Page three data transfer (#105)

isolate_example/lib/main.dart

@@ -41,7 +41,7 @@ class StartApp extends StatelessWidget {
             children: [
               PerformancePage(),
               InfiniteProcessPageStarter(),
-              DataTransferPage(),
+              DataTransferPageStarter(),
             ],
           ),
         ),

isolate_example/lib/page_three.dart

@@ -11,14 +11,239 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
-
 import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+import 'dart:isolate';
+import 'dart:math';
 
-class DataTransferPage extends StatelessWidget {
+class DataTransferPageStarter extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
-    return Center(
-      child: Text('Welcome to the Data Transfer Page'),
+    return ChangeNotifierProvider(
+      builder: (context) => DataTransferIsolateController(),
+      child: DataTransferPage(),
     );
   }
 }
+
+class DataTransferPage extends StatelessWidget {
+  @override
+  Widget build(context) {
+    return SafeArea(
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          Container(
+            child: Text(
+              'Number Generator Progress',
+              style: Theme.of(context).textTheme.title,
+            ),
+            padding: EdgeInsets.all(8),
+          ),
+          LinearProgressIndicator(
+            value: Provider.of<DataTransferIsolateController>(context)
+                .progressPercent,
+            backgroundColor: Colors.grey[200],
+          ),
+          Expanded(child: RunningList()),
+          Column(
+            mainAxisSize: MainAxisSize.min,
+            children: [
+              Row(
+                mainAxisAlignment: MainAxisAlignment.center,
+                children: [createButtons(context)],
+              ),
+            ],
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+class DataTransferIsolateController extends ChangeNotifier {
+  Isolate _newIsolate;
+  ReceivePort _mIceRP;
+  SendPort _newIceSP;
+
+  final currentProgress = <String>[];
+  bool running = false;
+  Stopwatch _timer = Stopwatch();
+  double progressPercent = 0;
+
+  DataTransferIsolateController() {
+    createIsolate();
+    listen();
+  }
+
+  Future<void> createIsolate() async {
+    _mIceRP = ReceivePort();
+    _newIsolate =
+        await Isolate.spawn(_secondIsolateEntryPoint, _mIceRP.sendPort);
+  }
+
+  void listen() {
+    _mIceRP.listen((dynamic message) {
+      if (message is SendPort) _newIceSP = message;
+
+      if (message is int) {
+        currentProgress.insert(
+            0, '$message% - ${_timer.elapsedMilliseconds / 1000} Sec');
+        progressPercent = message / 100;
+      }
+
+      if (message is String && message == 'done') {
+        running = false;
+        _timer.stop();
+      }
+
+      notifyListeners();
+    });
+  }
+
+  void generateOnSecondaryIsolate() {
+    if (running) return;
+
+    running = true;
+    _timer.reset();
+    currentProgress.clear();
+
+    _timer.start();
+    _newIceSP.send('start');
+
+    notifyListeners();
+  }
+
+  Future<void> generateRandomNumbers() async {
+    if (running) return;
+
+    running = true;
+    Random rng = Random();
+    _timer = Stopwatch();
+
+    currentProgress.clear();
+    _timer.start();
+
+    List<int> randNums = [];
+    for (int i = 0; i < 100; i++) {
+      randNums.clear();
+
+      for (int j = 0; j < 1000000; j++) {
+        randNums.add(rng.nextInt(100));
+      }
+      await sendNumbers(randNums);
+    }
+  }
+
+  Future<void> sendNumbers(List<int> numList) async {
+    return Future<void>(() {
+      _newIceSP.send(numList);
+    });
+  }
+
+  Isolate get newIsolate => _newIsolate;
+
+  void dispose() {
+    super.dispose();
+    _newIsolate?.kill(priority: Isolate.immediate);
+    _newIsolate = null;
+  }
+}
+
+class RunningList extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    final controller = Provider.of<DataTransferIsolateController>(context);
+    final progress = controller.currentProgress;
+
+    return DecoratedBox(
+      decoration: BoxDecoration(
+        color: Colors.grey[200],
+      ),
+      child: ListView.builder(
+        itemCount: progress.length,
+        itemBuilder: (context, index) {
+          return Column(
+            children: [
+              Card(
+                child: ListTile(
+                  title: Text(progress[index]),
+                ),
+                color: Colors.lightGreenAccent,
+              ),
+              Divider(
+                color: Colors.blue,
+                height: 3,
+              ),
+            ],
+          );
+        },
+      ),
+    );
+  }
+}
+
+Future<void> _secondIsolateEntryPoint(SendPort callerSP) async {
+  ReceivePort newIceRP = ReceivePort();
+  callerSP.send(newIceRP.sendPort);
+
+  newIceRP.listen(
+    (dynamic message) async {
+      if (message is String && message == 'start') {
+        await generateAndSum(callerSP, createNums());
+
+        callerSP.send('done');
+      } else {
+        await generateAndSum(callerSP, message as List<int>);
+
+        callerSP.send('done');
+      }
+    },
+  );
+}
+
+Iterable<int> createNums() sync* {
+  final rng = Random();
+  for (int i = 0; i < 100000000; i++) {
+    yield rng.nextInt(100);
+  }
+}
+
+Future<void> generateAndSum(SendPort callerSP, Iterable<int> iter) async {
+  int sum = 0;
+  int count = 0;
+
+  for (int x in iter) {
+    sum += x;
+    count++;
+    if ((count + 1) % 1000000 == 0) {
+      callerSP.send((count + 1) ~/ 1000000);
+    }
+  }
+
+  return sum;
+}
+
+Widget createButtons(BuildContext context) {
+  final controller =
+      Provider.of<DataTransferIsolateController>(context, listen: false);
+  return ButtonBar(
+    alignment: MainAxisAlignment.center,
+    children: [
+      Column(
+        children: [
+          RaisedButton(
+            child: const Text('Transfer Data to 2nd Isolate'),
+            elevation: 8.0,
+            onPressed: controller.generateRandomNumbers,
+          ),
+          RaisedButton(
+            child: const Text('Generate on 2nd Isolate'),
+            elevation: 8.0,
+            onPressed: controller.generateOnSecondaryIsolate,
+          ),
+        ],
+      ),
+    ],
+  );
+}

isolate_example/lib/page_two.dart

@@ -110,6 +110,7 @@ class InfiniteProcessIsolateController extends ChangeNotifier {
   Future<void> start() async {
     if (_running == false && _paused == false) {
       await createIsolate();
+      if (newIsolate == null) return;
       listen();
       _running = true;
       notifyListeners();