Parallel Operator & ObserveOn/ScheduledObserver Fixes

language-adaptors/rxjava-groovy/src/test/groovy/rx/lang/groovy/TestParallel.groovy

@@ -0,0 +1,21 @@
+package rx.lang.groovy
+
+import org.junit.Test
+
+import rx.Observable
+import rx.Scheduler
+import rx.concurrency.Schedulers
+import rx.util.functions.Func1
+
+class TestParallel {
+
+    @Test
+    public void testParallelOperator() {
+        Observable.range(0, 100)
+                .parallel({
+                    it.map({ return it; })
+                })
+                .toBlockingObservable()
+                .forEach({ println("T: " + it + " Thread: " + Thread.currentThread());  });
+    }
+}

language-adaptors/rxjava-scala/src/main/scala/rx/lang/scala/Observable.scala

@@ -176,7 +176,7 @@ class Observable[+T](val asJava: rx.Observable[_ <: T])
    *         Observable, and that synchronously notifies its {@link Observer}s
    */
   def synchronize: Observable[T] = {
-    Observable[T](JObservable.synchronize(asJava))
+    Observable[T](asJava.synchronize)
   }
 
   /**

rxjava-core/src/main/java/rx/Observable.java

@@ -34,10 +34,11 @@
 import rx.operators.OperationCache;
 import rx.operators.OperationCombineLatest;
 import rx.operators.OperationConcat;
+import rx.operators.OperationDebounce;
 import rx.operators.OperationDefer;
 import rx.operators.OperationDematerialize;
-import rx.operators.OperationDistinctUntilChanged;
 import rx.operators.OperationDistinct;
+import rx.operators.OperationDistinctUntilChanged;
 import rx.operators.OperationFilter;
 import rx.operators.OperationFinally;
 import rx.operators.OperationFirstOrDefault;
@@ -53,6 +54,7 @@
 import rx.operators.OperationOnErrorResumeNextViaObservable;
 import rx.operators.OperationOnErrorReturn;
 import rx.operators.OperationOnExceptionResumeNextViaObservable;
+import rx.operators.OperationParallel;
 import rx.operators.OperationRetry;
 import rx.operators.OperationSample;
 import rx.operators.OperationScan;
@@ -67,7 +69,6 @@
 import rx.operators.OperationTakeUntil;
 import rx.operators.OperationTakeWhile;
 import rx.operators.OperationThrottleFirst;
-import rx.operators.OperationDebounce;
 import rx.operators.OperationTimestamp;
 import rx.operators.OperationToObservableFuture;
 import rx.operators.OperationToObservableIterable;
@@ -1773,17 +1774,22 @@ public static <T> Observable<T> switchOnNext(Observable<? extends Observable<? e
      * its {@link Observer}s; it invokes {@code onCompleted} or {@code onError} only once; and it never invokes {@code onNext} after invoking either {@code onCompleted} or {@code onError}.
      * {@code synchronize} enforces this, and the Observable it returns invokes {@code onNext} and {@code onCompleted} or {@code onError} synchronously.
      * 
-     * @param observable
-     *            the source Observable
      * @param <T>
      *            the type of item emitted by the source Observable
      * @return an Observable that is a chronologically well-behaved version of the source
      *         Observable, and that synchronously notifies its {@link Observer}s
      */
-    public static <T> Observable<T> synchronize(Observable<? extends T> observable) {
-        return create(OperationSynchronize.synchronize(observable));
+    public Observable<T> synchronize() {
+        return create(OperationSynchronize.synchronize(this));
     }
 
+    /**
+     * @deprecated Replaced with instance method. 
+     */
+    @Deprecated
+    public static <T> Observable<T> synchronize(Observable<T> source) {
+        return create(OperationSynchronize.synchronize(source));
+    }
 
     /**
      * Emits an item each time interval (containing a sequential number).
@@ -3484,6 +3490,31 @@ public Observable<T> cache() {
         return create(OperationCache.cache(this));
     }
 
+    /**
+     * Perform work in parallel by sharding an {@code Observable<T>} on a {@link Schedulers#threadPoolForComputation()} {@link Scheduler} and return an {@code Observable<R>} with the output.
+     * 
+     * @param f
+     *            a {@link Func1} that applies Observable operators to {@code Observable<T>} in parallel and returns an {@code Observable<R>}
+     * @return an Observable with the output of the {@link Func1} executed on a {@link Scheduler}
+     */
+    public <R> Observable<R> parallel(Func1<Observable<T>, Observable<R>> f) {
+        return OperationParallel.parallel(this, f);
+    }
+
+    /**
+     * Perform work in parallel by sharding an {@code Observable<T>} on a {@link Scheduler} and return an {@code Observable<R>} with the output.
+     * 
+     * @param f
+     *            a {@link Func1} that applies Observable operators to {@code Observable<T>} in parallel and returns an {@code Observable<R>}
+     * @param s
+     *            a {@link Scheduler} to perform the work on.
+     * @return an Observable with the output of the {@link Func1} executed on a {@link Scheduler}
+     */
+
+    public <R> Observable<R> parallel(final Func1<Observable<T>, Observable<R>> f, final Scheduler s) {
+        return OperationParallel.parallel(this, f, s);
+    }
+
     /**
      * Returns a {@link ConnectableObservable}, which waits until its {@link ConnectableObservable#connect connect} method is called before it begins emitting
      * items to those {@link Observer}s that have subscribed to it.

rxjava-core/src/main/java/rx/Scheduler.java

@@ -212,12 +212,23 @@ public Subscription call(Scheduler scheduler, Void state) {
     }
 
     /**
-     * Returns the scheduler's notion of current absolute time in milliseconds.
+     * @return the scheduler's notion of current absolute time in milliseconds.
      */
     public long now() {
         return System.currentTimeMillis();
     }
 
+    /**
+     * Parallelism available to a Scheduler.
+     * <p>
+     * This defaults to {@code Runtime.getRuntime().availableProcessors()} but can be overridden for use cases such as scheduling work on a computer cluster.
+     * 
+     * @return the scheduler's available degree of parallelism.
+     */
+    public int degreeOfParallelism() {
+        return Runtime.getRuntime().availableProcessors();
+    }
+
     public static class UnitTest {
         @SuppressWarnings("unchecked") // mocking is unchecked, unfortunately
         @Test

rxjava-core/src/main/java/rx/concurrency/NewThreadScheduler.java

@@ -15,12 +15,15 @@
  */
 package rx.concurrency;
 
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLong;
 
 import rx.Scheduler;
 import rx.Subscription;
-import rx.operators.SafeObservableSubscription;
 import rx.subscriptions.CompositeSubscription;
 import rx.subscriptions.Subscriptions;
 import rx.util.functions.Func2;
@@ -29,27 +32,74 @@
  * Schedules work on a new thread.
  */
 public class NewThreadScheduler extends Scheduler {
-    private static final NewThreadScheduler INSTANCE = new NewThreadScheduler();
+
+    private final static NewThreadScheduler INSTANCE = new NewThreadScheduler();
+    private final static AtomicLong count = new AtomicLong();
 
     public static NewThreadScheduler getInstance() {
         return INSTANCE;
     }
 
-    @Override
-    public <T> Subscription schedule(final T state, final Func2<? super Scheduler, ? super T, ? extends Subscription> action) {
-        final SafeObservableSubscription subscription = new SafeObservableSubscription();
-        final Scheduler _scheduler = this;
+    private NewThreadScheduler() {
 
-        Thread t = new Thread(new Runnable() {
-            @Override
-            public void run() {
-                subscription.wrap(action.call(_scheduler, state));
-            }
-        }, "RxNewThreadScheduler");
+    }
 
-        t.start();
+    private static class EventLoopScheduler extends Scheduler {
+        private final ExecutorService executor;
 
-        return subscription;
+        private EventLoopScheduler() {
+            executor = Executors.newFixedThreadPool(1, new ThreadFactory() {
+
+                @Override
+                public Thread newThread(Runnable r) {
+                    return new Thread(r, "RxNewThreadScheduler-" + count.incrementAndGet());
+                }
+            });
+        }
+
+        @Override
+        public <T> Subscription schedule(final T state, final Func2<? super Scheduler, ? super T, ? extends Subscription> action) {
+            final Scheduler _scheduler = this;
+            return Subscriptions.from(executor.submit(new Runnable() {
+
+                @Override
+                public void run() {
+                    action.call(_scheduler, state);
+                }
+            }));
+        }
+
+        @Override
+        public <T> Subscription schedule(final T state, final Func2<? super Scheduler, ? super T, ? extends Subscription> action, final long delayTime, final TimeUnit unit) {
+            // we will use the system scheduler since it doesn't make sense to launch a new Thread and then sleep
+            // we will instead schedule the event then launch the thread after the delay has passed
+            final Scheduler _scheduler = this;
+            final CompositeSubscription subscription = new CompositeSubscription();
+            ScheduledFuture<?> f = GenericScheduledExecutorService.getInstance().schedule(new Runnable() {
+
+                @Override
+                public void run() {
+                    if (!subscription.isUnsubscribed()) {
+                        // when the delay has passed we now do the work on the actual scheduler
+                        Subscription s = _scheduler.schedule(state, action);
+                        // add the subscription to the CompositeSubscription so it is unsubscribed
+                        subscription.add(s);
+                    }
+                }
+            }, delayTime, unit);
+
+            // add the ScheduledFuture as a subscription so we can cancel the scheduled action if an unsubscribe happens
+            subscription.add(Subscriptions.create(f));
+
+            return subscription;
+        }
+
+    }
+
+    @Override
+    public <T> Subscription schedule(final T state, final Func2<? super Scheduler, ? super T, ? extends Subscription> action) {
+        EventLoopScheduler s = new EventLoopScheduler();
+        return s.schedule(state, action);
     }
 
     @Override

rxjava-core/src/main/java/rx/operators/OperationObserveOn.java

@@ -20,6 +20,7 @@
 
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
 
 import org.junit.Test;
 import org.mockito.InOrder;
@@ -33,6 +34,8 @@
 import rx.Subscription;
 import rx.concurrency.ImmediateScheduler;
 import rx.concurrency.Schedulers;
+import rx.subscriptions.CompositeSubscription;
+import rx.util.functions.Func2;
 
 /**
  * Asynchronously notify Observers on the specified Scheduler.
@@ -60,7 +63,9 @@ public Subscription onSubscribe(final Observer<? super T> observer) {
                 // do nothing if we request ImmediateScheduler so we don't invoke overhead
                 return source.subscribe(observer);
             } else {
-                return source.subscribe(new ScheduledObserver<T>(observer, scheduler));
+                CompositeSubscription s = new CompositeSubscription();
+                s.add(source.subscribe(new ScheduledObserver<T>(s, observer, scheduler)));
+                return s;
             }
         }
     }

rxjava-core/src/main/java/rx/operators/OperationParallel.java

@@ -0,0 +1,99 @@
+/**
+ * Copyright 2013 Netflix, Inc.
+ * 
+ * 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 rx.operators;
+
+import static org.junit.Assert.*;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.junit.Test;
+
+import rx.Observable;
+import rx.Scheduler;
+import rx.concurrency.Schedulers;
+import rx.observables.GroupedObservable;
+import rx.util.functions.Action1;
+import rx.util.functions.Func0;
+import rx.util.functions.Func1;
+
+/**
+ * Identifies unit of work that can be executed in parallel on a given Scheduler.
+ */
+public final class OperationParallel<T> {
+
+    public static <T, R> Observable<R> parallel(Observable<T> source, Func1<Observable<T>, Observable<R>> f) {
+        return parallel(source, f, Schedulers.threadPoolForComputation());
+    }
+
+    public static <T, R> Observable<R> parallel(final Observable<T> source, final Func1<Observable<T>, Observable<R>> f, final Scheduler s) {
+        return Observable.defer(new Func0<Observable<R>>() {
+
+            @Override
+            public Observable<R> call() {
+                final AtomicInteger i = new AtomicInteger(0);
+                return source.groupBy(new Func1<T, Integer>() {
+
+                    @Override
+                    public Integer call(T t) {
+                        return i.incrementAndGet() % s.degreeOfParallelism();
+                    }
+
+                }).flatMap(new Func1<GroupedObservable<Integer, T>, Observable<R>>() {
+
+                    @Override
+                    public Observable<R> call(GroupedObservable<Integer, T> group) {
+                        return f.call(group.observeOn(s));
+                    }
+                }).synchronize();
+            }
+        });
+    }
+
+    public static class UnitTest {
+
+        @Test
+        public void testParallel() {
+            int NUM = 1000;
+            final AtomicInteger count = new AtomicInteger();
+            Observable.range(1, NUM).parallel(
+                    new Func1<Observable<Integer>, Observable<Integer[]>>() {
+
+                        @Override
+                        public Observable<Integer[]> call(Observable<Integer> o) {
+                            return o.map(new Func1<Integer, Integer[]>() {
+
+                                @Override
+                                public Integer[] call(Integer t) {
+                                    return new Integer[] { t, t * 99 };
+                                }
+
+                            });
+                        }
+                    }).toBlockingObservable().forEach(new Action1<Integer[]>() {
+
+                @Override
+                public void call(Integer[] v) {
+                    count.incrementAndGet();
+                    System.out.println("V: " + v[0] + " R: " + v[1] + " Thread: " + Thread.currentThread());
+                }
+
+            });
+
+            // just making sure we finish and get the number we expect
+            assertEquals(NUM, count.get());
+        }
+    }
+}