git: add Static option to PlainOpen

Also adds Static configuration to Storage and DotGit. This option means
that the git repository is not expected to be modified while open and
enables some optimizations.

Each time a file is accessed the storer tries to open an object file for
the requested hash. When this is done for a lot of objects it is
expensive. With Static option a list of object files is generated the
first time an object is accessed and used to check if exists instead of
using system calls.

A similar optimization is done for packfiles.

Signed-off-by: Javi Fontan <jfontan@gmail.com>

1 files changed, 24 insertions, 3 deletions

diff --git a/storage/filesystem/storage.go b/storage/filesystem/storage.go
index 622bb4a..a969a1f 100644
--- a/storage/filesystem/storage.go
+++ b/storage/filesystem/storage.go
@@ -11,6 +11,8 @@ import (
 // standard git format (this is, the .git directory). Zero values of this type
 // are not safe to use, see the NewStorage function below.
 type Storage struct {
+	StorageOptions
+
 	fs  billy.Filesystem
 	dir *dotgit.DotGit
 
@@ -22,17 +24,36 @@ type Storage struct {
 	ModuleStorage
 }
 
+// StorageOptions holds configuration for the storage.
+type StorageOptions struct {
+	// Static means that the filesystem is not modified while the repo is open.
+	Static bool
+}
+
 // NewStorage returns a new Storage backed by a given `fs.Filesystem`
 func NewStorage(fs billy.Filesystem) (*Storage, error) {
-	dir := dotgit.New(fs)
+	return NewStorageWithOptions(fs, StorageOptions{})
+}
+
+// NewStorageWithOptions returns a new Storage backed by a given `fs.Filesystem`
+func NewStorageWithOptions(
+	fs billy.Filesystem,
+	ops StorageOptions,
+) (*Storage, error) {
+	dOps := dotgit.DotGitOptions{
+		Static: ops.Static,
+	}
+
+	dir := dotgit.NewWithOptions(fs, dOps)
 	o, err := NewObjectStorage(dir)
 	if err != nil {
 		return nil, err
 	}
 
 	return &Storage{
-		fs:  fs,
-		dir: dir,
+		StorageOptions: ops,
+		fs:             fs,
+		dir:            dir,
 
 		ObjectStorage:    o,
 		ReferenceStorage: ReferenceStorage{dir: dir},