Merge pull request #328 from restic/improve-backup-speed

Load trees from repository in parallel

cmd/restic/cmd_backup.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/restic/restic"
 	"github.com/restic/restic/backend"
+	"github.com/restic/restic/debug"
 	"github.com/restic/restic/filter"
 	"github.com/restic/restic/repository"
 	"golang.org/x/crypto/ssh/terminal"
@@ -300,6 +301,10 @@ func (cmd CmdBackup) Execute(args []string) error {
 			cmd.global.Warnf("error for exclude pattern: %v", err)
 		}
 
+		if matched {
+			debug.Log("backup.Execute", "path %q excluded by a filter", item)
+		}
+
 		return !matched
 	}
 

debug/debug.go

@@ -12,11 +12,18 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"time"
 )
 
+type process struct {
+	tag       string
+	goroutine int
+}
+
 var opts struct {
 	logger *log.Logger
 	tags   map[string]bool
+	last   map[process]time.Time
 	m      sync.Mutex
 }
 
@@ -65,6 +72,7 @@ func initDebugLogger() {
 
 func initDebugTags() {
 	opts.tags = make(map[string]bool)
+	opts.last = make(map[process]time.Time)
 
 	// defaults
 	opts.tags["break"] = true
@@ -113,14 +121,12 @@ func goroutineNum() int {
 }
 
 // taken from https://github.com/VividCortex/trace
-func getPosition() string {
+func getPosition(goroutine int) string {
 	_, file, line, ok := runtime.Caller(2)
 	if !ok {
 		return ""
 	}
 
-	goroutine := goroutineNum()
-
 	return fmt.Sprintf("%3d %s:%d", goroutine, filepath.Base(file), line)
 }
 
@@ -130,6 +136,15 @@ func Log(tag string, f string, args ...interface{}) {
 	opts.m.Lock()
 	defer opts.m.Unlock()
 
+	goroutine := goroutineNum()
+
+	last, ok := opts.last[process{tag, goroutine}]
+	if !ok {
+		last = time.Now()
+	}
+	current := time.Now()
+	opts.last[process{tag, goroutine}] = current
+
 	if f[len(f)-1] != '\n' {
 		f += "\n"
 	}
@@ -138,8 +153,8 @@ func Log(tag string, f string, args ...interface{}) {
 		maxTagLen = len(tag)
 	}
 
-	formatStringTag := "[%" + strconv.FormatInt(int64(maxTagLen), 10) + "s]"
-	formatString := fmt.Sprintf(formatStringTag+" %s %s", tag, getPosition(), f)
+	formatStringTag := "%2.3f [%" + strconv.FormatInt(int64(maxTagLen), 10) + "s]"
+	formatString := fmt.Sprintf(formatStringTag+" %s %s", current.Sub(last).Seconds(), tag, getPosition(goroutine), f)
 
 	dbgprint := func() {
 		fmt.Fprintf(os.Stderr, formatString, args...)

repository/repository_test.go

@@ -175,6 +175,28 @@ func TestLoadJSONPack(t *testing.T) {
 	OK(t, err)
 }
 
+func BenchmarkLoadJSONPack(t *testing.B) {
+	repo := SetupRepo()
+	defer TeardownRepo(repo)
+
+	if BenchArchiveDirectory == "" {
+		t.Skip("benchdir not set, skipping")
+	}
+
+	// archive a few files
+	sn := SnapshotDir(t, repo, BenchArchiveDirectory, nil)
+	OK(t, repo.Flush())
+
+	tree := restic.NewTree()
+
+	t.ResetTimer()
+
+	for i := 0; i < t.N; i++ {
+		err := repo.LoadJSONPack(pack.Tree, *sn.Tree, &tree)
+		OK(t, err)
+	}
+}
+
 func TestLoadJSONUnpacked(t *testing.T) {
 	repo := SetupRepo()
 	defer TeardownRepo(repo)

tree.go

@@ -8,7 +8,6 @@ import (
 	"github.com/restic/restic/backend"
 	"github.com/restic/restic/debug"
 	"github.com/restic/restic/pack"
-	"github.com/restic/restic/repository"
 )
 
 type Tree struct {
@@ -30,7 +29,11 @@ func (t Tree) String() string {
 	return fmt.Sprintf("Tree<%d nodes>", len(t.Nodes))
 }
 
-func LoadTree(repo *repository.Repository, id backend.ID) (*Tree, error) {
+type TreeLoader interface {
+	LoadJSONPack(pack.BlobType, backend.ID, interface{}) error
+}
+
+func LoadTree(repo TreeLoader, id backend.ID) (*Tree, error) {
 	tree := &Tree{}
 	err := repo.LoadJSONPack(pack.Tree, id, tree)
 	if err != nil {

walk.go

@@ -2,12 +2,14 @@ package restic
 
 import (
 	"path/filepath"
+	"sync"
 
 	"github.com/restic/restic/backend"
 	"github.com/restic/restic/debug"
-	"github.com/restic/restic/repository"
+	"github.com/restic/restic/pack"
 )
 
+// WalkTreeJob is a job sent from the tree walker.
 type WalkTreeJob struct {
 	Path  string
 	Error error
@@ -16,47 +18,168 @@ type WalkTreeJob struct {
 	Tree *Tree
 }
 
-func walkTree(repo *repository.Repository, path string, treeID backend.ID, done chan struct{}, jobCh chan<- WalkTreeJob) {
-	debug.Log("walkTree", "start on %q (%v)", path, treeID.Str())
+// TreeWalker traverses a tree in the repository depth-first and sends a job
+// for each item (file or dir) that it encounters.
+type TreeWalker struct {
+	ch  chan<- loadTreeJob
+	out chan<- WalkTreeJob
+}
 
-	t, err := LoadTree(repo, treeID)
-	if err != nil {
+// NewTreeWalker uses ch to load trees from the repository and sends jobs to
+// out.
+func NewTreeWalker(ch chan<- loadTreeJob, out chan<- WalkTreeJob) *TreeWalker {
+	return &TreeWalker{ch: ch, out: out}
+}
+
+// Walk starts walking the tree given by id. When the channel done is closed,
+// processing stops.
+func (tw *TreeWalker) Walk(path string, id backend.ID, done chan struct{}) {
+	debug.Log("TreeWalker.Walk", "starting on tree %v for %v", id.Str(), path)
+	defer debug.Log("TreeWalker.Walk", "done walking tree %v for %v", id.Str(), path)
+
+	resCh := make(chan loadTreeResult, 1)
+	tw.ch <- loadTreeJob{
+		id:  id,
+		res: resCh,
+	}
+
+	res := <-resCh
+	if res.err != nil {
 		select {
-		case jobCh <- WalkTreeJob{Path: path, Error: err}:
+		case tw.out <- WalkTreeJob{Path: path, Error: res.err}:
 		case <-done:
 			return
 		}
 		return
 	}
 
-	for _, node := range t.Nodes {
-		p := filepath.Join(path, node.Name)
+	tw.walk(path, res.tree, done)
+
+	select {
+	case tw.out <- WalkTreeJob{Path: path, Tree: res.tree}:
+	case <-done:
+		return
+	}
+}
+
+func (tw *TreeWalker) walk(path string, tree *Tree, done chan struct{}) {
+	debug.Log("TreeWalker.walk", "start on %q", path)
+	defer debug.Log("TreeWalker.walk", "done for %q", path)
+
+	// load all subtrees in parallel
+	results := make([]<-chan loadTreeResult, len(tree.Nodes))
+	for i, node := range tree.Nodes {
 		if node.Type == "dir" {
-			walkTree(repo, p, *node.Subtree, done, jobCh)
+			resCh := make(chan loadTreeResult, 1)
+			tw.ch <- loadTreeJob{
+				id:  *node.Subtree,
+				res: resCh,
+			}
+
+			results[i] = resCh
+		}
+	}
+
+	for i, node := range tree.Nodes {
+		p := filepath.Join(path, node.Name)
+		var job WalkTreeJob
+
+		if node.Type == "dir" {
+			if results[i] == nil {
+				panic("result chan should not be nil")
+			}
+
+			res := <-results[i]
+			tw.walk(p, res.tree, done)
+
+			job = WalkTreeJob{Path: p, Tree: res.tree, Error: res.err}
 		} else {
+			job = WalkTreeJob{Path: p, Node: node}
+		}
+
 		select {
-			case jobCh <- WalkTreeJob{Path: p, Node: node}:
+		case tw.out <- job:
 		case <-done:
 			return
 		}
 	}
 }
 
+type loadTreeResult struct {
+	tree *Tree
+	err  error
+}
+
+type loadTreeJob struct {
+	id  backend.ID
+	res chan<- loadTreeResult
+}
+
+type treeLoader func(backend.ID) (*Tree, error)
+
+func loadTreeWorker(wg *sync.WaitGroup, in <-chan loadTreeJob, load treeLoader, done <-chan struct{}) {
+	debug.Log("loadTreeWorker", "start")
+	defer debug.Log("loadTreeWorker", "exit")
+	defer wg.Done()
+
+	for {
 		select {
-	case jobCh <- WalkTreeJob{Path: path, Tree: t}:
 		case <-done:
+			debug.Log("loadTreeWorker", "done channel closed")
+			return
+		case job, ok := <-in:
+			if !ok {
+				debug.Log("loadTreeWorker", "input channel closed, exiting")
 				return
 			}
 
-	debug.Log("walkTree", "done for %q (%v)", path, treeID.Str())
+			debug.Log("loadTreeWorker", "received job to load tree %v", job.id.Str())
+			tree, err := load(job.id)
+
+			debug.Log("loadTreeWorker", "tree %v loaded, error %v", job.id.Str(), err)
+
+			select {
+			case job.res <- loadTreeResult{tree, err}:
+				debug.Log("loadTreeWorker", "job result sent")
+			case <-done:
+				debug.Log("loadTreeWorker", "done channel closed before result could be sent")
+				return
 			}
+		}
+	}
+}
+
+const loadTreeWorkers = 10
 
 // WalkTree walks the tree specified by id recursively and sends a job for each
 // file and directory it finds. When the channel done is closed, processing
 // stops.
-func WalkTree(repo *repository.Repository, id backend.ID, done chan struct{}, jobCh chan<- WalkTreeJob) {
-	debug.Log("WalkTree", "start on %v", id.Str())
-	walkTree(repo, "", id, done, jobCh)
+func WalkTree(repo TreeLoader, id backend.ID, done chan struct{}, jobCh chan<- WalkTreeJob) {
+	debug.Log("WalkTree", "start on %v, start workers", id.Str())
+
+	load := func(id backend.ID) (*Tree, error) {
+		tree := &Tree{}
+		err := repo.LoadJSONPack(pack.Tree, id, tree)
+		if err != nil {
+			return nil, err
+		}
+		return tree, nil
+	}
+
+	ch := make(chan loadTreeJob)
+
+	var wg sync.WaitGroup
+	for i := 0; i < loadTreeWorkers; i++ {
+		wg.Add(1)
+		go loadTreeWorker(&wg, ch, load, done)
+	}
+
+	tw := NewTreeWalker(ch, jobCh)
+	tw.Walk("", id, done)
 	close(jobCh)
+
+	close(ch)
+	wg.Wait()
+
 	debug.Log("WalkTree", "done")
 }