workeredux

Worker Redux — Run Redux reducers and middleware in a Web Worker.

This library makes it trivial to process expensive calculations in a Web Worker while using the Redux pattern you know and love.

If you know Redux, you already know how to use workeredux.

This library is built with TypeScript.

Installation

Using npm:

$ npm i workeredux
$ npm i -D worker-loader

Using Yarn:

$ yarn add workeredux
$ yarn add -D worker-loader

Action Flow via Redux with Web Workers

Actions pass through the Redux reducers and middlewares on the main thread as expected.

The reduxWorkerMiddleware will send Actions marked as WorkerActions to the Worker. If possible, actions will be sent in batches every 33ms.

• Create a WorkerAction with workerActionCreator.
• Mark an Action as a WorkerAction with markWorkerAction.

The WorkerAction will pass through the Redux reducers and middlewares in the Worker.

If an Effect in the Worker dispatches a ReturnAction it will be dispatched to the main thread.

• Create a ReturnAction with returnActionCreator.
• Mark an Action as a ReturnAction with markReturnAction.

Here's a fun little chart of the Action path.

           +----------+    +----------+    +----------+
ACTION1 -> | Reducers | -> |  Store   | -> | Effects  | -> ACTION2
    ↑      +----------+    +----------+ |  +----------+
    |                                   |  +----------+
    |             ACTION w/ Worker Flag +->|  Worker  | -> ACTION3
    |                                      +----------+ |
    |                                                   |
    +---------------------------------------------------+ ACTION w/ Return Flag

TIP: Take extra care to watch for infinite loops. Especially if setting postAll: true in createReduxWorkerMiddleware.

TIP: Only run expensive calculations in the Worker. Attempting to run everything in the worker will surely lead to madness.

TIP: Use ReturnActions to pass Worker state to the main thread.

Code Examples

counter.worker.ts

Example of code that will run in the Web Worker.

import { applyMiddleware } from 'redux';
import { createLogger } from 'redux-logger';
import createSagaMiddleware from 'redux-saga';
import { put, select, takeEvery } from 'redux-saga/effects';
import { createWorkerStore, returnActionCreator } from 'workeredux';

const defaultState = { counter: 0 };

const reducer = (state = defaultState, action: any) => {
  switch (action.type) {
    case 'counter/increment':
      return {
        counter: state.counter + action.payload || 0,
      };
  }
  return state;
};

const counterAction = returnActionCreator('reduxWorker/counter');

function* saga() {
  yield takeEvery('counter/increment', function*() {
    const { counter } = yield select();
    yield put(counterAction(counter));
  });
}

const sagaMiddleware = createSagaMiddleware();

createWorkerStore(
  reducer,
  applyMiddleware(
    createLogger({
      collapsed: false,
    }),
    sagaMiddleware,
  ),
);

sagaMiddleware.run(saga);

initStore.ts

Example of Redux store setup.

import { createReduxWorkerMiddleware } from 'workeredux';

import sagas from './sagas';
import reducers from './reducers';

// Use Webpack's worker-loader to import the Worker.
import ReduxWorker from 'worker-loader!./counter.worker';
// Create the middleware for the Worker.
const { reduxWorkerMiddleware } = createReduxWorkerMiddleware(new ReduxWorker());

const sagaMiddleware = createSagaMiddleware();
const composeMiddlewares = applyMiddleware(
  reduxWorkerMiddleware,
  sagaMiddleware,
  createLogger({
    collapsed: true,
  }),
);

export function initStore() {
  store = createStore(reducers, composeMiddlewares);
  sagaMiddleware.run(sagas);
  return store;
}

Library Interface

Client

/**
 * Error Action type.
 */
const REDUX_WORKER_ERROR = "@@redux-worker/error-action";`

/**
 * Type guard checks if the Action has a Worker Action flag.
 */
const isWorkerAction: <T extends string>(action: AnyAction) => action is Action<T>;

/**
 * Type guard checks for Worker Error Action.
 */
const isErrorAction: (action: AnyAction) => action is Action<'@@redux-worker/error-action'>;

/**
 * Mark any Action as a WorkerAction.
 */
const markWorkerAction: <T extends string>(action: Action<T>) => Action<T>;

/**
 * Worker Actions are sent to the web worker.
 */
const workerActionCreator: <T extends string>(
  type: T,
) => <P, M = undefined>(payload: P, meta?: M) => AnyAction;

/**
 * Function to create Redux Worker middleware.
 */
function createReduxWorkerMiddleware(
  worker: Worker,
  postAll?: boolean,
): {
  reduxWorkerMiddleware: (
    api: MiddlewareAPI<Dispatch<AnyAction>, any>,
  ) => (next: (value: Action<any>) => void) => (action: Action<any>) => void;
  terminate: () => void;
};

Worker

/**
 * Type guard checks if the action has a ReturnAction flag.
 */
export declare const isReturnAction: <T extends string>(action: any) => action is Action<T>;

/**
 * Mark any Action as a ReturnAction.
 */
export declare const markReturnAction: <T extends string>(action: Action<T>) => Action<T>;

/**
 * Return Actions are sent to the client.
 */
export declare const returnActionCreator: <T extends string>(
  type: T,
) => <P, M = undefined>(payload: P, meta?: M) => AnyAction;

/**
 * The createWorkerStore function is identical to the Redux createStore functon.
 * Except that it automatically includes the middleware to post ReturnActions to the main thread.
 */
const createWorkerStore: StoreCreator;

Webpack

Most likely, you are using Webpack to build your application. You will need to add worker-loader to your config script.

https://github.com/webpack-contrib/worker-loader

While using Workers, you may encounter the error window is not defined, especially if using new webpack.HotModuleReplacementPlugin(). To fix it, add output.globalObject: "this" to the Webpack config.

The MIT License (MIT)

Copyright (c) 2018 Patrick Martin

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.