Merge Amb Operator in PR https://github.com/Netflix/RxJava/pull/460

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

@@ -30,6 +30,7 @@
 import rx.observables.ConnectableObservable;
 import rx.observables.GroupedObservable;
 import rx.operators.OperationAll;
+import rx.operators.OperationAmb;
 import rx.operators.OperationAny;
 import rx.operators.OperationAverage;
 import rx.operators.OperationBuffer;
@@ -4576,6 +4577,196 @@ public Observable<TimeInterval<T>> timeInterval(Scheduler scheduler) {
         return create(OperationTimeInterval.timeInterval(this, scheduler));
     }
 
+    /**
+     * Propagates the observable sequence that reacts first.
+     *
+     * @param o1
+     *            an observable competing to react first.
+     * @param o2
+     *            an observable competing to react first.
+     * @return
+     *            an observable sequence that surfaces any of the given sequences, whichever reacted first.
+     * @see <a href="http://msdn.microsoft.com/en-us/library/hh229733(v=vs.103).aspx">MSDN: Observable.Amb</a>
+     */
+    public static <T> Observable<T> amb(Observable<? extends T> o1, Observable<? extends T> o2) {
+        return create(OperationAmb.amb(o1, o2));
+    }
+
+    /**
+     * Propagates the observable sequence that reacts first.
+     *
+     * @param o1
+     *            an observable competing to react first.
+     * @param o2
+     *            an observable competing to react first.
+     * @param o3
+     *            an observable competing to react first.
+     * @return
+     *            an observable sequence that surfaces any of the given sequences, whichever reacted first.
+     * @see <a href="http://msdn.microsoft.com/en-us/library/hh229733(v=vs.103).aspx">MSDN: Observable.Amb</a>
+     */
+    public static <T> Observable<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3) {
+        return create(OperationAmb.amb(o1, o2, o3));
+    }
+
+    /**
+     * Propagates the observable sequence that reacts first.
+     *
+     * @param o1
+     *            an observable competing to react first.
+     * @param o2
+     *            an observable competing to react first.
+     * @param o3
+     *            an observable competing to react first.
+     * @param o4
+     *            an observable competing to react first.
+     * @return
+     *            an observable sequence that surfaces any of the given sequences, whichever reacted first.
+     * @see <a href="http://msdn.microsoft.com/en-us/library/hh229733(v=vs.103).aspx">MSDN: Observable.Amb</a>
+     */
+    public static <T> Observable<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3, Observable<? extends T> o4) {
+        return create(OperationAmb.amb(o1, o2, o3, o4));
+    }
+
+    /**
+     * Propagates the observable sequence that reacts first.
+     *
+     * @param o1
+     *            an observable competing to react first.
+     * @param o2
+     *            an observable competing to react first.
+     * @param o3
+     *            an observable competing to react first.
+     * @param o4
+     *            an observable competing to react first.
+     * @param o5
+     *            an observable competing to react first.
+     * @return
+     *            an observable sequence that surfaces any of the given sequences, whichever reacted first.
+     * @see <a href="http://msdn.microsoft.com/en-us/library/hh229733(v=vs.103).aspx">MSDN: Observable.Amb</a>
+     */
+    public static <T> Observable<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3, Observable<? extends T> o4, Observable<? extends T> o5) {
+        return create(OperationAmb.amb(o1, o2, o3, o4, o5));
+    }
+
+    /**
+     * Propagates the observable sequence that reacts first.
+     *
+     * @param o1
+     *            an observable competing to react first.
+     * @param o2
+     *            an observable competing to react first.
+     * @param o3
+     *            an observable competing to react first.
+     * @param o4
+     *            an observable competing to react first.
+     * @param o5
+     *            an observable competing to react first.
+     * @param o6
+     *            an observable competing to react first.
+     * @return
+     *            an observable sequence that surfaces any of the given sequences, whichever reacted first.
+     * @see <a href="http://msdn.microsoft.com/en-us/library/hh229733(v=vs.103).aspx">MSDN: Observable.Amb</a>
+     */
+    public static <T> Observable<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3, Observable<? extends T> o4, Observable<? extends T> o5, Observable<? extends T> o6) {
+        return create(OperationAmb.amb(o1, o2, o3, o4, o5, o6));
+    }
+
+    /**
+     * Propagates the observable sequence that reacts first.
+     *
+     * @param o1
+     *            an observable competing to react first.
+     * @param o2
+     *            an observable competing to react first.
+     * @param o3
+     *            an observable competing to react first.
+     * @param o4
+     *            an observable competing to react first.
+     * @param o5
+     *            an observable competing to react first.
+     * @param o6
+     *            an observable competing to react first.
+     * @param o7
+     *            an observable competing to react first.
+     * @return
+     *            an observable sequence that surfaces any of the given sequences, whichever reacted first.
+     * @see <a href="http://msdn.microsoft.com/en-us/library/hh229733(v=vs.103).aspx">MSDN: Observable.Amb</a>
+     */
+    public static <T> Observable<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3, Observable<? extends T> o4, Observable<? extends T> o5, Observable<? extends T> o6, Observable<? extends T> o7) {
+        return create(OperationAmb.amb(o1, o2, o3, o4, o5, o6, o7));
+    }
+
+    /**
+     * Propagates the observable sequence that reacts first.
+     *
+     * @param o1
+     *            an observable competing to react first.
+     * @param o2
+     *            an observable competing to react first.
+     * @param o3
+     *            an observable competing to react first.
+     * @param o4
+     *            an observable competing to react first.
+     * @param o5
+     *            an observable competing to react first.
+     * @param o6
+     *            an observable competing to react first.
+     * @param o7
+     *            an observable competing to react first.
+     * @param o8
+     *            an observable competing to react first.
+     * @return
+     *            an observable sequence that surfaces any of the given sequences, whichever reacted first.
+     * @see <a href="http://msdn.microsoft.com/en-us/library/hh229733(v=vs.103).aspx">MSDN: Observable.Amb</a>
+     */
+    public static <T> Observable<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3, Observable<? extends T> o4, Observable<? extends T> o5, Observable<? extends T> o6, Observable<? extends T> o7, Observable<? extends T> o8) {
+        return create(OperationAmb.amb(o1, o2, o3, o4, o5, o6, o7, o8));
+    }
+
+    /**
+     * Propagates the observable sequence that reacts first.
+     *
+     * @param o1
+     *            an observable competing to react first.
+     * @param o2
+     *            an observable competing to react first.
+     * @param o3
+     *            an observable competing to react first.
+     * @param o4
+     *            an observable competing to react first.
+     * @param o5
+     *            an observable competing to react first.
+     * @param o6
+     *            an observable competing to react first.
+     * @param o7
+     *            an observable competing to react first.
+     * @param o8
+     *            an observable competing to react first.
+     * @param o9
+     *            an observable competing to react first.
+     * @return
+     *            an observable sequence that surfaces any of the given sequences, whichever reacted first.
+     * @see <a href="http://msdn.microsoft.com/en-us/library/hh229733(v=vs.103).aspx">MSDN: Observable.Amb</a>
+     */
+    public static <T> Observable<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3, Observable<? extends T> o4, Observable<? extends T> o5, Observable<? extends T> o6, Observable<? extends T> o7, Observable<? extends T> o8, Observable<? extends T> o9) {
+        return create(OperationAmb.amb(o1, o2, o3, o4, o5, o6, o7, o8, o9));
+    }
+
+    /**
+     * Propagates the observable sequence that reacts first.
+     *
+     * @param sources
+     *            observable sources competing to react first.
+     *
+     * @return
+     *            an observable sequence that surfaces any of the given sequences, whichever reacted first.
+     * @see <a href="http://msdn.microsoft.com/en-us/library/hh229115(v=vs.103).aspx">MSDN: Observable.Amb</a>
+     */
+    public static <T> Observable<T> amb(Iterable<? extends Observable<? extends T>> sources) {
+        return create(OperationAmb.amb(sources));
+    }
+
     /**
      * Whether a given {@link Function} is an internal implementation inside rx.* packages or not.
      * <p>

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

@@ -0,0 +1,191 @@
+/**
+ * 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 java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import rx.Observable;
+import rx.Observable.OnSubscribeFunc;
+import rx.Observer;
+import rx.Subscription;
+import rx.subscriptions.CompositeSubscription;
+
+/**
+ * Propagates the observable sequence that reacts first.
+ */
+public class OperationAmb {
+
+    public static <T> OnSubscribeFunc<T> amb(Observable<? extends T> o1, Observable<? extends T> o2) {
+        List<Observable<? extends T>> sources = new ArrayList<Observable<? extends T>>();
+        sources.add(o1);
+        sources.add(o2);
+        return amb(sources);
+    }
+
+    public static <T> OnSubscribeFunc<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3) {
+        List<Observable<? extends T>> sources = new ArrayList<Observable<? extends T>>();
+        sources.add(o1);
+        sources.add(o2);
+        sources.add(o3);
+        return amb(sources);
+    }
+
+    public static <T> OnSubscribeFunc<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3, Observable<? extends T> o4) {
+        List<Observable<? extends T>> sources = new ArrayList<Observable<? extends T>>();
+        sources.add(o1);
+        sources.add(o2);
+        sources.add(o3);
+        sources.add(o4);
+        return amb(sources);
+    }
+
+    public static <T> OnSubscribeFunc<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3, Observable<? extends T> o4, Observable<? extends T> o5) {
+        List<Observable<? extends T>> sources = new ArrayList<Observable<? extends T>>();
+        sources.add(o1);
+        sources.add(o2);
+        sources.add(o3);
+        sources.add(o4);
+        sources.add(o5);
+        return amb(sources);
+    }
+
+    public static <T> OnSubscribeFunc<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3, Observable<? extends T> o4, Observable<? extends T> o5, Observable<? extends T> o6) {
+        List<Observable<? extends T>> sources = new ArrayList<Observable<? extends T>>();
+        sources.add(o1);
+        sources.add(o2);
+        sources.add(o3);
+        sources.add(o4);
+        sources.add(o5);
+        sources.add(o6);
+        return amb(sources);
+    }
+
+    public static <T> OnSubscribeFunc<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3, Observable<? extends T> o4, Observable<? extends T> o5, Observable<? extends T> o6, Observable<? extends T> o7) {
+        List<Observable<? extends T>> sources = new ArrayList<Observable<? extends T>>();
+        sources.add(o1);
+        sources.add(o2);
+        sources.add(o3);
+        sources.add(o4);
+        sources.add(o5);
+        sources.add(o6);
+        sources.add(o7);
+        return amb(sources);
+    }
+
+    public static <T> OnSubscribeFunc<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3, Observable<? extends T> o4, Observable<? extends T> o5, Observable<? extends T> o6, Observable<? extends T> o7, Observable<? extends T> o8) {
+        List<Observable<? extends T>> sources = new ArrayList<Observable<? extends T>>();
+        sources.add(o1);
+        sources.add(o2);
+        sources.add(o3);
+        sources.add(o4);
+        sources.add(o5);
+        sources.add(o6);
+        sources.add(o7);
+        sources.add(o8);
+        return amb(sources);
+    }
+
+    public static <T> OnSubscribeFunc<T> amb(Observable<? extends T> o1, Observable<? extends T> o2, Observable<? extends T> o3, Observable<? extends T> o4, Observable<? extends T> o5, Observable<? extends T> o6, Observable<? extends T> o7, Observable<? extends T> o8, Observable<? extends T> o9) {
+        List<Observable<? extends T>> sources = new ArrayList<Observable<? extends T>>();
+        sources.add(o1);
+        sources.add(o2);
+        sources.add(o3);
+        sources.add(o4);
+        sources.add(o5);
+        sources.add(o6);
+        sources.add(o7);
+        sources.add(o8);
+        sources.add(o9);
+        return amb(sources);
+    }
+
+    public static <T> OnSubscribeFunc<T> amb(
+            final Iterable<? extends Observable<? extends T>> sources) {
+        return new OnSubscribeFunc<T>() {
+
+            @Override
+            public Subscription onSubscribe(final Observer<? super T> observer) {
+                AtomicInteger choice = new AtomicInteger(AmbObserver.NONE);
+                int index = 0;
+                CompositeSubscription parentSubscription = new CompositeSubscription();
+                for (Observable<? extends T> source : sources) {
+                    SafeObservableSubscription subscription = new SafeObservableSubscription();
+                    AmbObserver<T> ambObserver = new AmbObserver<T>(
+                            subscription, observer, index, choice);
+                    parentSubscription.add(subscription.wrap(source
+                            .subscribe(ambObserver)));
+                    index++;
+                }
+                return parentSubscription;
+            }
+        };
+    }
+
+    private static class AmbObserver<T> implements Observer<T> {
+
+        private static final int NONE = -1;
+
+        private Subscription subscription;
+        private Observer<? super T> observer;
+        private int index;
+        private AtomicInteger choice;
+
+        private AmbObserver(Subscription subscription,
+                Observer<? super T> observer, int index, AtomicInteger choice) {
+            this.subscription = subscription;
+            this.observer = observer;
+            this.choice = choice;
+            this.index = index;
+        }
+
+        @Override
+        public void onNext(T args) {
+            if (!isSelected()) {
+                subscription.unsubscribe();
+                return;
+            }
+            observer.onNext(args);
+        }
+
+        @Override
+        public void onCompleted() {
+            if (!isSelected()) {
+                subscription.unsubscribe();
+                return;
+            }
+            observer.onCompleted();
+        }
+
+        @Override
+        public void onError(Throwable e) {
+            if (!isSelected()) {
+                subscription.unsubscribe();
+                return;
+            }
+            observer.onError(e);
+        }
+
+        private boolean isSelected() {
+            if (choice.get() == NONE) {
+                return choice.compareAndSet(NONE, index);
+            }
+            return choice.get() == index;
+        }
+    }
+
+}