Merge pull request #1288 from davidmoten/string-from-bytes

Ensure StringObservable.from() does not perform unnecessary read

Author: benjchristensen

rxjava-contrib/rxjava-string/src/main/java/rx/observables/StringObservable.java

@@ -71,11 +71,11 @@ public void call(Subscriber<? super byte[]> o) {
                 try {
                     if (o.isUnsubscribed())
                         return;
-                    int n = 0;
-                    n = i.read(buffer);
+                    int n = i.read(buffer);
                     while (n != -1 && !o.isUnsubscribed()) {
                         o.onNext(Arrays.copyOf(buffer, n));
-                        n = i.read(buffer);
+                        if (!o.isUnsubscribed())
+                            n = i.read(buffer);
                     }
                 } catch (IOException e) {
                     o.onError(e);

rxjava-contrib/rxjava-string/src/test/java/rx/observables/StringObservableTest.java

@@ -33,6 +33,7 @@
 import java.nio.charset.MalformedInputException;
 import java.util.Arrays;
 import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import org.junit.Test;
 
@@ -246,6 +247,22 @@ public void testFromInputStream() {
         assertArrayEquals(inBytes, outBytes);
     }
 
+    @Test
+    public void testFromInputStreamWillUnsubscribeBeforeCallingNextRead() {
+        final byte[] inBytes = "test".getBytes();
+        final AtomicInteger numReads = new AtomicInteger(0);
+        ByteArrayInputStream is = new ByteArrayInputStream(inBytes) {
+
+            @Override
+            public synchronized int read(byte[] b, int off, int len) {
+                numReads.incrementAndGet();
+                return super.read(b, off, len);
+            }
+        };
+        StringObservable.from(is).first().toBlockingObservable().single();
+        assertEquals(1, numReads.get());
+    }
+    
     @Test
     public void testFromReader() {
         final String inStr = "test";