Refactor request context (#32956)

Introduce RequestContext: is a short-lived context that is used to store
request-specific data.

RequestContext could be used to clean form tmp files, close context git
repo, and do some tracing in the future.

Then a lot of legacy code could be removed or improved. For example:
most `ctx.Repo.GitRepo.Close()` could be removed because the git repo
could be closed when the request is done.

2 files changed, 22 insertions, 56 deletions

diff --git a/modules/gitrepo/gitrepo.go b/modules/gitrepo/gitrepo.go
index 14d809aedb..831b9d7bb7 100644
--- a/modules/gitrepo/gitrepo.go
+++ b/modules/gitrepo/gitrepo.go
@@ -10,6 +10,7 @@ import (
 	"strings"
 
 	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/reqctx"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/util"
 )
@@ -38,63 +39,32 @@ func OpenWikiRepository(ctx context.Context, repo Repository) (*git.Repository,
 
 // contextKey is a value for use with context.WithValue.
 type contextKey struct {
-	name string
-}
-
-// RepositoryContextKey is a context key. It is used with context.Value() to get the current Repository for the context
-var RepositoryContextKey = &contextKey{"repository"}
-
-// RepositoryFromContext attempts to get the repository from the context
-func repositoryFromContext(ctx context.Context, repo Repository) *git.Repository {
-	value := ctx.Value(RepositoryContextKey)
-	if value == nil {
-		return nil
-	}
-
-	if gitRepo, ok := value.(*git.Repository); ok && gitRepo != nil {
-		if gitRepo.Path == repoPath(repo) {
-			return gitRepo
-		}
-	}
-
-	return nil
+	repoPath string
 }
 
 // RepositoryFromContextOrOpen attempts to get the repository from the context or just opens it
 func RepositoryFromContextOrOpen(ctx context.Context, repo Repository) (*git.Repository, io.Closer, error) {
-	gitRepo := repositoryFromContext(ctx, repo)
-	if gitRepo != nil {
-		return gitRepo, util.NopCloser{}, nil
+	ds := reqctx.GetRequestDataStore(ctx)
+	if ds != nil {
+		gitRepo, err := RepositoryFromRequestContextOrOpen(ctx, ds, repo)
+		return gitRepo, util.NopCloser{}, err
 	}
-
 	gitRepo, err := OpenRepository(ctx, repo)
 	return gitRepo, gitRepo, err
 }
 
-// repositoryFromContextPath attempts to get the repository from the context
-func repositoryFromContextPath(ctx context.Context, path string) *git.Repository {
-	value := ctx.Value(RepositoryContextKey)
-	if value == nil {
-		return nil
+// RepositoryFromRequestContextOrOpen opens the repository at the given relative path in the provided request context
+// The repo will be automatically closed when the request context is done
+func RepositoryFromRequestContextOrOpen(ctx context.Context, ds reqctx.RequestDataStore, repo Repository) (*git.Repository, error) {
+	ck := contextKey{repoPath: repoPath(repo)}
+	if gitRepo, ok := ctx.Value(ck).(*git.Repository); ok {
+		return gitRepo, nil
 	}
-
-	if repo, ok := value.(*git.Repository); ok && repo != nil {
-		if repo.Path == path {
-			return repo
-		}
+	gitRepo, err := git.OpenRepository(ctx, ck.repoPath)
+	if err != nil {
+		return nil, err
 	}
-
-	return nil
-}
-
-// RepositoryFromContextOrOpenPath attempts to get the repository from the context or just opens it
-// Deprecated: Use RepositoryFromContextOrOpen instead
-func RepositoryFromContextOrOpenPath(ctx context.Context, path string) (*git.Repository, io.Closer, error) {
-	gitRepo := repositoryFromContextPath(ctx, path)
-	if gitRepo != nil {
-		return gitRepo, util.NopCloser{}, nil
-	}
-
-	gitRepo, err := git.OpenRepository(ctx, path)
-	return gitRepo, gitRepo, err
+	ds.AddCloser(gitRepo)
+	ds.SetContextValue(ck, gitRepo)
+	return gitRepo, nil
 }
diff --git a/modules/gitrepo/walk_gogit.go b/modules/gitrepo/walk_gogit.go
index 6370faf08e..709897ba0c 100644
--- a/modules/gitrepo/walk_gogit.go
+++ b/modules/gitrepo/walk_gogit.go
@@ -14,15 +14,11 @@ import (
 // WalkReferences walks all the references from the repository
 // refname is empty, ObjectTag or ObjectBranch. All other values should be treated as equivalent to empty.
 func WalkReferences(ctx context.Context, repo Repository, walkfn func(sha1, refname string) error) (int, error) {
-	gitRepo := repositoryFromContext(ctx, repo)
-	if gitRepo == nil {
-		var err error
-		gitRepo, err = OpenRepository(ctx, repo)
-		if err != nil {
-			return 0, err
-		}
-		defer gitRepo.Close()
+	gitRepo, closer, err := RepositoryFromContextOrOpen(ctx, repo)
+	if err != nil {
+		return 0, err
 	}
+	defer closer.Close()
 
 	i := 0
 	iter, err := gitRepo.GoGitRepo().References()