Golang Value.Bytes方法代碼示例

// Indirectly this tests that the transaction remembers the NodeID of the node
// being read from correctly, at least in this simple case. Not remembering the
// node would lead to thousands of transaction restarts and almost certainly a
// test timeout.
func TestUncertaintyRestarts(t *testing.T) {
	{
		db, eng, clock, mClock, _, transport, err := createTestDB()
		if err != nil {
			t.Fatal(err)
		}
		defer transport.Close()
		// Set a large offset so that a busy restart-loop
		// really shows. Also makes sure that the values
		// we write in the future below don't actually
		// wind up in the past.
		offset := 4000 * time.Millisecond
		clock.SetMaxOffset(offset)
		key := proto.Key("key")
		value := proto.Value{
			Bytes: nil, // Set for each Put
		}
		// With the correct restart behaviour, we see only one restart
		// and the value read is the very first one (as nothing else
		// has been written)
		wantedBytes := []byte("value-0")

		txnOpts := &client.TransactionOptions{
			Name: "uncertainty",
		}
		gr := &proto.GetResponse{}
		i := -1
		tErr := db.RunTransaction(txnOpts, func(txn *client.KV) error {
			i++
			mClock.Increment(1)
			futureTS := clock.Now()
			futureTS.WallTime++
			value.Bytes = []byte(fmt.Sprintf("value-%d", i))
			err = engine.MVCCPut(eng, nil, key, futureTS, value, nil)
			if err != nil {
				t.Fatal(err)
			}
			gr.Reset()
			if err := txn.Call(proto.Get, proto.GetArgs(key), gr); err != nil {
				return err
			}
			if gr.Value == nil || !bytes.Equal(gr.Value.Bytes, wantedBytes) {
				t.Fatalf("%d: read wrong value: %v, wanted %q", i,
					gr.Value, wantedBytes)
			}
			return nil
		})
		if i != 1 {
			t.Errorf("txn restarted %d times, expected only one restart", i)
		}
		if tErr != nil {
			t.Fatal(tErr)
		}
	}
}

// Indirectly this tests that the transaction remembers the NodeID of the node
// being read from correctly, at least in this simple case. Not remembering the
// node would lead to thousands of transaction restarts and almost certainly a
// test timeout.
func TestUncertaintyRestarts(t *testing.T) {
	defer leaktest.AfterTest(t)
	s := createTestDB(t)
	defer s.Stop()
	// Set a large offset so that a busy restart-loop
	// really shows. Also makes sure that the values
	// we write in the future below don't actually
	// wind up in the past.
	offset := 4000 * time.Millisecond
	s.Clock.SetMaxOffset(offset)
	key := proto.Key("key")
	value := proto.Value{
		Bytes: nil, // Set for each Put
	}
	// With the correct restart behaviour, we see only one restart
	// and the value read is the very first one (as nothing else
	// has been written)
	wantedBytes := []byte("value-0")

	i := -1
	tErr := s.DB.Txn(func(txn *client.Txn) error {
		i++
		s.Manual.Increment(1)
		futureTS := s.Clock.Now()
		futureTS.WallTime++
		value.Bytes = []byte(fmt.Sprintf("value-%d", i))
		if err := engine.MVCCPut(s.Eng, nil, key, futureTS, value, nil); err != nil {
			t.Fatal(err)
		}
		gr, err := txn.Get(key)
		if err != nil {
			return err
		}
		if !gr.Exists() || !bytes.Equal(gr.ValueBytes(), wantedBytes) {
			t.Fatalf("%d: read wrong value: %v, wanted %q", i, gr.Value, wantedBytes)
		}
		return nil
	})
	if i != 1 {
		t.Errorf("txn restarted %d times, expected only one restart", i)
	}
	if tErr != nil {
		t.Fatal(tErr)
	}
}

// marshalValue returns a proto.Value initialized from the source
// reflect.Value, returning an error if the types are not compatible.
func marshalValue(v reflect.Value) (proto.Value, error) {
	var r proto.Value
	if !v.IsValid() {
		return r, nil
	}

	switch t := v.Interface().(type) {
	case nil:
		return r, nil

	case string:
		r.Bytes = []byte(t)
		return r, nil

	case []byte:
		r.Bytes = t
		return r, nil

	case proto.Key:
		r.Bytes = []byte(t)
		return r, nil

	case gogoproto.Message:
		var err error
		r.Bytes, err = gogoproto.Marshal(t)
		return r, err

	case encoding.BinaryMarshaler:
		var err error
		r.Bytes, err = t.MarshalBinary()
		return r, err
	}

	switch v.Kind() {
	case reflect.Bool:
		i := int64(0)
		if v.Bool() {
			i = 1
		}
		r.SetInteger(i)
		return r, nil

	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		r.SetInteger(v.Int())
		return r, nil

	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
		r.SetInteger(int64(v.Uint()))
		return r, nil

	case reflect.Float32, reflect.Float64:
		r.SetInteger(int64(math.Float64bits(v.Float())))
		return r, nil

	case reflect.String:
		r.Bytes = []byte(v.String())
		return r, nil
	}

	return r, fmt.Errorf("unable to marshal value: %s", v)
}