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mongo-distributed-locks

2.0.1 • Public • Published

mongo-distributed-locks

Node.js distributed locking based on Mongodb.

Build Status Code Coverage npm version

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({
    resource: 'createPayment',
    id: params.userId,
    fn: takeFee.bind(null, params)
  });
}
 
function doWork() {
  let userId = 'userId';
  // current user balance is 60
  return Promise.all([
    takeFeeWithLock({ userId, fee: 10 }),
    takeFeeWithLock({ userId, fee: 25 })
  ]);
  // current user balance is 25
}
 
async function manageLockManually() {
  let userId = 'userId';
  let lock = await DLocks.lock({
    resource: 'user',
    id: userId
  });
 
  // current user balance is 60
  try {
    await takeFee({ userId, fee: 10 });
    await takeFee({ userId, fee: 25 });
    // current user balance is 25
  }
  finally {
    await DLocks.unlock(lock);
  }
}

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({ resource, id, fn })
    Creates a DLocks instance and executes its exec method. Shortcut for let instance = new DLocks(params); instance.exec();.

    • resource - operation: createPayment, or resource: user name.
    • id - id of the locking resource.
    • fn - function that does some operation on the locking resource.
  • static lock({ resource, id, fn })
    Locks resource and returns lock object. This method can be helpful when you need to manage lock manually. Accepts the same parameters as static exec.

  • unlock(lock)
    Unlocks the previously locked resource.

    • lock - previously generated lock object.

Author

Alexander Mac

License

Licensed under the MIT license.

install

npm i mongo-distributed-locks

Downloadsweekly downloads

10

version

2.0.1

license

MIT

homepage

github.com

repository

Gitgithub

last publish

collaborators

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