2.x: coverage and cleanup 10/12-1 (#4696)

Author: akarnokd

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

@@ -104,9 +104,6 @@ public void onSubscribe(Disposable d) {
                 }
                 return;
             }
-            if (once.get() || set.isDisposed()) {
-                return;
-            }
 
             // no need to have separate subscribers because inner is stateless
             c.subscribe(inner);

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

@@ -19,9 +19,10 @@
 
 import io.reactivex.*;
 import io.reactivex.disposables.Disposable;
-import io.reactivex.exceptions.MissingBackpressureException;
-import io.reactivex.internal.disposables.SequentialDisposable;
-import io.reactivex.internal.queue.SpscArrayQueue;
+import io.reactivex.exceptions.*;
+import io.reactivex.internal.disposables.DisposableHelper;
+import io.reactivex.internal.fuseable.*;
+import io.reactivex.internal.queue.*;
 import io.reactivex.internal.subscriptions.SubscriptionHelper;
 import io.reactivex.plugins.RxJavaPlugins;
 
@@ -36,133 +37,218 @@ public CompletableConcat(Publisher<? extends CompletableSource> sources, int pre
 
     @Override
     public void subscribeActual(CompletableObserver s) {
-        CompletableConcatSubscriber parent = new CompletableConcatSubscriber(s, prefetch);
-        sources.subscribe(parent);
+        sources.subscribe(new CompletableConcatSubscriber(s, prefetch));
     }
 
     static final class CompletableConcatSubscriber
     extends AtomicInteger
     implements Subscriber<CompletableSource>, Disposable {
-        private static final long serialVersionUID = 7412667182931235013L;
+        private static final long serialVersionUID = 9032184911934499404L;
+
         final CompletableObserver actual;
+
         final int prefetch;
-        final SequentialDisposable sd;
 
-        final SpscArrayQueue<CompletableSource> queue;
+        final int limit;
+
+        final ConcatInnerObserver inner;
+
+        final AtomicBoolean once;
+
+        int sourceFused;
+
+        int consumed;
+
+        SimpleQueue<CompletableSource> queue;
 
         Subscription s;
 
         volatile boolean done;
 
-        final AtomicBoolean once = new AtomicBoolean();
-
-        final ConcatInnerObserver inner;
+        volatile boolean active;
 
         CompletableConcatSubscriber(CompletableObserver actual, int prefetch) {
             this.actual = actual;
             this.prefetch = prefetch;
-            this.queue = new SpscArrayQueue<CompletableSource>(prefetch);
-            this.sd = new SequentialDisposable();
-            this.inner = new ConcatInnerObserver();
+            this.inner = new ConcatInnerObserver(this);
+            this.once = new AtomicBoolean();
+            this.limit = prefetch - (prefetch >> 2);
         }
 
         @Override
         public void onSubscribe(Subscription s) {
             if (SubscriptionHelper.validate(this.s, s)) {
                 this.s = s;
+
+                long r = prefetch == Integer.MAX_VALUE ? Long.MAX_VALUE : prefetch;
+
+                if (s instanceof QueueSubscription) {
+                    @SuppressWarnings("unchecked")
+                    QueueSubscription<CompletableSource> qs = (QueueSubscription<CompletableSource>) s;
+
+                    int m = qs.requestFusion(QueueSubscription.ANY);
+
+                    if (m == QueueSubscription.SYNC) {
+                        sourceFused = m;
+                        queue = qs;
+                        done = true;
+                        actual.onSubscribe(this);
+                        drain();
+                        return;
+                    }
+                    if (m == QueueSubscription.ASYNC) {
+                        sourceFused = m;
+                        queue = qs;
+                        actual.onSubscribe(this);
+                        s.request(r);
+                        return;
+                    }
+                }
+
+                if (prefetch == Integer.MAX_VALUE) {
+                    queue = new SpscLinkedArrayQueue<CompletableSource>(Flowable.bufferSize());
+                } else {
+                    queue = new SpscArrayQueue<CompletableSource>(prefetch);
+                }
+
                 actual.onSubscribe(this);
-                s.request(prefetch);
+
+                s.request(r);
             }
         }
 
         @Override
         public void onNext(CompletableSource t) {
-            if (!queue.offer(t)) {
-                onError(new MissingBackpressureException());
-                return;
-            }
-            if (getAndIncrement() == 0) {
-                next();
+            if (sourceFused == QueueSubscription.NONE) {
+                if (!queue.offer(t)) {
+                    onError(new MissingBackpressureException());
+                    return;
+                }
             }
+            drain();
         }
 
         @Override
         public void onError(Throwable t) {
             if (once.compareAndSet(false, true)) {
+                DisposableHelper.dispose(inner);
                 actual.onError(t);
-                return;
+            } else {
+                RxJavaPlugins.onError(t);
             }
-            done = true;
-            RxJavaPlugins.onError(t);
         }
 
         @Override
         public void onComplete() {
-            if (done) {
-                return;
-            }
             done = true;
-            if (getAndIncrement() == 0) {
-                next();
-            }
-        }
-
-        void innerError(Throwable e) {
-            s.cancel();
-            onError(e);
-        }
-
-        void innerComplete() {
-            if (decrementAndGet() != 0) {
-                next();
-            }
-            if (!done) {
-                s.request(1);
-            }
+            drain();
         }
 
         @Override
         public void dispose() {
             s.cancel();
-            sd.dispose();
+            DisposableHelper.dispose(inner);
         }
 
         @Override
         public boolean isDisposed() {
-            return sd.isDisposed();
+            return DisposableHelper.isDisposed(inner.get());
         }
 
-        void next() {
-            boolean d = done;
-            CompletableSource c = queue.poll();
-            if (c == null) {
-                if (d) {
-                    if (once.compareAndSet(false, true)) {
-                        actual.onComplete();
-                    }
+        void drain() {
+            if (getAndIncrement() != 0) {
+                return;
+            }
+
+            for (;;) {
+                if (isDisposed()) {
                     return;
                 }
-                RxJavaPlugins.onError(new IllegalStateException("Queue is empty?!"));
-                return;
+
+                if (!active) {
+
+                    boolean d = done;
+
+                    CompletableSource cs;
+
+                    try {
+                        cs = queue.poll();
+                    } catch (Throwable ex) {
+                        Exceptions.throwIfFatal(ex);
+                        innerError(ex);
+                        return;
+                    }
+
+                    boolean empty = cs == null;
+
+                    if (d && empty) {
+                        if (once.compareAndSet(false, true)) {
+                            actual.onComplete();
+                        }
+                        return;
+                    }
+
+                    if (!empty) {
+                        active = true;
+                        cs.subscribe(inner);
+                        request();
+                    }
+                }
+
+                if (decrementAndGet() == 0) {
+                    break;
+                }
+            }
+        }
+
+        void request() {
+            if (sourceFused != QueueSubscription.SYNC) {
+                int p = consumed + 1;
+                if (p == limit) {
+                    consumed = 0;
+                    s.request(p);
+                } else {
+                    consumed = p;
+                }
+            }
+        }
+
+        void innerError(Throwable e) {
+            if (once.compareAndSet(false, true)) {
+                s.cancel();
+                actual.onError(e);
+            } else {
+                RxJavaPlugins.onError(e);
             }
+        }
 
-            c.subscribe(inner);
+        void innerComplete() {
+            active = false;
+            drain();
         }
 
-        final class ConcatInnerObserver implements CompletableObserver {
+        static final class ConcatInnerObserver extends AtomicReference<Disposable> implements CompletableObserver {
+            private static final long serialVersionUID = -5454794857847146511L;
+
+            final CompletableConcatSubscriber parent;
+
+            ConcatInnerObserver(CompletableConcatSubscriber parent) {
+                this.parent = parent;
+            }
+
             @Override
             public void onSubscribe(Disposable d) {
-                sd.update(d);
+                DisposableHelper.replace(this, d);
             }
 
             @Override
             public void onError(Throwable e) {
-                innerError(e);
+                parent.innerError(e);
             }
 
             @Override
             public void onComplete() {
-                innerComplete();
+                parent.innerComplete();
             }
         }
     }