diff options
authorDerrick Stolee <>2018-06-27 13:24:46 (GMT)
committerJunio C Hamano <>2018-06-27 17:29:10 (GMT)
commitd5d5d7b64131a23a13698242797f11f6479e39e8 (patch)
parent59fb87701ff68eb114e54ce6834e91c4ae8f60a7 (diff)
gc: automatically write commit-graph files
The commit-graph file is a very helpful feature for speeding up git operations. In order to make it more useful, make it possible to write the commit-graph file during standard garbage collection operations. Add a 'gc.commitGraph' config setting that triggers writing a commit-graph file after any non-trivial 'git gc' command. Defaults to false while the commit-graph feature matures. We specifically do not want to have this on by default until the commit-graph feature is fully integrated with history-modifying features like shallow clones. Helped-by: Ævar Arnfjörð Bjarmason <> Signed-off-by: Derrick Stolee <> Signed-off-by: Junio C Hamano <>
4 files changed, 30 insertions, 3 deletions
diff --git a/Documentation/config.txt b/Documentation/config.txt
index 1cc18a8..978deec 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -904,9 +904,12 @@ core.notesRef::
This setting defaults to "refs/notes/commits", and it can be overridden by
the `GIT_NOTES_REF` environment variable. See linkgit:git-notes[1].
- Enable git commit graph feature. Allows reading from the
- commit-graph file.
+ If true, then gc will rewrite the commit-graph file when
+ linkgit:git-gc[1] is run. When using linkgit:git-gc[1]
+ '--auto' the commit-graph will be updated if housekeeping is
+ required. Default is false. See linkgit:git-commit-graph[1]
+ for details.
Enable "sparse checkout" feature. See section "Sparse checkout" in
diff --git a/Documentation/git-gc.txt b/Documentation/git-gc.txt
index 24b2dd4..f5bc98c 100644
--- a/Documentation/git-gc.txt
+++ b/Documentation/git-gc.txt
@@ -136,6 +136,10 @@ The optional configuration variable `gc.packRefs` determines if
it within all non-bare repos or it can be set to a boolean value.
This defaults to true.
+The optional configuration variable `gc.commitGraph` determines if
+'git gc' should run 'git commit-graph write'. This can be set to a
+boolean value. This defaults to false.
The optional configuration variable `gc.aggressiveWindow` controls how
much time is spent optimizing the delta compression of the objects in
the repository when the --aggressive option is specified. The larger
diff --git a/builtin/gc.c b/builtin/gc.c
index ccfb1ce..e103f0f 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -20,6 +20,7 @@
#include "sigchain.h"
#include "argv-array.h"
#include "commit.h"
+#include "commit-graph.h"
#include "packfile.h"
#include "object-store.h"
#include "pack.h"
@@ -40,6 +41,7 @@ static int aggressive_depth = 50;
static int aggressive_window = 250;
static int gc_auto_threshold = 6700;
static int gc_auto_pack_limit = 50;
+static int gc_write_commit_graph;
static int detach_auto = 1;
static timestamp_t gc_log_expire_time;
static const char *gc_log_expire = "";
@@ -129,6 +131,7 @@ static void gc_config(void)
git_config_get_int("gc.aggressivedepth", &aggressive_depth);
git_config_get_int("", &gc_auto_threshold);
git_config_get_int("gc.autopacklimit", &gc_auto_pack_limit);
+ git_config_get_bool("gc.writecommitgraph", &gc_write_commit_graph);
git_config_get_bool("gc.autodetach", &detach_auto);
git_config_get_expiry("gc.pruneexpire", &prune_expire);
git_config_get_expiry("gc.worktreepruneexpire", &prune_worktrees_expire);
@@ -641,6 +644,9 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
if ( > 0)
+ if (gc_write_commit_graph)
+ write_commit_graph_reachable(get_object_directory(), 0);
if (auto_gc && too_many_loose_objects())
warning(_("There are too many unreachable loose objects; "
"run 'git prune' to remove them."));
diff --git a/t/ b/t/
index 2208c26..5947de3 100755
--- a/t/
+++ b/t/
@@ -245,6 +245,20 @@ test_expect_success 'perform fast-forward merge in full repo' '
test_cmp expect output
+test_expect_success 'check that gc computes commit-graph' '
+ cd "$TRASH_DIRECTORY/full" &&
+ git commit --allow-empty -m "blank" &&
+ git commit-graph write --reachable &&
+ cp $objdir/info/commit-graph commit-graph-before-gc &&
+ git reset --hard HEAD~1 &&
+ git config gc.writeCommitGraph true &&
+ git gc &&
+ cp $objdir/info/commit-graph commit-graph-after-gc &&
+ ! test_cmp commit-graph-before-gc commit-graph-after-gc &&
+ git commit-graph write --reachable &&
+ test_cmp commit-graph-after-gc $objdir/info/commit-graph
# the verify tests below expect the commit-graph to contain
# exactly the commits reachable from the commits/8 branch.
# If the file changes the set of commits in the list, then the