wp

storage/cursor.go

@@ -6,6 +6,8 @@ import (
 
 	bin "gordenko.dev/dima/bin/little"
 	"gordenko.dev/dima/qb"
+	"gordenko.dev/dima/qb/enc"
+	"gordenko.dev/dima/qb/util"
 )
 
 type BackwardCursor struct {
@@ -29,6 +31,7 @@ type BackwardCursorOptions struct {
 }
 
 func NewBackwardCursor(opt BackwardCursorOptions) (*BackwardCursor, error) {
+	fmt.Printf("footer: % x\n", opt.PageData[DataPageSize-DataPageFooterSize:])
 	switch opt.MetricType {
 	case qb.Instant, qb.Cumulative:
 		// ok
@@ -90,6 +93,7 @@ func (s *BackwardCursor) Prev() (uint32, float64, bool, error) {
 	}
 
 	prevPageNo, _ := bin.GetUint32(s.pageData[prevPageIdx:])
+	fmt.Printf("CURSOR: prev pageNo %d\n", prevPageNo)
 	if prevPageNo == 0 {
 		return 0, 0, true, nil
 	}
@@ -129,8 +133,51 @@ func (s *BackwardCursor) Close() {
 	s.releasePage(s.pageNo)
 }
 
-// HELPER
+func CreateTimestampDecompressor(page []byte) (qb.TimestampDecompressor, error) {
+	size, _ := bin.GetUint16(page[timestampsSizeIdx:])
+	if int(size) > DataPagePayloadSize {
+		return nil, fmt.Errorf("bug: invalid timestamps size %d", size)
+	}
+	pos := DataPagePayloadSize - int(size)
+	d := enc.NewTimeDeltaDecompressor()
+	d.RestoreFromEnd(page[pos:DataPagePayloadSize])
 
-//func (s *BackwardCursor) makeDecompressors() error {
+	payload := page[pos:DataPagePayloadSize]
 
-//}
+	fmt.Printf("PAGE timestamps (CURSOR) %d:\n% x\n", len(payload), payload)
+	return d, nil
+}
+
+func CreateValueDecompressor(page []byte, metricType qb.MetricType, fracDigits byte) (qb.ValueDecompressor, error) {
+	size, _ := bin.GetUint16(page[valuesSizeIdx:])
+	if int(size) > DataPagePayloadSize {
+		return nil, fmt.Errorf("bug: invalid values size %d", size)
+	}
+	d := enc.NewValueDeltaDecompressor(metricType, fracDigits)
+	d.RestoreFromEnd(page[:size])
+	return d, nil
+}
+
+func VerifyDataPageCRC32(data []byte) error {
+	var (
+		calculatedCRC = util.CalculateCRC32(data[:dataCRC32Idx])
+		writtenCRC, _ = bin.GetUint32(data[dataCRC32Idx:])
+	)
+	if calculatedCRC != writtenCRC {
+		return fmt.Errorf("calculated CRC32 %d are not equal written CRC32 %d",
+			calculatedCRC, writtenCRC)
+	}
+	return nil
+}
+
+func VerifyIndexPageCRC32(data []byte) error {
+	var (
+		calculatedCRC = util.CalculateCRC32(data[:indexCRC32Idx])
+		writtenCRC, _ = bin.GetUint32(data[indexCRC32Idx:])
+	)
+	if calculatedCRC != writtenCRC {
+		return fmt.Errorf("calculated CRC32 %d are not equal written CRC32 %d",
+			calculatedCRC, writtenCRC)
+	}
+	return nil
+}