enrise-lock

Node.js lock module

An elasticsearch based lock mechanism for resources and ownership.

Introduction

This module provides abstraction methods to lock a resource with an owner. The owner is the name of the process requesting a lock. The resource would be the specific element/index/endpoint/etc.. that requires locking.

Installation

NPM: npm install enrise-lock --save
Yarn: yarn add enrise-lock

Initialization

Require and instantiate the locker. const lock = new require('enrise-lock')(config: Object);

Where config is an object with the following options. Type is optional, the rest is mandatory.

• esClient: elasticsearch: An elasticsearch client for the lock module to use. This can either be an elasticsearch or an enrise-esclient instance.
• index: String: The elasticsearch index that will be used to store all lock-documents.
• owner: String: The name of the process that is looking to place the lock.
• [type: String]: The index-type that will be used to store all lock-documents. This will default to 'lockdocument'.

Usage and API methods

lock.acquire(resource: String, callback: function)

Set a lock for resource: resource. Callback will be called with parameters [err, success: boolean]. The success paramater will be false if a lock already exists.

lock.release(resource: String, callback: function)

Release a lock for resource: resource. Callback will be called with parameter [err].

lock.isLocked(resource: String, callback: function)

Check if a resource is locked. Callback will be called with parameters [err, isLocked: boolean].

lock.list(callback: function)

Retrieve a list of all current locks. Callback will be called with parameters [err, locks: Object]. Where the key in locks represents the resource and the value an object with the owner.

lock.delete(callback: function)

Delete the entire lock-index. Callback will be called with parameter [err].

Example

const lock = new require('enrise-lock')({
  esClient: new require('elasticsearch').Client(),
  index: 'globallock',
  type: 'lockdocument',
  owner: 'api'
});

// Set lock
lock.acquire('my-resource', (err, success) => {
  // Do some asynchronous operation
  // ...

  // Release lock
  lock.release('my-resource', (err, success) => {
  	// ...
  });
});