Reimplement 'subscribeOn' using 'lift'

Author: zsxwing

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

@@ -80,7 +80,6 @@
 import rx.operators.OperationSkipLast;
 import rx.operators.OperationSkipUntil;
 import rx.operators.OperationSkipWhile;
-import rx.operators.OperationSubscribeOn;
 import rx.operators.OperationSum;
 import rx.operators.OperationSwitch;
 import rx.operators.OperationSynchronize;
@@ -97,6 +96,7 @@
 import rx.operators.OperationToObservableFuture;
 import rx.operators.OperationUsing;
 import rx.operators.OperationWindow;
+import rx.operators.OperatorSubscribeOn;
 import rx.operators.OperatorZip;
 import rx.operators.OperatorCast;
 import rx.operators.OperatorFromIterable;
@@ -6967,7 +6967,7 @@ public final Subscription subscribe(Subscriber<? super T> observer, Scheduler sc
      * @see <a href="https://github.com/Netflix/RxJava/wiki/Observable-Utility-Operators#wiki-subscribeon">RxJava Wiki: subscribeOn()</a>
      */
     public final Observable<T> subscribeOn(Scheduler scheduler) {
-        return create(OperationSubscribeOn.subscribeOn(this, scheduler));
+        return from(this).lift(new OperatorSubscribeOn<T>(scheduler));
     }
 
     /**

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

@@ -0,0 +1,105 @@
+/**
+ * Copyright 2014 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 rx.Observable;
+import rx.Scheduler;
+import rx.Scheduler.Inner;
+import rx.Subscriber;
+import rx.subscriptions.CompositeSubscription;
+import rx.subscriptions.Subscriptions;
+import rx.util.functions.Action0;
+import rx.util.functions.Action1;
+
+/**
+ * Asynchronously subscribes and unsubscribes Observers on the specified Scheduler.
+ * <p>
+ * <img width="640" src="https://github.com/Netflix/RxJava/wiki/images/rx-operators/subscribeOn.png">
+ */
+public class OperatorSubscribeOn<T> implements Operator<T, Observable<T>> {
+
+    private final Scheduler scheduler;
+
+    public OperatorSubscribeOn(Scheduler scheduler) {
+        this.scheduler = scheduler;
+    }
+
+    @Override
+    public Subscriber<? super Observable<T>> call(
+            final Subscriber<? super T> subscriber) {
+        return new Subscriber<Observable<T>>() {
+
+            @Override
+            public void onCompleted() {
+                // ignore
+            }
+
+            @Override
+            public void onError(Throwable e) {
+                subscriber.onError(e);
+            }
+
+            @Override
+            public void onNext(final Observable<T> o) {
+                scheduler.schedule(new Action1<Inner>() {
+
+                    @Override
+                    public void call(final Inner inner) {
+                        if (!inner.isUnsubscribed()) {
+                            final CompositeSubscription cs = new CompositeSubscription();
+                            subscriber.add(Subscriptions.create(new Action0() {
+
+                                @Override
+                                public void call() {
+                                    scheduler.schedule(new Action1<Inner>() {
+
+                                        @Override
+                                        public void call(final Inner inner) {
+                                            cs.unsubscribe();
+                                            inner.unsubscribe();
+                                        }
+
+                                    });
+                                }
+
+                            }));
+                            cs.add(subscriber);
+                            o.subscribe(new Subscriber<T>(cs) {
+
+                                @Override
+                                public void onCompleted() {
+                                    subscriber.onCompleted();
+                                }
+
+                                @Override
+                                public void onError(Throwable e) {
+                                    subscriber.onError(e);
+                                }
+
+                                @Override
+                                public void onNext(T t) {
+                                    subscriber.onNext(t);
+                                }
+                            });
+                        }
+                    }
+
+                });
+            }
+
+        };
+    }
+}