nest-cluster-hub

[![NPM version][npm-image]][npm-url]

> A Nest module for communication between master and worker processes based on node-cluster-hub

Installation

To begin using it, we first install the required dependency.

``bash
$ npm install --save nest-cluster-hub
`

Getting started

Once the installation is complete, import the ClusterHubModule into the root AppModule and run the forRoot() static method as shown below:

`typescript
import { Module } from '@nestjs/common';
import { ClusterHubModule } from 'nest-cluster-hub';

@Module({
imports: [
ClusterHubModule.forRoot(),
],
})
export class AppModule {}
`

Next, inject the ClusterHub instance using the @InjectClusterHub() decorator.

`typescript
constructor(@InjectClusterHub() private readonly hub: ClusterHub) {}
`

Sending messages

$3

`typescript
if (cluster.isPrimary) {
this.hub.sendToWorker(worker, 'master-to-worker', 1);
}
`

You can just pass any string instead of cluster.Worker. The library uses HashRing to let you find the correct worker for the key which is closest to the point after what the given key hashes to.

$3

`typescript
if (cluster.isPrimary) {
this.hub.sendToRandomWorker('master-to-worker', 1);
}
`

$3

`typescript
if (cluster.isPrimary) {
this.hub.sendToWorkers('master-to-worker', 1);
}
`

$3

`typescript
if (cluster.isPrimary) {
this.hub.sendToMaster('master-to-master', 1);
}

if (cluster.isWorker) {
this.hub.sendToMaster('worker-to-worker', 1);
}
`

$3

`typescript
if (cluster.isPrimary) {
this.hub.on('master-to-master', (data) => {
console.log('master-to-master received');
});

this.hub.on('worker-to-master', (data) => {
console.log('worker-to-master received');
});
}

if (cluster.isWorker) {
this.hub.on('master-to-worker', (data) => {
console.log('master-to-worker received');
});
}
`

$3

`typescript
@OnMessage('master-to-worker')
async handleMessage(data) {
console.log('master-to-worker received');
}
`

Request-response

$3

`typescript
if (cluster.isPrimary) {
this.hub.requestWorker(worker, 'mult', { a: 5, b: 7 }, (err, sum) => {
console.log('Mult in master: ' + sum);
});
}
`

You can also pass any string instead of cluster.Worker to find the correct worker.

$3

`typescript
if (cluster.isPrimary) {
this.hub.requestRandomWorker('mult', { a: 5, b: 7 }, (err, sum) => {
console.log('Mult in master: ' + sum);
});
}
`

$3

`typescript
if (cluster.isPrimary) {
this.hub.requestMaster('sum', { a: 5, b: 7 }, (err, sum) => {
console.log('Sum in master: ' + sum);
});
}

if (cluster.isWorker) {
this.hub.requestMaster('sum', { a: 5, b: 7 }, (err, sum) => {
console.log('Sum in worker: ' + sum);
});
}
`

$3

`typescript
if (cluster.isPrimary) {
this.hub.on('sum', (data, sender, callback) => {
callback(null, data.a + data.b);
});
}

if (cluster.isWorker) {
this.hub.on('mult', (data, sender, callback) => {
callback(null, data.a * data.b);
});
}
`

$3

`typescript
@OnRequest('mult')
async handleMessage(data, sender, callback) {
callback(null, data.a * data.b);
}
`

Sharing data between processes

`typescript
this.hub.set('foo', 'bar', () => {
this.hub.get('foo', (err, value) => {
console.log(value === 'bar'); // true
});
});
`

Retrieving existing workers

$3

`typescript
if (cluster.isPrimary) {
this.hub.getWorker('foo');
}
`

$3

`typescript
if (cluster.isPrimary) {
this.hub.getWorkers();
}
``

Example

A working example is available here.

License

MIT

[npm-image]: https://img.shields.io/npm/v/nest-cluster-hub.svg
[npm-url]: https://npmjs.com/package/nest-cluster-hub