1.x: add a source OnSubscribe which works from an array directly

Author: akarnokd

src/main/java/rx/Observable.java

@@ -1243,7 +1243,14 @@ public final static <T> Observable<T> from(Iterable<? extends T> iterable) {
      * @see <a href="http://reactivex.io/documentation/operators/from.html">ReactiveX operators documentation: From</a>
      */
     public final static <T> Observable<T> from(T[] array) {
-        return from(Arrays.asList(array));
+        int n = array.length;
+        if (n == 0) {
+            return empty();
+        } else
+        if (n == 1) {
+            return just(array[0]);
+        }
+        return create(new OnSubscribeFromArray<T>(array));
     }
 
     /**
@@ -1423,7 +1430,7 @@ public final static <T> Observable<T> just(final T value) {
     // suppress unchecked because we are using varargs inside the method
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> just(T t1, T t2) {
-        return from(Arrays.asList(t1, t2));
+        return from((T[])new Object[] { t1, t2 });
     }
 
     /**
@@ -1449,7 +1456,7 @@ public final static <T> Observable<T> just(T t1, T t2) {
     // suppress unchecked because we are using varargs inside the method
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> just(T t1, T t2, T t3) {
-        return from(Arrays.asList(t1, t2, t3));
+        return from((T[])new Object[] { t1, t2, t3 });
     }
 
     /**
@@ -1477,7 +1484,7 @@ public final static <T> Observable<T> just(T t1, T t2, T t3) {
     // suppress unchecked because we are using varargs inside the method
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> just(T t1, T t2, T t3, T t4) {
-        return from(Arrays.asList(t1, t2, t3, t4));
+        return from((T[])new Object[] { t1, t2, t3, t4 });
     }
 
     /**
@@ -1507,7 +1514,7 @@ public final static <T> Observable<T> just(T t1, T t2, T t3, T t4) {
     // suppress unchecked because we are using varargs inside the method
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> just(T t1, T t2, T t3, T t4, T t5) {
-        return from(Arrays.asList(t1, t2, t3, t4, t5));
+        return from((T[])new Object[] { t1, t2, t3, t4, t5 });
     }
 
     /**
@@ -1539,7 +1546,7 @@ public final static <T> Observable<T> just(T t1, T t2, T t3, T t4, T t5) {
     // suppress unchecked because we are using varargs inside the method
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> just(T t1, T t2, T t3, T t4, T t5, T t6) {
-        return from(Arrays.asList(t1, t2, t3, t4, t5, t6));
+        return from((T[])new Object[] { t1, t2, t3, t4, t5, t6 });
     }
 
     /**
@@ -1573,7 +1580,7 @@ public final static <T> Observable<T> just(T t1, T t2, T t3, T t4, T t5, T t6) {
     // suppress unchecked because we are using varargs inside the method
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> just(T t1, T t2, T t3, T t4, T t5, T t6, T t7) {
-        return from(Arrays.asList(t1, t2, t3, t4, t5, t6, t7));
+        return from((T[])new Object[] { t1, t2, t3, t4, t5, t6, t7 });
     }
 
     /**
@@ -1609,7 +1616,7 @@ public final static <T> Observable<T> just(T t1, T t2, T t3, T t4, T t5, T t6, T
     // suppress unchecked because we are using varargs inside the method
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> just(T t1, T t2, T t3, T t4, T t5, T t6, T t7, T t8) {
-        return from(Arrays.asList(t1, t2, t3, t4, t5, t6, t7, t8));
+        return from((T[])new Object[] { t1, t2, t3, t4, t5, t6, t7, t8 });
     }
 
     /**
@@ -1647,7 +1654,7 @@ public final static <T> Observable<T> just(T t1, T t2, T t3, T t4, T t5, T t6, T
     // suppress unchecked because we are using varargs inside the method
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> just(T t1, T t2, T t3, T t4, T t5, T t6, T t7, T t8, T t9) {
-        return from(Arrays.asList(t1, t2, t3, t4, t5, t6, t7, t8, t9));
+        return from((T[])new Object[] { t1, t2, t3, t4, t5, t6, t7, t8, t9 });
     }
 
     /**
@@ -1687,7 +1694,7 @@ public final static <T> Observable<T> just(T t1, T t2, T t3, T t4, T t5, T t6, T
     // suppress unchecked because we are using varargs inside the method
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> just(T t1, T t2, T t3, T t4, T t5, T t6, T t7, T t8, T t9, T t10) {
-        return from(Arrays.asList(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10));
+        return from((T[])new Object[] { t1, t2, t3, t4, t5, t6, t7, t8, t9, t10 });
     }
 
     /**
@@ -1821,7 +1828,7 @@ public final static <T> Observable<T> merge(Observable<? extends Observable<? ex
      */
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> merge(Observable<? extends T> t1, Observable<? extends T> t2) {
-        return merge(from(Arrays.asList(t1, t2)));
+        return merge(new Observable[] { t1, t2 });
     }
 
     /**
@@ -1847,7 +1854,7 @@ public final static <T> Observable<T> merge(Observable<? extends T> t1, Observab
      */
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> merge(Observable<? extends T> t1, Observable<? extends T> t2, Observable<? extends T> t3) {
-        return merge(from(Arrays.asList(t1, t2, t3)));
+        return merge(new Observable[] { t1, t2, t3 });
     }
 
     /**
@@ -1875,7 +1882,7 @@ public final static <T> Observable<T> merge(Observable<? extends T> t1, Observab
      */
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> merge(Observable<? extends T> t1, Observable<? extends T> t2, Observable<? extends T> t3, Observable<? extends T> t4) {
-        return merge(from(Arrays.asList(t1, t2, t3, t4)));
+        return merge(new Observable[] { t1, t2, t3, t4 });
     }
 
     /**
@@ -1905,7 +1912,7 @@ public final static <T> Observable<T> merge(Observable<? extends T> t1, Observab
      */
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> merge(Observable<? extends T> t1, Observable<? extends T> t2, Observable<? extends T> t3, Observable<? extends T> t4, Observable<? extends T> t5) {
-        return merge(from(Arrays.asList(t1, t2, t3, t4, t5)));
+        return merge(new Observable[] { t1, t2, t3, t4, t5 });
     }
 
     /**
@@ -1937,7 +1944,7 @@ public final static <T> Observable<T> merge(Observable<? extends T> t1, Observab
      */
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> merge(Observable<? extends T> t1, Observable<? extends T> t2, Observable<? extends T> t3, Observable<? extends T> t4, Observable<? extends T> t5, Observable<? extends T> t6) {
-        return merge(from(Arrays.asList(t1, t2, t3, t4, t5, t6)));
+        return merge(new Observable[] { t1, t2, t3, t4, t5, t6 });
     }
 
     /**
@@ -1971,7 +1978,7 @@ public final static <T> Observable<T> merge(Observable<? extends T> t1, Observab
      */
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> merge(Observable<? extends T> t1, Observable<? extends T> t2, Observable<? extends T> t3, Observable<? extends T> t4, Observable<? extends T> t5, Observable<? extends T> t6, Observable<? extends T> t7) {
-        return merge(from(Arrays.asList(t1, t2, t3, t4, t5, t6, t7)));
+        return merge(new Observable[] { t1, t2, t3, t4, t5, t6, t7 });
     }
 
     /**
@@ -2007,7 +2014,7 @@ public final static <T> Observable<T> merge(Observable<? extends T> t1, Observab
      */
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> merge(Observable<? extends T> t1, Observable<? extends T> t2, Observable<? extends T> t3, Observable<? extends T> t4, Observable<? extends T> t5, Observable<? extends T> t6, Observable<? extends T> t7, Observable<? extends T> t8) {
-        return merge(from(Arrays.asList(t1, t2, t3, t4, t5, t6, t7, t8)));
+        return merge(new Observable[] { t1, t2, t3, t4, t5, t6, t7, t8 });
     }
 
     /**
@@ -2045,7 +2052,7 @@ public final static <T> Observable<T> merge(Observable<? extends T> t1, Observab
      */
     @SuppressWarnings("unchecked")
     public final static <T> Observable<T> merge(Observable<? extends T> t1, Observable<? extends T> t2, Observable<? extends T> t3, Observable<? extends T> t4, Observable<? extends T> t5, Observable<? extends T> t6, Observable<? extends T> t7, Observable<? extends T> t8, Observable<? extends T> t9) {
-        return merge(from(Arrays.asList(t1, t2, t3, t4, t5, t6, t7, t8, t9)));
+        return merge(new Observable[] { t1, t2, t3, t4, t5, t6, t7, t8, t9 });
     }
 
     /**

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

@@ -0,0 +1,128 @@
+/**
+ * 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.internal.operators;
+
+import java.util.concurrent.atomic.AtomicLong;
+
+import rx.*;
+import rx.Observable.OnSubscribe;
+
+public final class OnSubscribeFromArray<T> implements OnSubscribe<T> {
+    final T[] array;
+    public OnSubscribeFromArray(T[] array) {
+        this.array = array;
+    }
+    
+    @Override
+    public void call(Subscriber<? super T> child) {
+        child.setProducer(new FromArrayProducer<T>(child, array));
+    }
+    
+    static final class FromArrayProducer<T>
+    extends AtomicLong
+    implements Producer {
+        /** */
+        private static final long serialVersionUID = 3534218984725836979L;
+        
+        final Subscriber<? super T> child;
+        final T[] array;
+        
+        int index;
+        
+        public FromArrayProducer(Subscriber<? super T> child, T[] array) {
+            this.child = child;
+            this.array = array;
+        }
+        
+        @Override
+        public void request(long n) {
+            if (n < 0) {
+                throw new IllegalArgumentException("n >= 0 required but it was " + n);
+            }
+            if (n == Long.MAX_VALUE) {
+                if (BackpressureUtils.getAndAddRequest(this, n) == 0) {
+                    fastPath();
+                }
+            } else
+            if (n != 0) {
+                if (BackpressureUtils.getAndAddRequest(this, n) == 0) {
+                    slowPath(n);
+                }
+            }
+        }
+        
+        void fastPath() {
+            final Subscriber<? super T> child = this.child;
+            
+            for (T t : array) {
+                if (child.isUnsubscribed()) {
+                    return;
+                }
+                
+                child.onNext(t);
+            }
+            
+            if (child.isUnsubscribed()) {
+                return;
+            }
+            child.onCompleted();
+        }
+        
+        void slowPath(long r) {
+            final Subscriber<? super T> child = this.child;
+            final T[] array = this.array;
+            final int n = array.length;
+            
+            long e = 0L;
+            int i = index;
+
+            for (;;) {
+                
+                while (r != 0L && i != n) {
+                    if (child.isUnsubscribed()) {
+                        return;
+                    }
+                    
+                    child.onNext(array[i]);
+                    
+                    i++;
+                    
+                    if (i == n) {
+                        if (!child.isUnsubscribed()) {
+                            child.onCompleted();
+                        }
+                        return;
+                    }
+                    
+                    r--;
+                    e--;
+                }
+                
+                r = get() + e;
+                
+                if (r == 0L) {
+                    index = i;
+                    r = addAndGet(e);
+                    if (r == 0L) {
+                        return;
+                    }
+                    e = 0L;
+                }
+            }
+        }
+    }
+}