Deprecate featuregate.Registry.List in favor of Visit. (#7041)

Signed-off-by: Bogdan Drutu <[email protected]>

Signed-off-by: Bogdan Drutu <[email protected]>

.chloggen/addvisit.yaml

@@ -0,0 +1,11 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: deprecation
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: featuregate
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Deprecate Registry.List in favor of Registry.Visit.
+
+# One or more tracking issues or pull requests related to the change
+issues: [7041]

featuregate/registry.go

@@ -16,6 +16,7 @@ package featuregate // import "go.opentelemetry.io/collector/featuregate"
 
 import (
 	"fmt"
+	"sort"
 	"sync"
 
 	"go.uber.org/atomic"
@@ -153,12 +154,26 @@ func (r *Registry) Set(id string, enabled bool) error {
 	return nil
 }
 
-// List returns a slice of copies of all registered Gates.
-func (r *Registry) List() []Gate {
-	var ret []Gate
+// Visit visits the gates in lexicographical order, calling fn for each.
+func (r *Registry) Visit(fn func(*Gate)) {
+	var gates []*Gate
 	r.gates.Range(func(key, value any) bool {
-		ret = append(ret, *(value.(*Gate)))
+		gates = append(gates, value.(*Gate))
 		return true
 	})
+	sort.Slice(gates, func(i, j int) bool {
+		return gates[i].ID() < gates[j].ID()
+	})
+	for i := range gates {
+		fn(gates[i])
+	}
+}
+
+// Deprecated: [v0.71.0] use Visit.
+func (r *Registry) List() []Gate {
+	var ret []Gate
+	r.Visit(func(gate *Gate) {
+		ret = append(ret, *gate)
+	})
 	return ret
 }

featuregate/registry_test.go

@@ -27,14 +27,17 @@ func TestGlobalRegistry(t *testing.T) {
 
 func TestRegistry(t *testing.T) {
 	r := NewRegistry()
+	// Expect that no gates to visit.
+	r.Visit(func(gate *Gate) {
+		t.FailNow()
+	})
 
 	const id = "foo"
-
-	assert.Empty(t, r.List())
-
 	g, err := r.Register(id, StageBeta, WithRegisterDescription("Test Gate"))
 	assert.NoError(t, err)
-	assert.Len(t, r.List(), 1)
+	r.Visit(func(gate *Gate) {
+		assert.Equal(t, id, gate.ID())
+	})
 	assert.True(t, g.IsEnabled())
 
 	assert.NoError(t, r.Set(id, false))

service/zpages.go

@@ -70,17 +70,16 @@ func handleFeaturezRequest(w http.ResponseWriter, r *http.Request) {
 
 func getFeaturesTableData() zpages.FeatureGateTableData {
 	data := zpages.FeatureGateTableData{}
-	for _, g := range featuregate.GlobalRegistry().List() {
+	featuregate.GlobalRegistry().Visit(func(gate *featuregate.Gate) {
 		data.Rows = append(data.Rows, zpages.FeatureGateTableRowData{
-			ID:             g.ID(),
-			Enabled:        g.IsEnabled(),
-			Description:    g.Description(),
-			ReferenceURL:   g.ReferenceURL(),
-			Stage:          g.Stage().String(),
-			RemovalVersion: g.RemovalVersion(),
+			ID:             gate.ID(),
+			Enabled:        gate.IsEnabled(),
+			Description:    gate.Description(),
+			ReferenceURL:   gate.ReferenceURL(),
+			Stage:          gate.Stage().String(),
+			RemovalVersion: gate.RemovalVersion(),
 		})
-	}
-
+	})
 	return data
 }