repository: Move writing of commit-graph into housekeeping package

We want to allow for OptimizeRepository to be called without invoking an
RPC in order to allow us to call it in more contexts. As a preparatory
step, we thus have to move all functionality which is invoked by it into
a package that is independent of gRPC services.

Move the writing of the commit-graph into the housekeeping package as
part of this move.

4 files changed, 73 insertions, 70 deletions

diff --git a/internal/git/housekeeping/commit_graph.go b/internal/git/housekeeping/commit_graph.go
new file mode 100644
index 000000000..dcdd2cb2e
--- /dev/null
+++ b/internal/git/housekeeping/commit_graph.go
@@ -0,0 +1,64 @@
+package housekeeping
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"gitlab.com/gitlab-org/gitaly/v14/internal/git"
+	"gitlab.com/gitlab-org/gitaly/v14/internal/git/localrepo"
+	"gitlab.com/gitlab-org/gitaly/v14/internal/git/stats"
+	"gitlab.com/gitlab-org/gitaly/v14/internal/helper"
+)
+
+// WriteCommitGraph updates the commit-graph in the given repository. The commit-graph is updated
+// incrementally, except in the case where it doesn't exist yet or in case it is detected that the
+// commit-graph is missing bloom filters.
+func WriteCommitGraph(ctx context.Context, repo *localrepo.Repo) error {
+	repoPath, err := repo.Path()
+	if err != nil {
+		return err
+	}
+
+	missingBloomFilters := true
+	if _, err := os.Stat(filepath.Join(repoPath, stats.CommitGraphRelPath)); err != nil {
+		if !errors.Is(err, os.ErrNotExist) {
+			return helper.ErrInternal(fmt.Errorf("remove commit graph file: %w", err))
+		}
+
+		// objects/info/commit-graph file doesn't exists
+		// check if commit-graph chain exists and includes Bloom filters
+		if missingBloomFilters, err = stats.IsMissingBloomFilters(repoPath); err != nil {
+			return helper.ErrInternal(fmt.Errorf("should remove commit graph chain: %w", err))
+		}
+	}
+
+	flags := []git.Option{
+		git.Flag{Name: "--reachable"},
+		git.Flag{Name: "--changed-paths"}, // enables Bloom filters
+		git.ValueFlag{Name: "--size-multiple", Value: "4"},
+	}
+
+	if missingBloomFilters {
+		// if commit graph doesn't use Bloom filters we instruct operation to replace
+		// existent commit graph with the new one
+		// https://git-scm.com/docs/git-commit-graph#Documentation/git-commit-graph.txt-emwriteem
+		flags = append(flags, git.Flag{Name: "--split=replace"})
+	} else {
+		flags = append(flags, git.Flag{Name: "--split"})
+	}
+
+	var stderr bytes.Buffer
+	if err := repo.ExecAndWait(ctx, git.SubSubCmd{
+		Name:   "commit-graph",
+		Action: "write",
+		Flags:  flags,
+	}, git.WithStderr(&stderr)); err != nil {
+		return helper.ErrInternalf("writing commit-graph: %s: %v", err, stderr.String())
+	}
+
+	return nil
+}
diff --git a/internal/gitaly/service/repository/commit_graph.go b/internal/gitaly/service/repository/commit_graph.go
index eaa3c9cbf..b329bc099 100644
--- a/internal/gitaly/service/repository/commit_graph.go
+++ b/internal/gitaly/service/repository/commit_graph.go
@@ -1,16 +1,9 @@
 package repository
 
 import (
-	"bytes"
 	"context"
-	"errors"
-	"fmt"
-	"os"
-	"path/filepath"
 
-	"gitlab.com/gitlab-org/gitaly/v14/internal/git"
-	"gitlab.com/gitlab-org/gitaly/v14/internal/git/localrepo"
-	"gitlab.com/gitlab-org/gitaly/v14/internal/git/stats"
+	"gitlab.com/gitlab-org/gitaly/v14/internal/git/housekeeping"
 	"gitlab.com/gitlab-org/gitaly/v14/internal/helper"
 	"gitlab.com/gitlab-org/gitaly/v14/proto/go/gitalypb"
 )
@@ -22,68 +15,13 @@ func (s *server) WriteCommitGraph(
 ) (*gitalypb.WriteCommitGraphResponse, error) {
 	repo := s.localrepo(in.GetRepository())
 
-	if err := writeCommitGraph(ctx, repo, in.GetSplitStrategy()); err != nil {
-		return nil, err
-	}
-
-	return &gitalypb.WriteCommitGraphResponse{}, nil
-}
-
-func writeCommitGraph(
-	ctx context.Context,
-	repo *localrepo.Repo,
-	splitStrategy gitalypb.WriteCommitGraphRequest_SplitStrategy,
-) error {
-	repoPath, err := repo.Path()
-	if err != nil {
-		return err
-	}
-
-	missingBloomFilters := true
-	if _, err := os.Stat(filepath.Join(repoPath, stats.CommitGraphRelPath)); err != nil {
-		if !errors.Is(err, os.ErrNotExist) {
-			return helper.ErrInternal(fmt.Errorf("remove commit graph file: %w", err))
-		}
-
-		// objects/info/commit-graph file doesn't exists
-		// check if commit-graph chain exists and includes Bloom filters
-		if missingBloomFilters, err = stats.IsMissingBloomFilters(repoPath); err != nil {
-			return helper.ErrInternal(fmt.Errorf("should remove commit graph chain: %w", err))
-		}
-	}
-
-	flags := []git.Option{
-		git.Flag{Name: "--reachable"},
-		git.Flag{Name: "--changed-paths"}, // enables Bloom filters
-	}
-
-	if missingBloomFilters {
-		// if commit graph doesn't use Bloom filters we instruct operation to replace
-		// existent commit graph with the new one
-		// https://git-scm.com/docs/git-commit-graph#Documentation/git-commit-graph.txt-emwriteem
-		flags = append(flags, git.Flag{Name: "--split=replace"})
-	} else {
-		flags = append(flags, git.Flag{Name: "--split"})
+	if in.GetSplitStrategy() != gitalypb.WriteCommitGraphRequest_SizeMultiple {
+		return nil, helper.ErrInvalidArgumentf("unsupported split strategy: %v", in.GetSplitStrategy())
 	}
 
-	switch splitStrategy {
-	case gitalypb.WriteCommitGraphRequest_SizeMultiple:
-		flags = append(flags,
-			// this flag has no effect if '--split=replace' is used
-			git.ValueFlag{Name: "--size-multiple", Value: "4"},
-		)
-	default:
-		return helper.ErrInvalidArgumentf("unsupported split strategy: %v", splitStrategy)
-	}
-
-	var stderr bytes.Buffer
-	if err := repo.ExecAndWait(ctx, git.SubSubCmd{
-		Name:   "commit-graph",
-		Action: "write",
-		Flags:  flags,
-	}, git.WithStderr(&stderr)); err != nil {
-		return helper.ErrInternalf("writing commit-graph: %s: %v", err, stderr.String())
+	if err := housekeeping.WriteCommitGraph(ctx, repo); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &gitalypb.WriteCommitGraphResponse{}, nil
 }
diff --git a/internal/gitaly/service/repository/gc.go b/internal/gitaly/service/repository/gc.go
index 13adfc326..cd609deeb 100644
--- a/internal/gitaly/service/repository/gc.go
+++ b/internal/gitaly/service/repository/gc.go
@@ -46,7 +46,7 @@ func (s *server) GarbageCollect(ctx context.Context, in *gitalypb.GarbageCollect
 		return nil, err
 	}
 
-	if err := writeCommitGraph(ctx, repo, gitalypb.WriteCommitGraphRequest_SizeMultiple); err != nil {
+	if err := housekeeping.WriteCommitGraph(ctx, repo); err != nil {
 		return nil, err
 	}
 
diff --git a/internal/gitaly/service/repository/repack.go b/internal/gitaly/service/repository/repack.go
index a3f428650..6d28084ed 100644
--- a/internal/gitaly/service/repository/repack.go
+++ b/internal/gitaly/service/repository/repack.go
@@ -8,6 +8,7 @@ import (
 
 	"github.com/prometheus/client_golang/prometheus"
 	"gitlab.com/gitlab-org/gitaly/v14/internal/git"
+	"gitlab.com/gitlab-org/gitaly/v14/internal/git/housekeeping"
 	"gitlab.com/gitlab-org/gitaly/v14/internal/git/localrepo"
 	"gitlab.com/gitlab-org/gitaly/v14/internal/git/stats"
 	"gitlab.com/gitlab-org/gitaly/v14/internal/helper"
@@ -85,7 +86,7 @@ func repack(ctx context.Context, repo *localrepo.Repo, cfg repackCommandConfig)
 		return err
 	}
 
-	if err := writeCommitGraph(ctx, repo, gitalypb.WriteCommitGraphRequest_SizeMultiple); err != nil {
+	if err := housekeeping.WriteCommitGraph(ctx, repo); err != nil {
 		return err
 	}