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 <avarab@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 1cc18a828ca63bc489726dc3f1489a5e5e5c8b2b..978deecfeee990d467c3a3adf1862b5f64b54f36 100644 (file)
--- 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].
 
-core.commitGraph::
-       Enable git commit graph feature. Allows reading from the
-       commit-graph file.
+gc.commitGraph::
+       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.
 
 core.sparseCheckout::
        Enable "sparse checkout" feature. See section "Sparse checkout" in

diff --git a/Documentation/git-gc.txt b/Documentation/git-gc.txt
index 24b2dd44fe445a66121fa957f0af8e2209a85676..f5bc98ccb3673079fa2e1205b57bc87acb3c1e90 100644 (file)
--- 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 ccfb1ceaeb3eb9c6a8cbe9297bceac94fa54bcac..e103f0f85d7995999fbd7e52057e563005ae819e 100644 (file)
--- 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 = "1.day.ago";
@@ -129,6 +131,7 @@ static void gc_config(void)
        git_config_get_int("gc.aggressivedepth", &aggressive_depth);
        git_config_get_int("gc.auto", &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 (pack_garbage.nr > 0)
                clean_pack_garbage();
 
+       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/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index 2208c266b50766a9300fdcac81be4b695012f1e6..5947de3d2438ea301e33f2fc3430ee703d1436b9 100755 (executable)
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -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