Merge pull request square#1065 from edenman/master

Fix memory leak: cancel deferred request if another is requested

Author: JakeWharton

picasso/src/main/java/com/squareup/picasso/Picasso.java

@@ -477,6 +477,10 @@ Request transformRequest(Request request) {
   }
 
   void defer(ImageView view, DeferredRequestCreator request) {
+    // If there is already a deferred request, cancel it.
+    if (targetToDeferredRequestCreator.containsKey(view)) {
+      cancelExistingRequest(view);
+    }
     targetToDeferredRequestCreator.put(view, request);
   }
 

picasso/src/test/java/com/squareup/picasso/PicassoTest.java

@@ -235,6 +235,18 @@ public class PicassoTest {
     assertThat(picasso.targetToDeferredRequestCreator).isEmpty();
   }
 
+  @Test public void enqueueingDeferredRequestCancelsThePreviousOne() throws Exception {
+    ImageView target = mockImageViewTarget();
+    DeferredRequestCreator firstRequestCreator = mockDeferredRequestCreator();
+    picasso.defer(target, firstRequestCreator);
+    assertThat(picasso.targetToDeferredRequestCreator).containsKey(target);
+
+    DeferredRequestCreator secondRequestCreator = mockDeferredRequestCreator();
+    picasso.defer(target, secondRequestCreator);
+    verify(firstRequestCreator).cancel();
+    assertThat(picasso.targetToDeferredRequestCreator).containsKey(target);
+  }
+
   @Test public void cancelExistingRequestWithTarget() {
     Target target = mockTarget();
     Action action = mockAction(URI_KEY_1, URI_1, target);