lib/api, lib/model: Avoid contention on filesystem for DB status call (ref #7270) (#7271)

This splits the ignore getting to two methods, one that loads from disk
(the old one) and one that just returns whatever is already loaded (the
new one). The folder summary service which is just interested in stats
now uses the latter method. This means that it, and API calls that call
it, does not get blocked by folder I/O.

lib/api/api.go

@@ -1218,7 +1218,7 @@ func (s *service) getDBIgnores(w http.ResponseWriter, r *http.Request) {
 
 	folder := qs.Get("folder")
 
-	lines, patterns, err := s.model.GetIgnores(folder)
+	lines, patterns, err := s.model.LoadIgnores(folder)
 	if err != nil && !ignore.IsParseError(err) {
 		http.Error(w, err.Error(), 500)
 		return

lib/api/mocked_model_test.go

@@ -80,7 +80,11 @@ func (m *mockedModel) Availability(folder string, file protocol.FileInfo, block
 	return nil
 }
 
-func (m *mockedModel) GetIgnores(folder string) ([]string, []string, error) {
+func (m *mockedModel) LoadIgnores(folder string) ([]string, []string, error) {
+	return nil, nil, nil
+}
+
+func (m *mockedModel) CurrentIgnores(folder string) ([]string, []string, error) {
 	return nil, nil, nil
 }
 

lib/model/folder_summary.go

@@ -142,7 +142,7 @@ func (c *folderSummaryService) Summary(folder string) (map[string]interface{}, e
 	res["version"] = ourSeq + remoteSeq  // legacy
 	res["sequence"] = ourSeq + remoteSeq // new name
 
-	ignorePatterns, _, _ := c.model.GetIgnores(folder)
+	ignorePatterns, _, _ := c.model.CurrentIgnores(folder)
 	res["ignorePatterns"] = false
 	for _, line := range ignorePatterns {
 		if len(line) > 0 && !strings.HasPrefix(line, "//") {

lib/model/model.go

@@ -83,7 +83,8 @@ type Model interface {
 	Override(folder string)
 	Revert(folder string)
 	BringToFront(folder, file string)
-	GetIgnores(folder string) ([]string, []string, error)
+	LoadIgnores(folder string) ([]string, []string, error)
+	CurrentIgnores(folder string) ([]string, []string, error)
 	SetIgnores(folder string, content []string) error
 
 	GetFolderVersions(folder string) (map[string][]versioner.FileVersion, error)
@@ -648,7 +649,7 @@ func (m *model) UsageReportingStats(report *contract.Report, version int, previe
 		// Ignore stats
 		var seenPrefix [3]bool
 		for folder := range m.cfg.Folders() {
-			lines, _, err := m.GetIgnores(folder)
+			lines, _, err := m.CurrentIgnores(folder)
 			if err != nil {
 				continue
 			}
@@ -1971,7 +1972,9 @@ func (m *model) Connection(deviceID protocol.DeviceID) (protocol.Connection, boo
 	return cn, ok
 }
 
-func (m *model) GetIgnores(folder string) ([]string, []string, error) {
+// LoadIgnores loads or refreshes the ignore patterns from disk, if the
+// folder is healthy, and returns the refreshed lines and patterns.
+func (m *model) LoadIgnores(folder string) ([]string, []string, error) {
 	m.fmut.RLock()
 	cfg, cfgOk := m.folderCfgs[folder]
 	ignores, ignoresOk := m.folderIgnores[folder]
@@ -1990,7 +1993,7 @@ func (m *model) GetIgnores(folder string) ([]string, []string, error) {
 	}
 
 	if !ignoresOk {
-		ignores = ignore.New(fs.NewFilesystem(cfg.FilesystemType, cfg.Path))
+		ignores = ignore.New(cfg.Filesystem())
 	}
 
 	err := ignores.Load(".stignore")
@@ -2004,6 +2007,27 @@ func (m *model) GetIgnores(folder string) ([]string, []string, error) {
 	return ignores.Lines(), ignores.Patterns(), err
 }
 
+// CurrentIgnores returns the currently loaded set of ignore patterns,
+// whichever it may be. No attempt is made to load or refresh ignore
+// patterns from disk.
+func (m *model) CurrentIgnores(folder string) ([]string, []string, error) {
+	m.fmut.RLock()
+	_, cfgOk := m.folderCfgs[folder]
+	ignores, ignoresOk := m.folderIgnores[folder]
+	m.fmut.RUnlock()
+
+	if !cfgOk {
+		return nil, nil, fmt.Errorf("folder %s does not exist", folder)
+	}
+
+	if !ignoresOk {
+		// Empty ignore patterns
+		return []string{}, []string{}, nil
+	}
+
+	return ignores.Lines(), ignores.Patterns(), nil
+}
+
 func (m *model) SetIgnores(folder string, content []string) error {
 	cfg, ok := m.cfg.Folder(folder)
 	if !ok {

lib/model/model_test.go

@@ -1405,7 +1405,7 @@ func changeIgnores(t *testing.T, m *testModel, expected []string) {
 		return true
 	}
 
-	ignores, _, err := m.GetIgnores("default")
+	ignores, _, err := m.LoadIgnores("default")
 	if err != nil {
 		t.Error(err)
 	}
@@ -1421,7 +1421,7 @@ func changeIgnores(t *testing.T, m *testModel, expected []string) {
 		t.Error(err)
 	}
 
-	ignores2, _, err := m.GetIgnores("default")
+	ignores2, _, err := m.LoadIgnores("default")
 	if err != nil {
 		t.Error(err)
 	}
@@ -1441,7 +1441,7 @@ func changeIgnores(t *testing.T, m *testModel, expected []string) {
 		t.Error(err)
 	}
 
-	ignores, _, err = m.GetIgnores("default")
+	ignores, _, err = m.LoadIgnores("default")
 	if err != nil {
 		t.Error(err)
 	}
@@ -1472,7 +1472,7 @@ func TestIgnores(t *testing.T) {
 
 	changeIgnores(t, m, expected)
 
-	_, _, err := m.GetIgnores("doesnotexist")
+	_, _, err := m.LoadIgnores("doesnotexist")
 	if err == nil {
 		t.Error("No error")
 	}
@@ -1490,7 +1490,7 @@ func TestIgnores(t *testing.T) {
 	m.folderIgnores[fcfg.ID] = ignores
 	m.fmut.Unlock()
 
-	_, _, err = m.GetIgnores("fresh")
+	_, _, err = m.LoadIgnores("fresh")
 	if err == nil {
 		t.Error("No error")
 	}