Remove allocations while logging an Array of Objects. (#38)

array.go

@@ -48,6 +48,7 @@ func (a *Array) Object(obj LogObjectMarshaler) *Array {
 	obj.MarshalZerologObject(e)
 	e.buf = append(e.buf, '}')
 	a.buf = append(a.buf, e.buf...)
+	eventPool.Put(e)
 	return a
 }
 

benchmark_test.go

@@ -96,6 +96,22 @@ func (o obj) MarshalZerologObject(e *Event) {
 		Int("priv", o.priv)
 }
 
+func BenchmarkLogArrayObject(b *testing.B) {
+	obj1 := obj{"a", "b", 2}
+	obj2 := obj{"c", "d", 3}
+	obj3 := obj{"e", "f", 4}
+	logger := New(ioutil.Discard)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		arr := Arr()
+		arr.Object(&obj1)
+		arr.Object(&obj2)
+		arr.Object(&obj3)
+		logger.Info().Array("objects", arr).Msg("test")
+	}
+}
+
 func BenchmarkLogFieldType(b *testing.B) {
 	bools := []bool{true, false, true, false, true, false, true, false, true, false}
 	ints := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}

event.go

@@ -2,7 +2,6 @@ package zerolog
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"runtime"
 	"strconv"
@@ -61,7 +60,9 @@ func (e *Event) write() (err error) {
 		return nil
 	}
 	e.buf = append(e.buf, '}', '\n')
+	if e.w != nil {
 		_, err = e.w.WriteLevel(e.level, e.buf)
+	}
 	eventPool.Put(e)
 	return
 }
@@ -142,7 +143,7 @@ func (e *Event) Dict(key string, dict *Event) *Event {
 // Call usual field methods like Str, Int etc to add fields to this
 // event and give it as argument the *Event.Dict method.
 func Dict() *Event {
-	return newEvent(levelWriterAdapter{ioutil.Discard}, 0, true)
+	return newEvent(nil, 0, true)
 }
 
 // Array adds the field key with an array to the event context.