Stop single file and `--files-from` operations iterating through the source bucket.

This works by making sure directory listings that use a filter only
iterate the files provided in the filter (if any).

Single file copies now don't iterate the source or destination
buckets.

Note that this could potentially slow down very long `--files-from`
lists - this is easy to fix (with another flag probably) if it causes
anyone a problem.

Fixes #610
Fixes #769

fs/filter.go

@@ -94,8 +94,8 @@ func (rs *rules) len() int {
 	return len(rs.rules)
 }
 
-// filesMap describes the map of files to transfer
-type filesMap map[string]struct{}
+// FilesMap describes the map of files to transfer
+type FilesMap map[string]struct{}
 
 // Filter describes any filtering in operation
 type Filter struct {
@@ -106,8 +106,8 @@ type Filter struct {
 	ModTimeTo      time.Time
 	fileRules      rules
 	dirRules       rules
-	files          filesMap // files if filesFrom
-	dirs           filesMap // dirs from filesFrom
+	files          FilesMap // files if filesFrom
+	dirs           FilesMap // dirs from filesFrom
 }
 
 // We use time conventions
@@ -313,8 +313,8 @@ func (f *Filter) AddRule(rule string) error {
 // AddFile adds a single file to the files from list
 func (f *Filter) AddFile(file string) error {
 	if f.files == nil {
-		f.files = make(filesMap)
-		f.dirs = make(filesMap)
+		f.files = make(FilesMap)
+		f.dirs = make(FilesMap)
 	}
 	file = strings.Trim(file, "/")
 	f.files[file] = struct{}{}
@@ -332,6 +332,13 @@ func (f *Filter) AddFile(file string) error {
 	return nil
 }
 
+// Files returns all the files from the `--files-from` list
+//
+// It may be nil if the list is empty
+func (f *Filter) Files() FilesMap {
+	return f.files
+}
+
 // Clear clears all the filter rules
 func (f *Filter) Clear() {
 	f.fileRules.clear()

fs/filter_test.go

@@ -180,11 +180,11 @@ func TestNewFilterIncludeFiles(t *testing.T) {
 	require.NoError(t, err)
 	err = f.AddFile("/file2.jpg")
 	require.NoError(t, err)
-	assert.Equal(t, filesMap{
+	assert.Equal(t, FilesMap{
 		"file1.jpg": {},
 		"file2.jpg": {},
 	}, f.files)
-	assert.Equal(t, filesMap{}, f.dirs)
+	assert.Equal(t, FilesMap{}, f.dirs)
 	testInclude(t, f, []includeTest{
 		{"file1.jpg", 0, 0, true},
 		{"file2.jpg", 1, 0, true},
@@ -206,7 +206,7 @@ func TestNewFilterIncludeFilesDirs(t *testing.T) {
 		err = f.AddFile(path)
 		require.NoError(t, err)
 	}
-	assert.Equal(t, filesMap{
+	assert.Equal(t, FilesMap{
 		"path":         {},
 		"path/to":      {},
 		"path/to/dir":  {},

fs/fs.go

@@ -114,6 +114,10 @@ type ListFser interface {
 	// Fses must support recursion levels of fs.MaxLevel and 1.
 	// They may return ErrorLevelNotSupported otherwise.
 	List(out ListOpts, dir string)
+
+	// NewObject finds the Object at remote.  If it can't be found
+	// it returns the error ErrorObjectNotFound.
+	NewObject(remote string) (Object, error)
 }
 
 // Fs is the interface a cloud storage system must provide
@@ -121,10 +125,6 @@ type Fs interface {
 	Info
 	ListFser
 
-	// NewObject finds the Object at remote.  If it can't be found
-	// it returns the error ErrorObjectNotFound.
-	NewObject(remote string) (Object, error)
-
 	// Put in to the remote path with the modTime given of the given size
 	//
 	// May create the object even if it returns an error - if so

fs/lister.go

@@ -31,13 +31,55 @@ func NewLister() *Lister {
 	return o.SetLevel(-1).SetBuffer(Config.Checkers)
 }
 
+// Finds and lists the files passed in
+//
+// Note we ignore the dir and just return all the files in the list
+func (o *Lister) listFiles(f ListFser, dir string, files FilesMap) {
+	buffer := o.Buffer()
+	jobs := make(chan string, buffer)
+	var wg sync.WaitGroup
+
+	// Start some listing go routines so we find those name in parallel
+	wg.Add(buffer)
+	for i := 0; i < buffer; i++ {
+		go func() {
+			defer wg.Done()
+			for remote := range jobs {
+				obj, err := f.NewObject(remote)
+				if err == ErrorObjectNotFound {
+					// silently ignore files that aren't found in the files list
+				} else if err != nil {
+					o.SetError(err)
+				} else {
+					o.Add(obj)
+				}
+			}
+		}()
+	}
+
+	// Pump the names in
+	for name := range files {
+		jobs <- name
+		if o.IsFinished() {
+			break
+		}
+	}
+	close(jobs)
+	wg.Wait()
+
+	// Signal that this listing is over
+	o.Finished()
+}
+
 // Start starts a go routine listing the Fs passed in.  It returns the
 // same Lister that was passed in for convenience.
 func (o *Lister) Start(f ListFser, dir string) *Lister {
 	o.results = make(chan listerResult, o.buffer)
-	go func() {
-		f.List(o, dir)
-	}()
+	if o.filter != nil && o.filter.Files() != nil {
+		go o.listFiles(f, dir, o.filter.Files())
+	} else {
+		go f.List(o, dir)
+	}
 	return o
 }
 

fs/lister_test.go

@@ -2,6 +2,7 @@ package fs
 
 import (
 	"io"
+	"sort"
 	"testing"
 	"time"
 
@@ -42,6 +43,10 @@ func (f *mockFs) List(o ListOpts, dir string) {
 	f.listFn(o, dir)
 }
 
+func (f *mockFs) NewObject(remote string) (Object, error) {
+	return mockObject(remote), nil
+}
+
 func TestListerStart(t *testing.T) {
 	f := &mockFs{}
 	ranList := false
@@ -56,6 +61,33 @@ func TestListerStart(t *testing.T) {
 	assert.Equal(t, true, ranList)
 }
 
+func TestListerStartWithFiles(t *testing.T) {
+	f := &mockFs{}
+	ranList := false
+	f.listFn = func(o ListOpts, dir string) {
+		ranList = true
+	}
+	filter, err := NewFilter()
+	require.NoError(t, err)
+	wantNames := []string{"potato", "sausage", "rutabaga", "carrot", "lettuce"}
+	sort.Strings(wantNames)
+	for _, name := range wantNames {
+		err = filter.AddFile(name)
+		require.NoError(t, err)
+	}
+	o := NewLister().SetFilter(filter).Start(f, "")
+	objs, dirs, err := o.GetAll()
+	require.Nil(t, err)
+	assert.Len(t, dirs, 0)
+	assert.Equal(t, false, ranList)
+	var gotNames []string
+	for _, obj := range objs {
+		gotNames = append(gotNames, obj.Remote())
+	}
+	sort.Strings(gotNames)
+	assert.Equal(t, wantNames, gotNames)
+}
+
 func TestListerSetLevel(t *testing.T) {
 	o := NewLister()
 	o.SetLevel(1)