wal: add a bench for write entry

wal/wal_bench_test.go

@@ -0,0 +1,53 @@
+package wal
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/coreos/etcd/raft/raftpb"
+)
+
+func BenchmarkWrite100EntryWithoutBatch(b *testing.B) { benchmarkWriteEntry(b, 100, 0) }
+func BenchmarkWrite100EntryBatch10(b *testing.B)      { benchmarkWriteEntry(b, 100, 10) }
+func BenchmarkWrite100EntryBatch100(b *testing.B)     { benchmarkWriteEntry(b, 100, 100) }
+func BenchmarkWrite100EntryBatch500(b *testing.B)     { benchmarkWriteEntry(b, 100, 500) }
+func BenchmarkWrite100EntryBatch1000(b *testing.B)    { benchmarkWriteEntry(b, 100, 1000) }
+
+func BenchmarkWrite1000EntryWithoutBatch(b *testing.B) { benchmarkWriteEntry(b, 1000, 0) }
+func BenchmarkWrite1000EntryBatch10(b *testing.B)      { benchmarkWriteEntry(b, 1000, 10) }
+func BenchmarkWrite1000EntryBatch100(b *testing.B)     { benchmarkWriteEntry(b, 1000, 100) }
+func BenchmarkWrite1000EntryBatch500(b *testing.B)     { benchmarkWriteEntry(b, 1000, 500) }
+func BenchmarkWrite1000EntryBatch1000(b *testing.B)    { benchmarkWriteEntry(b, 1000, 1000) }
+
+func benchmarkWriteEntry(b *testing.B, size int, batch int) {
+	p, err := ioutil.TempDir(os.TempDir(), "waltest")
+	if err != nil {
+		b.Fatal(err)
+	}
+	defer os.RemoveAll(p)
+
+	w, err := Create(p, []byte("somedata"))
+	if err != nil {
+		b.Fatalf("err = %v, want nil", err)
+	}
+	data := make([]byte, size)
+	for i := 0; i < len(data); i++ {
+		data[i] = byte(i)
+	}
+	e := &raftpb.Entry{Data: data}
+
+	b.ResetTimer()
+	n := 0
+	for i := 0; i < b.N; i++ {
+		err := w.SaveEntry(e)
+		if err != nil {
+			b.Fatal(err)
+		}
+		n++
+		if n > batch {
+			w.sync()
+			n = 0
+		}
+	}
+}