promise-critical-section

0.0.2 • Public • Published

promise-critical-section

Allows only one asynchronous operation to run every time.

Although JavaScript is single-threaded, there are times you may want to limit number of asynchronous operation to enter a block simultaneously. For example,

  • Pooling a single resource
  • Running a series of asynchronous steps one-by-one

How to use

In the code below, Step 1A and Step 1B will be run serially regardless of race condition from Step 2.

import CriticalSection from 'promise-critical-section';
 
const section = new CriticalSection();
 
Promise.race([
  section.enter()
    .then(() => {
      // do something that is limited to one asynchoronous operation
      console.log('Step 1A');
    })
    .then(() => {
      // do another thing
      console.log('Step 1B');
    })
    .then(() => section.leave()),
  section.enter()
    .then(() => {
      // do something in the critical section
      console.log('Step 2');
    })
    .then(() => section.leave())
])

You can also write it with ES7 async/await. The following example maybe a bit exaggerated.

return Promise.all([
  (async () => {
    await section.enter();
    console.log('Step 1A');
    console.log('Step 1B');
    await section.leave();
  })(),
  (async () => {
    await section.enter();
    console.log('Step 2');
    await section.leave();
  })()
]);

Contributions

Like us? Please star us or give us suggestions.

Please file an issue to us with minimal repro.

Readme

Keywords

none

Package Sidebar

Install

npm i promise-critical-section

Weekly Downloads

304

Version

0.0.2

License

MIT

Last publish

Collaborators

  • compulim