move func to gatherer

Signed-off-by: Owen Williams <owen.williams@grafana.com>

prometheus/promhttp/http.go

@@ -135,8 +135,8 @@ func HandlerForTransactional(reg prometheus.TransactionalGatherer, opts HandlerO
 				panic(err)
 			}
 		}
-		hasEscapedCollisions = opts.Registry.HasEscapedCollision()
 	}
+	hasEscapedCollisions = reg.HasEscapedCollision()
 
 	// Select compression formats to offer based on default or user choice.
 	var compressions []string

prometheus/promhttp/http_test.go

@@ -81,6 +81,10 @@ func (g *mockTransactionGatherer) Gather() (_ []*dto.MetricFamily, done func(),
 	return mfs, func() { g.doneInvoked++ }, err
 }
 
+func (g *mockTransactionGatherer) HasEscapedCollision() bool {
+	return g.g.HasEscapedCollision()
+}
+
 func readCompressedBody(r io.Reader, comp Compression) (string, error) {
 	switch comp {
 	case Gzip:
@@ -567,9 +571,7 @@ func TestEscapedCollisions(t *testing.T) {
 		Help: "A test metric with dots",
 	}))
 
-	handler := HandlerFor(reg, HandlerOpts{
-		Registry: reg,
-	})
+	handler := HandlerFor(reg, HandlerOpts{})
 
 	t.Run("fail case", func(t *testing.T) {
 		writer := httptest.NewRecorder()

prometheus/registry.go

@@ -137,11 +137,6 @@ type Registerer interface {
 	// instance must only collect consistent metrics throughout its
 	// lifetime.
 	Unregister(Collector) bool
-
-	// HasEscapedCollision returns true if any two of the registered metrics would
-	// be the same when escaped to underscores. This is needed to prevent
-	// duplicate metric issues when being scraped by a legacy system.
-	HasEscapedCollision() bool
 }
 
 // Gatherer is the interface for the part of a registry in charge of gathering
@@ -169,6 +164,11 @@ type Gatherer interface {
 	// expose an incomplete result and instead disregard the returned
 	// MetricFamily protobufs in case the returned error is non-nil.
 	Gather() ([]*dto.MetricFamily, error)
+
+	// HasEscapedCollision returns true if any two of the registered metrics would
+	// be the same when escaped to underscores. This is needed to prevent
+	// duplicate metric issues when being scraped by a legacy system.
+	HasEscapedCollision() bool
 }
 
 // Register registers the provided Collector with the DefaultRegisterer.
@@ -205,6 +205,10 @@ func (gf GathererFunc) Gather() ([]*dto.MetricFamily, error) {
 	return gf()
 }
 
+func (gf GathererFunc) HasEscapedCollision() bool {
+	return false
+}
+
 // AlreadyRegisteredError is returned by the Register method if the Collector to
 // be registered has already been registered before, or a different Collector
 // that collects the same metrics has been registered before. Registration fails
@@ -872,6 +876,15 @@ func (gs Gatherers) Gather() ([]*dto.MetricFamily, error) {
 	return internal.NormalizeMetricFamilies(metricFamiliesByName), errs.MaybeUnwrap()
 }
 
+func (gs Gatherers) HasEscapedCollision() bool {
+	for _, g := range gs {
+		if g.HasEscapedCollision() {
+			return true
+		}
+	}
+	return false
+}
+
 // checkSuffixCollisions checks for collisions with the “magic” suffixes the
 // Prometheus text format and the internal metric representation of the
 // Prometheus server add while flattening Summaries and Histograms.
@@ -1103,6 +1116,15 @@ func (r *MultiTRegistry) Gather() (mfs []*dto.MetricFamily, done func(), err err
 	}, errs.MaybeUnwrap()
 }
 
+func (r *MultiTRegistry) HasEscapedCollision() bool {
+	for _, g := range r.tGatherers {
+		if g.HasEscapedCollision() {
+			return true
+		}
+	}
+	return false
+}
+
 // TransactionalGatherer represents transactional gatherer that can be triggered to notify gatherer that memory
 // used by metric family is no longer used by a caller. This allows implementations with cache.
 type TransactionalGatherer interface {
@@ -1128,6 +1150,11 @@ type TransactionalGatherer interface {
 	// Important: done is expected to be triggered (even if the error occurs!)
 	// once caller does not need returned slice of dto.MetricFamily.
 	Gather() (_ []*dto.MetricFamily, done func(), err error)
+
+	// HasEscapedCollision returns true if any two of the registered metrics would
+	// be the same when escaped to underscores. This is needed to prevent
+	// duplicate metric issues when being scraped by a legacy system.
+	HasEscapedCollision() bool
 }
 
 // ToTransactionalGatherer transforms Gatherer to transactional one with noop as done function.
@@ -1144,3 +1171,7 @@ func (g *noTransactionGatherer) Gather() (_ []*dto.MetricFamily, done func(), er
 	mfs, err := g.g.Gather()
 	return mfs, func() {}, err
 }
+
+func (g *noTransactionGatherer) HasEscapedCollision() bool {
+	return g.g.HasEscapedCollision()
+}

prometheus/registry_test.go

@@ -1364,6 +1364,10 @@ func (g *tGatherer) Gather() (_ []*dto.MetricFamily, done func(), err error) {
 	}, func() { g.done = true }, g.err
 }
 
+func (g *tGatherer) HasEscapedCollision() bool {
+	return false
+}
+
 func TestNewMultiTRegistry(t *testing.T) {
 	treg := &tGatherer{}
 

prometheus/wrap.go

@@ -117,10 +117,6 @@ func (r *wrappingRegisterer) Unregister(c Collector) bool {
 	})
 }
 
-func (r *wrappingRegisterer) HasEscapedCollision() bool {
-	return r.wrappedRegisterer.HasEscapedCollision()
-}
-
 type wrappingCollector struct {
 	wrappedCollector Collector
 	prefix           string