reuse buffer option, closes #14

evio.go

@@ -30,6 +30,11 @@ const (
 type Options struct {
 	// TCPKeepAlive (SO_KEEPALIVE) socket option.
 	TCPKeepAlive time.Duration
+	// ReusePacketBuffer will force the connection to share and reuse the
+	// input packet buffer with all connections that also use this option.
+	// Default value is false, which means that all input data passed to the
+	// Data event will be a uniquely copied []byte slice.
+	ReusePacketBuffer bool
 }
 
 // Info represents a information about the connection

evio_loop.go

@@ -524,8 +524,13 @@ func serve(events Events, lns []*listener) error {
 			}
 			if c.action == None {
 				if events.Data != nil {
+					if c.opts.ReusePacketBuffer {
+						in = packet[:n]
+					} else {
+						in = append([]byte{}, packet[:n]...)
+					}
 					unlock()
-					out, c.action = events.Data(c.id, append([]byte{}, packet[:n]...))
+					out, c.action = events.Data(c.id, in)
 					lock()
 					if len(out) > 0 {
 						if events.Prewrite != nil {
@@ -580,7 +585,11 @@ func serve(events Events, lns []*listener) error {
 					c.err = err
 					goto close
 				}
-				in = append([]byte{}, packet[:n]...)
+				if c.opts.ReusePacketBuffer {
+					in = packet[:n]
+				} else {
+					in = append([]byte{}, packet[:n]...)
+				}
 			}
 			if events.Data != nil {
 				unlock()

evio_test.go

@@ -727,3 +727,40 @@ func testTranslate(network, addr string, kind string, stdlib bool) {
 // 	kind = "tcp6"
 // 	must(Serve(events, "tcp6://:9991"))
 // }
+
+func TestReuseBuffer(t *testing.T) {
+	reuses := []bool{true, false}
+	for _, reuse := range reuses {
+		var events Events
+		events.Opened = func(id int, info Info) (out []byte, opts Options, action Action) {
+			opts.ReusePacketBuffer = reuse
+			return
+		}
+		var prev []byte
+		events.Data = func(id int, in []byte) (out []byte, action Action) {
+			if prev == nil {
+				prev = in
+			} else {
+				reused := string(in) == string(prev)
+				if reused != reuse {
+					t.Fatalf("expected %v, got %v", reuse, reused)
+				}
+				action = Shutdown
+			}
+			return
+		}
+		events.Serving = func(_ Server) (action Action) {
+			go func() {
+				c, err := net.Dial("tcp", ":9991")
+				must(err)
+				defer c.Close()
+				c.Write([]byte("packet1"))
+				time.Sleep(time.Second / 5)
+				c.Write([]byte("packet2"))
+			}()
+			return
+		}
+		must(Serve(events, "tcp://:9991"))
+	}
+
+}