2.x: Merge AmbArray and AmbIterable into Amb for Single, Maybe and Completable types (#4647)

Author: VictorAlbertos

src/main/java/io/reactivex/Completable.java

@@ -61,7 +61,7 @@ public static Completable ambArray(final CompletableSource... sources) {
             return wrap(sources[0]);
         }
 
-        return RxJavaPlugins.onAssembly(new CompletableAmbArray(sources));
+        return RxJavaPlugins.onAssembly(new CompletableAmb(sources, null));
     }
 
     /**
@@ -79,7 +79,7 @@ public static Completable ambArray(final CompletableSource... sources) {
     public static Completable amb(final Iterable<? extends CompletableSource> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
 
-        return RxJavaPlugins.onAssembly(new CompletableAmbIterable(sources));
+        return RxJavaPlugins.onAssembly(new CompletableAmb(null, sources));
     }
 
     /**

src/main/java/io/reactivex/Maybe.java

@@ -57,7 +57,7 @@ public abstract class Maybe<T> implements MaybeSource<T> {
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Maybe<T> amb(final Iterable<? extends MaybeSource<? extends T>> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
-        return RxJavaPlugins.onAssembly(new MaybeAmbIterable<T>(sources));
+        return RxJavaPlugins.onAssembly(new MaybeAmb<T>(null, sources));
     }
 
     /**
@@ -80,7 +80,7 @@ public static <T> Maybe<T> ambArray(final MaybeSource<? extends T>... sources) {
         if (sources.length == 1) {
             return wrap((MaybeSource<T>)sources[0]);
         }
-        return RxJavaPlugins.onAssembly(new MaybeAmbArray<T>(sources));
+        return RxJavaPlugins.onAssembly(new MaybeAmb<T>(sources, null));
     }
 
     /**

src/main/java/io/reactivex/Single.java

@@ -73,7 +73,7 @@ public abstract class Single<T> implements SingleSource<T> {
     @SchedulerSupport(SchedulerSupport.NONE)
     public static <T> Single<T> amb(final Iterable<? extends SingleSource<? extends T>> sources) {
         ObjectHelper.requireNonNull(sources, "sources is null");
-        return RxJavaPlugins.onAssembly(new SingleAmbIterable<T>(sources));
+        return RxJavaPlugins.onAssembly(new SingleAmb<T>(null, sources));
     }
 
     /**
@@ -97,7 +97,7 @@ public static <T> Single<T> ambArray(final SingleSource<? extends T>... sources)
         if (sources.length == 1) {
             return wrap((SingleSource<T>)sources[0]);
         }
-        return RxJavaPlugins.onAssembly(new SingleAmbArray<T>(sources));
+        return RxJavaPlugins.onAssembly(new SingleAmb<T>(sources, null));
     }
 
     /**

src/main/java/io/reactivex/internal/operators/completable/CompletableAmbArray.java renamed to src/main/java/io/reactivex/internal/operators/completable/CompletableAmb.java

@@ -17,18 +17,47 @@
 
 import io.reactivex.*;
 import io.reactivex.disposables.*;
+import io.reactivex.exceptions.Exceptions;
+import io.reactivex.internal.disposables.EmptyDisposable;
 import io.reactivex.plugins.RxJavaPlugins;
 
-public final class CompletableAmbArray extends Completable {
+public final class CompletableAmb extends Completable {
+    private final CompletableSource[] sources;
+    private final Iterable<? extends CompletableSource> sourcesIterable;
 
-    final CompletableSource[] sources;
-
-    public CompletableAmbArray(CompletableSource[] sources) {
+    public CompletableAmb(CompletableSource[] sources, Iterable<? extends CompletableSource> sourcesIterable) {
         this.sources = sources;
+        this.sourcesIterable = sourcesIterable;
     }
 
     @Override
     public void subscribeActual(final CompletableObserver s) {
+        CompletableSource[] sources = this.sources;
+        int count = 0;
+        if (sources == null) {
+            sources = new CompletableSource[8];
+            try {
+                for (CompletableSource element : sourcesIterable) {
+                    if (element == null) {
+                        EmptyDisposable.error(new NullPointerException("One of the sources is null"), s);
+                        return;
+                    }
+                    if (count == sources.length) {
+                        CompletableSource[] b = new CompletableSource[count + (count >> 2)];
+                        System.arraycopy(sources, 0, b, 0, count);
+                        sources = b;
+                    }
+                    sources[count++] = element;
+                };
+            } catch (Throwable e) {
+                Exceptions.throwIfFatal(e);
+                EmptyDisposable.error(e, s);
+                return;
+            }
+        } else {
+            count = sources.length;
+        }
+
         final CompositeDisposable set = new CompositeDisposable();
         s.onSubscribe(set);
 
@@ -60,7 +89,8 @@ public void onSubscribe(Disposable d) {
 
         };
 
-        for (CompletableSource c : sources) {
+        for (int i = 0; i < count; i++) {
+            CompletableSource c = sources[i];
             if (set.isDisposed()) {
                 return;
             }
@@ -81,5 +111,9 @@ public void onSubscribe(Disposable d) {
             // no need to have separate subscribers because inner is stateless
             c.subscribe(inner);
         }
+
+        if (count == 0) {
+            s.onComplete();
+        }
     }
 }

src/main/java/io/reactivex/internal/operators/completable/CompletableAmbIterable.java

@@ -17,28 +17,58 @@
 
 import io.reactivex.*;
 import io.reactivex.disposables.*;
+import io.reactivex.exceptions.Exceptions;
+import io.reactivex.internal.disposables.EmptyDisposable;
 import io.reactivex.plugins.RxJavaPlugins;
 
 /**
  * Signals the event of the first MaybeSource that signals.
  *
  * @param <T> the value type emitted
  */
-public final class MaybeAmbArray<T> extends Maybe<T> {
+public final class MaybeAmb<T> extends Maybe<T> {
+    private final MaybeSource<? extends T>[] sources;
+    private final Iterable<? extends MaybeSource<? extends T>> sourcesIterable;
 
-    final MaybeSource<? extends T>[] sources;
-
-    public MaybeAmbArray(MaybeSource<? extends T>[] sources) {
+    public MaybeAmb(MaybeSource<? extends T>[] sources, Iterable<? extends MaybeSource<? extends T>> sourcesIterable) {
         this.sources = sources;
+        this.sourcesIterable = sourcesIterable;
     }
 
     @Override
+    @SuppressWarnings("unchecked")
     protected void subscribeActual(MaybeObserver<? super T> observer) {
+        MaybeSource<? extends T>[] sources = this.sources;
+        int count = 0;
+        if (sources == null) {
+            sources = new MaybeSource[8];
+            try {
+                for (MaybeSource<? extends T> element : sourcesIterable) {
+                    if (element == null) {
+                        EmptyDisposable.error(new NullPointerException("One of the sources is null"), observer);
+                        return;
+                    }
+                    if (count == sources.length) {
+                        MaybeSource<? extends T>[] b = new MaybeSource[count + (count >> 2)];
+                        System.arraycopy(sources, 0, b, 0, count);
+                        sources = b;
+                    }
+                    sources[count++] = element;
+                }
+            } catch (Throwable e) {
+                Exceptions.throwIfFatal(e);
+                EmptyDisposable.error(e, observer);
+                return;
+            }
+        } else {
+            count = sources.length;
+        }
 
         AmbMaybeObserver<T> parent = new AmbMaybeObserver<T>(observer);
         observer.onSubscribe(parent);
 
-        for (MaybeSource<? extends T> s : sources) {
+        for (int i = 0; i < count; i++) {
+            MaybeSource<? extends T> s = sources[i];
             if (parent.isDisposed()) {
                 return;
             }
@@ -50,6 +80,11 @@ protected void subscribeActual(MaybeObserver<? super T> observer) {
 
             s.subscribe(parent);
         }
+
+        if (count == 0) {
+            observer.onComplete();
+        }
+
     }
 
     static final class AmbMaybeObserver<T>