Observable.from(empty) tests hasNext on subscribe so can emit onCompleted even if request is 0

Author: davidmoten

src/main/java/rx/internal/operators/OnSubscribeFromIterable.java

@@ -65,12 +65,11 @@ private IterableProducer(Subscriber<? super T> o, Iterator<? extends T> it) {
 
         @Override
         public void request(long n) {
-            if (REQUESTED_UPDATER.get(this) == Long.MAX_VALUE) {
+            if (requested == Long.MAX_VALUE) {
                 // already started with fast-path
                 return;
             }
-            if (n == Long.MAX_VALUE) {
-                REQUESTED_UPDATER.set(this, n);
+            if (n == Long.MAX_VALUE && REQUESTED_UPDATER.compareAndSet(this, 0, Long.MAX_VALUE)) {
                 // fast-path without backpressure
                 while (it.hasNext()) {
                     if (o.isUnsubscribed()) {
@@ -81,7 +80,7 @@ public void request(long n) {
                 if (!o.isUnsubscribed()) {
                     o.onCompleted();
                 }
-            } else if(n > 0) {
+            } else if (n > 0) {
                 // backpressure is requested
                 long _c = BackpressureUtils.getAndAddRequest(REQUESTED_UPDATER, this, n);
                 if (_c == 0) {

src/test/java/rx/internal/operators/OnSubscribeFromIterableTest.java

@@ -75,12 +75,12 @@ public Iterator<String> iterator() {
 
                     @Override
                     public boolean hasNext() {
-                        return i++ < 3;
+                        return i < 3;
                     }
 
                     @Override
                     public String next() {
-                        return String.valueOf(i);
+                        return String.valueOf(++i);
                     }
 
                     @Override