Revert "lib/storage: remove unused fetchData arg from BlockRef.MustReadBlock"

This reverts commit bab6a15ae0.

Reason for revert: the `fetchData` arg is used in cluster branch.
Leaving this arg in master branch makes smaller the diff with cluster branch.

app/vmselect/netstorage/netstorage.go

@@ -386,7 +386,7 @@ func (sb *sortBlock) reset() {
 
 func (sb *sortBlock) unpackFrom(tmpBlock *storage.Block, br storage.BlockRef, tr storage.TimeRange) error {
 	tmpBlock.Reset()
-	br.MustReadBlock(tmpBlock)
+	br.MustReadBlock(tmpBlock, true)
 	if err := tmpBlock.UnmarshalData(); err != nil {
 		return fmt.Errorf("cannot unmarshal block: %w", err)
 	}

lib/storage/part_search_test.go

@@ -1251,7 +1251,7 @@ func testPartSearchSerial(p *part, tsids []TSID, tr TimeRange, expectedRawBlocks
 	var bs []Block
 	for ps.NextBlock() {
 		var b Block
-		ps.BlockRef.MustReadBlock(&b)
+		ps.BlockRef.MustReadBlock(&b, true)
 		bs = append(bs, b)
 	}
 	if err := ps.Error(); err != nil {

lib/storage/partition_search_test.go

@@ -243,7 +243,7 @@ func testPartitionSearchSerial(pt *partition, tsids []TSID, tr TimeRange, rbsExp
 	pts.Init(pt, tsids, tr)
 	for pts.NextBlock() {
 		var b Block
-		pts.BlockRef.MustReadBlock(&b)
+		pts.BlockRef.MustReadBlock(&b, true)
 		bs = append(bs, b)
 	}
 	if err := pts.Error(); err != nil {

lib/storage/search.go

@@ -31,9 +31,14 @@ func (br *BlockRef) init(p *part, bh *blockHeader) {
 }
 
 // MustReadBlock reads block from br to dst.
-func (br *BlockRef) MustReadBlock(dst *Block) {
+//
+// if fetchData is false, then only block header is read, otherwise all the data is read.
+func (br *BlockRef) MustReadBlock(dst *Block, fetchData bool) {
 	dst.Reset()
 	dst.bh = br.bh
+	if !fetchData {
+		return
+	}
 
 	dst.timestampsData = bytesutil.Resize(dst.timestampsData[:0], int(br.bh.TimestampsBlockSize))
 	br.p.timestampsFile.MustReadAt(dst.timestampsData, int64(br.bh.TimestampsBlockOffset))

lib/storage/search_test.go

@@ -222,7 +222,7 @@ func testSearchInternal(st *Storage, tr TimeRange, mrs []MetricRow, accountsCoun
 		var mbs []metricBlock
 		for s.NextMetricBlock() {
 			var b Block
-			s.MetricBlockRef.BlockRef.MustReadBlock(&b)
+			s.MetricBlockRef.BlockRef.MustReadBlock(&b, true)
 
 			var mb metricBlock
 			mb.MetricName = append(mb.MetricName, s.MetricBlockRef.MetricName...)

lib/storage/table_search_test.go

@@ -254,7 +254,7 @@ func testTableSearchSerial(tb *table, tsids []TSID, tr TimeRange, rbsExpected []
 	ts.Init(tb, tsids, tr)
 	for ts.NextBlock() {
 		var b Block
-		ts.BlockRef.MustReadBlock(&b)
+		ts.BlockRef.MustReadBlock(&b, true)
 		bs = append(bs, b)
 	}
 	if err := ts.Error(); err != nil {

lib/storage/table_search_timing_test.go

@@ -26,7 +26,11 @@ func BenchmarkTableSearch(b *testing.B) {
 				b.Run(fmt.Sprintf("tsidsCount_%d", tsidsCount), func(b *testing.B) {
 					for _, tsidsSearch := range []int{1, 1e1, 1e2, 1e3, 1e4} {
 						b.Run(fmt.Sprintf("tsidsSearch_%d", tsidsSearch), func(b *testing.B) {
-							benchmarkTableSearch(b, rowsCount, tsidsCount, tsidsSearch)
+							for _, fetchData := range []bool{true, false} {
+								b.Run(fmt.Sprintf("fetchData_%v", fetchData), func(b *testing.B) {
+									benchmarkTableSearch(b, rowsCount, tsidsCount, tsidsSearch, fetchData)
+								})
+							}
 						})
 					}
 				})
@@ -103,7 +107,7 @@ func createBenchTable(b *testing.B, path string, startTimestamp int64, rowsPerIn
 	tb.MustClose()
 }
 
-func benchmarkTableSearch(b *testing.B, rowsCount, tsidsCount, tsidsSearch int) {
+func benchmarkTableSearch(b *testing.B, rowsCount, tsidsCount, tsidsSearch int, fetchData bool) {
 	startTimestamp := timestampFromTime(time.Now()) - 365*24*3600*1000
 	rowsPerInsert := getMaxRawRowsPerPartition()
 
@@ -130,7 +134,7 @@ func benchmarkTableSearch(b *testing.B, rowsCount, tsidsCount, tsidsSearch int)
 			}
 			ts.Init(tb, tsids, tr)
 			for ts.NextBlock() {
-				ts.BlockRef.MustReadBlock(&tmpBlock)
+				ts.BlockRef.MustReadBlock(&tmpBlock, fetchData)
 			}
 			ts.MustClose()
 		}