[RFC PATCH 4/6] commit-graph: avoid writing when repo is shallow

From: Derrick Stolee <dstolee@microsoft.com>
Date: May 31, 2018, 17:41 UTC
Message-ID: <20180531174024.124488-5-dstolee@microsoft.com>
In-Reply-To: <20180531174024.124488-1-dstolee@microsoft.com>

Shallow clones do not interact well with the commit-graph feature for several reasons. Instead of doing the hard thing to fix those interactions, instead prevent reading or writing a commit-graph file for shallow repositories.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 commit-graph.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/commit-graph.c b/commit-graph.c
index 95af4ed519..80e377b90f 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -208,6 +208,9 @@ static void prepare_commit_graph(void)
 		return;
 	prepare_commit_graph_run_once = 1;
 
+	if (is_repository_shallow())
+		return;
+
 	obj_dir = get_object_directory();
 	prepare_commit_graph_one(obj_dir);
 	prepare_alt_odb();
@@ -711,6 +714,15 @@ void write_commit_graph(const char *obj_dir,
 	int num_extra_edges;
 	struct commit_list *parent;
 
+	/*
+	 * Shallow clones are not supproted, as they create bad
+	 * generation skips as they are un-shallowed.
+	 */
+	if (is_repository_shallow()) {
+		warning("writing a commit-graph in a shallow repository is not supported");
+		return;
+	}
+
 	oids.nr = 0;
 	oids.alloc = approximate_object_count() / 4;

-- 
2.16.2.338.gcfe06ae955