Reimplement encoder on top of bytes.Buffer

We anyway need to cache in sync.Pool instances of msgpack Encoder
object, and this object is bound to Writer instance (Buffer in our
case). There's no way to reset encoder to use different buffer, and
there's no way to avoid buffer from being recycled if returned, so it's
easier to use bytes.Buffer which has necessary APIs to avoid extra
allocations (see uber-go/zap#691).

The only allocation left in the benchmark is from msgpack's EncodeTime
function, PR is submitted for it: vmihailenco/msgpack#224

Makefile

@@ -1,4 +1,4 @@
-all: test lint
+all: test lint bench
 
 .PHONY: test
 test:
@@ -7,3 +7,7 @@ test:
 .PHONY: lint
 lint:
 	golangci-lint run
+
+.PHONY: bench
+bench:
+	go test -v -run=nothing -bench=. -benchmem .

encoder.go

@@ -21,17 +21,20 @@
 package zapmsgpack
 
 import (
+	"bytes"
 	"sync"
 
 	"github.com/vmihailenco/msgpack"
 	"go.uber.org/zap/buffer"
 	"go.uber.org/zap/zapcore"
 )
 
+const initialSize = 1024
+
 type encoder struct {
 	*zapcore.EncoderConfig
 
-	buf      *buffer.Buffer
+	buf      *bytes.Buffer
 	enc      *msgpack.Encoder
 	mapSize  int
 	sliceLen int
@@ -42,7 +45,13 @@ var bufPool = buffer.NewPool()
 
 var encoderPool = sync.Pool{
 	New: func() interface{} {
-		return &encoder{}
+		enc := &encoder{
+			buf: bytes.NewBuffer(make([]byte, 0, initialSize)),
+		}
+
+		enc.enc = msgpack.NewEncoder(enc.buf)
+
+		return enc
 	},
 }
 
@@ -51,8 +60,8 @@ func getEncoder() *encoder {
 }
 
 func putEncoder(enc *encoder) {
-	enc.buf = nil
-	enc.enc = nil
+	enc.buf.Reset()
+	enc.EncoderConfig = nil
 	enc.mapSize = 0
 	enc.sliceLen = 0
 	enc.nsPrefix = ""
@@ -65,13 +74,10 @@ func putEncoder(enc *encoder) {
 // Msgpack encoder could be used e.g. while delivering go.uber.org/zap logs
 // to fluentd destination.
 func NewEncoder(cfg zapcore.EncoderConfig) zapcore.Encoder {
-	buf := bufPool.Get()
+	enc := getEncoder()
+	enc.EncoderConfig = &cfg
 
-	return &encoder{
-		EncoderConfig: &cfg,
-		buf:           buf,
-		enc:           msgpack.NewEncoder(buf),
-	}
+	return enc
 }
 
 func (enc *encoder) encodeKey(key string) {
@@ -92,7 +98,6 @@ func (enc *encoder) encodeArray(arr zapcore.ArrayMarshaler) error {
 		return err
 	}
 
-	sliceEnc.buf.Free()
 	putEncoder(sliceEnc)
 
 	return nil
@@ -112,7 +117,6 @@ func (enc *encoder) encodeObject(obj zapcore.ObjectMarshaler) error {
 		return err
 	}
 
-	mapEnc.buf.Free()
 	putEncoder(mapEnc)
 
 	return nil
@@ -128,8 +132,6 @@ func (enc *encoder) OpenNamespace(key string) {
 func (enc *encoder) clone() *encoder {
 	clone := getEncoder()
 	clone.EncoderConfig = enc.EncoderConfig
-	clone.buf = bufPool.Get()
-	clone.enc = msgpack.NewEncoder(clone.buf)
 
 	return clone
 }
@@ -220,11 +222,11 @@ func (enc *encoder) EncodeEntry(ent zapcore.Entry, fields []zapcore.Field) (*buf
 
 	_ = finenc.enc.EncodeMapLen(final.mapSize)
 	_, _ = finenc.buf.Write(final.buf.Bytes())
-	final.buf.Free()
 
-	putEncoder(final)
+	buf := bufPool.Get()
+	_, _ = buf.Write(finenc.buf.Bytes())
 
-	buf := finenc.buf
+	putEncoder(final)
 	putEncoder(finenc)
 
 	return buf, nil

encoder_bench_test.go

@@ -0,0 +1,87 @@
+// Copyright (c) 2019 Andrey Smirnov
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapmsgpack_test
+
+import (
+	"testing"
+
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+
+	zapmsgpack "github.com/smira/zap-msgpack-encoder"
+)
+
+func testEncoderConfig() zapcore.EncoderConfig {
+	return zapcore.EncoderConfig{
+		MessageKey:     "msg",
+		LevelKey:       "level",
+		NameKey:        "name",
+		TimeKey:        "ts",
+		CallerKey:      "caller",
+		StacktraceKey:  "stacktrace",
+		LineEnding:     "\n",
+		EncodeTime:     zapcore.EpochTimeEncoder,
+		EncodeLevel:    zapcore.LowercaseLevelEncoder,
+		EncodeDuration: zapcore.SecondsDurationEncoder,
+		EncodeCaller:   zapcore.ShortCallerEncoder,
+	}
+}
+
+func BenchmarkZapMsgpack(b *testing.B) {
+	enc := zapmsgpack.NewEncoder(testEncoderConfig())
+	enc.AddString("str", "foo")
+	enc.AddInt64("int64-1", 1)
+	enc.AddInt64("int64-2", 2)
+	enc.AddFloat64("float64", 1.0)
+	enc.AddString("string1", "\n")
+	enc.AddString("string2", "💩")
+	enc.AddString("string3", "🤔")
+	enc.AddString("string4", "🙊")
+	enc.AddBool("bool", true)
+
+	entry := zapcore.Entry{
+		Message: "fake",
+		Level:   zap.DebugLevel,
+	}
+
+	fields := []zap.Field{
+		zap.String("string5", "yeah"),
+		zap.Int64("int64-3", 543210),
+		zap.Bool("yes", false),
+		zap.Int16s("setofints", []int16{0, 1, 2, 3, 4, 5}),
+		zap.Object("obj2", zapcore.ObjectMarshalerFunc(func(obj zapcore.ObjectEncoder) error {
+			obj.AddBinary("bits", []byte{0, 1, 2, 3})
+			obj.AddBool("why", true)
+			obj.AddByteString("bs", []byte{})
+			obj.AddFloat32("f", 3.5)
+			return nil
+		})),
+	}
+
+	b.ResetTimer()
+
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			buf, _ := enc.EncodeEntry(entry, fields)
+			buf.Free()
+		}
+	})
+}