fix ever-accumulating memory in logger

util/tele/span_logger.go

@@ -88,14 +88,18 @@ func (s *spanLogSink) Error(err error, msg string, keysAndValues ...interface{})
 	)
 }
 
-func (s *spanLogSink) WithValues(keysAndValues ...interface{}) logr.LogSink {
-	s.vals = append(s.vals, keysAndValues...)
-	return s
+func (s spanLogSink) WithValues(keysAndValues ...interface{}) logr.LogSink {
+	// always create a new slice to avoid multiple loggers writing to the same backing array
+	vals := make([]interface{}, len(s.vals)+len(keysAndValues))
+	copy(vals, s.vals)
+	copy(vals[len(s.vals):], keysAndValues)
+	s.vals = vals
+	return &s
 }
 
-func (s *spanLogSink) WithName(name string) logr.LogSink {
+func (s spanLogSink) WithName(name string) logr.LogSink {
 	s.name = name
-	return s
+	return &s
 }
 
 // NewSpanLogSink is the main entry-point to this implementation.

util/tele/span_logger_test.go

@@ -0,0 +1,48 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package tele
+
+import (
+	"testing"
+
+	"github.com/go-logr/logr"
+	. "github.com/onsi/gomega"
+)
+
+func TestSpanLogSinkWithValues(t *testing.T) {
+	g := NewGomegaWithT(t)
+
+	var log0 logr.LogSink = &spanLogSink{
+		// simulating a slice with cap() > len() where an append() will not create a new array
+		vals: make([]interface{}, 0, 4),
+	}
+
+	log0 = log0.WithValues("k0", "v0")
+
+	g.Expect(log0.(*spanLogSink).vals).To(HaveExactElements("k0", "v0"))
+
+	log1 := log0.WithValues("k1", "v1")
+
+	g.Expect(log0.(*spanLogSink).vals).To(HaveExactElements("k0", "v0"))
+	g.Expect(log1.(*spanLogSink).vals).To(HaveExactElements("k0", "v0", "k1", "v1"))
+
+	log2 := log0.WithValues("k2", "v2")
+
+	g.Expect(log0.(*spanLogSink).vals).To(HaveExactElements("k0", "v0"))
+	g.Expect(log1.(*spanLogSink).vals).To(HaveExactElements("k0", "v0", "k1", "v1"))
+	g.Expect(log2.(*spanLogSink).vals).To(HaveExactElements("k0", "v0", "k2", "v2"))
+}