added cache for len

posting/list.go

@@ -96,13 +96,15 @@ type MutableMap struct {
 	deleteMarker uint64
 	uidMap       map[uint64]int
 	uidsH        map[uint64]*pb.Posting
+	length       int
 }
 
 func newMutableMap() *MutableMap {
 	return &MutableMap{
 		oldList:      make(map[uint64]*pb.PostingList),
 		curTime:      0,
 		deleteMarker: math.MaxUint64,
+		length:       math.MaxInt,
 		uidsH:        make(map[uint64]*pb.Posting),
 	}
 }
@@ -116,6 +118,7 @@ func (mm *MutableMap) clone() *MutableMap {
 		curTime:      0,
 		deleteMarker: mm.deleteMarker,
 		uidsH:        mm.uidsH,
+		length:       mm.length,
 	}
 }
 
@@ -165,16 +168,30 @@ func (mm *MutableMap) listLen(readTs uint64) int {
 		return 0
 	}
 
-	count := 0
-	mm.iterate(func(ts uint64, pl *pb.PostingList) {
-		for _, mpost := range pl.Postings {
+	if mm.length == math.MaxInt {
+		count := 0
+		mm.iterate(func(ts uint64, pl *pb.PostingList) {
+			for _, mpost := range pl.Postings {
+				if mpost.Op == Del {
+					count -= 1
+				} else {
+					count += 1
+				}
+			}
+		}, readTs)
+		return count
+	}
+
+	count := mm.length
+	if mm.curList != nil {
+		for _, mpost := range mm.curList.Postings {
 			if mpost.Op == Del {
 				count -= 1
 			} else {
 				count += 1
 			}
 		}
-	}, readTs)
+	}
 	return count
 }
 
@@ -252,6 +269,11 @@ func (mm *MutableMap) insertOldPosting(pl *pb.PostingList) {
 		if _, ok := mm.uidsH[mpost.Uid]; !ok {
 			mm.uidsH[mpost.Uid] = mpost
 		}
+		if mpost.Op == Del {
+			mm.length -= 1
+		} else {
+			mm.length += 1
+		}
 	}
 	mm.oldList[pl.CommitTs] = pl
 }
@@ -824,6 +846,11 @@ func (l *List) setMutationAfterCommit(startTs, commitTs uint64, pl *pb.PostingLi
 		}
 
 		l.mutationMap.uidsH[mpost.Uid] = mpost
+		if mpost.Op == Del {
+			l.mutationMap.length -= 1
+		} else {
+			l.mutationMap.length += 1
+		}
 	}
 
 	l.mutationMap.curList = nil
@@ -1046,19 +1073,18 @@ func (l *List) IsEmpty(readTs, afterUid uint64) (bool, error) {
 func (l *List) getPostingAndLengthNoSort(readTs, afterUid, uid uint64) (int, bool, *pb.Posting) {
 	l.AssertRLock()
 
-	dec := codec.Decoder{Pack: l.plist.Pack}
-	uids := dec.Seek(uid, codec.SeekStart)
-	found := len(uids) > 0 && uids[0] == uid
 	length := l.mutationMap.listLen(readTs)
-	if !found && l.mutationMap != nil {
-		_, ok := l.mutationMap.uidsH[uid]
-		if ok {
-			found = true
-		}
-		_, ok = l.mutationMap.uidMap[uid]
-		if ok {
-			found = true
-		}
+
+	found := false
+
+	searchFurther, pos := l.mutationMap.findPosting(readTs, uid)
+	if pos != nil {
+		found = true
+	}
+	if !found && searchFurther {
+		dec := codec.Decoder{Pack: l.plist.Pack}
+		uids := dec.Seek(uid, codec.SeekStart)
+		found = len(uids) > 0 && uids[0] == uid
 	}
 
 	if l.mutationMap.populateDeleteAll(readTs) == 0 {

posting/mvcc.go

@@ -496,6 +496,7 @@ func ReadPostingList(key []byte, it *badger.Iterator) (*List, error) {
 				pl.CommitTs = item.Version()
 				if l.mutationMap == nil {
 					l.mutationMap = newMutableMap()
+					l.mutationMap.length = 0
 				}
 				l.mutationMap.insertOldPosting(pl)
 				return nil