flutter_isolatev2

Description:

flutter isolatev2

FlutterIsolate #
FlutterIsolate allows creation of an Isolate in flutter that is able to use flutter plugins. It creates the necessary platform specific bits (FlutterBackgroundView on android & FlutterEngine on iOS) to enable the platform channels to work inside an isolate.
FlutterIsolate API #




Android
iOS
Description




FlutterIsolate.spawn(entryPoint,message)
✅
✅
spawns a new FlutterIsolate


FlutterIsolate.pause()
✅
✅
pauses a running isolate


FlutterIsolate.resume()
✅
✅
resumed a paused isoalte


FlutterIsolate.kill()
✅
✅
kills a an isolate


FlutterIsolate.killAll()
✅
✅
kills all currently running isolates


FlutterIsolate.runningIsolates
✅
✅
returns the IDs associated with all currently running isolates



Usage #
import 'package:flutter_startup/flutter_startup.dart';
import 'package:flutter_isolate/flutter_isolate.dart';

void isolate2(String arg) {
FlutterStartup.startupReason.then((reason){
print("Isolate2 $reason");
});
Timer.periodic(Duration(seconds:1),(timer)=>print("Timer Running From Isolate 2"));
}

void isolate1(String arg) async {

final isolate = await FlutterIsolate.spawn(isolate2, "hello2");

FlutterStartup.startupReason.then((reason){
print("Isolate1 $reason");
});
Timer.periodic(Duration(seconds:1),(timer)=>print("Timer Running From Isolate 1"));
}

void main() async {
WidgetsFlutterBinding.ensureInitialized();

final isolate = await FlutterIsolate.spawn(isolate1, "hello");
Timer(Duration(seconds:5), (){print("Pausing Isolate 1");isolate.pause();});
Timer(Duration(seconds:10),(){print("Resuming Isolate 1");isolate.resume();});
Timer(Duration(seconds:20),(){print("Killing Isolate 1");isolate.kill();});

runApp(MyApp());
}
...
copied to clipboard
See example/lib/main.dart for example usage with the flutter_downloader plugin.
It is important to note that the entrypoint must be a top-level function:
void topLevelFunction(Map<String, dynamic> args) {
// performs work in an isolate
}

class MyApp extends StatefulWidget {
@override
_MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {

@override
void initState() {
FlutterIsolate.spawn(topLevelFunction, {});
super.initState();
}
Widget build(BuildContext context) {
return Container();
}
}
copied to clipboard
or a static method:
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {

static void topLevelFunction(Map<String, dynamic> args) {
// performs work in an isolate
}

@override
void initState() {
FlutterIsolate.spawn(_MyAppState.staticMethod, {});
super.initState();
}
Widget build(BuildContext context) {
return Container();
}
}
copied to clipboard
A class-level method will not work and will throw an Exception:
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {


void classMethod(Map<String, dynamic> args) {
// don't do this!
}

@override
void initState() {

FlutterIsolate.spawn(classMethod, {}); // this will throw NoSuchMethodError: The method 'toRawHandle' was called on null.
super.initState();
}
Widget build(BuildContext context) {
return Container();
}
}
copied to clipboard
Notes #
Due to a FlutterIsolate being backed by a platform specific 'view', the event loop will not terminate when there is no more 'user' work left to do and FlutterIsolates will require explict termination with kill().
Additionally this plugin has not been tested with a large range of plugins, only a small subset I have been using such as flutter_notification, flutter_blue and flutter_startup.
Communicating between isolates #
To pass data between isolates, a ReceivePort should be created on your (parent) isolate with the corresponding SendPort sent via the spawn method:
void spawnIsolate(SendPort port) {
port.send("Hello!");
}

void main() {
var port = ReceivePort();
port.listen((msg) {
print("Received message from isolate $msg");
});
var isolate = await FlutterIsolate.spawn(spawnIsolate, port.sendPort);

}
copied to clipboard
Only primitives can be sent via a SendPort - see the SendPort documentation for further details.
Custom plugin registrant #
See the example project for a sample implementation using a custom plugin registrant.
iOS
By default, flutter_isolate will register all plugins provided by Flutter's automatically generated GeneratedPluginRegistrant.m file.
If you want to register, e.g. some custom FlutterMethodChannels, you can define a custom registrant:
// Defines a custom plugin registrant, to be used specifically together with FlutterIsolatePlugin
@objc(IsolatePluginRegistrant) class IsolatePluginRegistrant: NSObject {
@objc static func register(withRegistry registry: FlutterPluginRegistry) {
// Register channels for Flutter Isolate
registerMethodChannelABC(bm: registry.registrar(forPlugin: "net.myapp.myChannelABC").messenger())

// Register default plugins
GeneratedPluginRegistrant.register(with: registry)
}
}

// In AppDelegate.swift
@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
override func application(
_ application: UIApplication,
didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
) -> Bool {
let controller = window.rootViewController as! FlutterViewController

// Register custom channels for Flutter
registerMethodChannelABC(bm: controller.binaryMessenger) // <-- the custom method channel

// Point FlutterIsolatePlugin to use our previously defined custom registrant.
// The string content must be equal to the plugin registrant class annotation
// value: @objc(IsolatePluginRegistrant)
FlutterIsolatePlugin.isolatePluginRegistrantClassName = "IsolatePluginRegistrant" // <--

GeneratedPluginRegistrant.register(with: self)
return super.application(application, didFinishLaunchingWithOptions: launchOptions)
}
}
copied to clipboard
Android
Define a custom plugin registrant, to be used specifically together with FlutterIsolatePlugin:
public final class CustomPluginRegistrant {
public static void registerWith(@NonNull FlutterEngine flutterEngine) {
flutterEngine.getPlugins().add(... [your plugin goes here]);
}
}
copied to clipboard
Create a MainApplication class that sets this custom isolate registrant:
public class MainApplication extends FlutterApplication {
public MainApplication() {
FlutterIsolatePlugin.setCustomIsolateRegistrant(CustomPluginRegistrant.class);
}
}
copied to clipboard