isolator 1.0.1
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Isolator is a package, which offer to you a simple way for creating two-component states with isolated part and frontend part of any kind - BLoC, MobX, ChangeNotifier and others

isolator #

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Isolator is a package, which offer to you a simple way for creating two-component states with isolated part and frontend part of any kind (BLoC, MobX, ChangeNotifier and many others). With this package you can take out all business logic from main thread (main isolate) in separated isolates with easiest way to do this.

This package is a proofed in production concept, when you take out heavy business logic to isolates for achievement a fully cleared from any junks application. With this package you can easy create a so-called "Backend" - class with your logic and second class, which uses a special mixin "Frontend" - a state of any kind - BLoC / MobX / ChangeNotifier (as in an example).

Possibilities:

  1. Send events from Frontend to Backend
  2. Call Backend's method in synchronous style from Frontend
  3. Subscribe on events, which Frontend can handle
  4. Have a hook, which will run on every new event in Frontend
  5. Send large data from Backend to Frontend via chunks automatically
  6. Send events between Backends
  7. Call Backend's method in synchronous style from another Backend
  8. Have always stable 60 / 90 / 120 / 144 and more FPS of your app

Example of interaction between Frontend and Backend #

import 'package:flutter/cupertino.dart';
import 'package:isolator/isolator.dart';

/// Values for tests
const int VALUE_AFTER_CREATION = 11;
const int ASYNC_INT = 10;
const int SYNC_INT = 12;

enum TestEvent {
  intSync,
  intAsync,
  intAsyncWithReturn,
  chunks,
  observer,
  errorOnBackend,
  invalidType,
  afterCreation,
  chunksCancel,
}

/// Frontend - anything else, what you want to use a state of your app
class FrontendTest with Frontend<TestEvent>, ChangeNotifier {
  int asyncIntFromBackend = 0;
  int syncIntFromBackend = 0;
  int valueAfterCreation = 0;
  bool isErrorHandled = false;
  List<int> intChunks = [];
  List<int> intChunksCancel = [];

  /// You can get any value (after calculating it on the backend) in synchronous style
  /// When you using [runBackendMethod] function - you call your Backend's method, which
  /// matches the passed event id, and get back value in that place
  ///
  /// It most simplest way to use Isolator
  Future<int> getValueFromBackendSynchronously() async {
    final int intFromBackend = await runBackendMethod(TestEvent.intSync);
    syncIntFromBackend = intFromBackend;
    return syncIntFromBackend;
  }

  /// Also, you can use asynchronous style
  /// It is the way, when you send some params (with event id) to Backend
  /// Then, Backend handle it, and after that you handle Backend response via Frontend task
  void sendEventToBackend() {
    send(TestEvent.intAsync);
  }

  /// You can return value from backend with simple "return" keyword
  /// without using [send] method of your Backend
  /// To see that - open [_returnIntBack] method of [BackendTest]
  void sendEventToBackendAndReturnResponseOnBackend() {
    send(TestEvent.intAsyncWithReturn);
  }

  /// When you want get a large amount of data from the Backend
  /// You can use [sendChunks] method of the Backend
  /// For example - see method [_returnChunks] of [BackendTest]
  void loadChunks() {
    send(TestEvent.chunks);
  }

  /// If you start loading 1th portion of chunks
  /// and does not finished it before loading 2th
  /// portion - 1th portion loading should be stopping
  /// 1th transaction will aborted
  void loadChunksWithCanceling() {
    send(TestEvent.chunksCancel);
  }

  /// This method need for test cases
  void invalidType() {
    send(TestEvent.invalidType);
  }

  /// This method need for test cases
  void runError() {
    send(TestEvent.errorOnBackend);
  }

  /// It is a task for handle Backend response
  /// for event id [TestEvent.intAsync]
  void _setValueFromBackend(int intFromBackend) {
    this.asyncIntFromBackend = intFromBackend;
  }

  /// Task for handle [sendChunks] event must take a [List] of data
  void _setIntChunks(List<int> intChunks) {
    this.intChunks.clear();
    this.intChunks.addAll(intChunks);
  }

  void _setIntChunksCancel(List<int> intChunks) {
    this.intChunksCancel.clear();
    this.intChunksCancel.addAll(intChunks);
  }

  /// This method need for test cases
  void _taskWithInvalidType(String intFromBackend) {
    // WAITING FOR ERROR
  }

  /// This method need for test cases
  void _handleError(dynamic error) {
    isErrorHandled = true;
  }

  /// This method need for test cases
  void _setValueAfterCreation(int valueAfterCreation) {
    this.valueAfterCreation = valueAfterCreation;
  }

  /// Before using Backend with Frontend, you should init your Backend
  /// To do this - simple use [initBackend] method of your Frontend
  Future<void> init(int id) async {
    await initBackend<int>(_backendFabric, data: VALUE_AFTER_CREATION, backendType: BackendTest, uniqueId: '$id');
  }

  /// If you want to destroy Backend - use [killBackend] method
  /// It can be useful, if your state lifetime is shorter than lifetime of app
  void kill() {
    killBackend();
  }

  /// Hook, which calls on every error
  /// Which throws in the Backend
  @override
  Future<void> onError(dynamic error) async {
    print(error);
  }

  /// Hook, which calls on every event from the Backend
  @override
  void onBackendResponse() {
    notifyListeners();
  }

  /// [tasks] - Map of methods, which calls on events with
  /// matched ids from Backend
  @override
  Map<TestEvent, Function> get tasks => {
        TestEvent.intAsync: _setValueFromBackend,
        TestEvent.intAsyncWithReturn: _setValueFromBackend,
        TestEvent.chunks: _setIntChunks,
        TestEvent.chunksCancel: _setIntChunksCancel,
        TestEvent.invalidType: _taskWithInvalidType,
        TestEvent.afterCreation: _setValueAfterCreation,
      };

  /// [errorsHandlers] - Map of methods, which calls, if error
  /// was thrown in the Backend, while Backend handle operation
  /// with matched event id
  @override
  Map<TestEvent, ErrorHandler> get errorsHandlers => {
        TestEvent.errorOnBackend: _handleError,
      };
}

/// Backend - class, which will handle your logic in separate isolate
class BackendTest extends Backend<TestEvent> {
  BackendTest(BackendArgument<int> argument) : super(argument) {
    _sendValueAfterCreation(argument.data!);
  }

  int counterOfChunksCancel = 0;

  /// You can send value to the Frontend with [send] method
  /// Also, you can use this method any times in all of you Backend methods
  void _sendIntBack() {
    send(TestEvent.intAsync, ASYNC_INT);
    send(TestEvent.observer);
  }

  /// Or you can simply return the value and your Frontend will receive a message with exact event id
  /// For example - there Frontend will receive event [TestEvent.intAsyncWithReturn] with value [ASYNC_INT]
  int _returnIntBack() {
    return ASYNC_INT;
  }

  void _sendValueAfterCreation(int value) {
    send(TestEvent.afterCreation, value);
  }

  int _returnSyncInt() {
    return SYNC_INT;
  }

  int _returnValue() {
    return SYNC_INT;
  }

  void _throwError() {
    throw Exception('Manual error');
  }

  /// Example of using [sendChunks] method for sending a large amount of data
  /// from the Backend to the Frontend without junks of your interface
  void _returnChunks() {
    final List<int> chunks = [];
    for (int i = 0; i < 10000; i++) {
      chunks.add(i);
    }

    /// You can control delay between chunks and amount of items in one chunk
    /// to achieve a lowest time for the data transfering and doesn't have any junks
    sendChunks(TestEvent.chunks, chunks, delay: const Duration(milliseconds: 3), itemsPerChunk: 1000);
  }

  void _returnChunksWithCancel() {
    counterOfChunksCancel++;
    final List<int> chunks = [];
    for (int i = 0; i < 10000; i++) {
      if (counterOfChunksCancel > 1) {
        chunks.add(counterOfChunksCancel);
      } else {
        chunks.add(i);
      }
    }
    sendChunks(TestEvent.chunksCancel, chunks, delay: const Duration(milliseconds: 3), itemsPerChunk: 1000);
  }

  /// [operations] - Map of methods, which similar to [tasks] of Frontend
  /// every operation will handle events from the Frontend with matched event id
  @override
  Map<TestEvent, Function> get operations => {
        TestEvent.intAsync: _sendIntBack,
        TestEvent.intAsyncWithReturn: _returnIntBack,
        TestEvent.intSync: _returnSyncInt,
        TestEvent.invalidType: _returnValue,
        TestEvent.errorOnBackend: _throwError,
        TestEvent.chunks: _returnChunks,
        TestEvent.chunksCancel: _returnChunksWithCancel,
      };
}

class AnotherFrontend {
  AnotherFrontend(this.frontendTest);

  final FrontendTest frontendTest;
  int intFromFrontendTest = 0;

  void subscriptionForFrontendTest() {
    this.intFromFrontendTest = frontendTest.asyncIntFromBackend;
  }

  /// You can subscribe on every available (your) event of your Frontend
  void subscribe() {
    frontendTest.onEvent(TestEvent.observer, subscriptionForFrontendTest);
  }
}

void _backendFabric(BackendArgument<int> argument) {
  BackendTest(argument);
}

Exampe of interaction between Backend and Backend #

First Backend #

import 'package:isolator/isolator.dart';

import 'another_test_states.dart';

/// Values for tests
const int OPERATION_VALUE = 89;
const int HANDLER_VALUE = 63;
const int BACK_VALUE = 812;

enum OneEvents {
  setValue,
  notificationOperation,
  notificationHandler,
  bidirectional,
  computeValue,
  computeValueOperation,
}

class OneTestFrontend with Frontend<OneEvents> {
  int value = 0;

  void setValue(int newValue) {
    value = newValue;
  }

  Future<void> init() async {
    await initBackend(createOneBackend, backendType: OneTestBackend);
  }

  void dispose() {
    killBackend();
  }

  @override
  Map<OneEvents, Function> get tasks {
    return {
      OneEvents.setValue: setValue,
    };
  }
}

class OneTestBackend extends Backend<OneEvents> {
  OneTestBackend(BackendArgument<void> argument) : super(argument);

  void _setValueWithOperation() {
    send(OneEvents.setValue, OPERATION_VALUE);
  }

  void _setValueWithHandler(int value) {
    send(OneEvents.setValue, HANDLER_VALUE + value);
  }

  void _setValueWithHandlerAndSendItBack(int value) {
    send(OneEvents.setValue, HANDLER_VALUE + value);
    sendToAnotherBackend(AnotherTestBackend, AnotherEvents.bidirectionalNotificationBack, HANDLER_VALUE + value);
  }

  int _returnBackValue(int value) {
    return BACK_VALUE + value;
  }

  @override
  Map<OneEvents, Function> get operations {
    return {
      OneEvents.notificationOperation: _setValueWithOperation,
      OneEvents.computeValueOperation: _returnBackValue,
    };
  }

  /// [busHandlers] are similar to [operations], but have any type of key and was made for
  /// being called from another isolates BUT
  /// also, you can call operation from different isolates too
  @override
  Map<dynamic, Function> get busHandlers {
    return {
      OneEvents.notificationHandler: _setValueWithHandler,
      OneEvents.bidirectional: _setValueWithHandlerAndSendItBack,
      OneEvents.computeValue: _returnBackValue,
    };
  }
}

void createOneBackend(BackendArgument<void> argument) {
  OneTestBackend(argument);
}

Second Backend #

import 'package:isolator/isolator.dart';

import 'one_test_states.dart';

/// Values for tests
const int VALUE_TO_ONE_BACKEND = 28;
const int BIDIRECTIONAL_VALUE = 158;
const int SYNC_VALUE = 451;

enum AnotherEvents {
  notificationOperation,
  notificationHandler,
  bidirectionalNotification,
  bidirectionalNotificationBack,
  computeHandler,
  computeOperation,
  setValue,
}

class AnotherTestFrontend with Frontend<AnotherEvents> {
  int valueFromBackend = 0;

  void _setValue(int value) {
    valueFromBackend = value;
  }

  void callNotificationOperation() {
    send(AnotherEvents.notificationOperation);
  }

  void callNotificationHandler() {
    send(AnotherEvents.notificationHandler);
  }

  void callBidirectionalNotificationHandler() {
    send(AnotherEvents.bidirectionalNotification, BIDIRECTIONAL_VALUE);
  }

  void callOneBackendHandlerMethod() {
    send(AnotherEvents.computeHandler, SYNC_VALUE);
  }

  void callOneBackendOperationMethod() {
    send(AnotherEvents.computeOperation, SYNC_VALUE);
  }

  Future<void> init() async {
    await initBackend(createAnotherBackend, backendType: AnotherTestBackend);
  }

  void dispose() {
    killBackend();
  }

  @override
  Map<AnotherEvents, Function> get tasks {
    return {
      AnotherEvents.setValue: _setValue,
    };
  }
}

class AnotherTestBackend extends Backend<AnotherEvents> {
  AnotherTestBackend(BackendArgument<void> argument) : super(argument);

  /// Send message to different Backend with calling one of [operations] methods
  void notificationOperation() {
    sendToAnotherBackend(OneTestBackend, OneEvents.notificationOperation);
  }

  /// Send message to different Backend with calling one of [busHandlers] methods
  void notificationHandler() {
    sendToAnotherBackend(OneTestBackend, OneEvents.notificationHandler, VALUE_TO_ONE_BACKEND);
  }

  /// Send message to different Backend and getting message back
  void bidirectionalNotification(int value) {
    sendToAnotherBackend(OneTestBackend, OneEvents.bidirectional, value);
  }

  /// Getting message back from different Backend
  void bidirectionalNotificationBack(int value) {
    send(AnotherEvents.setValue, value);
  }

  /// Call one of [busHandlers] methods of different backend in synchronous style
  Future<void> callOneBackendHandlerMethod(int value) async {
    final int valueFromOneBackend = await runAnotherBackendMethod(OneTestBackend, OneEvents.computeValue, value);
    send(AnotherEvents.setValue, valueFromOneBackend);
  }

  /// Call one of [operations] methods of different backend in synchronous style
  Future<void> callOneBackendOperationMethod(int value) async {
    final int valueFromOneBackend = await runAnotherBackendMethod(OneTestBackend, OneEvents.computeValueOperation, value);
    send(AnotherEvents.setValue, valueFromOneBackend);
  }

  @override
  Map<AnotherEvents, Function> get operations {
    return {
      AnotherEvents.notificationOperation: notificationOperation,
      AnotherEvents.notificationHandler: notificationHandler,
      AnotherEvents.bidirectionalNotification: bidirectionalNotification,
      AnotherEvents.bidirectionalNotificationBack: bidirectionalNotificationBack,
      AnotherEvents.computeHandler: callOneBackendHandlerMethod,
      AnotherEvents.computeOperation: callOneBackendOperationMethod,
    };
  }
}

void createAnotherBackend(BackendArgument<void> argument) {
  AnotherTestBackend(argument);
}

Restrictions #

  • Backend classes can't use a native layer (method-channel)
  • For one backend - one isolate (too many isolates take much time for initialization, for example: ~6000ms for 30 isolates at emulator in dev mode if do it coherently)

Schema of interaction #

Schema

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Publisher

alphamikle.dev

Isolator is a package, which offer to you a simple way for creating two-component states with isolated part and frontend part of any kind - BLoC, MobX, ChangeNotifier and others

Repository (GitHub)
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Documentation

API reference

License

MIT (LICENSE)

Dependencies

flutter, pedantic

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