[#12] Add benchmarks

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

benchmark_test.go

@@ -0,0 +1,65 @@
+package zapjournald
+
+import (
+	"testing"
+
+	"github.com/ssgreg/journald"
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+type nopSync struct{}
+
+func (nopSync) Write([]byte) (int, error) { return 0, nil }
+func (nopSync) Sync() error               { return nil }
+
+func BenchmarkLogger(b *testing.B) {
+	zc := zap.NewProductionConfig()
+	zc.EncoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
+	zc.Level = zap.NewAtomicLevelAt(zap.InfoLevel)
+
+	b.Run("standard", func(b *testing.B) {
+		encoder := zapcore.NewJSONEncoder(zc.EncoderConfig)
+		core := zapcore.NewCore(encoder, nopSync{}, zc.Level)
+		coreWithContext := core.With([]zapcore.Field{
+			SyslogFacility(LogDaemon),
+			SyslogIdentifier(),
+			SyslogPid()})
+		l := zap.New(coreWithContext)
+		benchmarkLog(b, l)
+	})
+	b.Run("journald", func(b *testing.B) {
+		encoder := zapcore.NewJSONEncoder(zc.EncoderConfig)
+		core := NewCore(zc.Level, encoder, &journald.Journal{}, SyslogFields)
+		core.j.TestModeEnabled = true // Disable actual writing to the journal.
+
+		coreWithContext := core.With([]zapcore.Field{
+			SyslogFacility(LogDaemon),
+			SyslogIdentifier(),
+			SyslogPid(),
+		})
+		l := zap.New(coreWithContext)
+		benchmarkLog(b, l)
+	})
+}
+
+func benchmarkLog(b *testing.B, l *zap.Logger) {
+	b.Run("no fields", func(b *testing.B) {
+		b.ReportAllocs()
+		for i := 0; i < b.N; i++ {
+			l.Info("Simple log message")
+		}
+	})
+	b.Run("application fields", func(b *testing.B) {
+		b.ReportAllocs()
+		for i := 0; i < b.N; i++ {
+			l.Info("Simple log message", zap.Uint32("count", 123), zap.String("details", "nothing"))
+		}
+	})
+	b.Run("journald fields", func(b *testing.B) {
+		b.ReportAllocs()
+		for i := 0; i < b.N; i++ {
+			l.Info("Simple log message", SyslogIdentifier())
+		}
+	})
+}