Timer helpers

Author: cl-bvl

prometheus/timer.go

@@ -13,7 +13,9 @@
 
 package prometheus
 
-import "time"
+import (
+	"time"
+)
 
 // Timer is a helper type to time functions. Use NewTimer to create new
 // instances.
@@ -79,3 +81,320 @@ func (t *Timer) ObserveDurationWithExemplar(exemplar Labels) time.Duration {
 	}
 	return d
 }
+
+// TimerHistogram is a thin convenience wrapper around a Prometheus Histogram
+// that makes it easier to time code paths in an idiomatic Go-style:
+//
+//	defer timer.Observe()()   // <-- starts the timer and defers the stop
+type TimerHistogram struct {
+	Histogram
+}
+
+func NewTimerHistogram(opts HistogramOpts) *TimerHistogram {
+	t := &TimerHistogram{
+		Histogram: NewHistogram(opts),
+	}
+	return t
+}
+
+// Observe starts a prom.Timer that records into the embedded Histogram and
+// returns a “stop” callback.  Best used with defer:
+//
+//	defer timer.Observe()()
+//
+// The inner closure calls ObserveDuration on the hidden prom.Timer, recording
+// the elapsed seconds into the histogram’s current bucket.
+func (t *TimerHistogram) Observe() func() {
+	timer := NewTimer(t.Histogram)
+	return func() {
+		timer.ObserveDuration()
+	}
+}
+
+// Wrap executes fn() and records the time it took.  Equivalent to:
+// Use when you don't need a defer chain (e.g., inside small helpers).
+func (t *TimerHistogram) Wrap(fn func()) {
+	defer t.Observe()()
+	fn()
+}
+
+type TimerHistogramVec struct {
+	*HistogramVec
+}
+
+func NewTimerHistogramVec(opts HistogramOpts, labelNames []string) *TimerHistogramVec {
+	t := &TimerHistogramVec{
+		HistogramVec: NewHistogramVec(opts, labelNames),
+	}
+
+	return t
+}
+
+// Observe return func for stop timer and observe value
+// Example
+// defer metric.Observe(map[string]string{"foo": "bar"})()
+func (t *TimerHistogramVec) Observe(labels map[string]string) func() {
+	timeStart := time.Now()
+	return func() {
+		d := time.Since(timeStart)
+		t.HistogramVec.With(labels).Observe(d.Seconds())
+	}
+}
+
+func (t *TimerHistogramVec) ObserveLabelValues(values ...string) func() {
+	timeStart := time.Now()
+	return func() {
+		d := time.Since(timeStart)
+		t.HistogramVec.WithLabelValues(values...).Observe(d.Seconds())
+	}
+}
+
+func (t *TimerHistogramVec) Wrap(labels map[string]string, fn func()) {
+	defer t.Observe(labels)()
+	fn()
+}
+
+func (t *TimerHistogramVec) WrapLV(values []string, fn func()) {
+	defer t.ObserveLabelValues(values...)()
+	fn()
+}
+
+// TimerCounter is a minimal helper that turns a Prometheus **Counter** into a
+// “stop-watch” for wall-clock time.
+//
+// Each call to Observe() starts a timer and, when the returned closure is
+// executed, adds the elapsed seconds to the embedded Counter.  The counter
+// therefore represents **the cumulative running time** across many code paths
+// (e.g. total time spent processing all requests since process start).
+//
+// Compared with a Histogram-based timer you gain:
+//
+//   - A single monotonically-increasing number that is cheap to aggregate or
+//     alert on (e.g. “CPU-seconds spent in GC”).
+//   - Zero bucket management or percentile math.
+//
+// But you lose per-request latency data, so use it when you care about total
+// time rather than distribution.
+type TimerCounter struct {
+	Counter
+}
+
+func NewTimerCounter(opts Opts) *TimerCounter {
+	t := &TimerCounter{
+		Counter: NewCounter(CounterOpts(opts)),
+	}
+
+	return t
+}
+
+// Observe starts a wall-clock timer and returns a “stop” closure.
+//
+// Typical usage:
+//
+//	defer myCounter.Observe()()   // records on function exit
+//
+// When the closure is executed it records the elapsed duration (in seconds)
+// into the Counter.  Thread-safe as long as the underlying Counter is
+// thread-safe (Prometheus counters are).
+func (t *TimerCounter) Observe() func() {
+	start := time.Now()
+
+	return func() {
+		d := time.Since(start)
+		t.Counter.Add(d.Seconds())
+	}
+}
+
+func (t *TimerCounter) Wrap(fn func()) {
+	defer t.Observe()()
+	fn()
+}
+
+type TimerCounterVec struct {
+	*CounterVec
+}
+
+func NewTimerCounterVec(opts Opts, labels []string) *TimerCounterVec {
+	t := &TimerCounterVec{
+		CounterVec: NewCounterVec(CounterOpts(opts), labels),
+	}
+
+	return t
+}
+
+func (t *TimerCounterVec) Observe(labels map[string]string) func() {
+	start := time.Now()
+
+	return func() {
+		d := time.Since(start)
+		t.CounterVec.With(labels).Add(d.Seconds())
+	}
+}
+
+func (t *TimerCounterVec) ObserveLabelValues(values ...string) func() {
+	start := time.Now()
+	return func() {
+		d := time.Since(start)
+		t.CounterVec.WithLabelValues(values...).Add(d.Seconds())
+	}
+}
+
+func (t *TimerCounterVec) Wrap(labels map[string]string, fn func()) {
+	defer t.Observe(labels)()
+	fn()
+}
+
+func (t *TimerCounterVec) WrapLabelValues(values []string, fn func()) {
+	defer t.ObserveLabelValues(values...)()
+	fn()
+}
+
+// TimerContinuous is a variant of the standard Timer that **continuously updates**
+// its underlying Counter while it is running—by default once every second—
+// instead of emitting a single measurement only when the timer stops.
+//
+// Trade-offs
+// ----------
+//   - **Higher overhead** than a one-shot Timer (extra goroutine + ticker).
+//   - **Finer-grained metrics** that are invaluable for long-running or
+//     indeterminate-length activities such as stream processing, background
+//     jobs, or large file transfers.
+//   - **Sensitive to clock skew**—if the system clock is moved **backwards**
+//     while the timer is running, the negative delta is silently discarded
+//     (no panic), so that slice of time is lost from the measurement.
+type TimerContinuous struct {
+	Counter
+	updateInterval time.Duration
+}
+
+func NewTimerContinuous(opts Opts, updateInterval time.Duration) *TimerContinuous {
+	t := &TimerContinuous{
+		Counter:        NewCounter(CounterOpts(opts)),
+		updateInterval: updateInterval,
+	}
+	if t.updateInterval == 0 {
+		t.updateInterval = time.Second
+	}
+
+	return t
+}
+
+func (t *TimerContinuous) Observe() func() {
+	start := time.Now()
+	ch := make(chan struct{})
+
+	go func() {
+		added := float64(0)
+		ticker := time.NewTicker(t.updateInterval)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-ch:
+				d := time.Since(start)
+				if diff := d.Seconds() - added; diff > 0 {
+					t.Counter.Add(diff)
+				}
+				return
+			case <-ticker.C:
+				d := time.Since(start)
+				if diff := d.Seconds() - added; diff > 0 {
+					t.Counter.Add(diff)
+					added += diff
+				}
+			}
+		}
+	}()
+
+	return func() {
+		ch <- struct{}{}
+	}
+}
+
+func (t *TimerContinuous) Wrap(fn func()) {
+	defer t.Observe()()
+	fn()
+}
+
+type TimerContinuousVec struct {
+	*CounterVec
+}
+
+func NewTimerContinuousVec(opts Opts, labels []string) *TimerCounterVec {
+	t := &TimerCounterVec{
+		CounterVec: NewCounterVec(CounterOpts(opts), labels),
+	}
+
+	return t
+}
+
+func (t *TimerContinuousVec) Observe(labels map[string]string) func() {
+	start := time.Now()
+	ch := make(chan struct{})
+
+	go func() {
+		added := float64(0)
+		ticker := time.NewTicker(time.Second)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-ch:
+				d := time.Since(start)
+				if diff := d.Seconds() - added; diff > 0 {
+					t.CounterVec.With(labels).Add(diff)
+				}
+				return
+			case <-ticker.C:
+				d := time.Since(start)
+				if diff := d.Seconds() - added; diff > 0 {
+					t.CounterVec.With(labels).Add(diff)
+					added += diff
+				}
+			}
+		}
+	}()
+
+	return func() {
+		ch <- struct{}{}
+	}
+}
+
+func (t *TimerContinuousVec) ObserveLabelValues(values ...string) func() {
+	start := time.Now()
+	ch := make(chan struct{})
+
+	go func() {
+		added := float64(0)
+		ticker := time.NewTicker(time.Second)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-ch:
+				d := time.Since(start)
+				if diff := d.Seconds() - added; diff > 0 {
+					t.CounterVec.WithLabelValues(values...).Add(diff)
+				}
+				return
+			case <-ticker.C:
+				d := time.Since(start)
+				if diff := d.Seconds() - added; diff > 0 {
+					t.CounterVec.WithLabelValues(values...).Add(diff)
+					added += diff
+				}
+			}
+		}
+	}()
+
+	return func() {
+		ch <- struct{}{}
+	}
+}
+
+func (t *TimerContinuousVec) Wrap(labels map[string]string, fn func()) {
+	defer t.Observe(labels)()
+	fn()
+}
+
+func (t *TimerContinuousVec) WrapLabelValues(values []string, fn func()) {
+	defer t.ObserveLabelValues(values...)()
+	fn()
+}