api-concurrency v1.3.0

api-concurrency

Function to restrict duplicate HTTP requests.

If an API request arrives for the very first time it will lock it (using redis) and another request for same API with same request body arrive even before the response of previous API is sent, it will return an error in response for that second (duplicate) request.

Tip: To increase the throughput of this function, connect the redis client with redis server using unix sockets

Installation

npm install api-concurrency

Usage

var express = require('express')
var apiLock = require('api-concurrency')
var redisClient = require('redis').createClient()
var app = express()

app.use(function (req, res, next) {
    var options = {
        payload: {
            path: req.path, // path should always be given in payload to determine same endpoint
            body: req.body // make sure your body contains a unique key for a given session
        },
        ttl: 60000,
        silent: false,
        key_prefix: 'apiLock:' // a prefix to redis's key
    }
    
    /*
     * Following function will invoke the next middleware with or without error depending on weather a request is duplicate or not.
     **/
    apiLock(redisClient, options, res, next)
})

app.get('/', function(req, res) {
  // We delay the response in order to mock the runtime of an actual API.
  // Now, you can try and hit the same API before 2 secs and it should throw an error
  setTimeout(() => {
    return res.status(200).json('Hello, World!')
  }, 2000)
})

app.listen(3000, function() {
  console.log('Server listening at port 3000')
})

Options