Example of a global distributed lock in node using timeouts and redis for locks

globalThrottleOnLock.js

const redis = require('redis')
const client = redis.createClient()


// will retry running a function until a lock is freed and it can run it
function retryUntilUnlocked(lock, func, seconds) {
  client.get(lock, function (err, result) {
    // while there is still a lock, keep re-trying every x seconds
    if(result === 'true') {
      setTimeout( () => {
        retryUntilUnlocked(lock, func, seconds)
      }, seconds * 1000)

    } else {
      // once the lock is freed, then call the function
      func()
    }
  })
}

// uses a redis key as a distributed global lock to throttle
// a function call to only run after x seconds have elapsed since
// it was last called, any repeat calls in between reset the lock,
// keeping it from running until the last call
function throttleOnLock(seconds, func, lock) {
  client.get(lock, function (err, result) {
    if (err || !result) {
      // if there is no lock, then we set one up and start a setTimeout loop
      client.setex(lock, seconds, true, () => {
        setTimeout( () => {retryUntilUnlocked(lock, func, seconds)}, seconds*1000)
      })
    } else {
      // if there is a lock, then this call should be throttled by resetting the lock
      client.setex(lock, seconds, true)
    }
  })
  
}

module.exports = {
  throttleOnLock,
}