Add reserved_words counter

.github/workflows/actions.yml

@@ -8,8 +8,7 @@ jobs:
     strategy:
       matrix:
         go-version:
-          - 1.19.x
-          - 1.20.x
+          - 1.22.x
 
     name: run-tests
     runs-on: ubuntu-latest

.golangci.yaml

@@ -6,7 +6,6 @@ linters:
     - gosimple
     - govet
     - ineffassign
-    - megacheck
     - misspell
     - nakedret
     - revive

stat_handler_wrapper_test.go

@@ -92,7 +92,7 @@ func TestHTTPHandler_WrapResponse(t *testing.T) {
 
 	h := NewStatHandler(
 		NewStore(NewNullSink(), false),
-		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {})).(*httpHandler)
+		http.HandlerFunc(func(http.ResponseWriter, *http.Request) {})).(*httpHandler)
 
 	for i, test := range tests {
 		tc := test

stats.go

@@ -346,6 +346,17 @@ type statStore struct {
 	sink Sink
 }
 
+var ReservedTagWords = map[string]bool{"asg": true, "az": true, "backend": true, "canary": true, "host": true, "period": true, "region": true, "shard": true, "window": true, "source": true, "project": true, "facet": true, "envoyservice": true}
+
+func (s *statStore) validateTags(tags map[string]string) {
+	for k := range tags {
+		if _, ok := ReservedTagWords[k]; ok {
+			// Keep track of how many times a reserved tag is used
+			s.NewCounter("reserved_tag").Inc()
+		}
+	}
+}
+
 func (s *statStore) StartContext(ctx context.Context, ticker *time.Ticker) {
 	for {
 		select {
@@ -403,6 +414,7 @@ func (s *statStore) Scope(name string) Scope {
 }
 
 func (s *statStore) ScopeWithTags(name string, tags map[string]string) Scope {
+	s.validateTags(tags)
 	return newSubScope(s, name, tags)
 }
 
@@ -422,6 +434,7 @@ func (s *statStore) NewCounter(name string) Counter {
 }
 
 func (s *statStore) NewCounterWithTags(name string, tags map[string]string) Counter {
+	s.validateTags(tags)
 	return s.newCounter(tagspkg.SerializeTags(name, tags))
 }
 
@@ -438,6 +451,7 @@ func (s *statStore) NewPerInstanceCounter(name string, tags map[string]string) C
 	if _, found := tags["_f"]; found {
 		return s.NewCounterWithTags(name, tags)
 	}
+	s.validateTags(tags)
 	return s.newCounterWithTagSet(name, tagspkg.TagSet(nil).MergePerInstanceTags(tags))
 }
 
@@ -457,6 +471,7 @@ func (s *statStore) NewGauge(name string) Gauge {
 }
 
 func (s *statStore) NewGaugeWithTags(name string, tags map[string]string) Gauge {
+	s.validateTags(tags)
 	return s.newGauge(tagspkg.SerializeTags(name, tags))
 }
 
@@ -471,6 +486,7 @@ func (s *statStore) NewPerInstanceGauge(name string, tags map[string]string) Gau
 	if _, found := tags["_f"]; found {
 		return s.NewGaugeWithTags(name, tags)
 	}
+	s.validateTags(tags)
 	return s.newGaugeWithTagSet(name, tagspkg.TagSet(nil).MergePerInstanceTags(tags))
 }
 
@@ -490,6 +506,7 @@ func (s *statStore) NewMilliTimer(name string) Timer {
 }
 
 func (s *statStore) NewMilliTimerWithTags(name string, tags map[string]string) Timer {
+	s.validateTags(tags)
 	return s.newTimer(tagspkg.SerializeTags(name, tags), time.Millisecond)
 }
 
@@ -498,6 +515,7 @@ func (s *statStore) NewTimer(name string) Timer {
 }
 
 func (s *statStore) NewTimerWithTags(name string, tags map[string]string) Timer {
+	s.validateTags(tags)
 	return s.newTimer(tagspkg.SerializeTags(name, tags), time.Microsecond)
 }
 
@@ -512,6 +530,7 @@ func (s *statStore) NewPerInstanceTimer(name string, tags map[string]string) Tim
 	if _, found := tags["_f"]; found {
 		return s.NewTimerWithTags(name, tags)
 	}
+	s.validateTags(tags)
 	return s.newTimerWithTagSet(name, tagspkg.TagSet(nil).MergePerInstanceTags(tags), time.Microsecond)
 }
 
@@ -522,6 +541,7 @@ func (s *statStore) NewPerInstanceMilliTimer(name string, tags map[string]string
 	if _, found := tags["_f"]; found {
 		return s.NewMilliTimerWithTags(name, tags)
 	}
+	s.validateTags(tags)
 	return s.newTimerWithTagSet(name, tagspkg.TagSet(nil).MergePerInstanceTags(tags), time.Millisecond)
 }
 
@@ -540,6 +560,7 @@ func (s *subScope) Scope(name string) Scope {
 }
 
 func (s *subScope) ScopeWithTags(name string, tags map[string]string) Scope {
+	s.registry.validateTags(tags)
 	return &subScope{
 		registry: s.registry,
 		name:     joinScopes(s.name, name),
@@ -599,6 +620,7 @@ func (s *subScope) NewMilliTimerWithTags(name string, tags map[string]string) Ti
 }
 
 func (s *subScope) NewPerInstanceMilliTimer(name string, tags map[string]string) Timer {
+	s.registry.validateTags(tags)
 	return s.registry.newTimerWithTagSet(joinScopes(s.name, name),
 		s.tags.MergePerInstanceTags(tags), time.Millisecond)
 }

stats_test.go

@@ -69,6 +69,33 @@ func TestStatsStartContext(_ *testing.T) {
 	wg.Wait()
 }
 
+// Ensure we create a counter and increment it for reserved tags
+func TestValidateTags(t *testing.T) {
+	// Ensure we don't create a counter without reserved tags
+	sink := &testStatSink{}
+	store := NewStore(sink, true)
+	store.NewCounter("test").Inc()
+	store.Flush()
+
+	expected := "test:1|c"
+	counter := sink.record
+	if !strings.Contains(counter, expected) {
+		t.Error("wanted counter value of test:1|c, got", counter)
+	}
+
+	// A reserved tag should trigger adding the reserved_tag counter
+	sink = &testStatSink{}
+	store = NewStore(sink, true)
+	store.NewCounterWithTags("test", map[string]string{"host": "i"}).Inc()
+	store.Flush()
+
+	expected = "reserved_tag:1|c\ntest.__host=i:1|c"
+	counter = sink.record
+	if !strings.Contains(counter, expected) {
+		t.Error("wanted counter value of test.___f=i:1|c, got", counter)
+	}
+}
+
 // Ensure timers and timespans are working
 func TestTimer(t *testing.T) {
 	testDuration := time.Duration(9800000)