Add Postings.Reset method

Signed-off-by: Arve Knudsen <[email protected]>

tsdb/index/index.go

@@ -1085,8 +1085,6 @@ type Reader struct {
 
 	// Provides a cache mapping series labels hash by series ID.
 	cacheProvider ReaderCacheProvider
-
-	postingsCache map[uint64]Postings
 }
 
 type postingOffset struct {
@@ -1153,7 +1151,6 @@ func newReader(b ByteSlice, c io.Closer, cacheProvider ReaderCacheProvider) (*Re
 		c:             c,
 		postings:      map[string][]postingOffset{},
 		cacheProvider: cacheProvider,
-		postingsCache: map[uint64]Postings{},
 	}
 
 	// Verify header.
@@ -1231,10 +1228,6 @@ func newReader(b ByteSlice, c io.Closer, cacheProvider ReaderCacheProvider) (*Re
 			copy(l, v)
 			r.postings[k] = l
 		}
-
-		if err := r.populateCache(); err != nil {
-			return nil, err
-		}
 	}
 
 	r.nameSymbols = make(map[uint32]string, len(r.postings))
@@ -1254,47 +1247,6 @@ func newReader(b ByteSlice, c io.Closer, cacheProvider ReaderCacheProvider) (*Re
 	return r, nil
 }
 
-func (r *Reader) populateCache() error {
-	for _, e := range r.postings {
-		d := encoding.NewDecbufAt(r.b, int(r.toc.PostingsTable), nil)
-		d.Skip(e[0].off)
-		lastVal := e[len(e)-1].value
-
-		skip := 0
-		for d.Err() == nil {
-			if skip == 0 {
-				// These are always the same number of bytes,
-				// and it's faster to skip than to parse.
-				skip = d.Len()
-				d.Uvarint()      // Keycount.
-				d.UvarintBytes() // Label name.
-				skip -= d.Len()
-			} else {
-				d.Skip(skip)
-			}
-
-			// Label value
-			v := yoloString(d.UvarintBytes())
-
-			postingsOff := d.Uvarint64()
-			// Read from the postings table
-			d2 := encoding.NewDecbufAt(r.b, int(postingsOff), castagnoliTable)
-			_, p, err := r.dec.Postings(d2.Get())
-			if err != nil {
-				return errors.Wrap(err, "decode postings")
-			}
-
-			r.postingsCache[postingsOff] = p
-
-			if v == lastVal {
-				break
-			}
-		}
-	}
-
-	return nil
-}
-
 // Version returns the file format version of the underlying index.
 func (r *Reader) Version() int {
 	return r.version
@@ -1927,6 +1879,7 @@ func (dec *Decoder) PostingsInPlace(b []byte, p *bigEndianPostings) (int, error)
 		return 0, fmt.Errorf("unexpected postings length, should be %d bytes for %d postings, got %d bytes", 4*n, n, len(l))
 	}
 	p.list = l
+	p.Reset()
 	return n, nil
 }
 

tsdb/index/labelvalues.go

@@ -186,26 +186,20 @@ func (r *Reader) LabelValuesIntersectingPostings(name string, postings Postings)
 		dec:      r.dec,
 		lastVal:  lastVal,
 		postings: postings,
-		cache:    r.postingsCache,
-		seen:     map[string]bool{},
 	}
 }
 
 type intersectLabelValues struct {
-	d         *encoding.Decbuf
-	b         ByteSlice
-	dec       *Decoder
-	postings  Postings
-	lastVal   string
-	skip      int
-	cur       string
-	exhausted bool
-	err       error
-	cache     map[uint64]Postings
-	its       [2]Postings
-	seen      map[string]bool
-	p1        bigEndianPostings
-	p2        bigEndianPostings
+	d           *encoding.Decbuf
+	b           ByteSlice
+	dec         *Decoder
+	postings    Postings
+	curPostings bigEndianPostings
+	lastVal     string
+	skip        int
+	cur         string
+	exhausted   bool
+	err         error
 }
 
 func (it *intersectLabelValues) Next() bool {
@@ -229,43 +223,38 @@ func (it *intersectLabelValues) Next() bool {
 		v := yoloString(it.d.UvarintBytes())
 
 		postingsOff := it.d.Uvarint64()
-		p, ok := it.cache[postingsOff]
-		if ok {
-			p.(*bigEndianPostings).CloneInPlace(&it.p1)
-		} else {
-			// Read from the postings table
-			d2 := encoding.NewDecbufAt(it.b, int(postingsOff), castagnoliTable)
-			var err error
-			_, err = it.dec.PostingsInPlace(d2.Get(), &it.p1)
-			if err != nil {
-				it.err = errors.Wrap(err, "decode postings")
-				return false
-			}
+		// Read from the postings table
+		d2 := encoding.NewDecbufAt(it.b, int(postingsOff), castagnoliTable)
+		_, err := it.dec.PostingsInPlace(d2.Get(), &it.curPostings)
+		if err != nil {
+			it.err = errors.Wrap(err, "decode postings")
+			return false
 		}
 
 		it.exhausted = v == it.lastVal
 
-		it.postings.(*bigEndianPostings).CloneInPlace(&it.p2)
-		if !it.p1.Next() || !it.p2.Next() {
+		it.postings.Reset()
+		if !it.curPostings.Next() || !it.postings.Next() {
 			continue
 		}
-		cur := it.p1.At()
-		if it.p2.At() > cur {
-			cur = it.p2.At()
+		cur := it.curPostings.At()
+		if it.postings.At() > cur {
+			cur = it.postings.At()
 		}
 
+		// Find at least one intersecting series
 		for {
-			if !it.p1.Seek(cur) {
+			if !it.curPostings.Seek(cur) {
 				break
 			}
-			if it.p1.At() > cur {
-				cur = it.p1.At()
+			if it.curPostings.At() > cur {
+				cur = it.curPostings.At()
 			}
-			if !it.p2.Seek(cur) {
+			if !it.postings.Seek(cur) {
 				break
 			}
-			if it.p2.At() > cur {
-				cur = it.p2.At()
+			if it.postings.At() > cur {
+				cur = it.postings.At()
 				continue
 			}