Chore: Log segment number when segment read failed (#7687)

* Chore: Log segment number when segment read failed

To manually fix the WAL files, it is good to know where the corrupt
happened so we should log the segment number when the read failed.

Related Issue #7506

Signed-off-by: gaston.qiu <gaston.qiu@umbocv.com>

tsdb/wal/watcher.go

@@ -391,7 +391,7 @@ func (w *Watcher) watch(segmentNum int, tail bool) error {
 
 			// Ignore errors reading to end of segment whilst replaying the WAL.
 			if !tail {
-				if err != nil && err != io.EOF {
+				if err != nil && errors.Cause(err) != io.EOF {
 					level.Warn(w.logger).Log("msg", "Ignoring error reading to end of segment, may have dropped data", "err", err)
 				} else if reader.Offset() != size {
 					level.Warn(w.logger).Log("msg", "Expected to have read whole segment, may have dropped data", "segment", segmentNum, "read", reader.Offset(), "size", size)
@@ -400,7 +400,7 @@ func (w *Watcher) watch(segmentNum int, tail bool) error {
 			}
 
 			// Otherwise, when we are tailing, non-EOFs are fatal.
-			if err != io.EOF {
+			if errors.Cause(err) != io.EOF {
 				return err
 			}
 
@@ -411,7 +411,7 @@ func (w *Watcher) watch(segmentNum int, tail bool) error {
 
 			// Ignore all errors reading to end of segment whilst replaying the WAL.
 			if !tail {
-				if err != nil && err != io.EOF {
+				if err != nil && errors.Cause(err) != io.EOF {
 					level.Warn(w.logger).Log("msg", "Ignoring error reading to end of segment, may have dropped data", "segment", segmentNum, "err", err)
 				} else if reader.Offset() != size {
 					level.Warn(w.logger).Log("msg", "Expected to have read whole segment, may have dropped data", "segment", segmentNum, "read", reader.Offset(), "size", size)
@@ -420,7 +420,7 @@ func (w *Watcher) watch(segmentNum int, tail bool) error {
 			}
 
 			// Otherwise, when we are tailing, non-EOFs are fatal.
-			if err != io.EOF {
+			if errors.Cause(err) != io.EOF {
 				return err
 			}
 		}
@@ -516,7 +516,7 @@ func (w *Watcher) readSegment(r *LiveReader, segmentNum int, tail bool) error {
 			return errors.New("unknown TSDB record type")
 		}
 	}
-	return r.Err()
+	return errors.Wrapf(r.Err(), "segment %d: %v", segmentNum, r.Err())
 }
 
 func (w *Watcher) SetStartTime(t time.Time) {
@@ -565,7 +565,7 @@ func (w *Watcher) readCheckpoint(checkpointDir string) error {
 		defer sr.Close()
 
 		r := NewLiveReader(w.logger, w.readerMetrics, sr)
-		if err := w.readSegment(r, index, false); err != io.EOF && err != nil {
+		if err := w.readSegment(r, index, false); errors.Cause(err) != io.EOF && err != nil {
 			return errors.Wrap(err, "readSegment")
 		}