]> git.ipfire.org Git - thirdparty/git.git/commitdiff
pack-bitmap: write multi-pack bitmaps
authorTaylor Blau <me@ttaylorr.com>
Tue, 31 Aug 2021 20:52:24 +0000 (16:52 -0400)
committerJunio C Hamano <gitster@pobox.com>
Wed, 1 Sep 2021 20:56:43 +0000 (13:56 -0700)
Write multi-pack bitmaps in the format described by
Documentation/technical/bitmap-format.txt, inferring their presence with
the absence of '--bitmap'.

To write a multi-pack bitmap, this patch attempts to reuse as much of
the existing machinery from pack-objects as possible. Specifically, the
MIDX code prepares a packing_data struct that pretends as if a single
packfile has been generated containing all of the objects contained
within the MIDX.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Documentation/git-multi-pack-index.txt
builtin/multi-pack-index.c
midx.c
midx.h

index 0af6beb2dd137a8f3e3d0bd4ce58f5c1480a57ba..a9df3dbd328f77d922420d8d0c8c697acb6d9d99 100644 (file)
@@ -10,7 +10,7 @@ SYNOPSIS
 --------
 [verse]
 'git multi-pack-index' [--object-dir=<dir>] [--[no-]progress]
-       [--preferred-pack=<pack>] <subcommand>
+       [--preferred-pack=<pack>] [--[no-]bitmap] <subcommand>
 
 DESCRIPTION
 -----------
@@ -42,6 +42,9 @@ write::
                multiple packs contain the same object. `<pack>` must
                contain at least one object. If not given, ties are
                broken in favor of the pack with the lowest mtime.
+
+       --[no-]bitmap::
+               Control whether or not a multi-pack bitmap is written.
 --
 
 verify::
@@ -83,6 +86,13 @@ EXAMPLES
 $ git multi-pack-index write
 -----------------------------------------------
 
+* Write a MIDX file for the packfiles in the current .git folder with a
+corresponding bitmap.
++
+-------------------------------------------------------------
+$ git multi-pack-index write --preferred-pack=<pack> --bitmap
+-------------------------------------------------------------
+
 * Write a MIDX file for the packfiles in an alternate object store.
 +
 -----------------------------------------------
index 8ff0dee2ecbb86881f77bc58ecf86f714a1d8622..73c0113b48b9a435173c62d5612c0db1afb3b184 100644 (file)
@@ -68,6 +68,8 @@ static int cmd_multi_pack_index_write(int argc, const char **argv)
                OPT_STRING(0, "preferred-pack", &opts.preferred_pack,
                           N_("preferred-pack"),
                           N_("pack for reuse when computing a multi-pack bitmap")),
+               OPT_BIT(0, "bitmap", &opts.flags, N_("write multi-pack bitmap"),
+                       MIDX_WRITE_BITMAP | MIDX_WRITE_REV_INDEX),
                OPT_END(),
        };
 
diff --git a/midx.c b/midx.c
index a839ab86ae6492c212ea7c0266c84a383ebb64e2..ccdc3e5702f17f63872eaf7d7340aa131c1cab0d 100644 (file)
--- a/midx.c
+++ b/midx.c
 #include "repository.h"
 #include "chunk-format.h"
 #include "pack.h"
+#include "pack-bitmap.h"
+#include "refs.h"
+#include "revision.h"
+#include "list-objects.h"
 
 #define MIDX_SIGNATURE 0x4d494458 /* "MIDX" */
 #define MIDX_VERSION 1
@@ -893,6 +897,166 @@ static int midx_checksum_valid(struct multi_pack_index *m)
        return hashfile_checksum_valid(m->data, m->data_len);
 }
 
+static void prepare_midx_packing_data(struct packing_data *pdata,
+                                     struct write_midx_context *ctx)
+{
+       uint32_t i;
+
+       memset(pdata, 0, sizeof(struct packing_data));
+       prepare_packing_data(the_repository, pdata);
+
+       for (i = 0; i < ctx->entries_nr; i++) {
+               struct pack_midx_entry *from = &ctx->entries[ctx->pack_order[i]];
+               struct object_entry *to = packlist_alloc(pdata, &from->oid);
+
+               oe_set_in_pack(pdata, to,
+                              ctx->info[ctx->pack_perm[from->pack_int_id]].p);
+       }
+}
+
+static int add_ref_to_pending(const char *refname,
+                             const struct object_id *oid,
+                             int flag, void *cb_data)
+{
+       struct rev_info *revs = (struct rev_info*)cb_data;
+       struct object *object;
+
+       if ((flag & REF_ISSYMREF) && (flag & REF_ISBROKEN)) {
+               warning("symbolic ref is dangling: %s", refname);
+               return 0;
+       }
+
+       object = parse_object_or_die(oid, refname);
+       if (object->type != OBJ_COMMIT)
+               return 0;
+
+       add_pending_object(revs, object, "");
+       if (bitmap_is_preferred_refname(revs->repo, refname))
+               object->flags |= NEEDS_BITMAP;
+       return 0;
+}
+
+struct bitmap_commit_cb {
+       struct commit **commits;
+       size_t commits_nr, commits_alloc;
+
+       struct write_midx_context *ctx;
+};
+
+static const struct object_id *bitmap_oid_access(size_t index,
+                                                const void *_entries)
+{
+       const struct pack_midx_entry *entries = _entries;
+       return &entries[index].oid;
+}
+
+static void bitmap_show_commit(struct commit *commit, void *_data)
+{
+       struct bitmap_commit_cb *data = _data;
+       int pos = oid_pos(&commit->object.oid, data->ctx->entries,
+                         data->ctx->entries_nr,
+                         bitmap_oid_access);
+       if (pos < 0)
+               return;
+
+       ALLOC_GROW(data->commits, data->commits_nr + 1, data->commits_alloc);
+       data->commits[data->commits_nr++] = commit;
+}
+
+static struct commit **find_commits_for_midx_bitmap(uint32_t *indexed_commits_nr_p,
+                                                   struct write_midx_context *ctx)
+{
+       struct rev_info revs;
+       struct bitmap_commit_cb cb = {0};
+
+       cb.ctx = ctx;
+
+       repo_init_revisions(the_repository, &revs, NULL);
+       setup_revisions(0, NULL, &revs, NULL);
+       for_each_ref(add_ref_to_pending, &revs);
+
+       /*
+        * Skipping promisor objects here is intentional, since it only excludes
+        * them from the list of reachable commits that we want to select from
+        * when computing the selection of MIDX'd commits to receive bitmaps.
+        *
+        * Reachability bitmaps do require that their objects be closed under
+        * reachability, but fetching any objects missing from promisors at this
+        * point is too late. But, if one of those objects can be reached from
+        * an another object that is included in the bitmap, then we will
+        * complain later that we don't have reachability closure (and fail
+        * appropriately).
+        */
+       fetch_if_missing = 0;
+       revs.exclude_promisor_objects = 1;
+
+       if (prepare_revision_walk(&revs))
+               die(_("revision walk setup failed"));
+
+       traverse_commit_list(&revs, bitmap_show_commit, NULL, &cb);
+       if (indexed_commits_nr_p)
+               *indexed_commits_nr_p = cb.commits_nr;
+
+       return cb.commits;
+}
+
+static int write_midx_bitmap(char *midx_name, unsigned char *midx_hash,
+                            struct write_midx_context *ctx,
+                            unsigned flags)
+{
+       struct packing_data pdata;
+       struct pack_idx_entry **index;
+       struct commit **commits = NULL;
+       uint32_t i, commits_nr;
+       char *bitmap_name = xstrfmt("%s-%s.bitmap", midx_name, hash_to_hex(midx_hash));
+       int ret;
+
+       prepare_midx_packing_data(&pdata, ctx);
+
+       commits = find_commits_for_midx_bitmap(&commits_nr, ctx);
+
+       /*
+        * Build the MIDX-order index based on pdata.objects (which is already
+        * in MIDX order; c.f., 'midx_pack_order_cmp()' for the definition of
+        * this order).
+        */
+       ALLOC_ARRAY(index, pdata.nr_objects);
+       for (i = 0; i < pdata.nr_objects; i++)
+               index[i] = &pdata.objects[i].idx;
+
+       bitmap_writer_show_progress(flags & MIDX_PROGRESS);
+       bitmap_writer_build_type_index(&pdata, index, pdata.nr_objects);
+
+       /*
+        * bitmap_writer_finish expects objects in lex order, but pack_order
+        * gives us exactly that. use it directly instead of re-sorting the
+        * array.
+        *
+        * This changes the order of objects in 'index' between
+        * bitmap_writer_build_type_index and bitmap_writer_finish.
+        *
+        * The same re-ordering takes place in the single-pack bitmap code via
+        * write_idx_file(), which is called by finish_tmp_packfile(), which
+        * happens between bitmap_writer_build_type_index() and
+        * bitmap_writer_finish().
+        */
+       for (i = 0; i < pdata.nr_objects; i++)
+               index[ctx->pack_order[i]] = &pdata.objects[i].idx;
+
+       bitmap_writer_select_commits(commits, commits_nr, -1);
+       ret = bitmap_writer_build(&pdata);
+       if (ret < 0)
+               goto cleanup;
+
+       bitmap_writer_set_checksum(midx_hash);
+       bitmap_writer_finish(index, pdata.nr_objects, bitmap_name, 0);
+
+cleanup:
+       free(index);
+       free(bitmap_name);
+       return ret;
+}
+
 static int write_midx_internal(const char *object_dir,
                               struct string_list *packs_to_drop,
                               const char *preferred_pack_name,
@@ -941,7 +1105,7 @@ static int write_midx_internal(const char *object_dir,
 
                        ctx.info[ctx.nr].orig_pack_int_id = i;
                        ctx.info[ctx.nr].pack_name = xstrdup(ctx.m->pack_names[i]);
-                       ctx.info[ctx.nr].p = NULL;
+                       ctx.info[ctx.nr].p = ctx.m->packs[i];
                        ctx.info[ctx.nr].expired = 0;
 
                        if (flags & MIDX_WRITE_REV_INDEX) {
@@ -975,8 +1139,26 @@ static int write_midx_internal(const char *object_dir,
        for_each_file_in_pack_dir(object_dir, add_pack_to_midx, &ctx);
        stop_progress(&ctx.progress);
 
-       if (ctx.m && ctx.nr == ctx.m->num_packs && !packs_to_drop)
-               goto cleanup;
+       if (ctx.m && ctx.nr == ctx.m->num_packs && !packs_to_drop) {
+               struct bitmap_index *bitmap_git;
+               int bitmap_exists;
+               int want_bitmap = flags & MIDX_WRITE_BITMAP;
+
+               bitmap_git = prepare_midx_bitmap_git(the_repository, ctx.m);
+               bitmap_exists = bitmap_git && bitmap_is_midx(bitmap_git);
+               free_bitmap_index(bitmap_git);
+
+               if (bitmap_exists || !want_bitmap) {
+                       /*
+                        * The correct MIDX already exists, and so does a
+                        * corresponding bitmap (or one wasn't requested).
+                        */
+                       if (!want_bitmap)
+                               clear_midx_files_ext(object_dir, ".bitmap",
+                                                    NULL);
+                       goto cleanup;
+               }
+       }
 
        if (preferred_pack_name) {
                int found = 0;
@@ -992,7 +1174,8 @@ static int write_midx_internal(const char *object_dir,
                if (!found)
                        warning(_("unknown preferred pack: '%s'"),
                                preferred_pack_name);
-       } else if (ctx.nr && (flags & MIDX_WRITE_REV_INDEX)) {
+       } else if (ctx.nr &&
+                  (flags & (MIDX_WRITE_REV_INDEX | MIDX_WRITE_BITMAP))) {
                struct packed_git *oldest = ctx.info[ctx.preferred_pack_idx].p;
                ctx.preferred_pack_idx = 0;
 
@@ -1124,9 +1307,6 @@ static int write_midx_internal(const char *object_dir,
        hold_lock_file_for_update(&lk, midx_name, LOCK_DIE_ON_ERROR);
        f = hashfd(get_lock_file_fd(&lk), get_lock_file_path(&lk));
 
-       if (ctx.m)
-               close_object_store(the_repository->objects);
-
        if (ctx.nr - dropped_packs == 0) {
                error(_("no pack files to index."));
                result = 1;
@@ -1157,14 +1337,25 @@ static int write_midx_internal(const char *object_dir,
        finalize_hashfile(f, midx_hash, CSUM_FSYNC | CSUM_HASH_IN_STREAM);
        free_chunkfile(cf);
 
-       if (flags & MIDX_WRITE_REV_INDEX)
+       if (flags & (MIDX_WRITE_REV_INDEX | MIDX_WRITE_BITMAP))
                ctx.pack_order = midx_pack_order(&ctx);
 
        if (flags & MIDX_WRITE_REV_INDEX)
                write_midx_reverse_index(midx_name, midx_hash, &ctx);
+       if (flags & MIDX_WRITE_BITMAP) {
+               if (write_midx_bitmap(midx_name, midx_hash, &ctx, flags) < 0) {
+                       error(_("could not write multi-pack bitmap"));
+                       result = 1;
+                       goto cleanup;
+               }
+       }
+
+       if (ctx.m)
+               close_object_store(the_repository->objects);
 
        commit_lock_file(&lk);
 
+       clear_midx_files_ext(object_dir, ".bitmap", midx_hash);
        clear_midx_files_ext(object_dir, ".rev", midx_hash);
 
 cleanup:
@@ -1181,6 +1372,7 @@ cleanup:
        free(ctx.pack_perm);
        free(ctx.pack_order);
        free(midx_name);
+
        return result;
 }
 
@@ -1241,6 +1433,7 @@ void clear_midx_file(struct repository *r)
        if (remove_path(midx))
                die(_("failed to clear multi-pack-index at %s"), midx);
 
+       clear_midx_files_ext(r->objects->odb->path, ".bitmap", NULL);
        clear_midx_files_ext(r->objects->odb->path, ".rev", NULL);
 
        free(midx);
diff --git a/midx.h b/midx.h
index 1172df1a711489e26b40c939e14087fdc6b6d6bb..350f4d0a7b4c205486ee0ce26542d886f3356cf4 100644 (file)
--- a/midx.h
+++ b/midx.h
@@ -41,6 +41,7 @@ struct multi_pack_index {
 
 #define MIDX_PROGRESS     (1 << 0)
 #define MIDX_WRITE_REV_INDEX (1 << 1)
+#define MIDX_WRITE_BITMAP (1 << 2)
 
 const unsigned char *get_midx_checksum(struct multi_pack_index *m);
 char *get_midx_filename(const char *object_dir);