func newRWFolder(model *Model, cfg config.FolderConfiguration, ver versioner.Versioner, mtimeFS *fs.MtimeFS) service {
	f := &rwFolder{
		folder: folder{
			stateTracker: newStateTracker(cfg.ID),
			scan:         newFolderScanner(cfg),
			stop:         make(chan struct{}),
			model:        model,
		},

		mtimeFS:        mtimeFS,
		dir:            cfg.Path(),
		versioner:      ver,
		ignorePerms:    cfg.IgnorePerms,
		copiers:        cfg.Copiers,
		pullers:        cfg.Pullers,
		order:          cfg.Order,
		maxConflicts:   cfg.MaxConflicts,
		allowSparse:    !cfg.DisableSparseFiles,
		checkFreeSpace: cfg.MinDiskFreePct != 0,
		ignoreDelete:   cfg.IgnoreDelete,
		fsync:          cfg.Fsync,

		queue:       newJobQueue(),
		pullTimer:   time.NewTimer(time.Second),
		remoteIndex: make(chan struct{}, 1), // This needs to be 1-buffered so that we queue a notification if we're busy doing a pull when it comes.

		errorsMut: sync.NewMutex(),

		initialScanCompleted: make(chan struct{}),
	}

	f.configureCopiersAndPullers(cfg)

	return f
}

func newRWFolder(m *Model, shortID uint64, cfg config.FolderConfiguration) *rwFolder {
	return &rwFolder{
		stateTracker: stateTracker{
			folder: cfg.ID,
			mut:    sync.NewMutex(),
		},

		model:            m,
		progressEmitter:  m.progressEmitter,
		virtualMtimeRepo: db.NewVirtualMtimeRepo(m.db, cfg.ID),

		folder:      cfg.ID,
		dir:         cfg.Path(),
		scanIntv:    time.Duration(cfg.RescanIntervalS) * time.Second,
		ignorePerms: cfg.IgnorePerms,
		copiers:     cfg.Copiers,
		pullers:     cfg.Pullers,
		shortID:     shortID,
		order:       cfg.Order,

		stop:        make(chan struct{}),
		queue:       newJobQueue(),
		pullTimer:   time.NewTimer(shortPullIntv),
		scanTimer:   time.NewTimer(time.Millisecond), // The first scan should be done immediately.
		delayScan:   make(chan time.Duration),
		scanNow:     make(chan rescanRequest),
		remoteIndex: make(chan struct{}, 1), // This needs to be 1-buffered so that we queue a notification if we're busy doing a pull when it comes.

		errorsMut: sync.NewMutex(),
	}
}

func newRWFolder(m *Model, shortID uint64, cfg config.FolderConfiguration) *rwFolder {
	p := &rwFolder{
		stateTracker: stateTracker{
			folder: cfg.ID,
			mut:    sync.NewMutex(),
		},

		model:            m,
		progressEmitter:  m.progressEmitter,
		virtualMtimeRepo: db.NewVirtualMtimeRepo(m.db, cfg.ID),

		folder:         cfg.ID,
		dir:            cfg.Path(),
		scanIntv:       time.Duration(cfg.RescanIntervalS) * time.Second,
		ignorePerms:    cfg.IgnorePerms,
		copiers:        cfg.Copiers,
		pullers:        cfg.Pullers,
		shortID:        shortID,
		order:          cfg.Order,
		maxConflicts:   cfg.MaxConflicts,
		allowSparse:    !cfg.DisableSparseFiles,
		checkFreeSpace: cfg.MinDiskFreePct != 0,

		stop:        make(chan struct{}),
		queue:       newJobQueue(),
		pullTimer:   time.NewTimer(time.Second),
		scanTimer:   time.NewTimer(time.Millisecond), // The first scan should be done immediately.
		delayScan:   make(chan time.Duration),
		scanNow:     make(chan rescanRequest),
		remoteIndex: make(chan struct{}, 1), // This needs to be 1-buffered so that we queue a notification if we're busy doing a pull when it comes.

		errorsMut: sync.NewMutex(),
	}

	if p.copiers == 0 {
		p.copiers = defaultCopiers
	}
	if p.pullers == 0 {
		p.pullers = defaultPullers
	}

	if cfg.PullerPauseS == 0 {
		p.pause = defaultPullerPause
	} else {
		p.pause = time.Duration(cfg.PullerPauseS) * time.Second
	}

	if cfg.PullerSleepS == 0 {
		p.sleep = defaultPullerSleep
	} else {
		p.sleep = time.Duration(cfg.PullerSleepS) * time.Second
	}

	return p
}

func newRWFolder(model *Model, cfg config.FolderConfiguration, ver versioner.Versioner) service {
	f := &rwFolder{
		folder: folder{
			stateTracker: stateTracker{
				folderID: cfg.ID,
				mut:      sync.NewMutex(),
			},
			scan: folderscan{
				interval: time.Duration(cfg.RescanIntervalS) * time.Second,
				timer:    time.NewTimer(time.Millisecond), // The first scan should be done immediately.
				now:      make(chan rescanRequest),
				delay:    make(chan time.Duration),
			},
			stop:  make(chan struct{}),
			model: model,
		},

		virtualMtimeRepo: db.NewVirtualMtimeRepo(model.db, cfg.ID),
		dir:              cfg.Path(),
		ignorePerms:      cfg.IgnorePerms,
		copiers:          cfg.Copiers,
		pullers:          cfg.Pullers,
		order:            cfg.Order,
		maxConflicts:     cfg.MaxConflicts,
		allowSparse:      !cfg.DisableSparseFiles,
		checkFreeSpace:   cfg.MinDiskFreePct != 0,
		versioner:        ver,

		queue:       newJobQueue(),
		pullTimer:   time.NewTimer(time.Second),
		remoteIndex: make(chan struct{}, 1), // This needs to be 1-buffered so that we queue a notification if we're busy doing a pull when it comes.

		errorsMut: sync.NewMutex(),

		initialScanCompleted: make(chan struct{}),
	}

	f.configureCopiersAndPullers(cfg)

	return f
}

func defaultConfig(myName string) config.Configuration {
	var defaultFolder config.FolderConfiguration

	if !noDefaultFolder {
		l.Infoln("Default folder created and/or linked to new config")
		folderID := rand.String(5) + "-" + rand.String(5)
		defaultFolder = config.NewFolderConfiguration(folderID, locations[locDefFolder])
		defaultFolder.Label = "Default Folder (" + folderID + ")"
		defaultFolder.RescanIntervalS = 60
		defaultFolder.MinDiskFreePct = 1
		defaultFolder.Devices = []config.FolderDeviceConfiguration{{DeviceID: myID}}
		defaultFolder.AutoNormalize = true
		defaultFolder.MaxConflicts = -1
	} else {
		l.Infoln("We will skip creation of a default folder on first start since the proper envvar is set")
	}

	thisDevice := config.NewDeviceConfiguration(myID, myName)
	thisDevice.Addresses = []string{"dynamic"}

	newCfg := config.New(myID)
	if !noDefaultFolder {
		newCfg.Folders = []config.FolderConfiguration{defaultFolder}
	}
	newCfg.Devices = []config.DeviceConfiguration{thisDevice}

	port, err := getFreePort("127.0.0.1", 8384)
	if err != nil {
		l.Fatalln("get free port (GUI):", err)
	}
	newCfg.GUI.RawAddress = fmt.Sprintf("127.0.0.1:%d", port)

	port, err = getFreePort("0.0.0.0", 22000)
	if err != nil {
		l.Fatalln("get free port (BEP):", err)
	}
	if port == 22000 {
		newCfg.Options.ListenAddresses = []string{"default"}
	} else {
		newCfg.Options.ListenAddresses = []string{
			fmt.Sprintf("tcp://%s", net.JoinHostPort("0.0.0.0", strconv.Itoa(port))),
			"dynamic+https://relays.syncthing.net/endpoint",
		}
	}

	return newCfg
}

func defaultConfig(myName string) config.Configuration {
	var defaultFolder config.FolderConfiguration

	if !noDefaultFolder {
		l.Infoln("Default folder created and/or linked to new config")

		defaultFolder = config.NewFolderConfiguration("default", locations[locDefFolder])
		defaultFolder.RescanIntervalS = 60
		defaultFolder.MinDiskFreePct = 1
		defaultFolder.Devices = []config.FolderDeviceConfiguration{{DeviceID: myID}}
		defaultFolder.AutoNormalize = true
		defaultFolder.MaxConflicts = -1
	} else {
		l.Infoln("We will skip creation of a default folder on first start since the proper envvar is set")
	}

	thisDevice := config.NewDeviceConfiguration(myID, myName)
	thisDevice.Addresses = []string{"dynamic"}

	newCfg := config.New(myID)
	if !noDefaultFolder {
		newCfg.Folders = []config.FolderConfiguration{defaultFolder}
	}
	newCfg.Devices = []config.DeviceConfiguration{thisDevice}

	port, err := getFreePort("127.0.0.1", 8384)
	if err != nil {
		l.Fatalln("get free port (GUI):", err)
	}
	newCfg.GUI.RawAddress = fmt.Sprintf("127.0.0.1:%d", port)

	port, err = getFreePort("0.0.0.0", 22000)
	if err != nil {
		l.Fatalln("get free port (BEP):", err)
	}
	newCfg.Options.ListenAddress = []string{fmt.Sprintf("tcp://0.0.0.0:%d", port)}
	return newCfg
}

func TestFolderErrors(t *testing.T) {
	// This test intentionally avoids starting the folders. If they are
	// started, they will perform an initial scan, which will create missing
	// folder markers and race with the stuff we do in the test.

	fcfg := config.FolderConfiguration{
		ID:      "folder",
		RawPath: "testdata/testfolder",
	}
	cfg := config.Wrap("/tmp/test", config.Configuration{
		Folders: []config.FolderConfiguration{fcfg},
	})

	for _, file := range []string{".stfolder", "testfolder/.stfolder", "testfolder"} {
		if err := os.Remove("testdata/" + file); err != nil && !os.IsNotExist(err) {
			t.Fatal(err)
		}
	}

	ldb := db.OpenMemory()

	// Case 1 - new folder, directory and marker created

	m := model.NewModel(cfg, protocol.LocalDeviceID, "device", "syncthing", "dev", ldb, nil)
	m.AddFolder(fcfg)

	if err := m.CheckFolderHealth("folder"); err != nil {
		t.Error("Unexpected error", cfg.Folders()["folder"].Invalid)
	}

	s, err := os.Stat("testdata/testfolder")
	if err != nil || !s.IsDir() {
		t.Error(err)
	}

	_, err = os.Stat("testdata/testfolder/.stfolder")
	if err != nil {
		t.Error(err)
	}

	if err := os.Remove("testdata/testfolder/.stfolder"); err != nil {
		t.Fatal(err)
	}
	if err := os.Remove("testdata/testfolder/"); err != nil {
		t.Fatal(err)
	}

	// Case 2 - new folder, marker created

	fcfg.RawPath = "testdata/"
	cfg = config.Wrap("/tmp/test", config.Configuration{
		Folders: []config.FolderConfiguration{fcfg},
	})

	m = model.NewModel(cfg, protocol.LocalDeviceID, "device", "syncthing", "dev", ldb, nil)
	m.AddFolder(fcfg)

	if err := m.CheckFolderHealth("folder"); err != nil {
		t.Error("Unexpected error", cfg.Folders()["folder"].Invalid)
	}

	_, err = os.Stat("testdata/.stfolder")
	if err != nil {
		t.Error(err)
	}

	if err := os.Remove("testdata/.stfolder"); err != nil {
		t.Fatal(err)
	}

	// Case 3 - Folder marker missing

	set := db.NewFileSet("folder", ldb)
	set.Update(protocol.LocalDeviceID, []protocol.FileInfo{
		{Name: "dummyfile"},
	})

	m = model.NewModel(cfg, protocol.LocalDeviceID, "device", "syncthing", "dev", ldb, nil)
	m.AddFolder(fcfg)

	if err := m.CheckFolderHealth("folder"); err == nil || err.Error() != "folder marker missing" {
		t.Error("Incorrect error: Folder marker missing !=", m.CheckFolderHealth("folder"))
	}

	// Case 3.1 - recover after folder marker missing

	if err = fcfg.CreateMarker(); err != nil {
		t.Error(err)
	}

	if err := m.CheckFolderHealth("folder"); err != nil {
		t.Error("Unexpected error", cfg.Folders()["folder"].Invalid)
	}

	// Case 4 - Folder path missing

	if err := os.Remove("testdata/testfolder/.stfolder"); err != nil && !os.IsNotExist(err) {
		t.Fatal(err)
	}
	if err := os.Remove("testdata/testfolder"); err != nil && !os.IsNotExist(err) {
//.........这里部分代码省略.........

func TestFolderWithoutRestart(t *testing.T) {
	log.Println("Cleaning...")
	err := removeAll("testfolder-p1", "testfolder-p4", "h1/index*", "h4/index*")
	if err != nil {
		t.Fatal(err)
	}
	defer removeAll("testfolder-p1", "testfolder-p4")

	if err := generateFiles("testfolder-p1", 50, 18, "../LICENSE"); err != nil {
		t.Fatal(err)
	}

	p1 := startInstance(t, 1)
	defer checkedStop(t, p1)

	p4 := startInstance(t, 4)
	defer checkedStop(t, p4)

	if ok, err := p1.ConfigInSync(); err != nil || !ok {
		t.Fatal("p1 should be in sync;", ok, err)
	}

	if ok, err := p4.ConfigInSync(); err != nil || !ok {
		t.Fatal("p4 should be in sync;", ok, err)
	}

	// Add a new folder to p1, shared with p4. Back up and restore the config
	// first.

	log.Println("Adding testfolder to p1...")

	os.Remove("h1/config.xml.orig")
	os.Rename("h1/config.xml", "h1/config.xml.orig")
	defer osutil.Rename("h1/config.xml.orig", "h1/config.xml")

	cfg, err := p1.GetConfig()
	if err != nil {
		t.Fatal(err)
	}

	newFolder := config.FolderConfiguration{
		ID:              "testfolder",
		RawPath:         "testfolder-p1",
		RescanIntervalS: 86400,
		Copiers:         1,
		Hashers:         1,
		Pullers:         1,
		Devices:         []config.FolderDeviceConfiguration{{DeviceID: p4.ID()}},
	}
	newDevice := config.DeviceConfiguration{
		DeviceID:    p4.ID(),
		Name:        "p4",
		Addresses:   []string{"dynamic"},
		Compression: protocol.CompressMetadata,
	}

	cfg.Folders = append(cfg.Folders, newFolder)
	cfg.Devices = append(cfg.Devices, newDevice)

	if err = p1.PostConfig(cfg); err != nil {
		t.Fatal(err)
	}

	// Add a new folder to p4, shared with p1. Back up and restore the config
	// first.

	log.Println("Adding testfolder to p4...")

	os.Remove("h4/config.xml.orig")
	os.Rename("h4/config.xml", "h4/config.xml.orig")
	defer osutil.Rename("h4/config.xml.orig", "h4/config.xml")

	cfg, err = p4.GetConfig()
	if err != nil {
		t.Fatal(err)
	}

	newFolder.RawPath = "testfolder-p4"
	newFolder.Devices = []config.FolderDeviceConfiguration{{DeviceID: p1.ID()}}
	newDevice.DeviceID = p1.ID()
	newDevice.Name = "p1"
	newDevice.Addresses = []string{"127.0.0.1:22001"}

	cfg.Folders = append(cfg.Folders, newFolder)
	cfg.Devices = append(cfg.Devices, newDevice)

	if err = p4.PostConfig(cfg); err != nil {
		t.Fatal(err)
	}

	// The change should not require a restart, so the config should be "in sync"

	if ok, err := p1.ConfigInSync(); err != nil || !ok {
		t.Fatal("p1 should be in sync;", ok, err)
	}
	if ok, err := p4.ConfigInSync(); err != nil || !ok {
		t.Fatal("p4 should be in sync;", ok, err)
	}

	// The folder should start and scan - wait for the event that signals this
//.........这里部分代码省略.........