();
  
              w.subscribeOn(Schedulers.newThread()).observeOn(Schedulers.computation())
              .unsubscribeOn(uiEventLoop)
              .take(2)
              .subscribe(observer);
  
              observer.awaitDone(1, TimeUnit.SECONDS);
  
              Thread unsubscribeThread = subscription.getThread();
  
              assertNotNull(unsubscribeThread);
              assertNotSame(Thread.currentThread(), unsubscribeThread);
  
              assertNotNull(subscribeThread.get());
              assertNotSame(Thread.currentThread(), subscribeThread.get());
              // True for Schedulers.newThread()
  
              System.out.println("UI Thread: " + uiEventLoop.getThread());
              System.out.println("unsubscribeThread: " + unsubscribeThread);
              System.out.println("subscribeThread.get(): " + subscribeThread.get());
              assertSame(unsubscribeThread, uiEventLoop.getThread());
  
              observer.assertValues(1, 2);
              observer.assertTerminated();
          } finally {
              uiEventLoop.shutdown();
          }
      }
  
      private static class ThreadSubscription extends AtomicBoolean implements Disposable {
  
          private static final long serialVersionUID = -5011338112974328771L;
  
          private volatile Thread thread;
  
          private final CountDownLatch latch = new CountDownLatch(1);
  
          @Override
          public void dispose() {
              set(true);
              System.out.println("unsubscribe invoked: " + Thread.currentThread());
              thread = Thread.currentThread();
              latch.countDown();
          }
  
          @Override public boolean isDisposed() {
              return get();
          }
  
          public Thread getThread() throws InterruptedException {
              latch.await();
              return thread;
          }
      }
  
      public static class UIEventLoopScheduler extends Scheduler {
  
          private final Scheduler eventLoop;
          private volatile Thread t;
  
          public UIEventLoopScheduler() {
  
              eventLoop = Schedulers.single();
  
              /*
               * DON'T DO THIS IN PRODUCTION CODE
               */
              final CountDownLatch latch = new CountDownLatch(1);
              eventLoop.scheduleDirect(new Runnable() {
  
                  @Override
                  public void run() {
                      t = Thread.currentThread();
                      latch.countDown();
                  }
  
              });
              try {
                  latch.await();
              } catch (InterruptedException e) {
                  throw new RuntimeException("failed to initialize and get inner thread");
              }
          }
  
          @NonNull
          @Override
          public Worker createWorker() {
              return eventLoop.createWorker();
          }
  
          public Thread getThread() {
              return t;
          }
  
      }
  
      @Test
      public void dispose() {
          TestHelper.checkDisposed(Observable.just(1).unsubscribeOn(Schedulers.single()));
      }
  
      @Test
      public void normal() {
          final int[] calls = { 0 };
  
          Observable.just(1)
          .doOnDispose(new Action() {
              @Override
              public void run() throws Exception {
                  calls[0]++;
              }
          })
          .unsubscribeOn(Schedulers.single())
          .test()
          .assertResult(1);
  
          assertEquals(0, calls[0]);
      }
  
      @Test
      public void error() {
          final int[] calls = { 0 };
  
          Observable.error(new TestException())
          .doOnDispose(new Action() {
              @Override
              public void run() throws Exception {
                  calls[0]++;
              }
          })
          .unsubscribeOn(Schedulers.single())
          .test()
          .assertFailure(TestException.class);
  
          assertEquals(0, calls[0]);
      }
  
      @Test
      public void signalAfterDispose() {
          List<Throwable> errors = TestHelper.trackPluginErrors();
          try {
              new Observable<Integer>() {
                  @Override
                  protected void subscribeActual(Observer<? super Integer> observer) {
                      observer.onSubscribe(Disposable.empty());
                      observer.onNext(1);
                      observer.onNext(2);
                      observer.onError(new TestException());
                      observer.onComplete();
                  }
              }
              .unsubscribeOn(Schedulers.single())
              .take(1)
              .test()
              .assertResult(1);
  
              TestHelper.assertUndeliverable(errors, 0, TestException.class);
          } finally {
              RxJavaPlugins.reset();
          }
      }
  
      @Test
      public void doubleOnSubscribe() {
          TestHelper.checkDoubleOnSubscribeObservable(o -> o.unsubscribeOn(ImmediateThinScheduler.INSTANCE));
      }
  }
  