[PATCH v4 6/7] fetch: after refetch, encourage auto gc repacking

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

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

After invoking `fetch --refetch`, 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                 | 19 ++++++++++++++++++-
 t/t5616-partial-clone.sh        | 29 +++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/Documentation/fetch-options.txt b/Documentation/fetch-options.txt
index d03fce5aae0..622bd84768b 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 e391a5dbc55..e3791f09ed5 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -2306,8 +2306,25 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
 					     NULL);
 	}
 
-	if (enable_auto_gc)
+	if (enable_auto_gc) {
+		if (refetch) {
+			/*
+			 * Hint auto-maintenance strongly to encourage repacking,
+			 * but respect config settings disabling it.
+			 */
+			int opt_val;
+			if (git_config_get_int("gc.autopacklimit", &opt_val))
+				opt_val = -1;
+			if (opt_val != 0)
+				git_config_push_parameter("gc.autoPackLimit=1");
+
+			if (git_config_get_int("maintenance.incremental-repack.auto", &opt_val))
+				opt_val = -1;
+			if (opt_val != 0)
+				git_config_push_parameter("maintenance.incremental-repack.auto=-1");
+		}
 		run_auto_maintenance(verbosity < 0);
+	}
 
  cleanup:
 	string_list_clear(&list, 0);
diff --git a/t/t5616-partial-clone.sh b/t/t5616-partial-clone.sh
index 87ebf4b0b1c..4a3778d04a8 100755
--- a/t/t5616-partial-clone.sh
+++ b/t/t5616-partial-clone.sh
@@ -216,6 +216,35 @@ test_expect_success 'fetch --refetch works with a shallow clone' '
 	test_line_count = 6 observed
 '
 
+test_expect_success 'fetch --refetch triggers repacking' '
+	GIT_TRACE2_CONFIG_PARAMS=gc.autoPackLimit,maintenance.incremental-repack.auto &&
+	export GIT_TRACE2_CONFIG_PARAMS &&
+
+	GIT_TRACE2_EVENT="$PWD/trace1.event" \
+	git -C pc1 fetch --refetch origin &&
+	test_subcommand git maintenance run --auto --no-quiet <trace1.event &&
+	grep \"param\":\"gc.autopacklimit\",\"value\":\"1\" trace1.event &&
+	grep \"param\":\"maintenance.incremental-repack.auto\",\"value\":\"-1\" trace1.event &&
+
+	GIT_TRACE2_EVENT="$PWD/trace2.event" \
+	git -c protocol.version=0 \
+		-c gc.autoPackLimit=0 \
+		-c maintenance.incremental-repack.auto=1234 \
+		-C pc1 fetch --refetch origin &&
+	test_subcommand git maintenance run --auto --no-quiet <trace2.event &&
+	grep \"param\":\"gc.autopacklimit\",\"value\":\"0\" trace2.event &&
+	grep \"param\":\"maintenance.incremental-repack.auto\",\"value\":\"-1\" trace2.event &&
+
+	GIT_TRACE2_EVENT="$PWD/trace3.event" \
+	git -c protocol.version=0 \
+		-c gc.autoPackLimit=1234 \
+		-c maintenance.incremental-repack.auto=0 \
+		-C pc1 fetch --refetch origin &&
+	test_subcommand git maintenance run --auto --no-quiet <trace3.event &&
+	grep \"param\":\"gc.autopacklimit\",\"value\":\"1\" trace3.event &&
+	grep \"param\":\"maintenance.incremental-repack.auto\",\"value\":\"0\" trace3.event
+'
+
 test_expect_success 'partial clone with transfer.fsckobjects=1 works with submodules' '
 	test_create_repo submodule &&
 	test_commit -C submodule mycommit &&
-- 
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