Speed up startup

providers/git.go

@@ -13,9 +13,12 @@ import (
 
 var InvalidBranchError = errors.New("The currently checked out branch does not match the requested branch. Please checkout the correct branch first.")
 var InvalidStateError = errors.New("The GitProvider is not in a valid state. Fix the issues or continue without Git data.")
+var NoURLProvidedError = errors.New("No URL provided for GitProvider.")
+var NoPathProvidedError = errors.New("No path or branch provided for GitProvider.")
 
-// NOTE: GitProvider does not open the files, it can only
-// - clone the repo, given an URL
+// NOTE: GitProvider does not open XML files, it can only
+// - read in information from the repo, given a path
+// - clone the repo, given an URL & a path
 // - pull the repo, given a path
 // In case of success in either case it updates the commit hash and date and closes the repo again.
 // The Files are opened  and serialized by the FSProvider, which operates on the same file path.
@@ -29,33 +32,67 @@ type GitProvider struct {
 	Date   time.Time
 }
 
-func NewGitProvider(url string, path string, branch string) *GitProvider {
-	if branch == "" || url == "" || path == "" {
-		return nil
+func NewGitProvider(url string, path string, branch string) (*GitProvider, error) {
+	// TODO: check if directory is empty
+	// TODO: force clone
+	if _, err := os.Stat(path); err == nil {
+		return GitProviderFromPath(path, branch)
 	}
-	return &GitProvider{URL: url, Path: path, Branch: branch}
+
+	return GitProviderFromURL(url, path, branch)
 }
 
-func (g *GitProvider) Pull() error {
+func GitProviderFromPath(path string, branch string) (*GitProvider, error) {
+	if branch == "" || path == "" {
+		return nil, NoPathProvidedError
+	}
+
+	gp := GitProvider{Path: path, Branch: branch}
+	if err := gp.Read(); err != nil {
+		return nil, err
+	}
+
+	return &gp, nil
+}
+
+func GitProviderFromURL(url string, path string, branch string) (*GitProvider, error) {
+	if url == "" {
+		return nil, NoURLProvidedError
+	}
+
+	if branch == "" || path == "" {
+		return nil, NoPathProvidedError
+	}
+
+	gp := GitProvider{URL: url, Path: path, Branch: branch}
+	if err := gp.Clone(); err != nil {
+		return nil, err
+	}
+
+	return &gp, nil
+}
+
+// Returs true if the repo was updated remotely, false otherwise
+func (g *GitProvider) Pull() (error, bool) {
 	g.mu.Lock()
 	defer g.mu.Unlock()
 
 	branch := plumbing.NewBranchReferenceName(g.Branch)
 	repo, err := git.PlainOpen(g.Path)
 	if err != nil {
-		return err
+		return err, false
 	}
 
 	wt, err := repo.Worktree()
 	if err != nil {
-		return err
+		return err, false
 	}
 
 	if err := wt.Checkout(&git.CheckoutOptions{
 		Branch: branch,
 		Force:  true,
 	}); err != nil {
-		return err
+		return err, false
 	}
 
 	if err := wt.Pull(&git.PullOptions{
@@ -63,14 +100,20 @@ func (g *GitProvider) Pull() error {
 		ReferenceName: branch,
 		Progress:      os.Stdout,
 	}); err != nil && err != git.NoErrAlreadyUpToDate {
-		return err
+		return err, false
+	} else if err == git.NoErrAlreadyUpToDate {
+		return nil, false
 	}
 	defer wt.Clean(&git.CleanOptions{Dir: true})
 
-	return g.setValues(repo)
+	return g.setValues(repo), true
 }
 
 func (g *GitProvider) Clone() error {
+	if g.URL == "" {
+		return NoURLProvidedError
+	}
+
 	g.mu.Lock()
 	defer g.mu.Unlock()
 
@@ -106,7 +149,7 @@ func (g *GitProvider) Clone() error {
 
 // Implement String Interface
 func (g *GitProvider) String() string {
-	return fmt.Sprintf("GitProvider{URL: %s, Path: %s, Branch: %s, Commit: %s, Date: %s}", g.URL, g.Path, g.Branch, g.Commit, g.Date)
+	return fmt.Sprintf("GitProvider\nURL: %s\nPath: %s\nBranch: %s\nCommit: %s\nDate: %s\n", g.URL, g.Path, g.Branch, g.Commit, g.Date)
 }
 
 func (g *GitProvider) setValues(repo *git.Repository) error {
@@ -124,10 +167,9 @@ func (g *GitProvider) setValues(repo *git.Repository) error {
 	g.Commit = commit.Hash.String()
 	g.Date = commit.Author.When
 
-	return err
+	return nil
 }
 
-// WARNING: this expects the repo to be in a certain state and is intended to be used in tests.
 func (g *GitProvider) Read() error {
 	g.mu.Lock()
 	defer g.mu.Unlock()
@@ -137,6 +179,47 @@ func (g *GitProvider) Read() error {
 		return err
 	}
 
+	if err := g.ValidateBranch(repo); err != nil {
+		branch := plumbing.NewBranchReferenceName(g.Branch)
+		wt, err := repo.Worktree()
+		if err != nil {
+			return err
+		}
+		defer wt.Clean(&git.CleanOptions{Dir: true})
+
+		if err := wt.Checkout(&git.CheckoutOptions{
+			Branch: branch,
+			Force:  true,
+		}); err != nil {
+			return err
+		}
+
+		if err := g.ValidateBranch(repo); err != nil {
+			return err
+		}
+	}
+
+	return g.setValues(repo)
+}
+
+func (g *GitProvider) Validate() error {
+	repo, err := git.PlainOpen(g.Path)
+	if err != nil {
+		return err
+	}
+
+	if err := g.ValidateBranch(repo); err != nil {
+		return err
+	}
+
+	if err := g.ValidateCommit(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (g *GitProvider) ValidateBranch(repo *git.Repository) error {
 	head, err := repo.Head()
 	if err != nil {
 		return err
@@ -147,13 +230,10 @@ func (g *GitProvider) Read() error {
 		return InvalidBranchError
 	}
 
-	return g.setValues(repo)
+	return nil
 }
 
-func (g *GitProvider) Validate() error {
-	g.mu.Lock()
-	defer g.mu.Unlock()
-
+func (g *GitProvider) ValidateCommit() error {
 	if g.Commit == "" || g.Date.IsZero() {
 		return InvalidStateError
 	}