js-synchronized

npm install --save js-synchronized

Sometimes the Promise act like multiple thread. For several lines of code in a function, when one call already waiting on a Promise been fulfilled, another call may come in, just like "concurrent" in mutiple thread. Which make the lies of code a "critical section".

There is critical section, there is synchronization. This lib is trying to solve these problems.

Full Documentation

"concurrent calls" in the following context actullay means another call on a method started without waiting for the previous call returned Promise fulfilled

synchronized

Make target instance method execute sequentially on "concurrent calls". It actually make every call on async method wait until the previously returned Promise fulfilled.

Example

class SomeClass {

  @synchronized()
  public async f1(wait: number) {
    await new Promise((resolve: any) => {
      setTimeout(resolve, wait);
    });
    console.log('f1-' + wait);
    return wait;
  }

}

const obj = new SomeClass();
obj.f1(3000);
obj.f1(2000);
obj.f1(1000);

The f1() will execute sequentially, so event the obj1.f1(3000) fulfilled take longer than obj1.f1(1000), the 1000 have to wait 3000 finish first.

takeLatest

Make all "concurrent calls" on target intance method return the value of the most latest call, all results of previous calls are abandoned.

takeLeading

Make all "concurrent calls" on target intance method return the value of the most leading call, all results of afterwards calls are abandoned.