traced-kew

A promise library compatible with Medium's kew promises library with support added for LightStep OpenTracing instrumentation.

Compatibility-note: the library implementation currently relies on several LightStep-specific methods and is not compatible with all OpenTracing tracer implementations.

• Getting started
• Demo
• API

Getting started

npm install --save traced-kew

Initialize the OpenTracing global tracer (the library currently uses the OpenTracing global tracer for all operations):

Tracer.initGlobalTracer(LightStep.tracer({
    access_token   : '{your_access_token}',
    component_name : 'kew-example',
}));

Use the library as you would use the kew library:

import Q from 'traced-kew';
 
Q.all([
  Q.delay(50),
  Q.delay(20),
]).then(() => {
  console.log('Done!');
});

Use the traced version of the various kew methods to add OpenTracing tracing annotations:

import Q from 'traced-kew';
 
// Start a span to track the chained promises
let span = Tracer.startSpan('Q.all');
Q.tracedAll(span, [
  Q.tracedDelay('a delay of 50ms', span, 50),
  Q.tracedDelay('a delay of 20ms', span, 20),
]).tracedThen((span) => {
  span.logEvent('The promises have resolved!');
  console.log('Done!');
})
.finish(); // Let the library know the chaining is done

:success_parrot:

Demo

The access_token values in the examples need to be updated to your project's access token, then the following can be run:

make demo-ok    # Makes a trace with only successful operations
make demo-fail  # Makes a trace containing spans with errors

Trace for the resolved promises

Trace for the rejected promises

API

• Static methods
  • all(promises), tracedAll(span, promises)
  • bindPromise(fn, scope, …boundArgs)
  • defer(), tracedDefer(name, parentSpan)
  • delay(ms), tracedDelay(name, parent, ms)
  • fcall is not yet implemented
  • isPromise is not yet implemented
  • isPromiseLike is not yet implemented
  • ncall is not yet implemented
  • nfcall is not yet implemented
  • reject(reason)
  • resolve(value)
  • spread(promise, fn)
  • stats()
  • allSettled(promises)
  • getNextTickFunction()
  • setNextTickFunction()
• Instance methods
  • fail(function(reason)), tracedFail(function(span, reason))
  • fin(function), tracedFin(function(span))
  • makeNodeResolver()
  • spread(…args), tracedSpread(span, …args)
  • reject(reason)
  • resolve(value)
  • then(function(result)), tracedThen(function(span, result))
  • finish(function(span))
  • span()

Testing

make test