feat(sync-gcsr): Synchronise all remote branches

Explicitly sets all local branches to all equivalent remote branches
after each update.

Branches deleted on the remote will eventually disappear when the
container is restarted.

ops/sync-gcsr/main.go

@@ -12,6 +12,7 @@ import (
 	"time"
 
 	git "gopkg.in/src-d/go-git.v4"
+	"gopkg.in/src-d/go-git.v4/plumbing"
 	"gopkg.in/src-d/go-git.v4/plumbing/transport/http"
 )
 
@@ -24,8 +25,43 @@ func EnvOr(key, def string) string {
 	return v
 }
 
-func updateRepo(repo *git.Repository, tree *git.Worktree, opts *git.PullOptions) error {
+// ensure that all remote branches exist locally & are up to date.
-	err := tree.Pull(opts)
+func updateBranches(auth *http.BasicAuth, repo *git.Repository) error {
+	origin, err := repo.Remote("origin")
+	if err != nil {
+		return err
+	}
+
+	refs, err := origin.List(&git.ListOptions{
+		Auth: auth,
+	})
+	if err != nil {
+		return err
+	}
+
+	for _, ref := range refs {
+		if !ref.Name().IsBranch() || ref.Type() != plumbing.HashReference {
+			continue
+		}
+
+		branch := plumbing.NewHashReference(
+			plumbing.NewBranchReferenceName(ref.Name().Short()),
+			ref.Hash(),
+		)
+
+		err := repo.Storer.SetReference(branch)
+		if err != nil {
+			return err
+		}
+		log.Println("Updated branch", ref.Name().String())
+	}
+
+	return nil
+}
+
+func updateRepo(auth *http.BasicAuth, repo *git.Repository, opts *git.FetchOptions) error {
+	err := repo.Fetch(opts)
+
 	if err == git.NoErrAlreadyUpToDate {
 		// nothing to do ...
 		return nil
@@ -33,8 +69,8 @@ func updateRepo(repo *git.Repository, tree *git.Worktree, opts *git.PullOptions)
 		return err
 	}
 
-	log.Println("Updated local repository mirror")
+	log.Println("Fetched updates from remote, updating local branches")
-	return nil
+	return updateBranches(auth, repo)
 }
 
 func cloneRepo(dest, project, repo string, auth *http.BasicAuth) (*git.Repository, error) {
@@ -43,13 +79,13 @@ func cloneRepo(dest, project, repo string, auth *http.BasicAuth) (*git.Repositor
 		URL:  fmt.Sprintf("https://source.developers.google.com/p/%s/r/%s", project, repo),
 	}
 
-	handle, err := git.PlainClone(dest, false, &cloneOpts)
+	handle, err := git.PlainClone(dest, true, &cloneOpts)
 
 	if err == git.ErrRepositoryAlreadyExists {
 		handle, err = git.PlainOpen(dest)
 	}
 
-	return handle, err
+	return handle, updateBranches(auth, handle)
 }
 
 func main() {
@@ -78,20 +114,16 @@ func main() {
 		log.Println("Initiating update loop")
 	}
 
-	tree, err := handle.Worktree()
+	fetchOpts := git.FetchOptions{
-	if err != nil {
-		log.Fatalln("Failed to open repository worktree:", err)
-	}
-
-	pullOpts := git.PullOptions{
 		Auth:  auth,
 		Force: true,
 	}
 
 	for {
-		if err = updateRepo(handle, tree, &pullOpts); err != nil {
+		if err = updateRepo(auth, handle, &fetchOpts); err != nil {
 			log.Fatalf("Failed to pull updated repository: %s", err)
 		}
-		time.Sleep(30 * time.Second) //  TODO(tazjin): Config option for pull interval?
+
+		time.Sleep(10 * time.Second)
 	}
 }