Disallowing multiple calls to connect().

The connect() method is used to obtain a DB connection, either from an
lf.schema.Builder instance, or from the generated #namespace.connect() method for
SPAC. Calling connect() on an instance with active DB connection has no
valid use case, but it was allowed until now, causing confusion. For example
users thought that a DB connection to WebSQL and IndexedDB could be opened at
the same time with subsequent calls to connect(), with unexpected results.
  With this change misuse of connect() will result in an exception. The
connect() method can be called again only after the current DB connection has
been closed with a call to db.close().
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=104422821

dist/error_code.json

@@ -1,7 +1,7 @@
 {
   "0": "System error",
   "1": "Lovefield library version mismatch.",
-  "2": "The database has not initialized yet.",
+  "2": "The database connection is not active.",
   "3": "Operation timeout.",
   "4": "Operation blocked.",
   "5": "Storage quota exceeded.",
@@ -20,6 +20,7 @@
   "110": "Attempt to import into a non-empty database.",
   "111": "Database name/version mismatch for import.",
   "112": "Import data not found.",
+  "113": "Attempt to call connect() on an already opened DB connection.",
 
   "200": "Constraint error",
   "201": "Duplicate keys are not allowed.",

docs/spec/03_life_of_db.md

@@ -23,7 +23,8 @@ It will do the following:
 `connect()` shall be called only once each session. In rare circumstances,
 one can call `close()` on the opened connection first, then call `connect()`
 again. However, this is not guaranteed to work due to IndexedDB limitations,
-see [Data Store](02_data_store.md) for details.
+see [Data Store](02_data_store.md) for details. Calling `connect()` when an
+open connection exists will result in an exception.
 
 Users are free to connect to two or more databases simultaneously in the same
 session. Users shall not connect to the same database more than once in the same

lib/proc/database.js

@@ -44,8 +44,11 @@ lf.proc.Database = function(global) {
   /** @private {!lf.schema.Database} */
   this.schema_ = global.getService(lf.service.SCHEMA);
 
-  /** @private {boolean} */
-  this.initialized_ = false;
+  /**
+   * Whether this connection to the database is active.
+   * @private {boolean}
+   */
+  this.isActive_ = false;
 
   /** @private {!lf.proc.Runner} */
   this.runner_;
@@ -64,7 +67,7 @@ lf.proc.Database.prototype.init = function(opt_options) {
 
   return /** @type  {!IThenable<!lf.proc.Database>} */ (
       lf.base.init(this.global_, opt_options).then(function() {
-        this.initialized_ = true;
+        this.isActive_ = true;
         this.runner_ = this.global_.getService(lf.service.RUNNER);
         return this;
       }.bind(this)));
@@ -78,17 +81,17 @@ lf.proc.Database.prototype.getSchema = function() {
 
 
 /** @private */
-lf.proc.Database.prototype.checkInit_ = function() {
-  if (!this.initialized_) {
-    // 2: The database has not initialized yet.
+lf.proc.Database.prototype.checkActive_ = function() {
+  if (!this.isActive_) {
+    // 2: The database connection is not active.
     throw new lf.Exception(2);
   }
 };
 
 
 /** @override @export */
 lf.proc.Database.prototype.select = function(var_args) {
-  this.checkInit_();
+  this.checkActive_();
   var columns =
       arguments.length == 1 && !goog.isDefAndNotNull(arguments[0]) ?
       [] : Array.prototype.slice.call(arguments);
@@ -98,35 +101,35 @@ lf.proc.Database.prototype.select = function(var_args) {
 
 /** @override @export */
 lf.proc.Database.prototype.insert = function() {
-  this.checkInit_();
+  this.checkActive_();
   return new lf.query.InsertBuilder(this.global_);
 };
 
 
 /** @override @export */
 lf.proc.Database.prototype.insertOrReplace = function() {
-  this.checkInit_();
+  this.checkActive_();
   return new lf.query.InsertBuilder(this.global_, /* allowReplace */ true);
 };
 
 
 /** @override @export */
 lf.proc.Database.prototype.update = function(table) {
-  this.checkInit_();
+  this.checkActive_();
   return new lf.query.UpdateBuilder(this.global_, table);
 };
 
 
 /** @override @export */
 lf.proc.Database.prototype.delete = function() {
-  this.checkInit_();
+  this.checkActive_();
   return new lf.query.DeleteBuilder(this.global_);
 };
 
 
 /** @override @export */
 lf.proc.Database.prototype.observe = function(query, callback) {
-  this.checkInit_();
+  this.checkActive_();
   var observerRegistry = this.global_.getService(
       lf.service.OBSERVER_REGISTRY);
   observerRegistry.addObserver(query, callback);
@@ -135,7 +138,7 @@ lf.proc.Database.prototype.observe = function(query, callback) {
 
 /** @override @export */
 lf.proc.Database.prototype.unobserve = function(query, callback) {
-  this.checkInit_();
+  this.checkActive_();
   var observerRegistry = this.global_.getService(
       lf.service.OBSERVER_REGISTRY);
   observerRegistry.removeObserver(query, callback);
@@ -144,7 +147,7 @@ lf.proc.Database.prototype.unobserve = function(query, callback) {
 
 /** @override @export */
 lf.proc.Database.prototype.createTransaction = function(opt_type) {
-  this.checkInit_();
+  this.checkActive_();
   return new lf.proc.Transaction(this.global_);
 };
 
@@ -153,13 +156,13 @@ lf.proc.Database.prototype.createTransaction = function(opt_type) {
 lf.proc.Database.prototype.close = function() {
   lf.base.closeDatabase(this.global_);
   this.global_.clear();
-  this.initialized_ = false;
+  this.isActive_ = false;
 };
 
 
 /** @override @export */
 lf.proc.Database.prototype.export = function() {
-  this.checkInit_();
+  this.checkActive_();
   var task = new lf.proc.ExportTask(this.global_);
   return this.runner_.scheduleTask(task).then(function(results) {
     return results[0].getPayloads()[0];
@@ -169,9 +172,15 @@ lf.proc.Database.prototype.export = function() {
 
 /** @override @export */
 lf.proc.Database.prototype.import = function(data) {
-  this.checkInit_();
+  this.checkActive_();
   var task = new lf.proc.ImportTask(this.global_, data);
   return this.runner_.scheduleTask(task).then(function() {
     return null;
   });
 };
+
+
+/** @return {boolean} */
+lf.proc.Database.prototype.isOpen = function() {
+  return this.isActive_;
+};

lib/schema/builder.js

@@ -48,6 +48,9 @@ lf.schema.Builder = function(dbName, dbVersion) {
 
   /** @private {boolean} */
   this.finalized_ = false;
+
+  /** @private {?lf.proc.Database} */
+  this.db_ = null;
 };
 
 
@@ -238,18 +241,27 @@ lf.schema.Builder.prototype.getGlobal = function() {
 
 
 /**
+ * Instantiates a connection to the database. Note: This method can only be
+ * called once per Builder instance. Subsequent calls will throw an error.
  * @param {!lf.schema.ConnectOptions=} opt_options
  * @return {!IThenable<!lf.proc.Database>}
  * @export
  */
 lf.schema.Builder.prototype.connect = function(opt_options) {
-  var global = this.getGlobal();
-  if (!global.isRegistered(lf.service.SCHEMA)) {
-    global.registerService(lf.service.SCHEMA, this.getSchema());
+  if (!goog.isNull(this.db_) && this.db_.isOpen()) {
+    // 113: Attempt to call connect() on an already opened DB connection.
+    throw new lf.Exception(113);
+  }
+
+  if (goog.isNull(this.db_)) {
+    var global = this.getGlobal();
+    if (!global.isRegistered(lf.service.SCHEMA)) {
+      global.registerService(lf.service.SCHEMA, this.getSchema());
+    }
+    this.db_ = new lf.proc.Database(global);
   }
 
-  var db = new lf.proc.Database(global);
-  return db.init(opt_options);
+  return this.db_.init(opt_options);
 };
 
 

spac/template/database.jstemplate

@@ -4,6 +4,7 @@ goog.provide('#namespace');
 
 /// #sort
 goog.require('#namespace.schema.Database');
+goog.require('lf.Exception');
 goog.require('lf.Global');
 /** @suppress {extraRequire} */
 goog.require('lf.fn');
@@ -51,7 +52,19 @@ goog.require('lf.service.ServiceId');
  * @return {!IThenable<!lf.proc.Database>}
  */
 #namespace.connect = function(opt_options) {
-  #namespace.getSchema();
-  var db = new lf.proc.Database(#namespace.getGlobal());
-  return db.init(opt_options);
+  if (!goog.isNull(#namespace.db_) && #namespace.db_.isOpen()) {
+    // 113: Attempt to call connect() on an already opened DB connection.
+    throw new lf.Exception(113);
+  }
+
+  if (goog.isNull(#namespace.db_)) {
+    #namespace.getSchema();
+    #namespace.db_ = new lf.proc.Database(#namespace.getGlobal());
+  }
+
+  return #namespace.db_.init(opt_options);
 };
+
+
+/** @private {?lf.proc.Database} */
+#namespace.db_ = null;

spac/testdata/database.js

@@ -1,5 +1,6 @@
 goog.provide('lovefield.db');
 
+goog.require('lf.Exception');
 goog.require('lf.Global');
 /** @suppress {extraRequire} */
 goog.require('lf.fn');
@@ -47,7 +48,19 @@ lovefield.db.getSchema = function() {
  * @return {!IThenable<!lf.proc.Database>}
  */
 lovefield.db.connect = function(opt_options) {
-  lovefield.db.getSchema();
-  var db = new lf.proc.Database(lovefield.db.getGlobal());
-  return db.init(opt_options);
+  if (!goog.isNull(lovefield.db.db_) && lovefield.db.db_.isOpen()) {
+    // 113: Attempt to call connect() on an already opened DB connection.
+    throw new lf.Exception(113);
+  }
+
+  if (goog.isNull(lovefield.db.db_)) {
+    lovefield.db.getSchema();
+    lovefield.db.db_ = new lf.proc.Database(lovefield.db.getGlobal());
+  }
+
+  return lovefield.db.db_.init(opt_options);
 };
+
+
+/** @private {?lf.proc.Database} */
+lovefield.db.db_ = null;

tests/backstore/external_change_observer_test.js

@@ -78,6 +78,11 @@ function setUp() {
 }
 
 
+function tearDown() {
+  db.close();
+}
+
+
 function testExternalChangesApplied() {
   asyncTestCase.waitForAsync('testExternalChangesApplied');
 

tests/base/simulate_error_test.js

@@ -49,6 +49,11 @@ function setUp() {
 }
 
 
+function tearDown() {
+  db.close();
+}
+
+
 /**
  * Tests that when simulateErrors has been called BaseBuilder#exec() rejects.
  */

tests/pred/combined_predicate_test.js

@@ -59,6 +59,11 @@ function setUp() {
 }
 
 
+function tearDown() {
+  db.close();
+}
+
+
 /**
  * Tests that copy() creates an identical tree where each node is a new
  * instance.

tests/pred/join_predicate_test.js

@@ -83,6 +83,11 @@ function setUp() {
 }
 
 
+function tearDown() {
+  db.close();
+}
+
+
 function testCopy() {
   var original = e.jobId.eq(j.id);
   var copy = original.copy();

tests/pred/not_operator_test.js

@@ -55,6 +55,11 @@ function setUp() {
 }
 
 
+function tearDown() {
+  db.close();
+}
+
+
 /**
  * Deletes the contents of all tables.
  * @return {!IThenable}

tests/pred/null_predicate_test.js

@@ -50,6 +50,11 @@ function setUp() {
 }
 
 
+function tearDown() {
+  db.close();
+}
+
+
 /**
  * Deletes the contents of all tables.
  * @return {!IThenable}

tests/proc/aggregation_step_test.js

@@ -26,7 +26,6 @@ goog.require('lf.pred.JoinPredicate');
 goog.require('lf.proc.AggregationStep');
 goog.require('lf.proc.NoOpStep');
 goog.require('lf.proc.Relation');
-goog.require('lf.schema.DataStoreType');
 goog.require('lf.testing.NullableDataGenerator');
 goog.require('lf.testing.hrSchema.MockDataGenerator');
 
@@ -82,13 +81,11 @@ function testFloatEquals(expected, value) {
 
 
 function setUp() {
-  asyncTestCase.waitForAsync('setUp');
   var schema = hr.db.getSchema();
   j = schema.getJob();
   e = schema.getEmployee();
   dataGenerator = new lf.testing.hrSchema.MockDataGenerator(schema);
   dataGenerator.generate(20, 100, 0);
-  hr.db.connect({storeType: lf.schema.DataStoreType.MEMORY});
 
   // For the tests involving nullable integer columns, a different schema
   // is created. The tables in hr schema do not handle nullable integer
@@ -98,10 +95,6 @@ function setUp() {
   nullableGenerator = new
       lf.testing.NullableDataGenerator(schemaWithNullable);
   nullableGenerator.generate();
-  schemaBuilder.connect({storeType: lf.schema.DataStoreType.MEMORY}).
-      then(function() {
-            asyncTestCase.continueTesting();
-          });
 }
 
 

tests/proc/end_to_end_test.js

@@ -76,15 +76,13 @@ function testEndToEnd_StaticSchemaBundled() {
   }
 
   asyncTestCase.waitForAsync('testEndToEnd_StaticSchemaBundled');
-  var dbGlobal;
-
+  var dbGlobal = new lf.Global();
   var globalFn = function() {
     return dbGlobal;
   };
   var connectFn = function() {
     stub.reset();
     var dbName = 'hrbdb' + goog.now();
-    dbGlobal = new lf.Global();
     stub.replace(
         goog.getObjectByName('hr.bdb.schema.Database.prototype'),
         'name',