mongo-distributed-locks

mongo-distributed-locks

Node.js distributed locking based on Mongodb.

Commands

# Add to project
$ npm i mongo-distributed-locks

Usage

const DLocks = require('mongo-distributed-locks');

async function takeFee({ userId, fee }) {
  let user = await User.findOne({ _id: userId });
  user.balance -= fee;
  return user.save();
}

function takeFeeWithLock(params) {
  return DLocks.exec({
    prefix: 'createPayment',
    objectId: params.userId,
    fn: takeFee.bind(null, params)
  });
}

function doWork() {
  let userId = 'some id';
  return Promise.all([
    takeFeeWithLock({ userId, fee: 10 }),
    takeFeeWithLock({ userId, fee: 25 })
  ]);
}

API

• static registerLoggerErrorFn(loggerErrorFn)
  Registers logger error function (DLocks can log a few error messages), if not provided console.error is used`.

  • loggerErrorFn - logger error function. Example of usage: DLocks.registerLoggerErrorFn(logger.error.bind(logger));

• static exec({ prefix, objectId, fn })
  Creates a DLocks instance and executes its exec method. Shortcut for let instance = new DLocks(params); instance.exec();.

  • prefix - the name of operation, createPayment, deleteUser, etc.
  • objectId - the id of locking object.
  • fn - the function that changes the locking object.

• exec()
  Locks the resource and executes the provided function. Returns a promise.

Author

Alexander Mac

License

Licensed under the MIT license.

Changelog

_v1.0.0

Feb. 8, 2018

• Released a stable version.