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var clusterStore = require("cluster-store")

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cluster-store v2.0.8

A wrapper to enable the use of any in-process store with node cluster via cluster process and worker messages (i.e. for Raspberry Pi servers).

cluster-store

Makes any storage strategy similar to express/session useful in both cluster and non-cluster environments by wrapping it with cluster-rpc.

Also works with level-session-store (leveldb), connect-session-knex (SQLite3), session-file-store (fs), and any other embedded / in-process store.

Note: Most people would probably prefer to just use Redis rather than wrap a dumb memstore as a service... but I am not most people.

Install

npm install --save cluster-store@2.x

v1.x vs v2.x

The old v1 used ws which makes it usable when clustering node processes without using cluster.

If you need that functionaliy, use v1 instead of v2.

Usage

In its simplest form, you use this module nearly exactly the way you would the any other storage module, with the exception that you must wait for the inter-process initialization to complete.

When not using any of the options the usage is the same for the master and the worker:

require('cluster-store').create().then(function (store) {
  // initialization is now complete
  store.set('foo', 'bar');
});

standalone (non-cluster)


There is no disadvantage to using this module standalone. The additional overhead of inter-process communication is only added when a worker is added.

As such, the standalone usage is identical to usage in master process, as seen below.

master

In the master process you will create the real store instance.

If you need to manually specify which worker will be enabled for this funcitonality you must set addOnFork to false and call addWorker() manually.

'use strict';

var cluster = require('cluster');

var cstore = require('cluster-store/master').create({
  name: 'foo-store'       // necessary when using multiple instances
, store: null             // use default in-memory store
, addOnFork: true         // default
});

// if you addOnFork is set to false you can add specific forks manually
//cstore.addWorker(cluster.fork());

cstore.then(function (store) {
  store.set('foo', 'bar');
});

Note: store can be replaced with any express/session-compatible store, such as:

  • new require('express-session/session/memory')()
  • require('level-session-store')(session)
  • and others

worker

'use strict';

// retrieve the instance
var cstore = require('cluster-store/worker').create({
  name: 'foo-store'
});

cstore.then(function (store) {
  store.get('foo', function (err, result) {
    console.log(result);
  });
});

API

This is modeled after Express' Session Store Implementation

Note: These are only exposed if the underlying store supports them.

CRUD methods

  • store.set(id, data, fn) => (error)
  • store.get(id, fn) => (error, data)
  • store.touch(id, data, fn) => (error)
  • store.destroy(id, fn) => (error)

Helpers

  • store.all(fn) => (error, array)
  • store.clear(fn) => (error)
  • store.length(fn) => (error, length)

See https://github.com/expressjs/session#session-store-implementation@4.x for full details

Example

'use strict';

var cluster = require('cluster');

require('cluster-store').create({
  name: 'foo-store'
}).then(function (store) {
  if (cluster.isMaster) {
    store.set('foo', 'bar');
  }

  store.get('foo', function (err, result) {
    console.log(result);
  });
});

if (cluster.isMaster) {
  cluster.fork();
  cluster.fork();
}
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