Don't cancel new runners from old jobs.

Fixes #91

library/src/androidTest/java/com/bumptech/glide/load/engine/EngineJobTest.java

@@ -105,9 +105,10 @@ public class EngineJobTest {
 
     @Test
     public void testListenerNotifiedOfCancelOnCancel() {
-        harness.getJob().cancel();
+        EngineJob job = harness.getJob();
+        job.cancel();
 
-        verify(harness.listener).onEngineJobCancelled(eq(harness.key));
+        verify(harness.listener).onEngineJobCancelled(eq(job), eq(harness.key));
     }
 
     @Test
@@ -164,7 +165,7 @@ public class EngineJobTest {
         job.onResourceReady(harness.resource);
         job.cancel();
 
-        verify(harness.listener, never()).onEngineJobCancelled(eq(harness.key));
+        verify(harness.listener, never()).onEngineJobCancelled(eq(job), eq(harness.key));
     }
 
     @Test
@@ -173,7 +174,7 @@ public class EngineJobTest {
         job.cancel();
         job.cancel();
 
-        verify(harness.listener, times(1)).onEngineJobCancelled(eq(harness.key));
+        verify(harness.listener, times(1)).onEngineJobCancelled(eq(job), eq(harness.key));
     }
 
     @Test

library/src/androidTest/java/com/bumptech/glide/load/engine/EngineTest.java

@@ -290,7 +290,7 @@ public class EngineTest {
     public void testRunnerIsRemovedFromRunnersOnEngineNotifiedJobCancel() {
         harness.doLoad();
 
-        harness.engine.onEngineJobCancelled(harness.cacheKey);
+        harness.engine.onEngineJobCancelled(harness.job, harness.cacheKey);
 
         assertFalse(harness.runners.containsKey(harness.cacheKey));
     }
@@ -299,11 +299,29 @@ public class EngineTest {
     public void testRunnerIsCancelledOnEngineNotifiedJobCanceled() {
         harness.doLoad();
 
-        harness.engine.onEngineJobCancelled(harness.cacheKey);
+        harness.engine.onEngineJobCancelled(harness.job, harness.cacheKey);
 
         verify(harness.runner).cancel();
     }
 
+    @Test
+    public void testRunnerIsNotRemovedFromRunnersIfOldJobIsCancelled() {
+        harness.doLoad();
+
+        harness.engine.onEngineJobCancelled(mock(EngineJob.class), harness.cacheKey);
+
+        assertEquals(harness.runner, harness.runners.get(harness.cacheKey));
+    }
+
+    @Test
+    public void testRunnerIsNotCancelledIfOldJobIsCancelled() {
+        harness.doLoad();
+
+        harness.engine.onEngineJobCancelled(mock(EngineJob.class), harness.cacheKey);
+
+        verify(harness.runner, never()).cancel();
+    }
+
     @Test
     public void testResourceIsAddedToCacheOnReleased() {
         harness.engine.onResourceReleased(harness.cacheKey, harness.resource);

library/src/main/java/com/bumptech/glide/load/engine/Engine.java

@@ -208,9 +208,12 @@ public class Engine implements EngineJobListener, MemoryCache.ResourceRemovedLis
     }
 
     @Override
-    public void onEngineJobCancelled(Key key) {
-        ResourceRunner runner = runners.remove(key);
-        runner.cancel();
+    public void onEngineJobCancelled(EngineJob engineJob, Key key) {
+        ResourceRunner runner = runners.get(key);
+        if (runner.getJob() == engineJob) {
+            runners.remove(key);
+            runner.cancel();
+        }
     }
 
     @Override

library/src/main/java/com/bumptech/glide/load/engine/EngineJob.java

@@ -13,7 +13,7 @@ import java.util.List;
  * A class that manages a load by adding and removing callbacks for for the load and notifying callbacks when the
  * load completes.
  */
-public class EngineJob implements ResourceCallback {
+class EngineJob implements ResourceCallback {
     private static final String TAG = "EngineJob";
     private boolean isCacheable;
     private final EngineJobListener listener;
@@ -61,7 +61,7 @@ public class EngineJob implements ResourceCallback {
             return;
         }
         isCancelled = true;
-        listener.onEngineJobCancelled(key);
+        listener.onEngineJobCancelled(this, key);
     }
 
     // Exposed for testing.

library/src/main/java/com/bumptech/glide/load/engine/EngineJobListener.java

@@ -6,5 +6,5 @@ interface EngineJobListener {
 
     public void onEngineJobComplete(Key key, Resource resource);
 
-    public void onEngineJobCancelled(Key key);
+    public void onEngineJobCancelled(EngineJob engineJob, Key key);
 }