Invalidate outdated annex UUID cache entries (#60)

The previous implementation could lead to errors e.g. when a repository
was removed and a new one with a new UUID was created under the same
name. This now checks the validity of the retrieved cache entry every
time and invalidates the cache if necessary.

Reviewed-on: https://codeberg.org/forgejo-aneksajo/forgejo-aneksajo/pulls/60
Co-authored-by: Matthias Riße <m.risse@fz-juelich.de>
Co-committed-by: Matthias Riße <m.risse@fz-juelich.de>

modules/annex/annex.go

@@ -20,6 +20,7 @@ import (
 	"strings"
 
 	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
 )
 
@@ -100,6 +101,14 @@ var (
 	repoPath2uuidCache = make(map[string]string)
 )
 
+func Init() error {
+	if !setting.Annex.Enabled {
+		return nil
+	}
+	log.Info("Populating the git-annex UUID cache with existing repositories")
+	return updateUUID2RepoPathCache()
+}
+
 func updateUUID2RepoPathCache() error {
 	return filepath.WalkDir(setting.RepoRootPath, func(path string, d fs.DirEntry, err error) error {
 		if err == nil && repoConfigFileRe.MatchString(path) {
@@ -122,7 +131,7 @@ func updateUUID2RepoPathCache() error {
 	})
 }
 
-func UUID2RepoPath(uuid string) (string, error) {
+func repoPathFromUUIDCache(uuid string) (string, error) {
 	if repoPath, ok := uuid2repoPathCache[uuid]; ok {
 		return repoPath, nil
 	}
@@ -135,3 +144,37 @@ func UUID2RepoPath(uuid string) (string, error) {
 	}
 	return "", fmt.Errorf("no repository known for UUID '%s'", uuid)
 }
+
+func checkValidity(uuid, repoPath string) (bool, error) {
+	stdout, _, err := git.NewCommand(git.DefaultContext, "config", "annex.uuid").RunStdString(&git.RunOpts{Dir: repoPath})
+	if err != nil {
+		return false, err
+	}
+	repoUUID := strings.TrimSpace(stdout)
+	return uuid == repoUUID, nil
+}
+
+func removeCachedEntries(uuid, repoPath string) {
+	delete(uuid2repoPathCache, uuid)
+	delete(repoPath2uuidCache, repoPath)
+}
+
+func UUID2RepoPath(uuid string) (string, error) {
+	// Get the current cache entry for the UUID
+	repoPath, err := repoPathFromUUIDCache(uuid)
+	if err != nil {
+		return "", err
+	}
+	// Check if it is still up-to-date
+	valid, err := checkValidity(uuid, repoPath)
+	if err != nil {
+		return "", err
+	}
+	if !valid {
+		// If it isn't, remove the cache entry and try again
+		removeCachedEntries(uuid, repoPath)
+		return UUID2RepoPath(uuid)
+	}
+	// Otherwise just return the cached entry
+	return repoPath, nil
+}

routers/init.go

@@ -11,6 +11,7 @@ import (
 	"code.gitea.io/gitea/models"
 	asymkey_model "code.gitea.io/gitea/models/asymkey"
 	authmodel "code.gitea.io/gitea/models/auth"
+	"code.gitea.io/gitea/modules/annex"
 	"code.gitea.io/gitea/modules/cache"
 	"code.gitea.io/gitea/modules/eventsource"
 	"code.gitea.io/gitea/modules/git"
@@ -167,6 +168,8 @@ func InitWebInstalled(ctx context.Context) {
 
 	actions_service.Init()
 
+	mustInit(annex.Init)
+
 	// Finally start up the cron
 	cron.NewContext(ctx)
 }