debug-promise

debug-promise consumes promises and outputs logs showing their progress, their resolution or rejection, and makes state dumps showing all promises that have not settled.

How?

debug-promise can consume any type of promises, but for the sake of this example we'll use one from Kriskowal's Q Library.

var Q = require('Q');
var debug = require('debug-promise')('test-logger');
var defer = Q.defer();
debug(defer.promise, 'arbitrary promise name for logging');

// sometime in the future resolve that promise
setTimeout(function () {
  defer.resolve();
}, 10000);

debug-promise returns the original promise so you can easily chain like so:

debug(Q.resolve('value'), 'value promise').then(function (res) {
    // res === 'value'
});

Example output

  debug-promise:test-logger 
--- OUTSTANDING PROMISES ---

arbitrary promise label 1		0 seconds

----------------------------

 +0ms
  debug-promise:test-logger 
--- OUTSTANDING PROMISES ---

arbitrary promise label 1		0.002 seconds
arbitrary promise label 2		0.001 seconds

----------------------------

 +3ms
  debug-promise:test-logger 
--- OUTSTANDING PROMISES ---

arbitrary promise label 1		0.003 seconds
arbitrary promise label 2		0.001 seconds
arbitrary promise label 3		0 seconds

----------------------------

 +0ms
  debug-promise:test-logger 
--- OUTSTANDING PROMISES ---

arbitrary promise label 1		0.003 seconds
arbitrary promise label 2		0.001 seconds
arbitrary promise label 3		0 seconds
arbitrary promise label 4		0 seconds

----------------------------

 +0ms
  debug-promise:test-logger 
--- OUTSTANDING PROMISES ---

arbitrary promise label 1		0.003 seconds
arbitrary promise label 2		0.001 seconds
arbitrary promise label 3		0 seconds
arbitrary promise label 4		0 seconds
arbitrary promise label 5		0.001 seconds

----------------------------

 +1ms
  debug-promise:test-logger progress (100): arbitrary promise label 1		0.004
 +0ms
  debug-promise:test-logger progress (undefined): arbitrary promise label 1		0.004
 +1ms
  debug-promise:test-logger resolved (undefined): arbitrary promise label 1		1.006
 +1s
  debug-promise:test-logger 
--- OUTSTANDING PROMISES ---

arbitrary promise label 2		1.004 seconds
arbitrary promise label 3		1.003 seconds
arbitrary promise label 4		1.003 seconds
arbitrary promise label 5		1.003 seconds

----------------------------

 +0ms
  debug-promise:test-logger rejected (undefined): arbitrary promise label 2		2.007
 +1s
  debug-promise:test-logger 
--- OUTSTANDING PROMISES ---

arbitrary promise label 3		2.006 seconds
arbitrary promise label 4		2.006 seconds
arbitrary promise label 5		2.006 seconds

----------------------------

 +0ms
  debug-promise:test-logger resolved (undefined): arbitrary promise label 3		3.001
 +995ms
  debug-promise:test-logger 
--- OUTSTANDING PROMISES ---

arbitrary promise label 4		3.002 seconds
arbitrary promise label 5		3.002 seconds

----------------------------

 +1ms
  debug-promise:test-logger rejected ('asdf'): arbitrary promise label 4		4.001
 +1s
  debug-promise:test-logger rejected ('asdf'): arbitrary promise label 5		4.002
 +0ms
  debug-promise:test-logger 
--- OUTSTANDING PROMISES ---

arbitrary promise label 5		4.002 seconds

----------------------------

 +0ms
  debug-promise:test-logger 
--- OUTSTANDING PROMISES ---


----------------------------

 +0ms