[PATCH 20/21] maintenance: add pack-files auto condition

["Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>]

From: Derrick Stolee <dstolee@microsoft.com>

The pack-files task updates the multi-pack-index by deleting pack-files
that have been replaced with new packs, then repacking a batch of small
pack-files into a larger pack-file. This incremental repack is faster
than rewriting all object data, but is slower than some other
maintenance activities.

The 'maintenance.pack-files.auto' config option specifies how many
pack-files should exist outside of the multi-pack-index before running
the step. These pack-files could be created by 'git fetch' commands or
by the loose-objects task. The default value is 10.

Setting the option to zero disables the task with the '--auto' option,
and a negative value makes the task run every time.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 Documentation/config/maintenance.txt |  9 ++++++++
 builtin/gc.c                         | 31 ++++++++++++++++++++++++++++
 t/t7900-maintenance.sh               | 30 +++++++++++++++++++++++++++
 3 files changed, 70 insertions(+)

diff --git a/Documentation/config/maintenance.txt b/Documentation/config/maintenance.txt
index a9442dd260..77b255318c 100644
--- a/Documentation/config/maintenance.txt
+++ b/Documentation/config/maintenance.txt
@@ -21,3 +21,12 @@ maintenance.loose-objects.auto::
 	positive value implies the command should run when the number of
 	loose objects is at least the value of `maintenance.loose-objects.auto`.
 	The default value is 100.
+
+maintenance.pack-files.auto::
+	This integer config option controls how often the `pack-files` task
+	should be run as part of `git maintenance run --auto`. If zero, then
+	the `pack-files` task will not run with the `--auto` option. A
+	negative value will force the task to run every time. Otherwise, a
+	positive value implies the command should run when the number of
+	pack-files not in the multi-pack-index is at least the value of
+	`maintenance.pack-files.auto`. The default value is 10.
diff --git a/builtin/gc.c b/builtin/gc.c
index 391e1e2121..c3531561c2 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -31,6 +31,7 @@
 #include "remote.h"
 #include "midx.h"
 #include "refs.h"
+#include "object-store.h"
 
 #define FAILED_RUN "failed to run %s"
 
@@ -1072,6 +1073,35 @@ static int maintenance_task_loose_objects(struct repository *r)
 	return prune_packed(r) || pack_loose(r);
 }
 
+static int pack_files_auto_condition(struct repository *r)
+{
+	struct packed_git *p;
+	int enabled;
+	int pack_files_auto_limit = 10;
+	int count = 0;
+
+	if (repo_config_get_bool(r, "core.multiPackIndex", &enabled) ||
+	    !enabled)
+		return 0;
+
+	repo_config_get_int(r, "maintenance.pack-files.auto",
+			    &pack_files_auto_limit);
+
+	if (!pack_files_auto_limit)
+		return 0;
+	if (pack_files_auto_limit < 0)
+		return 1;
+
+	for (p = get_packed_git(r);
+	     count < pack_files_auto_limit && p;
+	     p = p->next) {
+		if (!p->multi_pack_index)
+			count++;
+	}
+
+	return count >= pack_files_auto_limit;
+}
+
 static int multi_pack_index_write(struct repository *r)
 {
 	int result;
@@ -1345,6 +1375,7 @@ static void initialize_tasks(struct repository *r)
 
 	tasks[num_tasks]->name = "pack-files";
 	tasks[num_tasks]->fn = maintenance_task_pack_files;
+	tasks[num_tasks]->auto_condition = pack_files_auto_condition;
 	num_tasks++;
 
 	tasks[num_tasks]->name = "gc";
diff --git a/t/t7900-maintenance.sh b/t/t7900-maintenance.sh
index a55c36d249..1714d11bd9 100755
--- a/t/t7900-maintenance.sh
+++ b/t/t7900-maintenance.sh
@@ -178,4 +178,34 @@ test_expect_success 'pack-files task' '
 	test_line_count = 2 packs-after
 '
 
+test_expect_success 'maintenance.pack-files.auto' '
+	git repack -adk &&
+	git config core.multiPackIndex true &&
+	git multi-pack-index write &&
+	GIT_TRACE2_EVENT=1 git -c maintenance.pack-files.auto=1 maintenance \
+		run --auto --task=pack-files >out &&
+	! grep "\"multi-pack-index\"" out &&
+	for i in 1 2
+	do
+		test_commit A-$i &&
+		git pack-objects --revs .git/objects/pack/pack <<-\EOF &&
+		HEAD
+		^HEAD~1
+		EOF
+		GIT_TRACE2_EVENT=$(pwd)/trace-A-$i git \
+			-c maintenance.pack-files.auto=2 \
+			maintenance run --auto --task=pack-files &&
+		! grep "\"multi-pack-index\"" trace-A-$i &&
+		test_commit B-$i &&
+		git pack-objects --revs .git/objects/pack/pack <<-\EOF &&
+		HEAD
+		^HEAD~1
+		EOF
+		GIT_TRACE2_EVENT=$(pwd)/trace-B-$i git \
+			-c maintenance.pack-files.auto=2 \
+			maintenance run --auto --task=pack-files >out &&
+		grep "\"multi-pack-index\"" trace-B-$i >/dev/null || return 1
+	done
+'
+
 test_done
-- 
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