Allow metadata expiration

Adds the max_metadata_age_days parameter to the metadb configuration,
and runs a periodic thread to expire the old metadata.

cmd/tabacco/metadb.go

@@ -35,6 +35,7 @@ type metadbConfig struct {
 	Driver       string                   `yaml:"db_driver"`
 	DBURI        string                   `yaml:"db_uri"`
 	ServerConfig *serverutil.ServerConfig `yaml:"http_server"`
+	MaxAgeDays   int                      `yaml:"max_metadata_age_days"`
 }
 
 func loadMetadbConfig(path string) (*metadbConfig, error) {

metadb/server/debug_test.go

@@ -10,7 +10,7 @@ import (
 
 func TestDebugPage(t *testing.T) {
 	defer os.Remove(DBFILE)
-	svc, err := New("sqlite3", DBFILE)
+	svc, err := New("sqlite3", DBFILE, 0)
 	if err != nil {
 		t.Fatal(err)
 	}

metadb/server/service.go

@@ -136,12 +136,14 @@ func groupByBackup(dbAtoms []*dbAtom) []*tabacco.Backup {
 
 // Service implementation of the tabacco backup metadata server API.
 type Service struct {
-	db    *sql.DB
-	stmts statementMap
+	db     *sql.DB
+	stmts  statementMap
+	maxAge int
+	stop   chan struct{}
 }
 
 // New creates a new service and returns it.
-func New(dbDriver, dbURI string) (*Service, error) {
+func New(dbDriver, dbURI string, maxMetadataAgeDays int) (*Service, error) {
 	db, err := openDB(dbDriver, dbURI)
 	if err != nil {
 		return nil, err
@@ -152,11 +154,35 @@ func New(dbDriver, dbURI string) (*Service, error) {
 		return nil, err
 	}
 
-	return &Service{db, stmts}, nil
+	s := &Service{
+		db:     db,
+		stmts:  stmts,
+		maxAge: maxMetadataAgeDays,
+		stop:   make(chan struct{}),
+	}
+	if s.maxAge > 0 {
+		go func() {
+			t := time.NewTicker(12 * time.Hour)
+			defer t.Stop()
+			for {
+				select {
+				case <-t.C:
+					if err := s.purge(); err != nil {
+						log.Printf("purge() error: %v", err)
+					}
+				case <-s.stop:
+					return
+				}
+			}
+		}()
+	}
+
+	return s, nil
 }
 
 // Close the underlying database and all associated resources.
 func (s *Service) Close() {
+	close(s.stop)
 	s.db.Close() // nolint
 }
 
@@ -284,3 +310,18 @@ func (s *Service) FindAtoms(ctx context.Context, req *tabacco.FindRequest) ([]*t
 
 	return groupByBackup(keepNumVersions(atoms, req.NumVersions)), nil
 }
+
+func (s *Service) purge() error {
+	cutoff := time.Now().Add(time.Duration(-s.maxAge) * 24 * time.Hour)
+
+	ctx := context.Background()
+	return retryBusy(ctx, func() error {
+		return withTX(ctx, s.db, func(tx *sql.Tx) error {
+			_, err := tx.Exec(
+				`DELETE FROM log WHERE backup_timestamp < ?`,
+				cutoff,
+			)
+			return err
+		})
+	})
+}

metadb/server/service_test.go

@@ -41,7 +41,7 @@ func addTestEntry(t *testing.T, svc *Service, backupID, host, dsName string) {
 
 func TestService_AddDataset(t *testing.T) {
 	defer os.Remove(DBFILE)
-	svc, err := New("sqlite3", DBFILE)
+	svc, err := New("sqlite3", DBFILE, 0)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -52,7 +52,7 @@ func TestService_AddDataset(t *testing.T) {
 
 func TestService_FindAtoms(t *testing.T) {
 	defer os.Remove(DBFILE)
-	svc, err := New("sqlite3", DBFILE)
+	svc, err := New("sqlite3", DBFILE, 0)
 	if err != nil {
 		t.Fatal(err)
 	}