CHANGELOG.md

@@ -7,6 +7,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.18.1] - 2024-04-08
+
+### Fixed
+
+- Metrics API works when metrics are nil (e.g., not available in the context).
+  All calls are noop.
+
 ## [0.18.0] - 2024-04-05
 
 ### Added
@@ -197,7 +204,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - First public release.
 
-[unreleased]: https://gitlab.com/tozd/waf/-/compare/v0.18.0...main
+[unreleased]: https://gitlab.com/tozd/waf/-/compare/v0.18.1...main
+[0.18.1]: https://gitlab.com/tozd/waf/-/compare/v0.18.0...v0.18.1
 [0.18.0]: https://gitlab.com/tozd/waf/-/compare/v0.17.1...v0.18.0
 [0.17.1]: https://gitlab.com/tozd/waf/-/compare/v0.17.0...v0.17.1
 [0.17.0]: https://gitlab.com/tozd/waf/-/compare/v0.16.0...v0.17.0

metrics.go

@@ -30,7 +30,7 @@ type DurationMeasurement struct {
 
 // Start records the start of the duration.
 func (d *DurationMeasurement) Start() *DurationMeasurement {
-	if d.Discarded {
+	if d == nil || d.Discarded {
 		return d
 	}
 	if !d.startTime.IsZero() {
@@ -42,7 +42,7 @@ func (d *DurationMeasurement) Start() *DurationMeasurement {
 
 // Stop computes the duration.
 func (d *DurationMeasurement) Stop() *DurationMeasurement {
-	if d.Discarded {
+	if d == nil || d.Discarded {
 		return d
 	}
 	if d.startTime.IsZero() {
@@ -59,6 +59,9 @@ func (d *DurationMeasurement) Stop() *DurationMeasurement {
 //
 // Any future calls to measurement methods are ignored.
 func (d *DurationMeasurement) Discard() *DurationMeasurement {
+	if d == nil {
+		return d
+	}
 	d.Discarded = true
 	return d
 }
@@ -73,13 +76,16 @@ type DurationMetric struct {
 }
 
 func (d *DurationMetric) Name() string {
+	if d == nil {
+		return ""
+	}
 	return d.name
 }
 
 func (d *DurationMetric) MarshalZerologObject(e *zerolog.Event) {
 	// We use only really measured durations and not just started
 	// (it is impossible to both start and end the measurement with 0 duration).
-	if d.Discarded || d.Duration == 0 {
+	if d == nil || d.Discarded || d.Duration == 0 {
 		return
 	}
 
@@ -89,7 +95,7 @@ func (d *DurationMetric) MarshalZerologObject(e *zerolog.Event) {
 func (d *DurationMetric) ServerTimingString() string {
 	// We use only really measured durations and not just started
 	// (it is impossible to both start and end the measurement with 0 duration).
-	if d.Discarded || d.Duration == 0 {
+	if d == nil || d.Discarded || d.Duration == 0 {
 		return ""
 	}
 
@@ -101,7 +107,7 @@ func (d *DurationMetric) ServerTimingString() string {
 //
 // Can be called only once per metric.
 func (d *DurationMetric) Start() *DurationMetric {
-	if d.Discarded {
+	if d == nil || d.Discarded {
 		return d
 	}
 	if !d.startTime.IsZero() {
@@ -113,7 +119,7 @@ func (d *DurationMetric) Start() *DurationMetric {
 
 // Stop computes the duration.
 func (d *DurationMetric) Stop() *DurationMetric {
-	if d.Discarded {
+	if d == nil || d.Discarded {
 		return d
 	}
 	if d.startTime.IsZero() {
@@ -130,6 +136,9 @@ func (d *DurationMetric) Stop() *DurationMetric {
 //
 // Any future calls to metric methods are ignored.
 func (d *DurationMetric) Discard() *DurationMetric {
+	if d == nil {
+		return d
+	}
 	d.Discarded = true
 	return d
 }
@@ -143,11 +152,14 @@ type CounterMetric struct {
 }
 
 func (c *CounterMetric) Name() string {
+	if c == nil {
+		return ""
+	}
 	return c.name
 }
 
 func (c *CounterMetric) MarshalZerologObject(e *zerolog.Event) {
-	if c.Discarded {
+	if c == nil || c.Discarded {
 		return
 	}
 
@@ -162,7 +174,7 @@ func (c *CounterMetric) ServerTimingString() string {
 
 // Inc increases the counter by one.
 func (c *CounterMetric) Inc() *CounterMetric {
-	if c.Discarded {
+	if c == nil || c.Discarded {
 		return c
 	}
 	c.Count++
@@ -171,7 +183,7 @@ func (c *CounterMetric) Inc() *CounterMetric {
 
 // Add increases the counter by n.
 func (c *CounterMetric) Add(n int64) *CounterMetric {
-	if c.Discarded {
+	if c == nil || c.Discarded {
 		return c
 	}
 	c.Count += n
@@ -182,6 +194,9 @@ func (c *CounterMetric) Add(n int64) *CounterMetric {
 //
 // Any future calls to metric methods are ignored.
 func (c *CounterMetric) Discard() *CounterMetric {
+	if c == nil {
+		return c
+	}
 	c.Discarded = true
 	return c
 }
@@ -198,11 +213,14 @@ type DurationsMetric struct {
 }
 
 func (d *DurationsMetric) Name() string {
+	if d == nil {
+		return ""
+	}
 	return d.name
 }
 
 func (d *DurationsMetric) MarshalZerologObject(e *zerolog.Event) {
-	if d.Discarded {
+	if d == nil || d.Discarded {
 		return
 	}
 
@@ -252,6 +270,9 @@ func (d *DurationsMetric) ServerTimingString() string {
 //
 // Can be called multiple times per metric with each call returning a new measurement.
 func (d *DurationsMetric) Start() *DurationMeasurement {
+	if d == nil {
+		return nil
+	}
 	m := new(DurationMeasurement)
 	if d.Discarded {
 		m.Discarded = true
@@ -268,6 +289,9 @@ func (d *DurationsMetric) Start() *DurationMeasurement {
 //
 // Any future calls to Start return an already discarded duration measurement.
 func (d *DurationsMetric) Discard() *DurationsMetric {
+	if d == nil {
+		return d
+	}
 	d.Discarded = true
 	return d
 }
@@ -283,13 +307,16 @@ type DurationCounterMetric struct {
 }
 
 func (d *DurationCounterMetric) Name() string {
+	if d == nil {
+		return ""
+	}
 	return d.name
 }
 
 func (d *DurationCounterMetric) MarshalZerologObject(e *zerolog.Event) {
 	// We use only really measured durations and not just started
 	// (it is impossible to both start and end the measurement with 0 duration).
-	if d.Discarded || d.Duration == 0 {
+	if d == nil || d.Discarded || d.Duration == 0 {
 		return
 	}
 
@@ -307,7 +334,7 @@ func (d *DurationCounterMetric) MarshalZerologObject(e *zerolog.Event) {
 func (d *DurationCounterMetric) ServerTimingString() string {
 	// We use only really measured durations and not just started
 	// (it is impossible to both start and end the measurement with 0 duration).
-	if d.Discarded || d.Duration == 0 {
+	if d == nil || d.Discarded || d.Duration == 0 {
 		return ""
 	}
 
@@ -319,7 +346,7 @@ func (d *DurationCounterMetric) ServerTimingString() string {
 //
 // Can be called only once per metric.
 func (d *DurationCounterMetric) Start() *DurationCounterMetric {
-	if d.Discarded {
+	if d == nil || d.Discarded {
 		return d
 	}
 	if !d.startTime.IsZero() {
@@ -331,7 +358,7 @@ func (d *DurationCounterMetric) Start() *DurationCounterMetric {
 
 // Stop computes the duration.
 func (d *DurationCounterMetric) Stop() *DurationCounterMetric {
-	if d.Discarded {
+	if d == nil || d.Discarded {
 		return d
 	}
 	if d.startTime.IsZero() {
@@ -348,7 +375,7 @@ func (d *DurationCounterMetric) Stop() *DurationCounterMetric {
 //
 // Only possible after calling Start and before calling Stop.
 func (d *DurationCounterMetric) Inc() *DurationCounterMetric {
-	if d.Discarded {
+	if d == nil || d.Discarded {
 		return d
 	}
 	if d.startTime.IsZero() {
@@ -365,7 +392,7 @@ func (d *DurationCounterMetric) Inc() *DurationCounterMetric {
 //
 // Only possible after calling Start and before calling Stop.
 func (d *DurationCounterMetric) Add(n int64) *DurationCounterMetric {
-	if d.Discarded {
+	if d == nil || d.Discarded {
 		return d
 	}
 	if d.startTime.IsZero() {
@@ -382,6 +409,9 @@ func (d *DurationCounterMetric) Add(n int64) *DurationCounterMetric {
 //
 // Any future calls to metric methods are ignored.
 func (d *DurationCounterMetric) Discard() *DurationCounterMetric {
+	if d == nil {
+		return d
+	}
 	d.Discarded = true
 	return d
 }
@@ -418,6 +448,10 @@ func NewMetrics() *Metrics {
 // nothing is added if the existing metric is equal
 // to the metric being added. Otherwise Add panics.
 func (m *Metrics) Add(mt metric) {
+	if m == nil {
+		return
+	}
+
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -438,6 +472,10 @@ func (m *Metrics) Add(mt metric) {
 // If called with the name of an existing duration metric,
 // that duration metric is returned instead.
 func (m *Metrics) Duration(name string) *DurationMetric {
+	if m == nil {
+		return nil
+	}
+
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -460,6 +498,10 @@ func (m *Metrics) Duration(name string) *DurationMetric {
 // If called with the name of an existing counter metric,
 // that counter metric is returned instead.
 func (m *Metrics) Counter(name string) *CounterMetric {
+	if m == nil {
+		return nil
+	}
+
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -482,6 +524,10 @@ func (m *Metrics) Counter(name string) *CounterMetric {
 // If called with the name of an existing durations metric,
 // that durations metric is returned instead.
 func (m *Metrics) Durations(name string) *DurationsMetric {
+	if m == nil {
+		return nil
+	}
+
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -504,6 +550,10 @@ func (m *Metrics) Durations(name string) *DurationsMetric {
 // If called with the name of an existing duration counter metric,
 // that duration counter metric is returned instead.
 func (m *Metrics) DurationCounter(name string) *DurationCounterMetric {
+	if m == nil {
+		return nil
+	}
+
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -522,6 +572,10 @@ func (m *Metrics) DurationCounter(name string) *DurationCounterMetric {
 }
 
 func (m *Metrics) MarshalZerologObject(e *zerolog.Event) {
+	if m == nil {
+		return
+	}
+
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
@@ -542,6 +596,10 @@ func (m *Metrics) MarshalZerologObject(e *zerolog.Event) {
 }
 
 func (m *Metrics) ServerTimingString() string {
+	if m == nil {
+		return ""
+	}
+
 	m.mu.Lock()
 	defer m.mu.Unlock()
 

metrics_test.go

+package waf_test
+
+import (
+	"testing"
+
+	"gitlab.com/tozd/waf"
+)
+
+func TestMetrics(t *testing.T) {
+	t.Parallel()
+
+	metrics := (*waf.Metrics)(nil)
+
+	// There is a similar set of calls in TestMetricsMiddleware.
+	metrics.Counter("counter").Add(40)
+	metrics.Counter("discardedCounter").Inc().Discard()
+	metrics.Duration("duration").Start().Stop()
+	metrics.Duration("foreverDuration").Start()
+	metrics.Duration("discardedDuration1").Start().Discard().Stop()
+	metrics.Duration("discardedDuration2").Start().Stop().Discard()
+	ds := metrics.Durations("durations")
+	ds.Start().Stop()
+	ds.Start().Stop()
+	ds = metrics.Durations("discardedDurations")
+	ds.Start().Discard().Stop()
+	ds.Start().Stop().Discard()
+	dc := metrics.DurationCounter("dc").Start().Add(43)
+	metrics.DurationCounter("discardedDc1").Start().Add(32).Discard().Stop()
+	metrics.DurationCounter("discardedDc2").Start().Add(33).Stop().Discard()
+	metrics.DurationCounter("foreverDc").Start().Add(43)
+	metrics.Counter("counter").Inc()
+	metrics.DurationCounter("dc").Inc()
+	metrics.Duration("trailer").Start().Stop()
+	dc.Stop()
+}

middleware_test.go

@@ -635,6 +635,7 @@ func TestMetricsMiddleware(t *testing.T) {
 	})(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		ctx := r.Context()
 		metrics := MustGetMetrics(ctx)
+		// There is a similar set of calls in TestMetrics.
 		metrics.Counter("counter").Add(40)
 		metrics.Counter("discardedCounter").Inc().Discard()
 		metrics.Duration("duration").Start().Stop()