fast-rebase: demonstrate merge-ort's API via new test-tool command

Add a new test-tool command named 'fast-rebase', which is a
super-slimmed down and nowhere near as capable version of 'git rebase'.
'test-tool fast-rebase' is not currently planned for usage in the
testsuite, but is here for two purposes:

  1) Demonstrate the desired API of merge-ort.  In particular,
     fast-rebase takes advantage of the separation of the merging
     operation from the updating of the index and working tree, to
     allow it to pick N commits, but only update the index and working
     tree once at the end.  Look for the calls to
     merge_incore_nonrecursive() and merge_switch_to_result().

  2) Provide a convenient benchmark that isn't polluted by the heavy
     disk writing and forking of unnecessary processes that comes from
     sequencer.c and merge-recursive.c.  fast-rebase is not meant to
     replace sequencer.c, just give ideas on how sequencer.c can be
     changed.  Updating sequencer.c with these goals is probably a
     large amount of work; writing a simple targeted command with
     no documentation, less-than-useful help messages, numerous
     limitations in terms of flags it can accept and situations it can
     handle, and which is flagged off from users is a much easier
     interim step.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Elijah Newren 2020-10-29 20:32:13 +00:00 коммит произвёл Junio C Hamano
Родитель 47b1e890e3
Коммит fe1a21d526
4 изменённых файлов: 214 добавлений и 0 удалений

Просмотреть файл

@ -704,6 +704,7 @@ TEST_BUILTINS_OBJS += test-dump-fsmonitor.o
TEST_BUILTINS_OBJS += test-dump-split-index.o
TEST_BUILTINS_OBJS += test-dump-untracked-cache.o
TEST_BUILTINS_OBJS += test-example-decorate.o
TEST_BUILTINS_OBJS += test-fast-rebase.o
TEST_BUILTINS_OBJS += test-genrandom.o
TEST_BUILTINS_OBJS += test-genzeros.o
TEST_BUILTINS_OBJS += test-hash-speed.o

211
t/helper/test-fast-rebase.c Normal file
Просмотреть файл

@ -0,0 +1,211 @@
/*
* "git fast-rebase" builtin command
*
* FAST: Forking Any Subprocesses (is) Taboo
*
* This is meant SOLELY as a demo of what is possible. sequencer.c and
* rebase.c should be refactored to use the ideas here, rather than attempting
* to extend this file to replace those (unless Phillip or Dscho say that
* refactoring is too hard and we need a clean slate, but I'm guessing that
* refactoring is the better route).
*/
#define USE_THE_INDEX_COMPATIBILITY_MACROS
#include "test-tool.h"
#include "cache-tree.h"
#include "commit.h"
#include "lockfile.h"
#include "merge-ort.h"
#include "refs.h"
#include "revision.h"
#include "sequencer.h"
#include "strvec.h"
#include "tree.h"
static const char *short_commit_name(struct commit *commit)
{
return find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV);
}
static struct commit *peel_committish(const char *name)
{
struct object *obj;
struct object_id oid;
if (get_oid(name, &oid))
return NULL;
obj = parse_object(the_repository, &oid);
return (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
}
static char *get_author(const char *message)
{
size_t len;
const char *a;
a = find_commit_header(message, "author", &len);
if (a)
return xmemdupz(a, len);
return NULL;
}
static struct commit *create_commit(struct tree *tree,
struct commit *based_on,
struct commit *parent)
{
struct object_id ret;
struct object *obj;
struct commit_list *parents = NULL;
char *author;
char *sign_commit = NULL;
struct commit_extra_header *extra;
struct strbuf msg = STRBUF_INIT;
const char *out_enc = get_commit_output_encoding();
const char *message = logmsg_reencode(based_on, NULL, out_enc);
const char *orig_message = NULL;
const char *exclude_gpgsig[] = { "gpgsig", NULL };
commit_list_insert(parent, &parents);
extra = read_commit_extra_headers(based_on, exclude_gpgsig);
find_commit_subject(message, &orig_message);
strbuf_addstr(&msg, orig_message);
author = get_author(message);
reset_ident_date();
if (commit_tree_extended(msg.buf, msg.len, &tree->object.oid, parents,
&ret, author, NULL, sign_commit, extra)) {
error(_("failed to write commit object"));
return NULL;
}
free(author);
strbuf_release(&msg);
obj = parse_object(the_repository, &ret);
return (struct commit *)obj;
}
int cmd__fast_rebase(int argc, const char **argv)
{
struct commit *onto;
struct commit *last_commit = NULL, *last_picked_commit = NULL;
struct object_id head;
struct lock_file lock = LOCK_INIT;
int clean = 1;
struct strvec rev_walk_args = STRVEC_INIT;
struct rev_info revs;
struct commit *commit;
struct merge_options merge_opt;
struct tree *next_tree, *base_tree, *head_tree;
struct merge_result result;
struct strbuf reflog_msg = STRBUF_INIT;
struct strbuf branch_name = STRBUF_INIT;
/*
* test-tool stuff doesn't set up the git directory by default; need to
* do that manually.
*/
setup_git_directory();
if (argc == 2 && !strcmp(argv[1], "-h")) {
printf("Sorry, I am not a psychiatrist; I can not give you the help you need. Oh, you meant usage...\n");
exit(129);
}
if (argc != 5 || strcmp(argv[1], "--onto"))
die("usage: read the code, figure out how to use it, then do so");
onto = peel_committish(argv[2]);
strbuf_addf(&branch_name, "refs/heads/%s", argv[4]);
/* Sanity check */
if (get_oid("HEAD", &head))
die(_("Cannot read HEAD"));
assert(oideq(&onto->object.oid, &head));
hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
assert(repo_read_index(the_repository) >= 0);
repo_init_revisions(the_repository, &revs, NULL);
revs.verbose_header = 1;
revs.max_parents = 1;
revs.cherry_mark = 1;
revs.limited = 1;
revs.reverse = 1;
revs.right_only = 1;
revs.sort_order = REV_SORT_IN_GRAPH_ORDER;
revs.topo_order = 1;
strvec_pushl(&rev_walk_args, "", argv[4], "--not", argv[3], NULL);
if (setup_revisions(rev_walk_args.nr, rev_walk_args.v, &revs, NULL) > 1)
return error(_("unhandled options"));
strvec_clear(&rev_walk_args);
if (prepare_revision_walk(&revs) < 0)
return error(_("error preparing revisions"));
init_merge_options(&merge_opt, the_repository);
memset(&result, 0, sizeof(result));
merge_opt.show_rename_progress = 1;
merge_opt.branch1 = "HEAD";
head_tree = get_commit_tree(onto);
result.tree = head_tree;
last_commit = onto;
while ((commit = get_revision(&revs))) {
struct commit *base;
fprintf(stderr, "Rebasing %s...\r",
oid_to_hex(&commit->object.oid));
assert(commit->parents && !commit->parents->next);
base = commit->parents->item;
next_tree = get_commit_tree(commit);
base_tree = get_commit_tree(base);
merge_opt.branch2 = short_commit_name(commit);
merge_opt.ancestor = xstrfmt("parent of %s", merge_opt.branch2);
merge_incore_nonrecursive(&merge_opt,
base_tree,
result.tree,
next_tree,
&result);
free((char*)merge_opt.ancestor);
merge_opt.ancestor = NULL;
if (!result.clean)
die("Aborting: Hit a conflict and restarting is not implemented.");
last_picked_commit = commit;
last_commit = create_commit(result.tree, commit, last_commit);
}
fprintf(stderr, "\nDone.\n");
/* TODO: There should be some kind of rev_info_free(&revs) call... */
memset(&revs, 0, sizeof(revs));
merge_switch_to_result(&merge_opt, head_tree, &result, 1, !result.clean);
if (result.clean < 0)
exit(128);
strbuf_addf(&reflog_msg, "finish rebase %s onto %s",
oid_to_hex(&last_picked_commit->object.oid),
oid_to_hex(&last_commit->object.oid));
if (update_ref(reflog_msg.buf, branch_name.buf,
&last_commit->object.oid,
&last_picked_commit->object.oid,
REF_NO_DEREF, UPDATE_REFS_MSG_ON_ERR)) {
error(_("could not update %s"), argv[4]);
die("Failed to update %s", argv[4]);
}
if (create_symref("HEAD", branch_name.buf, reflog_msg.buf) < 0)
die(_("unable to update HEAD"));
strbuf_release(&reflog_msg);
strbuf_release(&branch_name);
prime_cache_tree(the_repository, the_repository->index, result.tree);
if (write_locked_index(&the_index, &lock,
COMMIT_LOCK | SKIP_IF_UNCHANGED))
die(_("unable to write %s"), get_index_file());
return (clean == 0);
}

Просмотреть файл

@ -28,6 +28,7 @@ static struct test_cmd cmds[] = {
{ "dump-split-index", cmd__dump_split_index },
{ "dump-untracked-cache", cmd__dump_untracked_cache },
{ "example-decorate", cmd__example_decorate },
{ "fast-rebase", cmd__fast_rebase },
{ "genrandom", cmd__genrandom },
{ "genzeros", cmd__genzeros },
{ "hashmap", cmd__hashmap },

Просмотреть файл

@ -18,6 +18,7 @@ int cmd__dump_fsmonitor(int argc, const char **argv);
int cmd__dump_split_index(int argc, const char **argv);
int cmd__dump_untracked_cache(int argc, const char **argv);
int cmd__example_decorate(int argc, const char **argv);
int cmd__fast_rebase(int argc, const char **argv);
int cmd__genrandom(int argc, const char **argv);
int cmd__genzeros(int argc, const char **argv);
int cmd__hashmap(int argc, const char **argv);