refactor(log): restore customized nop logger (#15257)

log/bench_test.go

@@ -94,9 +94,9 @@ func BenchmarkLoggers(b *testing.B) {
 		}
 	})
 
-	// The nop logger we use in tests,
+	// The nop logger we use expose in the public API,
 	// also useful as a reference for how expensive zerolog is.
-	b.Run("nop logger", func(b *testing.B) {
+	b.Run("specialized nop logger", func(b *testing.B) {
 		for _, bc := range nopCases {
 			bc := bc
 			b.Run(bc.name, func(b *testing.B) {
@@ -108,11 +108,30 @@ func BenchmarkLoggers(b *testing.B) {
 			})
 		}
 	})
+
+	// To compare with the custom nop logger.
+	// The zerolog wrapper is about 1/3 the speed of the specialized nop logger,
+	// so we offer the specialized version in the exported API.
+	b.Run("zerolog nop logger", func(b *testing.B) {
+		for _, bc := range nopCases {
+			bc := bc
+			b.Run(bc.name, func(b *testing.B) {
+				logger := log.NewCustomLogger(zerolog.Nop())
+
+				for i := 0; i < b.N; i++ {
+					logger.Info(message, bc.keyVals...)
+				}
+			})
+		}
+	})
 }
 
 func BenchmarkLoggers_StructuredVsFields(b *testing.B) {
 	b.ReportAllocs()
 
+	errorToLog := errors.New("error")
+	byteSliceToLog := []byte{0xde, 0xad, 0xbe, 0xef}
+
 	b.Run("logger structured", func(b *testing.B) {
 		zl := zerolog.New(io.Discard)
 		var logger log.Logger = log.NewCustomLogger(zl)
@@ -123,8 +142,8 @@ func BenchmarkLoggers_StructuredVsFields(b *testing.B) {
 			zerolog.Error().
 				Int64("foo", 100000).
 				Str("bar", "foo").
-				Bytes("other", []byte{0xde, 0xad, 0xbe, 0xef}).
-				Err(errors.New("error")).
+				Bytes("other", byteSliceToLog).
+				Err(errorToLog).
 				Msg(message)
 		}
 	})
@@ -135,7 +154,7 @@ func BenchmarkLoggers_StructuredVsFields(b *testing.B) {
 		for i := 0; i < b.N; i++ {
 			logger.Info(message, "foo", 100000)
 			logger.Info(message, "foo", "foo")
-			logger.Error(message, "foo", 100000, "bar", "foo", "other", []byte{0xde, 0xad, 0xbe, 0xef}, "error", errors.New("error"))
+			logger.Error(message, "foo", 100000, "bar", "foo", "other", byteSliceToLog, "error", errorToLog)
 		}
 	})
 }

log/logger.go

@@ -21,11 +21,11 @@ type Logger interface {
 	// The key of the tuple must be a string.
 	Info(msg string, keyVals ...any)
 
-	// Error takes a message and a set of key/value pairs and logs with level DEBUG.
+	// Error takes a message and a set of key/value pairs and logs with level ERR.
 	// The key of the tuple must be a string.
 	Error(msg string, keyVals ...any)
 
-	// Debug takes a message and a set of key/value pairs and logs with level ERR.
+	// Debug takes a message and a set of key/value pairs and logs with level DEBUG.
 	// The key of the tuple must be a string.
 	Debug(msg string, keyVals ...any)
 
@@ -42,13 +42,13 @@ type zeroLogWrapper struct {
 	*zerolog.Logger
 }
 
-// NewNopLogger returns a new logger that does nothing
+// NewNopLogger returns a new logger that does nothing.
 func NewNopLogger() Logger {
-	logger := zerolog.Nop()
-	return zeroLogWrapper{&logger}
+	// The custom nopLogger is about 3x faster than a zeroLogWrapper with zerolog.Nop().
+	return nopLogger{}
 }
 
-// NewLogger returns a new logger
+// NewLogger returns a new logger that writes to stdout.
 func NewLogger() Logger {
 	output := zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: time.Kitchen}
 	logger := zerolog.New(output).With().Timestamp().Logger()
@@ -62,7 +62,7 @@ func NewLoggerWithKV(key, value string) Logger {
 	return zeroLogWrapper{&logger}
 }
 
-// NewCustomLogger returns a new logger with the given zerolog logger
+// NewCustomLogger returns a new logger with the given zerolog logger.
 func NewCustomLogger(logger zerolog.Logger) Logger {
 	return zeroLogWrapper{&logger}
 }
@@ -85,19 +85,19 @@ func (l zeroLogWrapper) Debug(msg string, keyVals ...interface{}) {
 	l.Logger.Debug().Fields(keyVals).Msg(msg)
 }
 
-// With returns a new wrapped logger with additional context provided by a set
+// With returns a new wrapped logger with additional context provided by a set.
 func (l zeroLogWrapper) With(keyVals ...interface{}) Logger {
 	logger := l.Logger.With().Fields(keyVals).Logger()
 	return zeroLogWrapper{&logger}
 }
 
-// Impl returns the underlying zerolog logger
-// It can be used to used zerolog structured API directly instead of the wrapper
+// Impl returns the underlying zerolog logger.
+// It can be used to used zerolog structured API directly instead of the wrapper.
 func (l zeroLogWrapper) Impl() interface{} {
 	return l.Logger
 }
 
-// FilterKeys returns a new logger that filters out all key/value pairs that do not match the filter
+// FilterKeys returns a new logger that filters out all key/value pairs that do not match the filter.
 // This functions assumes that the logger is a zerolog.Logger, which is the case for the logger returned by log.NewLogger()
 // NOTE: filtering has a performance impact on the logger
 func FilterKeys(logger Logger, filter func(key, level string) bool) Logger {
@@ -120,3 +120,14 @@ func FilterKeys(logger Logger, filter func(key, level string) bool) Logger {
 
 	return NewCustomLogger(filteredLogger)
 }
+
+// nopLogger is a Logger that does nothing when called.
+// See the "specialized nop logger" benchmark and compare with the "zerolog nop logger" benchmark.
+// The custom implementation is about 3x faster.
+type nopLogger struct{}
+
+func (nopLogger) Info(string, ...any)  {}
+func (nopLogger) Error(string, ...any) {}
+func (nopLogger) Debug(string, ...any) {}
+func (nopLogger) With(...any) Logger   { return nopLogger{} }
+func (nopLogger) Impl() any            { return nopLogger{} }