waitron

Waitron provides a kind of asynchronous-semaphore-like like functionality (Asynchronous_semaphore): it creates an object through which asynchronous operations can let others know that they need to "hold on" for them, until they can "go" on.

With each call to hold method, caller marks object as "delayed" and gets a function that, when called, will finish that "delay". Calling go will remove the initial "delay" and wait for any other "delays" before calling back. Once all "delays" are finished, no more can be created (well... they can, they just won't delay anything).

It allows to start multiple asynchronous and synchronous functions and wait for all of them to finish before continuing. It is similar to async.parallel, but also differs quite a bit:

• it does not call/execute those functions, it merely provides simple way for them to mark when they're done;
• it waits for all of them to call back and gathers all errors before calling back (async.parallel calls back after first error);
• it does not gather and pass any results from those functions when calling back;

Unless you need these, async.parallel might be a better choice for you. Or maybe even neo-async.parallel, which seems to be even faster.

Installation

npm install waitron

or:

npm install https://github.com/ahwayakchih/waitron

Usage

Example use:

const waitron = require('waitron');
 
// Somewhere inside rocket-manned module...
process.on('prepare-for-launch', hold => {
  // Fastening seatbelts is asynchronous, we have to wait
  // until everyone is done.
  pilots.fastenSeatbelts(hold());
  passengers.fastenSeatbelts(hold());
});
 
// Somewhere else inside rocket-log module...
process.on('prepare-for-launch', hold => {
  // We do not need to delay anything.
  console.log('Preparing for launch');
});
 
// Somewhere in command center...
var launcher = waitron();
process.emit('prepare-for-launch', launcher.hold);
var selfTest = launcher.hold();
selfTest() && launcher.go(null, errors => {
  // If everything is OK, launch!
  if (!errors) {
    start();
  }
});

Benchmarks

These benchmarks are just to make sure that working with Waitron is not much slower than working with async.parallel. Both modules provide different functionality, so they shouldn't be evaluated solely by results of these benchmarks. You can re-run them locally with: npm run benchmarks.

Running inside Docker (Alpine Linux v3.10) with Node v12.10.0 and Intel(R) Core(TM) i7-3537U CPU @ 2.00GHz x 4
 
Testing:
- async     v3.1.0 https://caolan.github.io/async/         
- neo-async v2.6.1 https://github.com/suguru03/neo-async   
- waitron   v2.0.0 https://github.com/ahwayakchih/waitron  
 
Test with 0 holders
 
  3 tests completed.
 
  neo-async x 337,702 ops/sec ±1.03% (77 runs sampled)
  waitron   x 323,296 ops/sec ±1.26% (74 runs sampled)
  async     x 309,637 ops/sec ±1.72% (76 runs sampled)
 
Test with 5 holders
 
  3 tests completed.
 
  neo-async x 225,758 ops/sec ±1.36% (80 runs sampled)
  waitron   x 188,512 ops/sec ±1.24% (74 runs sampled)
  async     x 183,181 ops/sec ±1.61% (76 runs sampled)
 
Test with 15 holders
 
  3 tests completed.
 
  neo-async x 130,311 ops/sec ±1.40% (76 runs sampled)
  waitron   x 121,419 ops/sec ±1.48% (74 runs sampled)
  async     x 101,664 ops/sec ±1.73% (78 runs sampled)
 
Test with 29 holders
 
  3 tests completed.
 
  neo-async x 82,468 ops/sec ±1.18% (79 runs sampled)
  waitron   x 76,747 ops/sec ±1.46% (73 runs sampled)
  async     x 63,677 ops/sec ±1.87% (79 runs sampled)