Re: [PATCH v4 0/4] Beginning of new merge strategy: New API, empty implementation

>
> In this series, I show the new merge API I have developed in merge-ort, and
> show how it differs from that provided by merge-recursive. I do this in four
> steps, each corresponding to a patch.
>

> Changes since v3:
>
>  * Make 'fast-rebase' be a test-tool subcommand instead of a special hidden
>    builtin, as suggested by Jonathan Tan and SZEDER Gábor
>
> Elijah Newren (4):
>   merge-ort: barebones API of new merge strategy with empty
>     implementation
>   merge-ort-wrappers: new convience wrappers to mimic the old merge API
>   fast-rebase: demonstrate merge-ort's API via new test-tool command
>   merge,rebase,revert: select ort or recursive by config or environment
>
>  Makefile                    |   3 +
>  builtin/merge.c             |  26 ++++-
>  builtin/rebase.c            |   9 +-
>  builtin/revert.c            |   2 +
>  merge-ort-wrappers.c        |  62 +++++++++++
>  merge-ort-wrappers.h        |  25 +++++
>  merge-ort.c                 |  52 +++++++++
>  merge-ort.h                 |  58 ++++++++++
>  sequencer.c                 |  71 ++++++++++--
>  t/helper/test-fast-rebase.c | 211 ++++++++++++++++++++++++++++++++++++
>  t/helper/test-tool.c        |   1 +
>  t/helper/test-tool.h        |   1 +
>  12 files changed, 506 insertions(+), 15 deletions(-)
>  create mode 100644 merge-ort-wrappers.c
>  create mode 100644 merge-ort-wrappers.h
>  create mode 100644 merge-ort.c
>  create mode 100644 merge-ort.h
>  create mode 100644 t/helper/test-fast-rebase.c
>
>
> base-commit: 69986e19ffcfb9af674ae5180689ab7bbf92ed28
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-895%2Fnewren%2Fort-api-with-empty-implementation-v4
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-895/newren/ort-api-with-empty-implementation-v4
> Pull-Request: https://github.com/git/git/pull/895
>
> Range-diff vs v3:
>
>  1:  3357ea415e = 1:  3357ea415e merge-ort: barebones API of new merge strategy with empty implementation
>  2:  d7f6a834ab = 2:  d7f6a834ab merge-ort-wrappers: new convience wrappers to mimic the old merge API
>  3:  27ad756600 ! 3:  fce0db8778 fast-rebase: demonstrate merge-ort's API via temporary/hidden command
>      @@ Metadata
>       Author: Elijah Newren <newren@gmail.com>
>
>        ## Commit message ##
>      -    fast-rebase: demonstrate merge-ort's API via temporary/hidden command
>      +    fast-rebase: demonstrate merge-ort's API via new test-tool command
>
>      -    Add a special built-in that is only of use to git-developers and only
>      -    during the development of merge-ort, and which is designed to
>      -    immediately fail and print:
>      -       git: 'fast-rebase' is not a git command
>      -    unless a special GIT_TEST_MERGE_ALGORITHM environment variable is set.
>      -
>      -    This special builtin serves two purposes:
>      +    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_inmemory_nonrecursive() and merge_switch_to_result().
>      +         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
>      @@ Commit message
>           Signed-off-by: Elijah Newren <newren@gmail.com>
>
>        ## Makefile ##
>      -@@ Makefile: BUILTIN_OBJS += builtin/difftool.o
>      - BUILTIN_OBJS += builtin/env--helper.o
>      - BUILTIN_OBJS += builtin/fast-export.o
>      - BUILTIN_OBJS += builtin/fast-import.o
>      -+BUILTIN_OBJS += builtin/fast-rebase.o
>      - BUILTIN_OBJS += builtin/fetch-pack.o
>      - BUILTIN_OBJS += builtin/fetch.o
>      - BUILTIN_OBJS += builtin/fmt-merge-msg.o
>      -
>      - ## builtin.h ##
>      -@@ builtin.h: int cmd_difftool(int argc, const char **argv, const char *prefix);
>      - int cmd_env__helper(int argc, const char **argv, const char *prefix);
>      - int cmd_fast_export(int argc, const char **argv, const char *prefix);
>      - int cmd_fast_import(int argc, const char **argv, const char *prefix);
>      -+int cmd_fast_rebase(int argc, const char **argv, const char *prefix);
>      - int cmd_fetch(int argc, const char **argv, const char *prefix);
>      - int cmd_fetch_pack(int argc, const char **argv, const char *prefix);
>      - int cmd_fmt_merge_msg(int argc, const char **argv, const char *prefix);
>      +@@ Makefile: 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
>
>      - ## builtin/fast-rebase.c (new) ##
>      + ## t/helper/test-fast-rebase.c (new) ##
>       @@
>       +/*
>       + * "git fast-rebase" builtin command
>      @@ builtin/fast-rebase.c (new)
>       + */
>       +
>       +#define USE_THE_INDEX_COMPATIBILITY_MACROS
>      -+#include "builtin.h"
>      ++#include "test-tool.h"
>       +
>       +#include "cache-tree.h"
>       +#include "commit.h"
>      @@ builtin/fast-rebase.c (new)
>       + return (struct commit *)obj;
>       +}
>       +
>      -+int cmd_fast_rebase(int argc, const char **argv, const char *prefix)
>      ++int cmd__fast_rebase(int argc, const char **argv)
>       +{
>       + struct commit *onto;
>       + struct commit *last_commit = NULL, *last_picked_commit = NULL;
>      @@ builtin/fast-rebase.c (new)
>       + 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 (!getenv("GIT_TEST_MERGE_ALGORITHM")) {
>      -+         fprintf_ln(stderr, _("git: 'fast-rebase' is not a git command. See 'git --help'."));
>      -+         exit(1);
>      -+ }
>      -+
>       + if (argc != 5 || strcmp(argv[1], "--onto"))
>       +         die("usage: read the code, figure out how to use it, then do so");
>       +
>      @@ builtin/fast-rebase.c (new)
>       + return (clean == 0);
>       +}
>
>      - ## git.c ##
>      -@@ git.c: static struct cmd_struct commands[] = {
>      -  { "env--helper", cmd_env__helper },
>      -  { "fast-export", cmd_fast_export, RUN_SETUP },
>      -  { "fast-import", cmd_fast_import, RUN_SETUP | NO_PARSEOPT },
>      -+ { "fast-rebase", cmd_fast_rebase, RUN_SETUP /* | NEED_WORK_TREE */ },
>      -  { "fetch", cmd_fetch, RUN_SETUP },
>      -  { "fetch-pack", cmd_fetch_pack, RUN_SETUP | NO_PARSEOPT },
>      -  { "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
>      + ## t/helper/test-tool.c ##
>      +@@ t/helper/test-tool.c: 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 },
>      +
>      + ## t/helper/test-tool.h ##
>      +@@ t/helper/test-tool.h: 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);
>  4:  0479d59c33 = 4:  75d19804bd merge,rebase,revert: select ort or recursive by config or environment
>
> --
> gitgitgadget