first draft

Signed-off-by: Krasi Georgiev <kgeorgie@redhat.com>

cmd/tsdb/main.go

@@ -65,15 +65,72 @@ func main() {
 		}
 		printBlocks(db.Blocks())
 	case scanCmd.FullCommand():
-		corrupted, err := tsdb.Scan(*scanPath)
+		useless, err := tsdb.Scan(*scanPath)
 		if err != nil {
 			exitWithError(err)
 		}
-		// list corrupted blocks with date ranges and prompt: "Do you want to delete corrupted blocks N,y ?"
+
+		if len(useless) == 0 {
+			fmt.Println("Hooray! The db has no corrupted blocks (or the scan tool is broken).\U0001f638")
+			return
+		}
+
+		for err, paths := range useless {
+			fmt.Println(err)
+			for _, path := range paths {
+				fmt.Println(path)
+			}
+			switch err.(type) {
+			case tsdb.ErrorTmp:
+				fmt.Println(`
+Scanning found some temporary files!
+These are usually caused by a crash or incomplete compaction and 
+are safe to delete as long as you are sure that no other application is currently using this database folder.`)
+			case tsdb.ErrorOpen:
+				fmt.Println(`
+Scanning found some blocks that cannot be opened!
+Deleting these will allow a clean startup, but you will loose all data in the listed time ranges.`)
+			case tsdb.ErrorSequence:
+				fmt.Println(`
+Scanning found some overlapping blocks!
+Deleting these will allow a clean startup, but you will loose all data in the listed time ranges.`)
+			}
+
+			if yes := prompt(); yes {
+				for _, path := range paths {
+					if err := os.Remove(path); err != nil {
+						fmt.Printf("error deleting: %v, %v", path, err)
+					}
+					fmt.Printf("%v \n", path)
+				}
+			}
+		}
 	}
 	flag.CommandLine.Set("log.level", "debug")
 }
 
+func prompt() bool {
+	fmt.Printf("Do you want to delete these (y/N)? ")
+	var s string
+	_, err := fmt.Scanln(&s)
+	if err != nil {
+		exitWithError(err)
+	}
+
+	s = strings.TrimSpace(s)
+	s = strings.ToLower(s)
+
+	if s == "y" || s == "yes" {
+		return true
+	}
+	if s == "n" || s == "no" {
+		return false
+	}
+	fmt.Printf("%v is not a valid answer \n", s)
+	prompt()
+	return false
+}
+
 type writeBenchmark struct {
 	outPath     string
 	samplesFile string

db.go

@@ -250,11 +250,6 @@ func (db *DB) Dir() string {
 	return db.dir
 }
 
-// Scan checks the integrity of the db for a given directory and returns a list of unreadable blocks that can be deleted to allow a clean startup.
-func Scan(dir string) ([]string, error) {
-	return nil, nil
-}
-
 func (db *DB) run() {
 	defer close(db.donec)
 
@@ -528,8 +523,8 @@ func (db *DB) reload(deleteable ...string) (err error) {
 		exist[meta.ULID] = struct{}{}
 	}
 
-	if err := validateBlockSequence(blocks); err != nil {
-		return errors.Wrap(err, "invalid block sequence")
+	if overlaps := validateBlockSequence(blocks); overlaps != nil {
+		return errors.Errorf("invalid block sequence , block time ranges overlap: %s", overlaps)
 	}
 
 	// Swap in new blocks first for subsequently created readers to be seen.
@@ -562,7 +557,7 @@ func (db *DB) reload(deleteable ...string) (err error) {
 }
 
 // validateBlockSequence returns error if given block meta files indicate that some blocks overlaps within sequence.
-func validateBlockSequence(bs []*Block) error {
+func validateBlockSequence(bs []*Block) Overlaps {
 	if len(bs) <= 1 {
 		return nil
 	}
@@ -574,7 +569,7 @@ func validateBlockSequence(bs []*Block) error {
 
 	overlaps := OverlappingBlocks(metas)
 	if len(overlaps) > 0 {
-		return errors.Errorf("block time ranges overlap: %s", overlaps)
+		return overlaps
 	}
 
 	return nil

scan.go

@@ -0,0 +1,85 @@
+package tsdb
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/pkg/errors"
+)
+
+type ErrorOpen string
+
+func (e ErrorOpen) Error() string {
+	return fmt.Sprintf("block open error: %v", e)
+}
+
+type ErrorSequence string
+
+func (e ErrorSequence) Error() string {
+	return fmt.Sprintf("block sequence error %v", e)
+}
+
+type ErrorTmp struct{}
+
+func (e ErrorTmp) Error() string {
+	return fmt.Sprintf("abandoned tmp files")
+}
+
+// Scan checks the integrity of the tsdb for a given directory and returns a list of files and folders that can be deleted.
+// It returns a map of error to explain the reason and slice of dirs for further processing.
+func Scan(dir string) (map[error][]string, error) {
+	useless := make(map[error][]string)
+
+	if _, err := os.Stat(dir); os.IsNotExist(err) {
+		return nil, err
+	}
+
+	db := &DB{
+		dir:    dir,
+		logger: nil,
+		opts:   &Options{},
+	}
+
+	dirs, err := blockDirs(db.dir)
+	if err != nil {
+		return nil, errors.Wrap(err, "find blocks")
+	}
+
+	// Scan for blocks that can't be opened.
+	var errOpen ErrorOpen
+	for _, dir := range dirs {
+		b, err := OpenBlock(dir, nil)
+		if err != nil {
+			errOpen = ErrorOpen(err.Error())
+			useless[errOpen] = append(useless[errOpen], dir)
+			break
+		}
+
+		db.blocks = append(db.blocks, b)
+	}
+
+	// Scan for overlaping blocks.
+	if overlaps := validateBlockSequence(db.blocks); overlaps != nil {
+		var dirs []string
+		for _, b := range db.blocks {
+			dirs = append(dirs, b.Dir())
+		}
+		useless[ErrorSequence(overlaps.String())] = dirs
+	}
+
+	// Scan for temporary files.
+	var tmpFiles []string
+	filepath.Walk(db.dir, func(path string, f os.FileInfo, _ error) error {
+		if !f.IsDir() {
+			if filepath.Ext(path) == ".tmp" {
+				tmpFiles = append(tmpFiles, path)
+			}
+		}
+		return nil
+	})
+	if len(tmpFiles) > 0 {
+		useless[ErrorTmp{}] = tmpFiles
+	}
+	return useless, nil
+}