Finish retry piping

Change-Id: I6095b5df433c155c993100031b2633ee1670fb2d

Author: samtstern

firestore/src/main/java/com/firebase/ui/firestore/paging/FirestorePagingAdapter.java

@@ -9,6 +9,7 @@
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.v7.widget.RecyclerView;
+import android.util.Log;
 
 import com.firebase.ui.firestore.SnapshotParser;
 import com.google.firebase.firestore.DocumentSnapshot;
@@ -22,6 +23,8 @@ public abstract class FirestorePagingAdapter<T, VH extends RecyclerView.ViewHold
         extends PagedListAdapter<DocumentSnapshot, VH>
         implements LifecycleObserver {
 
+    private static final String TAG = "FirestorePagingAdapter";
+
     private final SnapshotParser<T> mParser;
     private final PagingData mData;
 
@@ -60,6 +63,20 @@ public FirestorePagingAdapter(@NonNull FirestorePagingOptions<T> options) {
         }
     }
 
+    /**
+     * If {@link #onLoadingStateChanged(LoadingState)} indicates error state, call this method
+     * to attempt to retry the most recent failure.
+     */
+    public void retry() {
+        FirestoreDataSource source = mData.getDataSource().getValue();
+        if (source == null) {
+            Log.w(TAG, "Called retry() when FirestoreDataSource is null!");
+            return;
+        }
+
+        source.retry();
+    }
+
     @OnLifecycleEvent(Lifecycle.Event.ON_START)
     public void startListening() {
         mData.getSnapshots().observeForever(mDataObserver);

firestore/src/main/java/com/firebase/ui/firestore/paging/PagingData.java

@@ -17,6 +17,7 @@ public class PagingData {
 
     private final LiveData<PagedList<DocumentSnapshot>> mSnapshots;
     private final LiveData<LoadingState> mLoadingState;
+    private final LiveData<FirestoreDataSource> mDataSource;
 
     public PagingData(@NonNull LiveData<PagedList<DocumentSnapshot>> snapshots) {
         mSnapshots = snapshots;
@@ -29,6 +30,14 @@ public LiveData<LoadingState> apply(PagedList<DocumentSnapshot> input) {
                         return dataSource.getLoadingState();
                     }
                 });
+
+        mDataSource = Transformations.map(mSnapshots,
+                new Function<PagedList<DocumentSnapshot>, FirestoreDataSource>() {
+                    @Override
+                    public FirestoreDataSource apply(PagedList<DocumentSnapshot> input) {
+                        return (FirestoreDataSource) input.getDataSource();
+                    }
+                });
     }
 
     public LiveData<PagedList<DocumentSnapshot>> getSnapshots() {
@@ -39,4 +48,6 @@ public LiveData<LoadingState> getLoadingState() {
         return mLoadingState;
     }
 
+    public LiveData<FirestoreDataSource> getDataSource() { return mDataSource; }
+
 }