Refactor cache and 'cache' command

cache.go

@@ -5,6 +5,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/restic/restic/backend"
 	"github.com/restic/restic/debug"
@@ -43,12 +44,15 @@ func (c *Cache) Has(t backend.Type, subtype string, id backend.ID) (bool, error)
 	defer fd.Close()
 	if err != nil {
 		if os.IsNotExist(err) {
+			debug.Log("Cache.Has", "test for file %v: not cached", filename)
 			return false, nil
 		}
 
+		debug.Log("Cache.Has", "test for file %v: error %v", filename, err)
 		return false, err
 	}
 
+	debug.Log("Cache.Has", "test for file %v: is cached", filename)
 	return true, nil
 }
 
@@ -66,9 +70,11 @@ func (c *Cache) Store(t backend.Type, subtype string, id backend.ID) (io.WriteCl
 
 	file, err := os.Create(filename)
 	if err != nil {
+		debug.Log("Cache.Store", "error creating file %v: %v", filename, err)
 		return nil, err
 	}
 
+	debug.Log("Cache.Store", "created file %v", filename)
 	return file, nil
 }
 
@@ -82,6 +88,105 @@ func (c *Cache) Load(t backend.Type, subtype string, id backend.ID) (io.ReadClos
 	return os.Open(filename)
 }
 
+func (c *Cache) Purge(t backend.Type, subtype string, id backend.ID) error {
+	filename, err := c.filename(t, subtype, id)
+	if err != nil {
+		return err
+	}
+
+	err = os.Remove(filename)
+	debug.Log("Cache.Purge", "Remove file %v: %v", filename, err)
+
+	if err != nil && os.IsNotExist(err) {
+		return nil
+	}
+
+	return err
+}
+
+func (c *Cache) Clear(s backend.Backend) error {
+	list, err := c.List(backend.Snapshot)
+	if err != nil {
+		return err
+	}
+
+	for _, entry := range list {
+		debug.Log("Cache.Clear", "found entry %v", entry)
+
+		if ok, err := s.Test(backend.Snapshot, entry.ID); !ok || err != nil {
+			debug.Log("Cache.Clear", "snapshot %v doesn't exist any more, removing %v", entry.ID, entry)
+
+			err = c.Purge(backend.Snapshot, entry.Subtype, entry.ID)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+type CacheEntry struct {
+	ID      backend.ID
+	Subtype string
+}
+
+func (c CacheEntry) String() string {
+	if c.Subtype != "" {
+		return c.ID.Str() + "." + c.Subtype
+	}
+	return c.ID.Str()
+}
+
+func (c *Cache) List(t backend.Type) ([]CacheEntry, error) {
+	var dir string
+
+	switch t {
+	case backend.Snapshot:
+		dir = filepath.Join(c.base, "snapshots")
+	case backend.Tree:
+		dir = filepath.Join(c.base, "trees")
+	default:
+		return nil, fmt.Errorf("cache not supported for type %v", t)
+	}
+
+	fd, err := os.Open(dir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return []CacheEntry{}, nil
+		}
+		return nil, err
+	}
+	defer fd.Close()
+
+	fis, err := fd.Readdir(-1)
+	if err != nil {
+		return nil, err
+	}
+
+	entries := make([]CacheEntry, 0, len(fis))
+
+	for _, fi := range fis {
+		parts := strings.SplitN(fi.Name(), ".", 2)
+
+		id, err := backend.ParseID(parts[0])
+		// ignore invalid cache entries for now
+		if err != nil {
+			continue
+		}
+
+		e := CacheEntry{ID: id}
+
+		if len(parts) == 2 {
+			e.Subtype = parts[1]
+		}
+
+		entries = append(entries, e)
+	}
+
+	return entries, nil
+}
+
 // Construct file name for given Type.
 func (c *Cache) filename(t backend.Type, subtype string, id backend.ID) (string, error) {
 	filename := id.String()

cmd/restic/cmd_cache.go

@@ -2,11 +2,8 @@ package main
 
 import (
 	"fmt"
-	"io"
-	"sync"
 
 	"github.com/restic/restic"
-	"github.com/restic/restic/backend"
 )
 
 type CmdCache struct{}
@@ -35,87 +32,17 @@ func (cmd CmdCache) Execute(args []string) error {
 		return err
 	}
 
-	fmt.Printf("update cache, load trees\n")
-
-	list, err := s.List(backend.Tree)
-	if err != nil {
-		return err
-	}
-
 	cache, err := restic.NewCache(s)
 	if err != nil {
 		return err
 	}
 
-	treeCh := make(chan backend.ID)
-	worker := func(wg *sync.WaitGroup, ch chan backend.ID) {
-		for treeID := range ch {
-			cached, err := cache.Has(backend.Tree, "", treeID)
+	fmt.Printf("clear cache for old snapshots\n")
+	err = cache.Clear(s)
 	if err != nil {
-				fmt.Printf("tree %v cache error: %v\n", treeID.Str(), err)
-				continue
+		return err
 	}
-
-			if cached {
-				fmt.Printf("tree %v already cached\n", treeID.Str())
-				continue
-			}
-
-			rd, err := s.GetReader(backend.Tree, treeID)
-			if err != nil {
-				fmt.Printf("  load error: %v\n", err)
-				continue
-			}
-
-			decRd, err := s.Key().DecryptFrom(rd)
-			if err != nil {
-				fmt.Printf("  store error: %v\n", err)
-				continue
-			}
-
-			wr, err := cache.Store(backend.Tree, "", treeID)
-			if err != nil {
-				fmt.Printf("  store error: %v\n", err)
-				continue
-			}
-
-			_, err = io.Copy(wr, decRd)
-			if err != nil {
-				fmt.Printf("  Copy error: %v\n", err)
-				continue
-			}
-
-			err = decRd.Close()
-			if err != nil {
-				fmt.Printf("  close error: %v\n", err)
-				continue
-			}
-
-			err = rd.Close()
-			if err != nil {
-				fmt.Printf("  close error: %v\n", err)
-				continue
-			}
-
-			fmt.Printf("tree %v stored\n", treeID.Str())
-		}
-		wg.Done()
-	}
-
-	var wg sync.WaitGroup
-	// start workers
-	for i := 0; i < 500; i++ {
-		wg.Add(1)
-		go worker(&wg, treeCh)
-	}
-
-	for _, treeID := range list {
-		treeCh <- treeID
-	}
-
-	close(treeCh)
-
-	wg.Wait()
+	fmt.Printf("done\n")
 
 	return nil
 }