run migrations and schema update through new Realm apis

object_store.cpp

@@ -351,7 +351,7 @@ bool ObjectStore::is_schema_at_version(Group *group, uint64_t version) {
     if (old_version > version && old_version != NotVersioned) {
         throw ObjectStoreException(old_version, version);
     }
-    return old_version != version;
+    return old_version == version;
 }
 
 
@@ -362,7 +362,7 @@ bool ObjectStore::update_realm_with_schema(Group *group,
     // Recheck the schema version after beginning the write transaction as
     // another process may have done the migration after we opened the read
     // transaction
-    bool migrating = is_schema_at_version(group, version);
+    bool migrating = !is_schema_at_version(group, version);
 
     // create tables
     bool changed = create_metadata_tables(group);

object_store_exceptions.cpp

@@ -59,10 +59,9 @@ ObjectStoreException::ObjectStoreException(uint64_t old_version, uint64_t new_ve
 }
 
 ObjectStoreException::ObjectStoreException(vector<ObjectStoreException> validation_errors, const string &object_type) :
-    m_validation_errors(validation_errors),
-    m_kind(Kind::ObjectStoreValidationFailure),
-    m_info({{InfoKeyObjectType, object_type}}),
-    m_what(generate_what()) {
+    m_validation_errors(validation_errors), m_kind(Kind::ObjectStoreValidationFailure) {
+    m_info[InfoKeyObjectType] = object_type;
+    m_what = generate_what();
 }
 
 string ObjectStoreException::generate_what() const {
@@ -88,7 +87,7 @@ std::string ObjectStoreException::populate_format_string(const std::string & for
     while(regex_search(current, sm, re)) {
         out_string += sm.prefix();
         const string &key = sm[1];
-        if (key == "ValidationString") {
+        if (key == "ValidationErrors") {
             out_string += validation_errors_string();
         }
         else {

shared_realm.cpp

@@ -84,13 +84,14 @@ SharedRealm Realm::get_shared_realm(Config &config)
         return realm;
     }
 
-    realm = make_shared<Realm>(config);
+    realm = SharedRealm(new Realm(config));
 
     // we want to ensure we are only initializing a single realm at a time
     lock_guard<mutex> lock(s_init_mutex);
 
     if (!config.schema) {
         // get schema from group and skip validation
+        realm->m_config.schema_version = ObjectStore::get_schema_version(realm->read_group());
         realm->m_config.schema = make_unique<ObjectStore::Schema>(ObjectStore::schema_from_group(realm->read_group()));
     }
     else if (config.read_only) {
@@ -107,21 +108,45 @@ SharedRealm Realm::get_shared_realm(Config &config)
         realm->m_config.schema = make_unique<ObjectStore::Schema>(*existing->m_config.schema);
     }
     else {
-        // its a new realm so update/migrate if needed
-        ObjectStore::update_realm_with_schema(realm->read_group(), config.schema_version, *realm->m_config.schema, realm->m_config.migration_function);
+        // its a non-cached realm so update/migrate if needed
+        realm->update_schema(*realm->m_config.schema, config.schema_version);
     }
 
     s_global_cache.cache_realm(realm, realm->m_thread_id);
     return realm;
 }
 
-static void check_read_write(Realm *realm) {
+bool Realm::update_schema(ObjectStore::Schema &schema, uint64_t version)
+{
+    bool changed = false;
+    try {
+        begin_transaction();
+        changed = ObjectStore::update_realm_with_schema(read_group(), version, schema, m_config.migration_function);
+        commit_transaction();
+        m_config.schema_version = version;
+        if (m_config.schema.get() != &schema) {
+            m_config.schema = make_unique<ObjectStore::Schema>(schema);
+        }
+    }
+    catch (...) {
+        if (is_in_transaction()) {
+            cancel_transaction();
+        }
+        throw;
+    }
+
+    return changed;
+}
+
+static void check_read_write(Realm *realm)
+{
     if (realm->config().read_only) {
         throw RealmException(RealmException::Kind::InvalidTransaction, "Can't perform transactions on read-only Realms.");
     }
 }
 
-void Realm::verify_thread() {
+void Realm::verify_thread()
+{
     if (m_thread_id != this_thread::get_id()) {
         throw RealmException(RealmException::Kind::IncorrectThread, "Realm accessed from incorrect thread.");
     }

shared_realm.hpp

@@ -52,11 +52,20 @@ namespace realm {
             Config(const Config& c);
         };
 
-        Realm(Config &config);
-        Realm(const Realm& r) = delete;
-
+        // Get a cached Realm or create a new one if no cached copies exists
+        // Caching is done by path - mismatches for inMemory and readOnly Config properties
+        // will raise an exception
+        // If schema/schema_version is specified, update_schema is called automatically on the realm
+        // and a migration is performed. If not specified, the schema version and schema are dynamically
+        // read from the the existing Realm.
         static SharedRealm get_shared_realm(Config &config);
 
+        // Updates a Realm to a given target schema/version creating tables and updating indexes as necessary
+        // Uses the existing migration function on the Config, and the resulting Schema and version with updated
+        // column mappings are set on the realms config upon success.
+        // returns if any changes were made
+        bool update_schema(ObjectStore::Schema &schema, uint64_t version);
+
         const Config &config() const { return m_config; }
 
         void begin_transaction();
@@ -83,6 +92,9 @@ namespace realm {
         const std::string DidChangeNotification = "DidChangeNotification";
 
       private:
+        Realm(Config &config);
+        //Realm(const Realm& r) = delete;
+
         Config m_config;
         std::thread::id m_thread_id;
         bool m_in_transaction;
@@ -131,6 +143,9 @@ namespace realm {
             IncompatibleLockFile,
             InvalidTransaction,
             IncorrectThread,
+            /** Thrown when trying to open an unitialized Realm without a target schema or with a mismatching
+             schema version **/
+            InvalidSchemaVersion
         };
         RealmException(Kind kind, std::string message) : m_kind(kind), m_what(message) {}