storage: shallow storage (#180)

* storage: shallow storage

* changes

* changes

4 files changed, 142 insertions, 1 deletions

diff --git a/storage/filesystem/internal/dotgit/dotgit.go b/storage/filesystem/internal/dotgit/dotgit.go
index 3a6227e..3405908 100644
--- a/storage/filesystem/internal/dotgit/dotgit.go
+++ b/storage/filesystem/internal/dotgit/dotgit.go
@@ -17,6 +17,7 @@ const (
 	suffix         = ".git"
 	packedRefsPath = "packed-refs"
 	configPath     = "config"
+	shallowPath    = "shallow"
 
 	objectsPath = "objects"
 	packPath    = "pack"
@@ -60,15 +61,35 @@ func New(fs fs.Filesystem) *DotGit {
 	return &DotGit{fs: fs}
 }
 
+// ConfigWriter returns a file pointer for write to the config file
 func (d *DotGit) ConfigWriter() (fs.File, error) {
 	return d.fs.Create(configPath)
 }
 
-// Config returns the path of the config file
+// Config returns a file pointer for read to the config file
 func (d *DotGit) Config() (fs.File, error) {
 	return d.fs.Open(configPath)
 }
 
+// ShallowWriter returns a file pointer for write to the shallow file
+func (d *DotGit) ShallowWriter() (fs.File, error) {
+	return d.fs.Create(shallowPath)
+}
+
+// Shallow returns a file pointer for read to the shallow file
+func (d *DotGit) Shallow() (fs.File, error) {
+	f, err := d.fs.Open(shallowPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, nil
+		}
+
+		return nil, err
+	}
+
+	return f, nil
+}
+
 // NewObjectPack return a writer for a new packfile, it saves the packfile to
 // disk and also generates and save the index for the given packfile.
 func (d *DotGit) NewObjectPack() (*PackWriter, error) {
diff --git a/storage/filesystem/internal/dotgit/dotgit_test.go b/storage/filesystem/internal/dotgit/dotgit_test.go
index 3a1f194..b645a85 100644
--- a/storage/filesystem/internal/dotgit/dotgit_test.go
+++ b/storage/filesystem/internal/dotgit/dotgit_test.go
@@ -130,6 +130,61 @@ func (s *SuiteDotGit) TestConfig(c *C) {
 	c.Assert(filepath.Base(file.Filename()), Equals, "config")
 }
 
+func (s *SuiteDotGit) TestConfigWriteAndConfig(c *C) {
+	tmp, err := ioutil.TempDir("", "dot-git")
+	c.Assert(err, IsNil)
+	defer os.RemoveAll(tmp)
+
+	fs := osfs.New(tmp)
+	dir := New(fs)
+
+	f, err := dir.ConfigWriter()
+	c.Assert(err, IsNil)
+
+	_, err = f.Write([]byte("foo"))
+	c.Assert(err, IsNil)
+
+	f, err = dir.Config()
+	c.Assert(err, IsNil)
+
+	cnt, err := ioutil.ReadAll(f)
+	c.Assert(err, IsNil)
+
+	c.Assert(string(cnt), Equals, "foo")
+}
+
+func (s *SuiteDotGit) TestShallow(c *C) {
+	fs := fixtures.Basic().ByTag(".git").One().DotGit()
+	dir := New(fs)
+
+	file, err := dir.Shallow()
+	c.Assert(err, IsNil)
+	c.Assert(file, IsNil)
+}
+
+func (s *SuiteDotGit) TestShallowWriteAndShallow(c *C) {
+	tmp, err := ioutil.TempDir("", "dot-git")
+	c.Assert(err, IsNil)
+	defer os.RemoveAll(tmp)
+
+	fs := osfs.New(tmp)
+	dir := New(fs)
+
+	f, err := dir.ShallowWriter()
+	c.Assert(err, IsNil)
+
+	_, err = f.Write([]byte("foo"))
+	c.Assert(err, IsNil)
+
+	f, err = dir.Shallow()
+	c.Assert(err, IsNil)
+
+	cnt, err := ioutil.ReadAll(f)
+	c.Assert(err, IsNil)
+
+	c.Assert(string(cnt), Equals, "foo")
+}
+
 func findReference(refs []*plumbing.Reference, name string) *plumbing.Reference {
 	n := plumbing.ReferenceName(name)
 	for _, ref := range refs {
@@ -222,6 +277,18 @@ func (s *SuiteDotGit) TestObjects(c *C) {
 	c.Assert(hashes[2].String(), Equals, "03db8e1fbe133a480f2867aac478fd866686d69e")
 }
 
+func (s *SuiteDotGit) TestObjectsNoFolder(c *C) {
+	tmp, err := ioutil.TempDir("", "dot-git")
+	c.Assert(err, IsNil)
+	defer os.RemoveAll(tmp)
+
+	fs := osfs.New(tmp)
+	dir := New(fs)
+	hash, err := dir.Objects()
+	c.Assert(err, IsNil)
+	c.Assert(hash, HasLen, 0)
+}
+
 func (s *SuiteDotGit) TestObject(c *C) {
 	fs := fixtures.ByTag(".git").ByTag("unpacked").One().DotGit()
 	dir := New(fs)
diff --git a/storage/filesystem/shallow.go b/storage/filesystem/shallow.go
new file mode 100644
index 0000000..ec8d20e
--- /dev/null
+++ b/storage/filesystem/shallow.go
@@ -0,0 +1,51 @@
+package filesystem
+
+import (
+	"bufio"
+	"fmt"
+
+	"gopkg.in/src-d/go-git.v4/plumbing"
+	"gopkg.in/src-d/go-git.v4/storage/filesystem/internal/dotgit"
+)
+
+// ShallowStorage where the shallow commits are stored, an internal to
+// manipulate the shallow file
+type ShallowStorage struct {
+	dir *dotgit.DotGit
+}
+
+// SetShallow save the shallows in the shallow file in the .git folder as one
+// commit per line represented by 40-byte hexadecimal object terminated by a
+// newline.
+func (s *ShallowStorage) SetShallow(commits []plumbing.Hash) error {
+	f, err := s.dir.ShallowWriter()
+	if err != nil {
+		return err
+	}
+
+	defer f.Close()
+	for _, h := range commits {
+		if _, err := fmt.Fprintf(f, "%s\n", h); err != err {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Shallow return the shallow commits reading from shallo file from .git
+func (s *ShallowStorage) Shallow() ([]plumbing.Hash, error) {
+	f, err := s.dir.Shallow()
+	if err != nil {
+		return nil, err
+	}
+
+	var hash []plumbing.Hash
+
+	scn := bufio.NewScanner(f)
+	for scn.Scan() {
+		hash = append(hash, plumbing.NewHash(scn.Text()))
+	}
+
+	return hash, scn.Err()
+}
diff --git a/storage/filesystem/storage.go b/storage/filesystem/storage.go
index 7e05cd3..e414428 100644
--- a/storage/filesystem/storage.go
+++ b/storage/filesystem/storage.go
@@ -12,6 +12,7 @@ import (
 type Storage struct {
 	ObjectStorage
 	ReferenceStorage
+	ShallowStorage
 	ConfigStorage
 }
 
@@ -26,6 +27,7 @@ func NewStorage(fs fs.Filesystem) (*Storage, error) {
 	return &Storage{
 		ObjectStorage:    o,
 		ReferenceStorage: ReferenceStorage{dir: dir},
+		ShallowStorage:   ShallowStorage{dir: dir},
 		ConfigStorage:    ConfigStorage{dir: dir},
 	}, nil
 }