Merge branch 'jasonyunicorn-master'

log.go

@@ -8,17 +8,37 @@ type Logger interface {
 	Printf(format string, v ...interface{})
 }
 
+// Log outputs each metric in the given registry periodically using the given logger.
 func Log(r Registry, freq time.Duration, l Logger) {
 	LogScaled(r, freq, time.Nanosecond, l)
 }
 
-// Output each metric in the given registry periodically using the given
+// LogOnCue outputs each metric in the given registry on demand through the channel
+// using the given logger
+func LogOnCue(r Registry, ch chan interface{}, l Logger) {
+	LogScaledOnCue(r, ch, time.Nanosecond, l)
+}
+
+// LogScaled outputs each metric in the given registry periodically using the given
 // logger. Print timings in `scale` units (eg time.Millisecond) rather than nanos.
 func LogScaled(r Registry, freq time.Duration, scale time.Duration, l Logger) {
+	ch := make(chan interface{})
+	go func(channel chan interface{}) {
+		for _ = range time.Tick(freq) {
+			channel <- struct{}{}
+		}
+	}(ch)
+	LogScaledOnCue(r, ch, scale, l)
+}
+
+// LogScaledOnCue outputs each metric in the given registry on demand through the channel
+// using the given logger. Print timings in `scale` units (eg time.Millisecond) rather
+// than nanos.
+func LogScaledOnCue(r Registry, ch chan interface{}, scale time.Duration, l Logger) {
 	du := float64(scale)
 	duSuffix := scale.String()[1:]
 
-	for _ = range time.Tick(freq) {
+	for _ = range ch {
 		r.Each(func(name string, i interface{}) {
 			switch metric := i.(type) {
 			case Counter: