Golang Posting.ValueBytes方法代碼示例

func ExternalId(uid uint64) (xid string, rerr error) {
	key := posting.Key(uid, "_xid_") // uid -> "_xid_" -> xid
	pl := posting.GetOrCreate(key, uidStore)
	if pl.Length() == 0 {
		return "", errors.New("NO external id")
	}

	if pl.Length() > 1 {
		glog.WithField("uid", uid).Fatal("This shouldn't be happening.")
		return "", errors.New("Multiple external ids for this uid.")
	}

	var p types.Posting
	if ok := pl.Get(&p, 0); !ok {
		glog.WithField("uid", uid).Error("While retrieving posting")
		return "", errors.New("While retrieving posting")
	}

	if p.Uid() != math.MaxUint64 {
		glog.WithField("uid", uid).Fatal("Value uid must be MaxUint64.")
	}
	var t interface{}
	rerr = posting.ParseValue(&t, p.ValueBytes())
	xid = t.(string)
	return xid, rerr
}

func samePosting(a *types.Posting, b *types.Posting) bool {
	if a.Uid() != b.Uid() {
		return false
	}
	if a.ValueLength() != b.ValueLength() {
		return false
	}
	if !bytes.Equal(a.ValueBytes(), b.ValueBytes()) {
		return false
	}
	if !bytes.Equal(a.Source(), b.Source()) {
		return false
	}
	return true
}

func allocateUniqueUid(xid string, instanceIdx uint64,
	numInstances uint64) (uid uint64, rerr error) {

	mod := math.MaxUint64 / numInstances
	minIdx := instanceIdx * mod
	for sp := ""; ; sp += " " {
		txid := xid + sp

		uid1 := farm.Fingerprint64([]byte(txid)) // Generate from hash.
		uid = (uid1 % mod) + minIdx

		glog.WithField("txid", txid).WithField("uid", uid).Debug("Generated")
		if uid == math.MaxUint64 {
			glog.Debug("Hit uint64max while generating fingerprint. Ignoring...")
			continue
		}

		// Check if this uid has already been allocated.
		key := posting.Key(uid, "_xid_") // uid -> "_xid_" -> xid
		pl := posting.GetOrCreate(key, uidStore)

		if pl.Length() > 0 {
			// Something already present here.
			var p types.Posting
			pl.Get(&p, 0)

			var tmp interface{}
			posting.ParseValue(&tmp, p.ValueBytes())
			glog.Debug("Found existing xid: [%q]. Continuing...", tmp.(string))
			continue
		}

		// Uid hasn't been assigned yet.
		t := x.DirectedEdge{
			Value:     xid, // not txid
			Source:    "_assigner_",
			Timestamp: time.Now(),
		}
		rerr = pl.AddMutation(t, posting.Set)
		if rerr != nil {
			glog.WithError(rerr).Error("While adding mutation")
		}
		return uid, rerr
	}
	return 0, errors.New("Some unhandled route lead me here." +
		" Wake the stupid developer up.")
}

func addPosting(b *flatbuffers.Builder, p types.Posting) flatbuffers.UOffsetT {
	so := b.CreateByteString(p.Source()) // Do this before posting start.
	var bo flatbuffers.UOffsetT
	if p.ValueLength() > 0 {
		bo = b.CreateByteVector(p.ValueBytes())
	}

	types.PostingStart(b)
	types.PostingAddUid(b, p.Uid())
	if bo > 0 {
		types.PostingAddValue(b, bo)
	}
	types.PostingAddSource(b, so)
	types.PostingAddTs(b, p.Ts())
	types.PostingAddOp(b, p.Op())
	return types.PostingEnd(b)
}

func (l *List) Value() (result []byte, rerr error) {
	l.wg.Wait()
	l.RLock()
	defer l.RUnlock()

	if l.length() == 0 {
		return result, fmt.Errorf("No value found")
	}

	var p types.Posting
	if ok := l.get(&p, l.length()-1); !ok {
		return result, fmt.Errorf("Unable to get last posting")
	}
	if p.Uid() != math.MaxUint64 {
		return result, fmt.Errorf("No value found")
	}
	return p.ValueBytes(), nil
}

func TestAddMutation_Value(t *testing.T) {
	// logrus.SetLevel(logrus.DebugLevel)
	glog.Debug("Running init...")
	ol := NewList()
	key := Key(10, "value")
	dir, err := ioutil.TempDir("", "storetest_")
	if err != nil {
		t.Error(err)
		return
	}

	defer os.RemoveAll(dir)
	ps := new(store.Store)
	ps.Init(dir)

	clog := commit.NewLogger(dir, "mutations", 50<<20)
	clog.Init()
	defer clog.Close()

	ol.init(key, ps, clog)
	glog.Debug("Init successful.")

	edge := x.DirectedEdge{
		Value:     "oh hey there",
		Source:    "new-testing",
		Timestamp: time.Now(),
	}
	if err := ol.AddMutation(edge, Set); err != nil {
		t.Error(err)
	}
	var p types.Posting
	ol.Get(&p, 0)
	if p.Uid() != math.MaxUint64 {
		t.Errorf("All value uids should go to MaxUint64. Got: %v", p.Uid())
	}
	var iout interface{}
	if err := ParseValue(&iout, p.ValueBytes()); err != nil {
		t.Error(err)
	}
	out := iout.(string)
	if out != "oh hey there" {
		t.Errorf("Expected a value. Got: [%q]", out)
	}

	// Run the same check after committing.
	if _, err := ol.MergeIfDirty(); err != nil {
		t.Error(err)
	}
	{
		var tp types.Posting
		if ok := ol.Get(&tp, 0); !ok {
			t.Error("While retrieving posting")
		}
		if err := ParseValue(&iout, tp.ValueBytes()); err != nil {
			t.Error(err)
		}
		out := iout.(string)
		if out != "oh hey there" {
			t.Errorf("Expected a value. Got: [%q]", out)
		}
	}

	// The value made it to the posting list. Changing it now.
	edge.Value = 119
	if err := ol.AddMutation(edge, Set); err != nil {
		t.Error(err)
	}
	if ol.Length() != 1 {
		t.Errorf("Length should be one. Got: %v", ol.Length())
	}
	if ok := ol.Get(&p, 0); !ok {
		t.Error("While retrieving posting")
	}
	if err := ParseValue(&iout, p.ValueBytes()); err != nil {
		t.Error(err)
	}
	intout := iout.(float64)
	if intout != 119 {
		t.Errorf("Expected 119. Got: %v", intout)
	}
}