[PATCH v2 7/8] fetch: after repair, encourage auto gc repacking

["Robert Coup via GitGitGadget" <gitgitgadget@gmail.com>]

From: Robert Coup <robert@coup.net.nz>

After invoking `fetch --repair`, the object db will likely contain many
duplicate objects. If auto-maintenance is enabled, invoke it with
appropriate settings to encourage repacking/consolidation.

* gc.autoPackLimit: unless this is set to 0 (disabled), override the
  value to 1 to force pack consolidation.
* maintenance.incremental-repack.auto: unless this is set to 0, override
  the value to -1 to force incremental repacking.

Signed-off-by: Robert Coup <robert@coup.net.nz>
---
 Documentation/fetch-options.txt |  3 ++-
 builtin/fetch.c                 | 23 +++++++++++++++++++++--
 t/t5616-partial-clone.sh        |  6 ++++--
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/Documentation/fetch-options.txt b/Documentation/fetch-options.txt
index 1131aaad252..73abafdfc41 100644
--- a/Documentation/fetch-options.txt
+++ b/Documentation/fetch-options.txt
@@ -169,7 +169,8 @@ ifndef::git-pull[]
 	associated objects that are already present locally, this option fetches
 	all objects as a fresh clone would. Use this to reapply a partial clone
 	filter from configuration or using `--filter=` when the filter
-	definition has changed.
+	definition has changed. Automatic post-fetch maintenance will perform
+	object database pack consolidation to remove any duplicate objects.
 endif::git-pull[]
 
 --refmap=<refspec>::
diff --git a/builtin/fetch.c b/builtin/fetch.c
index f32b24d182b..7d023341ac0 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -2020,6 +2020,8 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
 	struct remote *remote = NULL;
 	int result = 0;
 	int prune_tags_ok = 1;
+	struct strvec auto_maint_opts = STRVEC_INIT;
+	int opt_val;
 
 	packet_trace_identity("fetch");
 
@@ -2226,10 +2228,27 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
 					     NULL);
 	}
 
-	if (enable_auto_gc)
-		run_auto_maintenance(verbosity < 0, NULL);
+	if (enable_auto_gc) {
+		if (repair) {
+			/*
+			 * Hint auto-maintenance strongly to encourage repacking,
+			 * but respect config settings disabling it.
+			 */
+			if (git_config_get_int("gc.autopacklimit", &opt_val))
+				opt_val = -1;
+			if (opt_val != 0)
+				strvec_push(&auto_maint_opts, "gc.autoPackLimit=1");
+
+			if (git_config_get_int("maintenance.incremental-repack.auto", &opt_val))
+				opt_val = -1;
+			if (opt_val != 0)
+				strvec_push(&auto_maint_opts, "maintenance.incremental-repack.auto=-1");
+		}
+		run_auto_maintenance(verbosity < 0, &auto_maint_opts);
+	}
 
  cleanup:
 	string_list_clear(&list, 0);
+	strvec_clear(&auto_maint_opts);
 	return result;
 }
diff --git a/t/t5616-partial-clone.sh b/t/t5616-partial-clone.sh
index 230b2dcbc94..60f1817cda6 100755
--- a/t/t5616-partial-clone.sh
+++ b/t/t5616-partial-clone.sh
@@ -187,7 +187,7 @@ test_expect_success 'push new commits to server for file.4.txt' '
 # Do partial fetch to fetch smaller files; then verify that without --repair
 # applying a new filter does not refetch missing large objects. Then use
 # --repair to apply the new filter on existing commits. Test it under both
-# protocol v2 & v0.
+# protocol v2 & v0. Check repacking auto-maintenance is kicked off.
 test_expect_success 'apply a different filter using --repair' '
 	git -C pc1 fetch --filter=blob:limit=999 origin &&
 	git -C pc1 rev-list --quiet --objects --missing=print \
@@ -199,11 +199,13 @@ test_expect_success 'apply a different filter using --repair' '
 		main..origin/main >observed &&
 	test_line_count = 2 observed &&
 
+	GIT_TRACE2_EVENT="$(pwd)/trace.log" \
 	git -c protocol.version=0 -C pc1 fetch --filter=blob:limit=29999 \
 		--repair origin &&
 	git -C pc1 rev-list --quiet --objects --missing=print \
 		main..origin/main >observed &&
-	test_line_count = 0 observed
+	test_line_count = 0 observed &&
+	test_subcommand git -c gc.autoPackLimit=1 -c maintenance.incremental-repack.auto=-1 maintenance run --auto --no-quiet <trace.log
 '
 
 test_expect_success 'fetch --repair works with a shallow clone' '
-- 
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