Improve listing performance by using go-git (#6478)

* Use go-git for tree reading and commit info lookup.

Signed-off-by: Filip Navara <navara@emclient.com>

* Use TreeEntry.IsRegular() instead of ObjectType that was removed.

Signed-off-by: Filip Navara <navara@emclient.com>

* Use the treePath to optimize commit info search.

Signed-off-by: Filip Navara <navara@emclient.com>

* Extract the latest commit at treePath along with the other commits.

Signed-off-by: Filip Navara <navara@emclient.com>

* Fix listing commit info for a directory that was created in one commit and never modified after.

Signed-off-by: Filip Navara <navara@emclient.com>

* Avoid nearly all external 'git' invocations when doing directory listing (.editorconfig code path is still hit).

Signed-off-by: Filip Navara <navara@emclient.com>

* Use go-git for reading blobs.

Signed-off-by: Filip Navara <navara@emclient.com>

* Make SHA1 type alias for plumbing.Hash in go-git.

Signed-off-by: Filip Navara <navara@emclient.com>

* Make Signature type alias for object.Signature in go-git.

Signed-off-by: Filip Navara <navara@emclient.com>

* Fix GetCommitsInfo for repository with only one commit.

Signed-off-by: Filip Navara <navara@emclient.com>

* Fix PGP signature verification.

Signed-off-by: Filip Navara <navara@emclient.com>

* Fix issues with walking commit graph across merges.

Signed-off-by: Filip Navara <navara@emclient.com>

* Fix typo in condition.

Signed-off-by: Filip Navara <navara@emclient.com>

* Speed up loading branch list by keeping the repository reference (and thus all the loaded packfile indexes).

Signed-off-by: Filip Navara <navara@emclient.com>

* Fix lising submodules.

Signed-off-by: Filip Navara <navara@emclient.com>

* Fix build

Signed-off-by: Filip Navara <navara@emclient.com>

* Add back commit cache because of name-rev

Signed-off-by: Filip Navara <navara@emclient.com>

* Fix tests

Signed-off-by: Filip Navara <navara@emclient.com>

* Fix code style

* Fix spelling

* Address PR feedback

Signed-off-by: Filip Navara <navara@emclient.com>

* Update vendor module list

Signed-off-by: Filip Navara <navara@emclient.com>

* Fix getting trees by commit id

Signed-off-by: Filip Navara <navara@emclient.com>

* Fix remaining unit test failures

* Fix GetTreeBySHA

* Avoid running `git name-rev` if not necessary

Signed-off-by: Filip Navara <navara@emclient.com>

* Move Branch code to git module

* Clean up GPG signature verification and fix it for tagged commits

* Address PR feedback (import formatting, copyright headers)

* Make blob lookup by SHA working

* Update tests to use public API

* Allow getting content from any type of object through the blob interface

* Change test to actually expect the object content that is in the GIT repository

* Change one more test to actually expect the object content that is in the GIT repository

* Add comments

1 files changed, 55 insertions, 11 deletions

diff --git a/modules/git/repo_branch.go b/modules/git/repo_branch.go
index 6414abbec5..83689ee9dc 100644
--- a/modules/git/repo_branch.go
+++ b/modules/git/repo_branch.go
@@ -9,7 +9,6 @@ import (
 	"fmt"
 	"strings"
 
-	"gopkg.in/src-d/go-git.v4"
 	"gopkg.in/src-d/go-git.v4/plumbing"
 )
 
@@ -29,13 +28,19 @@ func IsBranchExist(repoPath, name string) bool {
 
 // IsBranchExist returns true if given branch exists in current repository.
 func (repo *Repository) IsBranchExist(name string) bool {
-	return IsBranchExist(repo.Path, name)
+	_, err := repo.gogitRepo.Reference(plumbing.ReferenceName(BranchPrefix+name), true)
+	if err != nil {
+		return false
+	}
+	return true
 }
 
 // Branch represents a Git branch.
 type Branch struct {
 	Name string
 	Path string
+
+	gitRepo *Repository
 }
 
 // GetHEADBranch returns corresponding branch of HEAD.
@@ -51,8 +56,9 @@ func (repo *Repository) GetHEADBranch() (*Branch, error) {
 	}
 
 	return &Branch{
-		Name: stdout[len(BranchPrefix):],
-		Path: stdout,
+		Name:    stdout[len(BranchPrefix):],
+		Path:    stdout,
+		gitRepo: repo,
 	}, nil
 }
 
@@ -64,23 +70,56 @@ func (repo *Repository) SetDefaultBranch(name string) error {
 
 // GetBranches returns all branches of the repository.
 func (repo *Repository) GetBranches() ([]string, error) {
-	r, err := git.PlainOpen(repo.Path)
+	var branchNames []string
+
+	branches, err := repo.gogitRepo.Branches()
 	if err != nil {
 		return nil, err
 	}
 
-	branchIter, err := r.Branches()
+	branches.ForEach(func(branch *plumbing.Reference) error {
+		branchNames = append(branchNames, strings.TrimPrefix(branch.Name().String(), BranchPrefix))
+		return nil
+	})
+
+	// TODO: Sort?
+
+	return branchNames, nil
+}
+
+// GetBranch returns a branch by it's name
+func (repo *Repository) GetBranch(branch string) (*Branch, error) {
+	if !repo.IsBranchExist(branch) {
+		return nil, ErrBranchNotExist{branch}
+	}
+	return &Branch{
+		Path:    repo.Path,
+		Name:    branch,
+		gitRepo: repo,
+	}, nil
+}
+
+// GetBranchesByPath returns a branch by it's path
+func GetBranchesByPath(path string) ([]*Branch, error) {
+	gitRepo, err := OpenRepository(path)
 	if err != nil {
 		return nil, err
 	}
-	branches := make([]string, 0)
-	if err = branchIter.ForEach(func(branch *plumbing.Reference) error {
-		branches = append(branches, branch.Name().Short())
-		return nil
-	}); err != nil {
+
+	brs, err := gitRepo.GetBranches()
+	if err != nil {
 		return nil, err
 	}
 
+	branches := make([]*Branch, len(brs))
+	for i := range brs {
+		branches[i] = &Branch{
+			Path:    path,
+			Name:    brs[i],
+			gitRepo: gitRepo,
+		}
+	}
+
 	return branches, nil
 }
 
@@ -132,3 +171,8 @@ func (repo *Repository) RemoveRemote(name string) error {
 	_, err := NewCommand("remote", "remove", name).RunInDir(repo.Path)
 	return err
 }
+
+// GetCommit returns the head commit of a branch
+func (branch *Branch) GetCommit() (*Commit, error) {
+	return branch.gitRepo.GetBranchCommit(branch.Name)
+}