tsdb/index.Symbols: Drop context argument from Lookup method (#13058)

Drop context argument from tsdb/index.Symbols.Lookup since lookup
should be fast and the context checking is a performance hit.

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

tsdb/index/index.go

@@ -923,7 +923,7 @@ func (w *Writer) writePostingsToTmpFiles() error {
 			// Symbol numbers are in order, so the strings will also be in order.
 			slices.Sort(values)
 			for _, v := range values {
-				value, err := w.symbols.Lookup(w.ctx, v)
+				value, err := w.symbols.Lookup(v)
 				if err != nil {
 					return err
 				}
@@ -1295,7 +1295,7 @@ func NewSymbols(bs ByteSlice, version, off int) (*Symbols, error) {
 	return s, nil
 }
 
-func (s Symbols) Lookup(ctx context.Context, o uint32) (string, error) {
+func (s Symbols) Lookup(o uint32) (string, error) {
 	d := encoding.Decbuf{
 		B: s.bs.Range(0, s.bs.Len()),
 	}
@@ -1307,9 +1307,6 @@ func (s Symbols) Lookup(ctx context.Context, o uint32) (string, error) {
 		d.Skip(s.offsets[int(o/symbolFactor)])
 		// Walk until we find the one we want.
 		for i := o - (o / symbolFactor * symbolFactor); i > 0; i-- {
-			if ctx.Err() != nil {
-				return "", ctx.Err()
-			}
 			d.UvarintBytes()
 		}
 	} else {
@@ -1441,7 +1438,7 @@ func (r *Reader) lookupSymbol(ctx context.Context, o uint32) (string, error) {
 	if s, ok := r.nameSymbols[o]; ok {
 		return s, nil
 	}
-	return r.symbols.Lookup(ctx, o)
+	return r.symbols.Lookup(o)
 }
 
 // Symbols returns an iterator over the symbols that exist within the index.

tsdb/index/index_test.go

@@ -519,7 +519,6 @@ func TestNewFileReaderErrorNoOpenFiles(t *testing.T) {
 }
 
 func TestSymbols(t *testing.T) {
-	ctx := context.Background()
 	buf := encoding.Encbuf{}
 
 	// Add prefix to the buffer to simulate symbols as part of larger buffer.
@@ -542,11 +541,11 @@ func TestSymbols(t *testing.T) {
 	require.Equal(t, 32, s.Size())
 
 	for i := 99; i >= 0; i-- {
-		s, err := s.Lookup(ctx, uint32(i))
+		s, err := s.Lookup(uint32(i))
 		require.NoError(t, err)
 		require.Equal(t, string(rune(i)), s)
 	}
-	_, err = s.Lookup(ctx, 100)
+	_, err = s.Lookup(100)
 	require.Error(t, err)
 
 	for i := 99; i >= 0; i-- {