Passing function parameters to events

[mykevinjung]

This is more of a question than an issue. I like to use the parameters that were passed in the action function and do something in the event. For instance, let's say x and y are passed in asyncFunctionThatCouldFail function and I like to print out the x and y on timeout event. How can I do that?

const circuitBreaker = require('opossum');

function asyncFunctionThatCouldFail (x, y) {
  return new Promise((resolve, reject) => {
    // Do something, maybe on the network or a disk
  });
}

const options = {
  timeout: 3000, // If our function takes longer than 3 seconds, trigger a failure
  errorThresholdPercentage: 50, // When 50% of requests fail, trip the circuit
  resetTimeout: 30000 // After 30 seconds, try again.
};
const breaker = circuitBreaker(asyncFunctionThatCouldFail, options);

breaker.fire(params);
circuit.on('timeout',
  () => console.log(`x equal ${x} and y equal ${y}`)); // the parameters of asyncFunctionThatCouldFail

[lholmquist]

It doesn't look like that is currently possible. The timeout event is only emitted with the error and the latency value.

@lance what do you think about adding the original function arguments to the timeout event when it is emitted?

I can send a PR

[lance]

@lholmquist yes - that sounds good. I wonder if it should necessarily be limited to timeout. The open and failure events might benefit from this as well.

[lholmquist]

agreed, i'll added them too, to see how it feels.

[mykevinjung]

Thanks for the response. It would be great to help diagnose the issue if we can know the inputs especially for those events like timeout and failure.