fix(aws-datastore): ignore foreign key error during sync (#1058)

Author: raphkim

aws-datastore/src/main/java/com/amplifyframework/datastore/syncengine/Merger.java

@@ -15,6 +15,7 @@
 
 package com.amplifyframework.datastore.syncengine;
 
+import android.database.sqlite.SQLiteConstraintException;
 import androidx.annotation.NonNull;
 
 import com.amplifyframework.core.Amplify;
@@ -27,6 +28,7 @@
 import com.amplifyframework.datastore.appsync.ModelWithMetadata;
 import com.amplifyframework.datastore.storage.LocalStorageAdapter;
 import com.amplifyframework.datastore.storage.StorageItemChange;
+import com.amplifyframework.datastore.utils.ErrorInspector;
 import com.amplifyframework.hub.HubChannel;
 import com.amplifyframework.hub.HubEvent;
 import com.amplifyframework.logging.Logger;
@@ -109,6 +111,15 @@ <T extends Model> Completable merge(
                 announceSuccessfulMerge(modelWithMetadata);
                 LOG.debug("Remote model update was sync'd down into local storage: " + modelWithMetadata);
             })
+            // Remote store may not always respect the foreign key constraint, so
+            // swallow any error caused by foreign key constraint violation.
+            .onErrorComplete(failure -> {
+                if (!ErrorInspector.contains(failure, SQLiteConstraintException.class)) {
+                    return false;
+                }
+                LOG.warn("Failed to sync due to foreign key constraint violation: " + modelWithMetadata, failure);
+                return true;
+            })
             .doOnError(failure ->
                 LOG.warn("Failed to sync remote model into local storage: " + modelWithMetadata, failure)
             );

aws-datastore/src/main/java/com/amplifyframework/datastore/utils/ErrorInspector.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file 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 com.amplifyframework.datastore.utils;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import java.util.Objects;
+
+/**
+ * Utility class to provide helpful functions to use on throwable instances.
+ */
+public final class ErrorInspector {
+    private ErrorInspector() {}
+
+    /**
+     * Returns true if an error object was caused by a specific throwable type.
+     * @param error Error object to perform the check on.
+     * @param causeType Class type of the error to look for in stacktrace.
+     * @return true if an error object contains given cause.
+     */
+    public static boolean contains(
+        @Nullable Throwable error,
+        @NonNull Class<? extends Throwable> causeType
+    ) {
+        Objects.requireNonNull(causeType);
+        if (error == null) {
+            return false;
+        }
+        try {
+            return causeType.isInstance(error) || contains(error.getCause(), causeType);
+        } catch (Throwable unexpected) {
+            // May encounter unexpected error during recursive search.
+            // e.g. StackOverflowError, NoClassDefFoundError, etc.
+            return false;
+        }
+    }
+}

aws-datastore/src/test/java/com/amplifyframework/datastore/syncengine/MergerTest.java

@@ -15,6 +15,8 @@
 
 package com.amplifyframework.datastore.syncengine;
 
+import android.database.sqlite.SQLiteConstraintException;
+
 import com.amplifyframework.AmplifyException;
 import com.amplifyframework.core.model.ModelSchema;
 import com.amplifyframework.core.model.query.Where;
@@ -25,6 +27,7 @@
 import com.amplifyframework.datastore.appsync.ModelWithMetadata;
 import com.amplifyframework.datastore.storage.InMemoryStorageAdapter;
 import com.amplifyframework.datastore.storage.SynchronousStorageAdapter;
+import com.amplifyframework.testmodels.commentsblog.Blog;
 import com.amplifyframework.testmodels.commentsblog.BlogOwner;
 import com.amplifyframework.testutils.random.RandomString;
 
@@ -41,6 +44,10 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.spy;
 
 /**
  * Tests the {@link Merger}.
@@ -49,6 +56,7 @@
 public final class MergerTest {
     private static final long REASONABLE_WAIT_TIME = TimeUnit.SECONDS.toMillis(2);
 
+    private InMemoryStorageAdapter inMemoryStorageAdapter;
     private SynchronousStorageAdapter storageAdapter;
     private MutationOutbox mutationOutbox;
     private Merger merger;
@@ -62,7 +70,7 @@ public final class MergerTest {
      */
     @Before
     public void setup() {
-        InMemoryStorageAdapter inMemoryStorageAdapter = InMemoryStorageAdapter.create();
+        this.inMemoryStorageAdapter = spy(InMemoryStorageAdapter.create());
         this.storageAdapter = SynchronousStorageAdapter.delegatingTo(inMemoryStorageAdapter);
         this.mutationOutbox = new PersistentMutationOutbox(inMemoryStorageAdapter);
         VersionRepository versionRepository = new VersionRepository(inMemoryStorageAdapter);
@@ -347,4 +355,39 @@ public void itemWithoutVersionIsNotMerged() throws DataStoreException, Interrupt
             storageAdapter.query(ModelMetadata.class, Where.id(existingModel.getId()))
         );
     }
+
+    /**
+     * Assume item A is dependent on item B, but the remote store has an
+     * orphaned item A without item B. Then, we try to merge a save for a
+     * item A. This should gracefully fail, with A not being in the local
+     * store, at the end.
+     * @throws DataStoreException On failure to query results for assertions
+     * @throws InterruptedException If interrupted while awaiting terminal result in test observer
+     */
+    @Test
+    public void orphanedItemIsNotMerged() throws DataStoreException, InterruptedException {
+        // Arrange: an item and its parent are not in the local store
+        BlogOwner badOwner = BlogOwner.builder()
+                .name("Raphael")
+                .build();
+        Blog orphanedBlog = Blog.builder()
+                .name("How Not To Save Blogs")
+                .owner(badOwner)
+                .build();
+        ModelMetadata metadata = new ModelMetadata(orphanedBlog.getId(), false, 1, Temporal.Timestamp.now());
+
+        // Enforce foreign key constraint on in-memory storage adapter
+        doThrow(SQLiteConstraintException.class)
+                .when(inMemoryStorageAdapter)
+                .save(eq(orphanedBlog), any(), any(), any(), any());
+
+        // Act: merge a creation for an item
+        TestObserver<Void> observer = merger.merge(new ModelWithMetadata<>(orphanedBlog, metadata)).test();
+        assertTrue(observer.await(REASONABLE_WAIT_TIME, TimeUnit.MILLISECONDS));
+        observer.assertNoErrors().assertComplete();
+
+        // Assert: orphaned model was not merged locally
+        final List<Blog> blogsInStorage = storageAdapter.query(Blog.class);
+        assertTrue(blogsInStorage.isEmpty());
+    }
 }