lib/db: Be more lenient during migration (fixes #6397) (#6398)

build.go

@@ -654,7 +654,11 @@ func shouldBuildSyso(dir string) (string, error) {
 	}
 
 	jsonPath := filepath.Join(dir, "versioninfo.json")
-	ioutil.WriteFile(jsonPath, bs, 0644)
+	err = ioutil.WriteFile(jsonPath, bs, 0644)
+	if err != nil {
+		return "", errors.New("failed to create " + jsonPath + ": " + err.Error())
+	}
+
 	defer func() {
 		if err := os.Remove(jsonPath); err != nil {
 			log.Printf("Warning: unable to remove generated %s: %v. Please remove it manually.", jsonPath, err)
@@ -860,13 +864,22 @@ func getVersion() string {
 	return "unknown-dev"
 }
 
-func semanticVersion() (major, minor, patch, build string) {
+func semanticVersion() (major, minor, patch, build int) {
 	r := regexp.MustCompile(`v(?P<Major>\d+)\.(?P<Minor>\d+).(?P<Patch>\d+).*\+(?P<CommitsAhead>\d+)`)
 	matches := r.FindStringSubmatch(getVersion())
 	if len(matches) != 5 {
-		return "0", "0", "0", "0"
+		return 0, 0, 0, 0
 	}
-	return matches[1], matches[2], matches[3], matches[4]
+
+	var ints [4]int
+	for i := 1; i < 5; i++ {
+		value, err := strconv.Atoi(matches[i])
+		if err != nil {
+			return 0, 0, 0, 0
+		}
+		ints[i-1] = value
+	}
+	return ints[0], ints[1], ints[2], ints[3]
 }
 
 func getBranchSuffix() string {

lib/db/lowlevel.go

@@ -488,8 +488,18 @@ func (db *Lowlevel) dropPrefix(prefix []byte) error {
 }
 
 func (db *Lowlevel) gcRunner() {
-	t := time.NewTimer(db.timeUntil(indirectGCTimeKey, indirectGCInterval))
+	// Calculate the time for the next GC run. Even if we should run GC
+	// directly, give the system a while to get up and running and do other
+	// stuff first. (We might have migrations and stuff which would be
+	// better off running before GC.)
+	next := db.timeUntil(indirectGCTimeKey, indirectGCInterval)
+	if next < time.Minute {
+		next = time.Minute
+	}
+
+	t := time.NewTimer(next)
 	defer t.Stop()
+
 	for {
 		select {
 		case <-db.gcStop:
@@ -558,10 +568,11 @@ func (db *Lowlevel) gcIndirect() error {
 	// Iterate the FileInfos, unmarshal the block and version hashes and
 	// add them to the filter.
 
-	it, err := db.NewPrefixIterator([]byte{KeyTypeDevice})
+	it, err := t.NewPrefixIterator([]byte{KeyTypeDevice})
 	if err != nil {
 		return err
 	}
+	defer it.Release()
 	for it.Next() {
 		var bl BlocksHashOnly
 		if err := bl.Unmarshal(it.Value()); err != nil {
@@ -579,10 +590,11 @@ func (db *Lowlevel) gcIndirect() error {
 	// Iterate over block lists, removing keys with hashes that don't match
 	// the filter.
 
-	it, err = db.NewPrefixIterator([]byte{KeyTypeBlockList})
+	it, err = t.NewPrefixIterator([]byte{KeyTypeBlockList})
 	if err != nil {
 		return err
 	}
+	defer it.Release()
 	matchedBlocks := 0
 	for it.Next() {
 		key := blockListKey(it.Key())

lib/db/schemaupdater.go

@@ -57,6 +57,11 @@ type schemaUpdater struct {
 }
 
 func (db *schemaUpdater) updateSchema() error {
+	// Updating the schema can touch any and all parts of the database. Make
+	// sure we do not run GC concurrently with schema migrations.
+	db.gcMut.Lock()
+	defer db.gcMut.Unlock()
+
 	miscDB := NewMiscDataNamespace(db.Lowlevel)
 	prevVersion, _, err := miscDB.Int64("dbVersion")
 	if err != nil {
@@ -447,7 +452,16 @@ func (db *schemaUpdater) updateSchemato9(prev int) error {
 	metas := make(map[string]*metadataTracker)
 	for it.Next() {
 		intf, err := t.unmarshalTrunc(it.Value(), false)
-		if err != nil {
+		if backend.IsNotFound(err) {
+			// Unmarshal error due to missing parts (block list), probably
+			// due to a bad migration in a previous RC. Drop this key, as
+			// getFile would anyway return this as a "not found" in the
+			// normal flow of things.
+			if err := t.Delete(it.Key()); err != nil {
+				return err
+			}
+			continue
+		} else if err != nil {
 			return err
 		}
 		fi := intf.(protocol.FileInfo)