structs: adding encode and decode

nomad/structs/structs.go

@@ -1,5 +1,11 @@
 package structs
 
+import (
+	"bytes"
+
+	"github.com/hashicorp/go-msgpack/codec"
+)
+
 type MessageType uint8
 
 const (
@@ -14,3 +20,19 @@ const (
 	// old servers to crash when the FSM attempts to process them.
 	IgnoreUnknownTypeFlag MessageType = 128
 )
+
+// msgpackHandle is a shared handle for encoding/decoding of structs
+var msgpackHandle = &codec.MsgpackHandle{}
+
+// Decode is used to decode a MsgPack encoded object
+func Decode(buf []byte, out interface{}) error {
+	return codec.NewDecoder(bytes.NewReader(buf), msgpackHandle).Decode(out)
+}
+
+// Encode is used to encode a MsgPack object with type prefix
+func Encode(t MessageType, msg interface{}) ([]byte, error) {
+	var buf bytes.Buffer
+	buf.WriteByte(uint8(t))
+	err := codec.NewEncoder(&buf, msgpackHandle).Encode(msg)
+	return buf.Bytes(), err
+}

nomad/structs/structs_test.go

@@ -0,0 +1,33 @@
+package structs
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestEncodeDecode(t *testing.T) {
+	type FooRequest struct {
+		Foo string
+		Bar int
+		Baz bool
+	}
+	arg := &FooRequest{
+		Foo: "test",
+		Bar: 42,
+		Baz: true,
+	}
+	buf, err := Encode(1, arg)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	var out FooRequest
+	err = Decode(buf[1:], &out)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	if !reflect.DeepEqual(arg, &out) {
+		t.Fatalf("bad: %#v %#v", arg, out)
+	}
+}