commit-graph: build graph from starting commits

Teach git-commit-graph to read commits from stdin when the
--stdin-commits flag is specified. Commits reachable from these
commits are added to the graph. This is a much faster way to construct
the graph than inspecting all packed objects, but is restricted to
known tips.

For the Linux repository, 700,000+ commits were added to the graph
file starting from 'master' in 7-9 seconds, depending on the number
of packfiles in the repo (1, 24, or 120).

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

diff --git a/Documentation/git-commit-graph.txt b/Documentation/git-commit-graph.txt
index 8143cc3f078e46b0070c1212c1278b517db336e5..442ac243e689adfe0dba9d17ee506e10d0eeb7ca 100644 (file)
--- a/Documentation/git-commit-graph.txt
+++ b/Documentation/git-commit-graph.txt
@@ -36,7 +36,13 @@ COMMANDS
 Write a commit graph file based on the commits found in packfiles.
 +
 With the `--stdin-packs` option, generate the new commit graph by
-walking objects only in the specified pack-indexes.
+walking objects only in the specified pack-indexes. (Cannot be combined
+with --stdin-commits.)
++
+With the `--stdin-commits` option, generate the new commit graph by
+walking commits starting at the commits specified in stdin as a list
+of OIDs in hex, one OID per line. (Cannot be combined with
+--stdin-packs.)
 
 'read'::
 
@@ -60,6 +66,12 @@ $ git commit-graph write
 $ echo <pack-index> | git commit-graph write --stdin-packs
 ------------------------------------------------
 
+* Write a graph file containing all reachable commits.
++
+------------------------------------------------
+$ git show-ref -s | git commit-graph write --stdin-commits
+------------------------------------------------
+
 * Read basic information from the commit-graph file.
 +
 ------------------------------------------------

diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index 5c7019900307f034d8c26b491fa416a7cfd35d8c..b5c0b0890562cbdfc305450a8696b4a4f580edea 100644 (file)
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c
@@ -8,7 +8,7 @@
 static char const * const builtin_commit_graph_usage[] = {
        N_("git commit-graph [--object-dir <objdir>]"),
        N_("git commit-graph read [--object-dir <objdir>]"),
-       N_("git commit-graph write [--object-dir <objdir>] [--stdin-packs]"),
+       N_("git commit-graph write [--object-dir <objdir>] [--stdin-packs|--stdin-commits]"),
        NULL
 };
 
@@ -18,13 +18,14 @@ static const char * const builtin_commit_graph_read_usage[] = {
 };
 
 static const char * const builtin_commit_graph_write_usage[] = {
-       N_("git commit-graph write [--object-dir <objdir>] [--stdin-packs]"),
+       N_("git commit-graph write [--object-dir <objdir>] [--stdin-packs|--stdin-commits]"),
        NULL
 };
 
 static struct opts_commit_graph {
        const char *obj_dir;
        int stdin_packs;
+       int stdin_commits;
 } opts;
 
 static int graph_read(int argc, const char **argv)
@@ -79,6 +80,8 @@ static int graph_write(int argc, const char **argv)
 {
        const char **pack_indexes = NULL;
        int packs_nr = 0;
+       const char **commit_hex = NULL;
+       int commits_nr = 0;
        const char **lines = NULL;
        int lines_nr = 0;
        int lines_alloc = 0;
@@ -89,6 +92,8 @@ static int graph_write(int argc, const char **argv)
                        N_("The object directory to store the graph")),
                OPT_BOOL(0, "stdin-packs", &opts.stdin_packs,
                        N_("scan pack-indexes listed by stdin for commits")),
+               OPT_BOOL(0, "stdin-commits", &opts.stdin_commits,
+                       N_("start walk at commits listed by stdin")),
                OPT_END(),
        };
 
@@ -96,10 +101,12 @@ static int graph_write(int argc, const char **argv)
                             builtin_commit_graph_write_options,
                             builtin_commit_graph_write_usage, 0);
 
+       if (opts.stdin_packs && opts.stdin_commits)
+               die(_("cannot use both --stdin-commits and --stdin-packs"));
        if (!opts.obj_dir)
                opts.obj_dir = get_object_directory();
 
-       if (opts.stdin_packs) {
+       if (opts.stdin_packs || opts.stdin_commits) {
                struct strbuf buf = STRBUF_INIT;
                lines_nr = 0;
                lines_alloc = 128;
@@ -110,13 +117,21 @@ static int graph_write(int argc, const char **argv)
                        lines[lines_nr++] = strbuf_detach(&buf, NULL);
                }
 
-               pack_indexes = lines;
-               packs_nr = lines_nr;
+               if (opts.stdin_packs) {
+                       pack_indexes = lines;
+                       packs_nr = lines_nr;
+               }
+               if (opts.stdin_commits) {
+                       commit_hex = lines;
+                       commits_nr = lines_nr;
+               }
        }
 
        write_commit_graph(opts.obj_dir,
                           pack_indexes,
-                          packs_nr);
+                          packs_nr,
+                          commit_hex,
+                          commits_nr);
 
        return 0;
 }

diff --git a/commit-graph.c b/commit-graph.c
index 70472840a3bfb99fb0e1c63978f49d464df1fdb1..a59d1e387bea6ae1004eea0c5fe72a4a0b809d7e 100644 (file)
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -551,7 +551,9 @@ static void close_reachable(struct packed_oid_list *oids)
 
 void write_commit_graph(const char *obj_dir,
                        const char **pack_indexes,
-                       int nr_packs)
+                       int nr_packs,
+                       const char **commit_hex,
+                       int nr_commits)
 {
        struct packed_oid_list oids;
        struct packed_commit_list commits;
@@ -591,7 +593,28 @@ void write_commit_graph(const char *obj_dir,
                        close_pack(p);
                }
                strbuf_release(&packname);
-       } else
+       }
+
+       if (commit_hex) {
+               for (i = 0; i < nr_commits; i++) {
+                       const char *end;
+                       struct object_id oid;
+                       struct commit *result;
+
+                       if (commit_hex[i] && parse_oid_hex(commit_hex[i], &oid, &end))
+                               continue;
+
+                       result = lookup_commit_reference_gently(&oid, 1);
+
+                       if (result) {
+                               ALLOC_GROW(oids.list, oids.nr + 1, oids.alloc);
+                               oidcpy(&oids.list[oids.nr], &(result->object.oid));
+                               oids.nr++;
+                       }
+               }
+       }
+
+       if (!pack_indexes && !commit_hex)
                for_each_packed_object(add_packed_commits, &oids, 0);
 
        close_reachable(&oids);

diff --git a/commit-graph.h b/commit-graph.h
index f065f0866f83e274b0e9e8cdb10415b84d5d74f8..fd035101b282bc1bcf7b94318300b608881cde0f 100644 (file)
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -38,6 +38,8 @@ struct commit_graph *load_commit_graph_one(const char *graph_file);
 
 void write_commit_graph(const char *obj_dir,
                        const char **pack_indexes,
-                       int nr_packs);
+                       int nr_packs,
+                       const char **commit_hex,
+                       int nr_commits);
 
 #endif

diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index 3bb44d0c09e15c771f68efa8fb2c24a86f340fa7..c28cfb5d7fb2e6b520888fcdbdedc405e0260157 100755 (executable)
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -177,6 +177,19 @@ test_expect_success 'build graph from latest pack with closure' '
 graph_git_behavior 'graph from pack, commit 8 vs merge 1' full commits/8 merge/1
 graph_git_behavior 'graph from pack, commit 8 vs merge 2' full commits/8 merge/2
 
+test_expect_success 'build graph from commits with closure' '
+       cd "$TRASH_DIRECTORY/full" &&
+       git tag -a -m "merge" tag/merge merge/2 &&
+       git rev-parse tag/merge >commits-in &&
+       git rev-parse merge/1 >>commits-in &&
+       cat commits-in | git commit-graph write --stdin-commits &&
+       test_path_is_file $objdir/info/commit-graph &&
+       graph_read_expect "6"
+'
+
+graph_git_behavior 'graph from commits, commit 8 vs merge 1' full commits/8 merge/1
+graph_git_behavior 'graph from commits, commit 8 vs merge 2' full commits/8 merge/2
+
 test_expect_success 'setup bare repo' '
        cd "$TRASH_DIRECTORY" &&
        git clone --bare --no-local full bare &&