Golang Posting.Ts方法代碼示例

// In benchmarks, the time taken per AddMutation before was
// plateauing at 2.5 ms with sync per 10 log entries, and increasing
// for sync per 100 log entries (to 3 ms per AddMutation), largely because
// of how index generation was being done.
//
// With this change, the benchmarks perform as good as benchmarks for
// commit.Logger, where the less frequently file sync happens, the faster
// AddMutations run.
//
// PASS
// BenchmarkAddMutations_SyncEveryLogEntry-6    	     100	  24712455 ns/op
// BenchmarkAddMutations_SyncEvery10LogEntry-6  	     500	   2485961 ns/op
// BenchmarkAddMutations_SyncEvery100LogEntry-6 	   10000	    298352 ns/op
// BenchmarkAddMutations_SyncEvery1000LogEntry-6	   30000	     63544 ns/op
// ok  	github.com/dgraph-io/dgraph/posting	10.291s
func (l *List) AddMutation(t x.DirectedEdge, op byte) error {
	l.wg.Wait()
	l.Lock()
	defer l.Unlock()
	if l.deleteMe {
		return E_TMP_ERROR
	}

	if t.Timestamp.UnixNano() < l.maxMutationTs {
		return fmt.Errorf("Mutation ts lower than committed ts.")
	}

	// Mutation arrives:
	// - Check if we had any(SET/DEL) before this, stored in the mutation list.
	//		- If yes, then replace that mutation. Jump to a)
	// a)		check if the entity exists in main posting list.
	// 				- If yes, store the mutation.
	// 				- If no, disregard this mutation.

	// All edges with a value set, have the same uid. In other words,
	// an (entity, attribute) can only have one interface{} value.
	if t.Value != nil {
		t.ValueId = math.MaxUint64
	}
	if t.ValueId == 0 {
		return fmt.Errorf("ValueId cannot be zero.")
	}

	mbuf := newPosting(t, op)
	uo := flatbuffers.GetUOffsetT(mbuf)
	mpost := new(types.Posting)
	mpost.Init(mbuf, uo)

	glog.WithFields(logrus.Fields{
		"uid":    mpost.Uid(),
		"source": string(mpost.Source()),
		"ts":     mpost.Ts(),
	}).Debug("Add mutation")

	l.mergeMutation(mpost)
	l.maxMutationTs = t.Timestamp.UnixNano()
	if len(l.mindex)+len(l.mlayer) > 0 {
		atomic.StoreInt64(&l.dirtyTs, time.Now().UnixNano())
		if dirtymap != nil {
			dirtymap.Put(l.ghash, true)
		}
	}
	if l.clog == nil {
		return nil
	}
	return l.clog.AddLog(t.Timestamp.UnixNano(), l.hash, mbuf)
}

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) init(key []byte, pstore *store.Store, clog *commit.Logger) {
	l.Lock()
	defer l.Unlock()
	defer l.wg.Done()

	if len(empty) == 0 {
		glog.Fatal("empty should have some bytes.")
	}
	l.key = key
	l.pstore = pstore
	l.clog = clog

	posting := l.getPostingList()
	l.maxMutationTs = posting.CommitTs()
	l.hash = farm.Fingerprint32(key)
	l.ghash = gotomic.IntKey(farm.Fingerprint64(key))
	l.mlayer = make(map[int]types.Posting)

	if clog == nil {
		return
	}
	glog.Debug("Starting stream entries...")

	err := clog.StreamEntries(posting.CommitTs()+1, l.hash,
		func(hdr commit.Header, buffer []byte) {

			uo := flatbuffers.GetUOffsetT(buffer)
			m := new(types.Posting)
			m.Init(buffer, uo)
			if m.Ts() > l.maxMutationTs {
				l.maxMutationTs = m.Ts()
			}
			glog.WithFields(logrus.Fields{
				"uid":    m.Uid(),
				"source": string(m.Source()),
				"ts":     m.Ts(),
			}).Debug("Got entry from log")
			l.mergeMutation(m)
		})
	if err != nil {
		glog.WithError(err).Error("While streaming entries.")
	}
	glog.Debug("Done streaming entries.")
}