Merge pull request realm#5385 from realm/kk/migration

Fixed an issue that crash when enumerating after clearing data during migration.
noxchen · Oct 13, 2017 · ccd1f35 · ccd1f35
2 parents 1f42c2a + 6f89f75
commit ccd1f35
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Showing 3 changed files with 53 additions and 7 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -10,6 +10,7 @@ x.x.x Release notes (yyyy-MM-dd)
   level.
 * Fix a race condition that could lead to a crash accessing to the freed configuration object
   if a default configuration was set from a different thread.
+* Fixed an issue that crash when enumerating after clearing data during migration.
 
 3.0.0-rc.1 Release notes (2017-10-03)
 =============================================================

diff --git a/Realm/RLMMigration.mm b/Realm/RLMMigration.mm
@@ -57,6 +57,7 @@ - (void)beginWriteTransaction {
 @implementation RLMMigration {
     realm::Schema *_schema;
     NSMutableDictionary *deletedObjectIndices;
+    NSMutableSet *deletedClasses;
 }
 
 - (instancetype)initWithRealm:(RLMRealm *)realm oldRealm:(RLMRealm *)oldRealm schema:(realm::Schema &)schema {
@@ -67,6 +68,7 @@ - (instancetype)initWithRealm:(RLMRealm *)realm oldRealm:(RLMRealm *)oldRealm sc
         _schema = &schema;
         object_setClass(_oldRealm, RLMMigrationRealm.class);
         deletedObjectIndices = [NSMutableDictionary dictionary];
+        deletedClasses = [NSMutableSet set];
     }
     return self;
 }
@@ -80,6 +82,10 @@ - (RLMSchema *)newSchema {
 }
 
 - (void)enumerateObjects:(NSString *)className block:(RLMObjectMigrationBlock)block {
+    if ([deletedClasses containsObject:className]) {
+        return;
+    }
+
     // get all objects
     RLMResults *objects = [_realm.schema schemaForClassName:className] ? [_realm allObjects:className] : nil;
     RLMResults *oldObjects = [_oldRealm.schema schemaForClassName:className] ? [_oldRealm allObjects:className] : nil;
@@ -128,7 +134,9 @@ - (void)execute:(RLMMigrationBlock)block {
         }
 
         block(self, _oldRealm->_realm->schema_version());
+
         [self deleteObjectsMarkedForDeletion];
+        [self deleteDataMarkedForDeletion];
 
         _oldRealm = nil;
         _realm = nil;
@@ -167,16 +175,25 @@ - (BOOL)deleteDataForClassName:(NSString *)name {
         return false;
     }
 
-    if ([_realm.schema schemaForClassName:name]) {
-        table->clear();
-    }
-    else {
-        realm::ObjectStore::delete_data_for_object(_realm.group, name.UTF8String);
-    }
-
+    [deletedClasses addObject:name];
     return true;
 }
 
+- (void)deleteDataMarkedForDeletion {
+    for (NSString *className in deletedClasses) {
+        TableRef table = ObjectStore::table_for_object_type(_realm.group, className.UTF8String);
+        if (!table) {
+            continue;
+        }
+        if ([_realm.schema schemaForClassName:className]) {
+            table->clear();
+        }
+        else {
+            realm::ObjectStore::delete_data_for_object(_realm.group, className.UTF8String);
+        }
+    }
+}
+
 - (void)renamePropertyForClass:(NSString *)className oldName:(NSString *)oldName newName:(NSString *)newName {
     const char *objectType = className.UTF8String;
     realm::ObjectStore::rename_property(_realm.group, *_schema, objectType, oldName.UTF8String, newName.UTF8String);

diff --git a/RealmSwift/Tests/MigrationTests.swift b/RealmSwift/Tests/MigrationTests.swift
@@ -369,6 +369,34 @@ class MigrationTests: TestCase {
         }
     }
 
+    func testEnumerateObjectsAfterDeleteData() {
+        autoreleasepool {
+            // add object
+            try! Realm().write {
+                try! Realm().create(SwiftStringObject.self, value: ["1"])
+                try! Realm().create(SwiftStringObject.self, value: ["2"])
+                try! Realm().create(SwiftStringObject.self, value: ["3"])
+            }
+        }
+
+        migrateAndTestDefaultRealm(1) { migration, _ in
+            var count = 0
+            migration.enumerateObjects(ofType: "SwiftStringObject") { _, _ in
+                count += 1
+            }
+            XCTAssertEqual(count, 3)
+
+            migration.deleteData(forType: "SwiftStringObject")
+            migration.create("SwiftStringObject", value: ["A"])
+
+            count = 0
+            migration.enumerateObjects(ofType: "SwiftStringObject") { _, _ in
+                count += 1
+            }
+            XCTAssertEqual(count, 0)
+        }
+    }
+
     func testCreate() {
         autoreleasepool {
             _ = try! Realm()