// deleteDir attempts to delete the given directory
func (f *rwFolder) deleteDir(file protocol.FileInfo, matcher *ignore.Matcher) {
	// Used in the defer closure below, updated by the function body. Take
	// care not declare another err.
	var err error

	events.Default.Log(events.ItemStarted, map[string]string{
		"folder": f.folderID,
		"item":   file.Name,
		"type":   "dir",
		"action": "delete",
	})

	defer func() {
		events.Default.Log(events.ItemFinished, map[string]interface{}{
			"folder": f.folderID,
			"item":   file.Name,
			"error":  events.Error(err),
			"type":   "dir",
			"action": "delete",
		})
	}()

	realName, err := rootedJoinedPath(f.dir, file.Name)
	if err != nil {
		f.newError(file.Name, err)
		return
	}
	// Delete any temporary files lying around in the directory
	dir, _ := os.Open(realName)
	if dir != nil {
		files, _ := dir.Readdirnames(-1)
		for _, dirFile := range files {
			fullDirFile := filepath.Join(file.Name, dirFile)
			if defTempNamer.IsTemporary(dirFile) || (matcher != nil && matcher.Match(fullDirFile).IsDeletable()) {
				os.RemoveAll(filepath.Join(f.dir, fullDirFile))
			}
		}
		dir.Close()
	}

	err = osutil.InWritableDir(os.Remove, realName)
	if err == nil || os.IsNotExist(err) {
		// It was removed or it doesn't exist to start with
		f.dbUpdates <- dbUpdateJob{file, dbUpdateDeleteDir}
	} else if _, serr := f.mtimeFS.Lstat(realName); serr != nil && !os.IsPermission(serr) {
		// We get an error just looking at the directory, and it's not a
		// permission problem. Lets assume the error is in fact some variant
		// of "file does not exist" (possibly expressed as some parent being a
		// file and not a directory etc) and that the delete is handled.
		f.dbUpdates <- dbUpdateJob{file, dbUpdateDeleteDir}
	} else {
		l.Infof("Puller (folder %q, dir %q): delete: %v", f.folderID, file.Name, err)
		f.newError(file.Name, err)
	}
}

// pullerIteration runs a single puller iteration for the given folder and
// returns the number items that should have been synced (even those that
// might have failed). One puller iteration handles all files currently
// flagged as needed in the folder.
func (p *rwFolder) pullerIteration(ignores *ignore.Matcher) int {
	pullChan := make(chan pullBlockState)
	copyChan := make(chan copyBlocksState)
	finisherChan := make(chan *sharedPullerState)

	updateWg := sync.NewWaitGroup()
	copyWg := sync.NewWaitGroup()
	pullWg := sync.NewWaitGroup()
	doneWg := sync.NewWaitGroup()

	if debug {
		l.Debugln(p, "c", p.copiers, "p", p.pullers)
	}

	p.dbUpdates = make(chan dbUpdateJob)
	updateWg.Add(1)
	go func() {
		// dbUpdaterRoutine finishes when p.dbUpdates is closed
		p.dbUpdaterRoutine()
		updateWg.Done()
	}()

	for i := 0; i < p.copiers; i++ {
		copyWg.Add(1)
		go func() {
			// copierRoutine finishes when copyChan is closed
			p.copierRoutine(copyChan, pullChan, finisherChan)
			copyWg.Done()
		}()
	}

	for i := 0; i < p.pullers; i++ {
		pullWg.Add(1)
		go func() {
			// pullerRoutine finishes when pullChan is closed
			p.pullerRoutine(pullChan, finisherChan)
			pullWg.Done()
		}()
	}

	doneWg.Add(1)
	// finisherRoutine finishes when finisherChan is closed
	go func() {
		p.finisherRoutine(finisherChan)
		doneWg.Done()
	}()

	p.model.fmut.RLock()
	folderFiles := p.model.folderFiles[p.folder]
	p.model.fmut.RUnlock()

	// !!!
	// WithNeed takes a database snapshot (by necessity). By the time we've
	// handled a bunch of files it might have become out of date and we might
	// be attempting to sync with an old version of a file...
	// !!!

	changed := 0
	pullFileSize := int64(0)

	fileDeletions := map[string]protocol.FileInfo{}
	dirDeletions := []protocol.FileInfo{}
	buckets := map[string][]protocol.FileInfo{}

	folderFiles.WithNeed(protocol.LocalDeviceID, func(intf db.FileIntf) bool {
		// Needed items are delivered sorted lexicographically. We'll handle
		// directories as they come along, so parents before children. Files
		// are queued and the order may be changed later.

		file := intf.(protocol.FileInfo)

		if ignores.Match(file.Name) {
			// This is an ignored file. Skip it, continue iteration.
			return true
		}

		if debug {
			l.Debugln(p, "handling", file.Name)
		}

		switch {
		case file.IsDeleted():
			// A deleted file, directory or symlink
			if file.IsDirectory() {
				dirDeletions = append(dirDeletions, file)
			} else {
				fileDeletions[file.Name] = file
				df, ok := p.model.CurrentFolderFile(p.folder, file.Name)
				// Local file can be already deleted, but with a lower version
				// number, hence the deletion coming in again as part of
				// WithNeed, furthermore, the file can simply be of the wrong
				// type if we haven't yet managed to pull it.
				if ok && !df.IsDeleted() && !df.IsSymlink() && !df.IsDirectory() {
					// Put files into buckets per first hash
					key := string(df.Blocks[0].Hash)
					buckets[key] = append(buckets[key], df)
//.........这里部分代码省略.........