on disk coldsets

blockstore/splitstore/coldset.go

@@ -0,0 +1,102 @@
+package splitstore
+
+import (
+	"bufio"
+	"io"
+	"os"
+
+	"golang.org/x/xerrors"
+
+	cid "github.com/ipfs/go-cid"
+)
+
+type ColdSetWriter struct {
+	file *os.File
+	buf  *bufio.Writer
+}
+
+type ColdSetReader struct {
+	file *os.File
+	buf  *bufio.Reader
+}
+
+func NewColdSetWriter(path string) (*ColdSetWriter, error) {
+	file, err := os.OpenFile(path, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644)
+	if err != nil {
+		return nil, xerrors.Errorf("error creating coldset: %w", err)
+	}
+	buf := bufio.NewWriter(file)
+
+	return &ColdSetWriter{
+		file: file,
+		buf:  buf,
+	}, nil
+}
+
+func NewColdSetReader(path string) (*ColdSetReader, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, xerrors.Errorf("error opening coldset: %w", err)
+	}
+	buf := bufio.NewReader(file)
+
+	return &ColdSetReader{
+		file: file,
+		buf:  buf,
+	}, nil
+}
+
+func (s *ColdSetWriter) Write(c cid.Cid) error {
+	return writeRawCid(s.buf, c, false)
+}
+
+func (s *ColdSetWriter) Close() error {
+	if s.file == nil {
+		return nil
+	}
+
+	err1 := s.buf.Flush()
+	err2 := s.file.Close()
+	s.buf = nil
+	s.file = nil
+
+	if err1 != nil {
+		return err1
+	}
+	return err2
+}
+
+func (s *ColdSetReader) ForEach(f func(cid.Cid) error) error {
+	hbuf := make([]byte, 256)
+	for {
+		next, err := readRawCid(s.buf, hbuf)
+		if err != nil {
+			if err == io.EOF {
+				return nil
+			}
+
+			return xerrors.Errorf("error reading coldset: %w", err)
+		}
+
+		if err := f(next); err != nil {
+			return err
+		}
+	}
+}
+
+func (s *ColdSetReader) Reset() error {
+	_, err := s.file.Seek(0, io.SeekStart)
+	return err
+}
+
+func (s *ColdSetReader) Close() error {
+	if s.file == nil {
+		return nil
+	}
+
+	err := s.file.Close()
+	s.file = nil
+	s.buf = nil
+
+	return err
+}