IPC-Mutex

Inter-Process-Communication (IPC) Mutual Exclusion Lock (Mutex) Abstraction Layer

About

This Node.js module provides an abstraction layer for Inter-Process-Communication (IPC) through a Mutual Exclusion Lock (Mutex). It supports the following modes (in order of increasing process scope and overall complexity):

• Single-Process-Model (SPM): This is for Node applications NOT using the cluster module. The coordination is performed with an in-memory data structure. No external resource is needed.

• Multi-Process-Model (MPM): This is for Node applications using the cluster module. The coordination is performed with an in-memory data structure in the master process and an IPC message exchange between the worker processes and the master process with the help of the cluster module. No external resource is needed.

• Remote-Process-Model (RPM): This is for Node applications split into distinct processes (not created through the cluster module), usually running also on distinct machines. The coordination is performed with the help of an external lock manager. Currently Redis, PostgreSQL, Consul and EtcD are supported.

Installation

$ npm install ipc-mutex --save-dev

Usage

(async () => {
    const Mutex = require("ipc-mutex")

    /*  open connection (once per Node process only)  */
    let mutex = new Mutex("spm:foo")
    await mutex.open()

    /*  acquire exclusive lock (and blocks until available)  */
    await mutex.acquire()

    /*  release exclusive lock  */
    await mutex.release()

    /*  close connection (once per Node process only)  */
    await mutex.close()
})

The following URLs are supported on new Mutex(url):

• spm:<id>
• mpm:<id>
• rpm+redis://[xxx:<secret>@]<host>[:<port>]/<id>
• rpm+pgsql://[<username>:<password>@]<host>[:<port>][/<database>]/<id>[?tls=true[&&key=<file>&&crt=<file>&&ca=<file>]]
• rpm+consul://[xxx:<token>@]<host>[:<port>]/<id>[?tls=true[&&key=<file>&&crt=<file>&&ca=<file>]]
• rpm+etcd://[<username>:<password>@]<host>[:<port>]/<id>[?tls=true[&&key=<file>&&crt=<file>&&ca=<file>]]

The <id> is an arbitrary unique identifier matching the regular expression ^[a-zA-Z][a-zA-Z0-9-]*$.

Application Programming Interface (API)

declare class Mutex {
    constructor (url: string);
    open():    Promise<void>;
    acquire(): Promise<void>;
    release(): Promise<void>;
    close():   Promise<void>;
}

License

Copyright (c) 2018-2019 Dr. Ralf S. Engelschall (http://engelschall.com/)

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.