Zoo-lock NPM | npm.io

zoo-lock

This package provides zookeeper locking following ZooKeeper Recipes and Solutions using node-zookeeper-client

The library exposes a single function, createClient which creates zookeeper client instance.

All locks are stored in a folder which has to be set by client using setDir method, through which getZooLock method is exposed where path is specified for locking.

Locks must be released with the release method which is returned while applying lock.

ZookeeperLock

Install

usage:

  npm i zoo-lock

Initialize

usage:

  import createClient from "zoo-lock";

  const client = await createClient("localhost:2181", {
    logger: console,
  });

Lock And Unlock

usage:

    const zooUnLock = await client
      .setDir("/test")
      .getZooLock("/mylock")

    // perform some task
    // above method can throw error if it could not get lock

    await zooUnLock.release(); // it can also throw error

Get Node-Zookeeper-Client Object

if for some reason you need node-zookeeper-client object, it is accessible through getClient method

usage:

    const nodeZookeeperClient = client.getClient()

Lock Options

Timeouts

Timeout can be set for locks through ZooLockOption where timeout is calculated by overall time between creating and removing node.

getZooLock method could also throw error if due to timeout node was already removed.

release method could also throw error if due to timeout node was already removed usage:

    const zooUnLock = await client
      .setDir("/test")
      .getZooLock("/mylock", { timeout: 3000 })   // timeout in ms

    await zooUnLock.release();

MaxChildLockLimit

MaxChildLockLimit can be set for locks through ZooLockOption where MaxChildLockLimit represent max number of lock a directory can hold.

Lock limit can exceed - 1. before creating node 2. after creating node

usage:

    const zooUnLock = await client
      .setDir("/test")
      .getZooLock("/mylock", { maxChildLockLimit: 2 })   // will throw error if directory already has 2 nodes

    await zooUnLock.release();