feat: initial tracing support (#1623)

vendor/github.com/go-logr/logr/discard.go

@@ -0,0 +1,54 @@
+/*
+Copyright 2020 The logr 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 logr
+
+// Discard returns a Logger that discards all messages logged to it.  It can be
+// used whenever the caller is not interested in the logs.  Logger instances
+// produced by this function always compare as equal.
+func Discard() Logger {
+	return Logger{
+		level: 0,
+		sink:  discardLogSink{},
+	}
+}
+
+// discardLogSink is a LogSink that discards all messages.
+type discardLogSink struct{}
+
+// Verify that it actually implements the interface
+var _ LogSink = discardLogSink{}
+
+func (l discardLogSink) Init(RuntimeInfo) {
+}
+
+func (l discardLogSink) Enabled(int) bool {
+	return false
+}
+
+func (l discardLogSink) Info(int, string, ...interface{}) {
+}
+
+func (l discardLogSink) Error(error, string, ...interface{}) {
+}
+
+func (l discardLogSink) WithValues(...interface{}) LogSink {
+	return l
+}
+
+func (l discardLogSink) WithName(string) LogSink {
+	return l
+}