Access to RealmResults based on deleted RealmList

* When the original RealmList is deleted, for most methods of
  RealmResults should just work without crash by just treat it like an
  empty RealmResults.
* RealmResults.where() throws IllegalStateExecption in this case.
* RealmResults.isValid() returns false in this case.

This is a temp fix, check realm/realm-core#1434
for more details.

Close #1945

realm/realm-jni/src/io_realm_internal_Util.cpp

@@ -169,7 +169,11 @@ JNIEXPORT jstring JNICALL Java_io_realm_internal_Util_nativeTestcase(
             if (dotest)
                 ThrowException(env, BadVersion, "parm1", "parm2");
             break;
-
+        case DeletedLinkViewException:
+            expect = "io.realm.internal.DeletedRealmListException: parm1";
+            if (dotest)
+                ThrowException(env, DeletedLinkViewException, "parm1", "parm2");
+            break;
     }
     if (dotest) {
         return NULL;

realm/realm-jni/src/io_realm_internal_tableview.cpp

@@ -25,20 +25,32 @@
 using namespace realm;
 
 // if you disable the validation, please remember to call sync_in_needed() 
-#define VIEW_VALID_AND_IN_SYNC(env, ptr) view_valid_and_in_sync(env, ptr)
+#define VIEW_VALID_AND_IN_SYNC(env, ptr) (is_view_valid(env, ptr) && is_view_in_sync(env, ptr))
 
-inline bool view_valid_and_in_sync(JNIEnv* env, jlong nativeViewPtr) {
-    bool valid = (TV(nativeViewPtr) != NULL);
-    if (valid) {
-        if (!TV(nativeViewPtr)->is_attached()) {
-            ThrowException(env, TableInvalid, "The Realm has been closed and is no longer accessible.");
-            return false;
-        }
-        TV(nativeViewPtr)->sync_if_needed();
+inline bool is_view_valid(JNIEnv* env, jlong nativeViewPtr) {
+    if (TV(nativeViewPtr) == NULL) {
+        // Should never get here
+        ThrowException(env, FatalError, "Null pointer of table view.");
+        return false;
+    }
+    if (!TV(nativeViewPtr)->is_attached()) {
+        ThrowException(env, TableInvalid, "The Realm has been closed and is no longer accessible.");
+        return false;
     }
-    return valid;
+    return true;
 }
 
+inline bool is_view_in_sync(JNIEnv* /*env*/, jlong nativeViewPtr) {
+    try {
+        TV(nativeViewPtr)->sync_if_needed();
+    } catch (realm::DeletedLinkView&) {
+        // FIXME: Temp fix for https://github.com/realm/realm-core/pull/1434
+        // Better solution would be core only throw the exception when really necessary, methods like size
+        // should just return 0.
+        return false;
+    }
+    return true;
+}
 
 JNIEXPORT jlong JNICALL Java_io_realm_internal_TableView_createNativeTableView(
     JNIEnv* env, jobject, jobject, jlong)
@@ -105,10 +117,16 @@ JNIEXPORT jlong JNICALL Java_io_realm_internal_TableView_nativeGetSourceRowIndex
 (JNIEnv *env, jobject, jlong nativeViewPtr, jlong rowIndex)
 {
     try {
-        if (!VIEW_VALID_AND_IN_SYNC(env, nativeViewPtr))
-            return 0;
+        if (!is_view_valid(env, nativeViewPtr)) {
+            return npos;
+        }
+        if (!is_view_in_sync(env, nativeViewPtr)) {
+            TR_ERR("The source LinkView created this TableView has been deleted.");
+            // Let it fall through. Since the size will return 0, an ArrayIndexOutOfBoundsException
+            // will be thrown in ROW_INDEX_VALID check.
+        }
         if (!ROW_INDEX_VALID(env, TV(nativeViewPtr), rowIndex))
-            return 0;
+            return npos;
     } CATCH_STD()
     return TV(nativeViewPtr)->get_source_ndx(S(rowIndex));   // noexcept
 }
@@ -117,7 +135,8 @@ JNIEXPORT jlong JNICALL Java_io_realm_internal_TableView_nativeGetColumnCount
   (JNIEnv *env, jobject, jlong nativeViewPtr)
 {
     try {
-        if (!VIEW_VALID_AND_IN_SYNC(env, nativeViewPtr))
+        // No need to sync here.
+        if (!is_view_valid(env, nativeViewPtr))
             return 0;
     } CATCH_STD()
     return TV(nativeViewPtr)->get_column_count();
@@ -127,7 +146,8 @@ JNIEXPORT jstring JNICALL Java_io_realm_internal_TableView_nativeGetColumnName
   (JNIEnv *env, jobject, jlong nativeViewPtr, jlong columnIndex)
 {
     try {
-        if (!VIEW_VALID_AND_IN_SYNC(env, nativeViewPtr) || !COL_INDEX_VALID(env, TV(nativeViewPtr), columnIndex))
+        // No need to sync here.
+        if (!is_view_valid(env, nativeViewPtr) || !COL_INDEX_VALID(env, TV(nativeViewPtr), columnIndex))
             return NULL;
         return to_jstring(env, TV(nativeViewPtr)->get_column_name( S(columnIndex)));
     } CATCH_STD()
@@ -138,8 +158,9 @@ JNIEXPORT jlong JNICALL Java_io_realm_internal_TableView_nativeGetColumnIndex
    (JNIEnv *env, jobject, jlong nativeViewPtr, jstring columnName)
 {
     try {
-        if (!VIEW_VALID_AND_IN_SYNC(env, nativeViewPtr))
-        return 0;
+        // No need to sync here.
+        if (!is_view_valid(env, nativeViewPtr))
+            return 0;
 
         JStringAccessor columnName2(env, columnName); // throws
         return to_jlong_or_not_found( TV(nativeViewPtr)->get_column_index(columnName2) ); // noexcept
@@ -151,7 +172,8 @@ JNIEXPORT jint JNICALL Java_io_realm_internal_TableView_nativeGetColumnType
   (JNIEnv *env, jobject, jlong nativeViewPtr, jlong columnIndex)
 {
     try {
-        if (!VIEW_VALID_AND_IN_SYNC(env, nativeViewPtr) || !COL_INDEX_VALID(env, TV(nativeViewPtr), columnIndex))
+        // No need to sync here.
+        if (!is_view_valid(env, nativeViewPtr) || !COL_INDEX_VALID(env, TV(nativeViewPtr), columnIndex))
             return 0;
     } CATCH_STD()
     return static_cast<int>( TV(nativeViewPtr)->get_column_type( S(columnIndex)) );

realm/realm-jni/src/util.cpp

@@ -53,6 +53,10 @@ void ConvertException(JNIEnv* env, const char *file, int line)
         ss << e.what() << " in " << file << " line " << line;
         ThrowException(env, BadVersion, ss.str());
     }
+    catch (realm::DeletedLinkView& e) {
+        ss << e.what() << " in " << file << " line " << line;
+        ThrowException(env, DeletedLinkViewException, ss.str());
+    }
     catch (std::exception& e) {
         ss << e.what() << " in " << file << " line " << line;
         ThrowException(env, FatalError, ss.str());
@@ -152,6 +156,11 @@ void ThrowException(JNIEnv* env, ExceptionKind exception, const std::string& cla
             jExceptionClass = env->FindClass("io/realm/internal/async/BadVersionException");
             message = classStr;
             break;
+
+        case DeletedLinkViewException:
+            jExceptionClass = env->FindClass("io/realm/internal/DeleteRealmListException");
+            message = classStr;
+            break;
     }
     if (jExceptionClass != NULL) {
         env->ThrowNew(jExceptionClass, message.c_str());

realm/realm-jni/src/util.hpp

@@ -121,7 +121,8 @@ enum ExceptionKind {
     RuntimeError = 12,
     RowInvalid = 13,
     CrossTableLink = 15,
-    BadVersion = 16
+    BadVersion = 16,
+    DeletedLinkViewException = 17
 // NOTE!!!!: Please also add test cases to Util.java when introducing a new exception kind.
 };
 

realm/realm-library/src/androidTest/java/io/realm/RealmResultsTest.java

@@ -280,9 +280,9 @@ public void testMinValueForAllNullRows() {
         TestHelper.populateAllNullRowsForNumericTesting(testRealm);
 
         RealmResults<NullTypes> results = testRealm.where(NullTypes.class).findAll();
-        assertNull(results.max(NullTypes.FIELD_INTEGER_NULL));
-        assertNull(results.max(NullTypes.FIELD_FLOAT_NULL));
-        assertNull(results.max(NullTypes.FIELD_DOUBLE_NULL));
+        assertNull(results.min(NullTypes.FIELD_INTEGER_NULL));
+        assertNull(results.min(NullTypes.FIELD_FLOAT_NULL));
+        assertNull(results.min(NullTypes.FIELD_DOUBLE_NULL));
         assertNull(results.maxDate(NullTypes.FIELD_DATE_NULL));
     }
 
@@ -1146,4 +1146,100 @@ public void testComparisons() {
         assertEquals(10, testRealm.where(AllTypes.class).lessThanOrEqualTo(AllTypes.FIELD_LONG, -1).findAll().size());
         assertEquals(10, testRealm.where(AllTypes.class).lessThan(AllTypes.FIELD_LONG, 0).findAll().size());
     }
+
+    private RealmResults<Dog> populateRealmResultsOnDeletedLinkView() {
+        testRealm.beginTransaction();
+        Owner owner = testRealm.createObject(Owner.class);
+        for (int i = 0; i < 10; i++) {
+            Dog dog = new Dog();
+            dog.setName("name_" + i);
+            dog.setOwner(owner);
+            owner.getDogs().add(dog);
+        }
+        testRealm.commitTransaction();
+
+
+        RealmResults<Dog> dogs = owner.getDogs().where().equalTo(Dog.FIELD_NAME, "name_0").findAll();
+        //dogs = dogs.where().findFirst().getOwner().getDogs().where().equalTo(Dog.FIELD_NAME, "name_0").findAll();
+
+        testRealm.beginTransaction();
+        owner.removeFromRealm();
+        testRealm.commitTransaction();
+        return dogs;
+    }
+
+    public void testisValidResultsBuiltOnDeletedLinkView() {
+        assertEquals(false, populateRealmResultsOnDeletedLinkView().isValid());
+    }
+
+    public void testSizeResultsBuiltOnDeletedLinkView() {
+        assertEquals(0, populateRealmResultsOnDeletedLinkView().size());
+    }
+
+    public void testFirstResultsBuiltOnDeletedLinkView() {
+        try {
+            populateRealmResultsOnDeletedLinkView().first();
+        } catch (ArrayIndexOutOfBoundsException ignored) {
+        }
+    }
+
+    public void testLastResultsBuiltOnDeletedLinkView() {
+        try {
+            populateRealmResultsOnDeletedLinkView().last();
+        } catch (ArrayIndexOutOfBoundsException ignored) {
+        }
+    }
+
+    public void testSumResultsBuiltOnDeletedLinkView() {
+        RealmResults<Dog> dogs = populateRealmResultsOnDeletedLinkView();
+        assertEquals(0, dogs.sum(Dog.FIELD_AGE).intValue());
+        assertEquals(0f, dogs.sum(Dog.FIELD_HEIGHT).floatValue(), 0f);
+        assertEquals(0d, dogs.sum(Dog.FIELD_WEIGHT).doubleValue(), 0d);
+    }
+
+    public void testAverageResultsBuiltOnDeletedLinkView() {
+        RealmResults<Dog> dogs = populateRealmResultsOnDeletedLinkView();
+        assertEquals(0d, dogs.average(Dog.FIELD_AGE), 0d);
+        assertEquals(0d, dogs.average(Dog.FIELD_HEIGHT), 0d);
+        assertEquals(0d, dogs.average(Dog.FIELD_WEIGHT), 0d);
+    }
+
+    public void testClearResultsBuiltOnDeletedLinkView() {
+        RealmResults<Dog> dogs = populateRealmResultsOnDeletedLinkView();
+        testRealm.beginTransaction();
+        dogs.clear();
+        assertEquals(0, dogs.size());
+        testRealm.commitTransaction();
+    }
+
+    public void testMaxResultsBuiltOnDeletedLinkView() {
+        RealmResults<Dog> dogs = populateRealmResultsOnDeletedLinkView();
+        assertNull(dogs.max(Dog.FIELD_AGE));
+        assertNull(dogs.max(Dog.FIELD_HEIGHT));
+        assertNull(dogs.max(Dog.FIELD_WEIGHT));
+    }
+
+    public void testMaxDateResultsBuiltOnDeletedLinkView() {
+        assertEquals(null, populateRealmResultsOnDeletedLinkView().maxDate(Dog.FIELD_BIRTHDAY));
+    }
+
+    public void testMinResultsBuiltOnDeletedLinkView() {
+        RealmResults<Dog> dogs = populateRealmResultsOnDeletedLinkView();
+        assertNull(dogs.min(Dog.FIELD_AGE));
+        assertNull(dogs.min(Dog.FIELD_HEIGHT));
+        assertNull(dogs.min(Dog.FIELD_WEIGHT));
+    }
+
+    public void testMinDateResultsBuiltOnDeletedLinkView() {
+        assertEquals(null, populateRealmResultsOnDeletedLinkView().minDate(Dog.FIELD_BIRTHDAY));
+    }
+
+    public void testWhereResultsBuiltOnDeletedLinkView() {
+        try {
+            populateRealmResultsOnDeletedLinkView().where();
+            fail();
+        } catch (IllegalStateException e) {
+            assertEquals("The RealmList which this RealmResults is created on has been deleted.", e.getMessage());
+        }
+    }
 }

realm/realm-library/src/androidTest/java/io/realm/TypeBasedNotificationsTest.java

@@ -27,7 +27,6 @@
 import java.io.InputStream;
 import java.lang.ref.WeakReference;
 import java.util.Date;
-import java.util.WeakHashMap;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -1827,8 +1826,8 @@ public void onChange() {
                         // Check if cat has been added to the realmObjects in case of the behaviour of getCat changes
                         for (WeakReference<RealmObject> weakReference : realm.handlerController.realmObjects.keySet()) {
                             if (weakReference.get() == cat) {
-                               foundKey = true;
-                               break;
+                                foundKey = true;
+                                break;
                             }
                         }
                         assertTrue(foundKey);
@@ -1890,4 +1889,58 @@ public void onChange() {
 
         finishedLatch.await();
     }
+
+    // Build a RealmResults from a RealmList, and delete the RealmList. Test the behavior of ChangeListener on the
+    // "invalid" RealmResults.
+    public void test_changeListener_onResultsBuiltOnDeletedLinkView() {
+        handler.post(new Runnable() {
+            @Override
+            public void run() {
+                realm = Realm.getInstance(configuration);
+                realm.beginTransaction();
+                AllTypes allTypes = realm.createObject(AllTypes.class);
+                for (int i = 0; i < 10; i++) {
+                    Dog dog = new Dog();
+                    dog.setName("name_" + i);
+                    allTypes.getColumnRealmList().add(dog);
+                }
+                realm.commitTransaction();
+
+                final RealmResults<Dog> dogs =
+                        allTypes.getColumnRealmList().where().equalTo(Dog.FIELD_NAME, "name_0").findAll();
+                dogs.addChangeListener(new RealmChangeListener() {
+                    @Override
+                    public void onChange() {
+                        if (typebasedCommitInvocations.getAndIncrement() == 0) {
+                            assertFalse(dogs.isValid());
+                            assertEquals(0, dogs.size());
+                        } else {
+                            fail("This listener should only be called once.");
+                        }
+                    }
+                });
+
+                // Trigger the listener at the first time.
+                realm.beginTransaction();
+                allTypes.removeFromRealm();
+                realm.commitTransaction();
+
+                // Try to trigger the listener second time.
+                realm.beginTransaction();
+                realm.commitTransaction();
+
+                // Close the realm and finish the test. This needs to follow the REALM_CHANGED in the queue.
+                handler.post(new Runnable() {
+                    @Override
+                    public void run() {
+                        realm.close();
+                        signalTestFinished.countDown();
+                    }
+                });
+            }
+        });
+
+        TestHelper.awaitOrFail(signalTestFinished);
+        assertEquals(1, typebasedCommitInvocations.get());
+    }
 }

realm/realm-library/src/androidTest/java/io/realm/entities/Dog.java

@@ -24,6 +24,12 @@
 
 public class Dog extends RealmObject {
 
+    public static final String FIELD_NAME = "name";
+    public static final String FIELD_AGE = "age";
+    public static final String FIELD_HEIGHT = "height";
+    public static final String FIELD_WEIGHT = "weight";
+    public static final String FIELD_BIRTHDAY = "birthday";
+
     @Index
     private String name;
     private long age;