housekeeping: Split commit-graph writing out of object repacks

Writing commit-graphs and repacking objects is currently both done in
`RepackObjects()`. Back when the code was introduced this was done to
keep required code changes at bay by continuing to always rewrite the
commit-graph when we repack objects. We're about to iterate on the
strategy we use to write commit-graphs though, which requires us to
start doing so independently of whether we did or didn't repack objects.

Pull out the logic to write commit-graphs from `RepackObjects()` and
adjust all callsites of the latter to manually write commit-graphs. This
has merit on its own given that we can now properly report metrics for
writing the commit-graph on its own.

5 files changed, 27 insertions, 6 deletions

diff --git a/internal/git/housekeeping/objects.go b/internal/git/housekeeping/objects.go
index 7ce675c6e..232fec629 100644
--- a/internal/git/housekeeping/objects.go
+++ b/internal/git/housekeeping/objects.go
@@ -52,10 +52,6 @@ func RepackObjects(ctx context.Context, repo *localrepo.Repo, cfg RepackObjectsC
 		return err
 	}
 
-	if err := WriteCommitGraph(ctx, repo); err != nil {
-		return err
-	}
-
 	stats.LogObjectsInfo(ctx, repo)
 
 	return nil
diff --git a/internal/git/housekeeping/optimize_repository.go b/internal/git/housekeeping/optimize_repository.go
index 2837cd065..a6ec186f9 100644
--- a/internal/git/housekeeping/optimize_repository.go
+++ b/internal/git/housekeeping/optimize_repository.go
@@ -85,7 +85,17 @@ func optimizeRepository(ctx context.Context, m *RepositoryManager, repo *localre
 			optimizations["written_bitmap"] = "success"
 		}
 	}
+	timer.ObserveDuration()
 
+	timer = prometheus.NewTimer(m.tasksLatency.WithLabelValues("commit-graph"))
+	if didRepack {
+		if err := WriteCommitGraph(ctx, repo); err != nil {
+			optimizations["written_commit_graph"] = "failure"
+			return fmt.Errorf("could not write commit-graph: %w", err)
+		}
+
+		optimizations["written_commit_graph"] = "success"
+	}
 	timer.ObserveDuration()
 
 	timer = prometheus.NewTimer(m.tasksLatency.WithLabelValues("prune"))
diff --git a/internal/git/housekeeping/optimize_repository_ext_test.go b/internal/git/housekeeping/optimize_repository_ext_test.go
index 13940b9b6..7eae05993 100644
--- a/internal/git/housekeeping/optimize_repository_ext_test.go
+++ b/internal/git/housekeeping/optimize_repository_ext_test.go
@@ -120,8 +120,9 @@ func TestPruneIfNeeded(t *testing.T) {
 
 			require.NoError(t, housekeeping.NewManager(cfg.Prometheus, nil).OptimizeRepository(ctx, repo))
 			expectedLogEntry := map[string]string{
-				"packed_objects_full": "success",
-				"written_bitmap":      "success",
+				"packed_objects_full":  "success",
+				"written_commit_graph": "success",
+				"written_bitmap":       "success",
 			}
 
 			if tc.expectedPrune {
diff --git a/internal/git/housekeeping/optimize_repository_test.go b/internal/git/housekeeping/optimize_repository_test.go
index 939dab9b1..453dd4ca7 100644
--- a/internal/git/housekeeping/optimize_repository_test.go
+++ b/internal/git/housekeeping/optimize_repository_test.go
@@ -546,6 +546,7 @@ gitaly_housekeeping_tasks_total{housekeeping_task="total", status="success"} 1
 			expectedMetrics: `# HELP gitaly_housekeeping_tasks_total Total number of housekeeping tasks performed in the repository
 # TYPE gitaly_housekeeping_tasks_total counter
 gitaly_housekeeping_tasks_total{housekeeping_task="packed_objects_full", status="success"} 1
+gitaly_housekeeping_tasks_total{housekeeping_task="written_commit_graph", status="success"} 1
 gitaly_housekeeping_tasks_total{housekeeping_task="written_bitmap", status="success"} 1
 gitaly_housekeeping_tasks_total{housekeeping_task="total", status="success"} 1
 `,
@@ -562,6 +563,7 @@ gitaly_housekeeping_tasks_total{housekeeping_task="total", status="success"} 1
 			expectedMetrics: `# HELP gitaly_housekeeping_tasks_total Total number of housekeeping tasks performed in the repository
 # TYPE gitaly_housekeeping_tasks_total counter
 gitaly_housekeeping_tasks_total{housekeeping_task="packed_objects_full", status="success"} 1
+gitaly_housekeeping_tasks_total{housekeeping_task="written_commit_graph", status="success"} 1
 gitaly_housekeeping_tasks_total{housekeeping_task="written_bitmap", status="success"} 1
 gitaly_housekeeping_tasks_total{housekeeping_task="total", status="success"} 1
 `,
@@ -588,6 +590,7 @@ gitaly_housekeeping_tasks_total{housekeeping_task="total", status="success"} 1
 # TYPE gitaly_housekeeping_tasks_total counter
 gitaly_housekeeping_tasks_total{housekeeping_task="packed_objects_full", status="success"} 1
 gitaly_housekeeping_tasks_total{housekeeping_task="written_bitmap", status="success"} 1
+gitaly_housekeeping_tasks_total{housekeeping_task="written_commit_graph", status="success"} 1
 gitaly_housekeeping_tasks_total{housekeeping_task="total", status="success"} 1
 `,
 		},
@@ -635,6 +638,7 @@ gitaly_housekeeping_tasks_total{housekeeping_task="total", status="success"} 1
 			expectedMetrics: `# HELP gitaly_housekeeping_tasks_total Total number of housekeeping tasks performed in the repository
 # TYPE gitaly_housekeeping_tasks_total counter
 gitaly_housekeeping_tasks_total{housekeeping_task="packed_objects_incremental", status="success"} 1
+gitaly_housekeeping_tasks_total{housekeeping_task="written_commit_graph", status="success"} 1
 gitaly_housekeeping_tasks_total{housekeeping_task="total", status="success"} 1
 `,
 		},
@@ -664,6 +668,7 @@ gitaly_housekeeping_tasks_total{housekeeping_task="total", status="success"} 1
 			expectedMetrics: `# HELP gitaly_housekeeping_tasks_total Total number of housekeeping tasks performed in the repository
 # TYPE gitaly_housekeeping_tasks_total counter
 gitaly_housekeeping_tasks_total{housekeeping_task="packed_objects_incremental", status="success"} 1
+gitaly_housekeeping_tasks_total{housekeeping_task="written_commit_graph", status="success"} 1
 gitaly_housekeeping_tasks_total{housekeeping_task="pruned_objects",status="success"} 1
 gitaly_housekeeping_tasks_total{housekeeping_task="total", status="success"} 1
 `,
@@ -671,6 +676,7 @@ gitaly_housekeeping_tasks_total{housekeeping_task="total", status="success"} 1
 			expectedMetricsForPool: `# HELP gitaly_housekeeping_tasks_total Total number of housekeeping tasks performed in the repository
 # TYPE gitaly_housekeeping_tasks_total counter
 gitaly_housekeeping_tasks_total{housekeeping_task="packed_objects_incremental", status="success"} 1
+gitaly_housekeeping_tasks_total{housekeeping_task="written_commit_graph", status="success"} 1
 gitaly_housekeeping_tasks_total{housekeeping_task="total", status="success"} 1
 `,
 		},
diff --git a/internal/gitaly/service/repository/repack.go b/internal/gitaly/service/repository/repack.go
index 66184ef1b..752e3c4c3 100644
--- a/internal/gitaly/service/repository/repack.go
+++ b/internal/gitaly/service/repository/repack.go
@@ -40,6 +40,10 @@ func (s *server) RepackFull(ctx context.Context, in *gitalypb.RepackFullRequest)
 		return nil, helper.ErrInternalf("repacking objects: %w", err)
 	}
 
+	if err := housekeeping.WriteCommitGraph(ctx, repo); err != nil {
+		return nil, helper.ErrInternalf("writing commit-graph: %w", err)
+	}
+
 	return &gitalypb.RepackFullResponse{}, nil
 }
 
@@ -60,5 +64,9 @@ func (s *server) RepackIncremental(ctx context.Context, in *gitalypb.RepackIncre
 		return nil, helper.ErrInternalf("repacking objects: %w", err)
 	}
 
+	if err := housekeeping.WriteCommitGraph(ctx, repo); err != nil {
+		return nil, helper.ErrInternalf("writing commit-graph: %w", err)
+	}
+
 	return &gitalypb.RepackIncrementalResponse{}, nil
 }