processor,pkg(ticdc): add Span and package spanz (#7722)

ref #7720

cdc/processor/tablepb/table.go

@@ -14,6 +14,13 @@
 package tablepb
 
 import (
+	"bytes"
+	"encoding"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"strconv"
+	"strings"
 	"sync/atomic"
 
 	"github.com/pingcap/tiflow/cdc/model"
@@ -61,3 +68,75 @@ type TablePipeline interface {
 	// RemainEvents return the amount of kv events remain in sorter.
 	RemainEvents() int64
 }
+
+// Key is a custom type for bytes in proto.
+type Key []byte
+
+var (
+	_ fmt.Stringer = Key{}
+	_ fmt.Stringer = (*Key)(nil)
+)
+
+func (k Key) String() string {
+	return hex.EncodeToString(k)
+}
+
+var (
+	_ json.Marshaler = Key{}
+	_ json.Marshaler = (*Key)(nil)
+)
+
+// MarshalJSON implements json.Marshaler.
+// It is helpful to format span in log.
+func (k Key) MarshalJSON() ([]byte, error) {
+	return json.Marshal(k.String())
+}
+
+var (
+	_ encoding.TextMarshaler = Span{}
+	_ encoding.TextMarshaler = (*Span)(nil)
+)
+
+// MarshalText implements encoding.TextMarshaler (used in proto.CompactTextString).
+// It is helpful to format span in log.
+func (s Span) MarshalText() ([]byte, error) {
+	return []byte(s.String()), nil
+}
+
+func (s *Span) String() string {
+	length := len("{table_id:,start_key:,end_key:}")
+	length += 8 // for TableID
+	length += len(s.StartKey) + len(s.EndKey)
+	b := strings.Builder{}
+	b.Grow(length)
+	b.Write([]byte("{table_id:"))
+	b.Write([]byte(strconv.Itoa(int(s.TableID))))
+	if len(s.StartKey) > 0 {
+		b.Write([]byte(",start_key:"))
+		b.Write([]byte(s.StartKey.String()))
+	}
+	if len(s.EndKey) > 0 {
+		b.Write([]byte(",end_key:"))
+		b.Write([]byte(s.EndKey.String()))
+	}
+	b.Write([]byte("}"))
+	return b.String()
+}
+
+// Less compares two Spans, defines the order between spans.
+func (s *Span) Less(b *Span) bool {
+	if s.TableID < b.TableID {
+		return true
+	}
+	if bytes.Compare(s.StartKey, b.StartKey) < 0 {
+		return true
+	}
+	return false
+}
+
+// Eq compares two Spans, defines the equality between spans.
+func (s *Span) Eq(b *Span) bool {
+	return s.TableID == b.TableID &&
+		bytes.Equal(s.StartKey, b.StartKey) &&
+		bytes.Equal(s.EndKey, b.EndKey)
+}