Store - add constructor from an existing C pointer to allow sharing store between multiple isolates

Author: vaind

lib/src/store.dart

@@ -92,6 +92,8 @@ class Store {
     }
   }
 
+  Store.fromPtr(this.defs, this._cStore);
+
   /// Closes this store.
   ///
   /// Don't try to call any other ObjectBox methods after the store is closed.

test/isolates_test.dart

@@ -0,0 +1,125 @@
+import 'dart:async';
+import 'dart:ffi';
+import 'dart:isolate';
+
+import 'package:objectbox/src/bindings/bindings.dart';
+import 'package:test/test.dart';
+
+import 'entity.dart';
+import 'objectbox.g.dart';
+import 'test_env.dart';
+
+// We want to have types explicit - verifying the return types of functions.
+// ignore_for_file: omit_local_variable_types
+void main() {
+  /// Set up a simple echo isolate with request-response communication.
+  /// This isn't really a test, just an example of how isolates can communicate.
+  test('isolates two-way communication example', () async {
+    var receivePort = ReceivePort();
+    await Isolate.spawn(echoIsolate, receivePort.sendPort);
+
+    Completer sendPortCompleter = Completer<SendPort>();
+    Completer responseCompleter;
+    receivePort.listen((data) {
+      if (data is SendPort) {
+        sendPortCompleter.complete(data);
+      } else {
+        print('Main received: $data');
+        responseCompleter.complete(data);
+      }
+    });
+
+    // Receive the SendPort from the Isolate
+    SendPort sendPort = await sendPortCompleter.future;
+
+    final call = (message) {
+      responseCompleter = Completer<String>();
+      sendPort.send(message);
+      return responseCompleter.future;
+    };
+
+    // Send a message to the isolate
+    expect(await call('hello'), equals('re:hello'));
+    expect(await call('foo'), equals('re:foo'));
+  });
+
+  /// Work with a single store accross multiple isolates
+  test('single store in multiple isolates', () async {
+    var receivePort = ReceivePort();
+    await Isolate.spawn(createDataIsolate, receivePort.sendPort);
+
+    final sendPortCompleter = Completer<SendPort>();
+    Completer<dynamic> responseCompleter;
+    receivePort.listen((data) {
+      if (data is SendPort) {
+        sendPortCompleter.complete(data);
+      } else {
+        print('Main received: $data');
+        responseCompleter.complete(data);
+      }
+    });
+
+    // Receive the SendPort from the Isolate
+    SendPort sendPort = await sendPortCompleter.future;
+
+    final call = (message) {
+      responseCompleter = Completer<dynamic>();
+      sendPort.send(message);
+      return responseCompleter.future;
+    };
+
+    // Pass the store to the isolate
+    final env = TestEnv('isolates');
+    expect(await call(env.store.ptr.address), equals('store set'));
+
+    expect(env.box.isEmpty(), isTrue);
+    expect(await call(['put', 'Foo']), equals(1)); // returns inserted id = 1
+    expect(env.box.get(1).tString, equals('Foo'));
+  });
+}
+
+// Echoes back any received message.
+void echoIsolate(SendPort sendPort) async {
+  // Open the ReceivePort to listen for incoming messages
+  var port = ReceivePort();
+
+  // Send the port where the main isolate can contact us
+  sendPort.send(port.sendPort);
+
+  // Listen for messages
+  await for (var data in port) {
+    // `data` is the message received.
+    print('Isolate received: $data');
+    sendPort.send('re:$data');
+  }
+}
+
+// Creates data in the background, in the [Store] received as the first message.
+void createDataIsolate(SendPort sendPort) async {
+  // Open the ReceivePort to listen for incoming messages
+  var port = ReceivePort();
+
+  // Send the port where the main isolate can contact us
+  sendPort.send(port.sendPort);
+
+  TestEnv env;
+  // Listen for messages
+  await for (var data in port) {
+    if (env == null) {
+      // first message data is Store's C pointer address
+      env = TestEnv.fromPtr(Pointer<OBX_store>.fromAddress(data));
+      sendPort.send('store set');
+    } else {
+      print('Isolate received: $data');
+      if (data is! List) {
+        sendPort.send('unknown message type, list expected');
+      } else {
+        switch (data[0]) {
+          case 'put':
+            final id = env.box.put(TestEntity(tString: data[1]));
+            sendPort.send(id);
+        }
+      }
+    }
+  }
+}

test/test_env.dart

@@ -1,4 +1,7 @@
+import 'dart:ffi';
 import 'dart:io';
+import 'package:objectbox/src/bindings/bindings.dart';
+
 import 'entity.dart';
 import 'objectbox.g.dart';
 
@@ -14,9 +17,14 @@ class TestEnv {
     box = Box<TestEntity>(store);
   }
 
+  TestEnv.fromPtr(Pointer<OBX_store> cStore) : dir = null {
+    store = Store.fromPtr(getObjectBoxModel(), cStore);
+    box = Box<TestEntity>(store);
+  }
+
   void close() {
     store.close();
-    if (dir.existsSync()) dir.deleteSync(recursive: true);
+    if (dir != null && dir.existsSync()) dir.deleteSync(recursive: true);
   }
 }