@matheusbsbs / matheus-bagliano / commits / 530ca19c02

fast-export: add --reference-excluded-parents option

git filter-branch has a nifty feature allowing you to rewrite, e.g. just the last 8 commits of a linear history git filter-branch $OPTIONS HEAD~8..HEAD If you try the same with git fast-export, you instead get a history of only 8 commits, with HEAD~7 being rewritten into a root commit. There are two alternatives: 1) Don't use the negative revision specification, and when you're filtering the output to make modifications to the last 8 commits, just be careful to not modify any earlier commits somehow. 2) First run 'git fast-export --export-marks=somefile HEAD~8', then run 'git fast-export --import-marks=somefile HEAD~8..HEAD'. Both are more error prone than I'd like (the first for obvious reasons; with the second option I have sometimes accidentally included too many revisions in the first command and then found that the corresponding extra revisions were not exported by the second command and thus were not modified as I expected). Also, both are poor from a performance perspective. Add a new --reference-excluded-parents option which will cause fast-export to refer to commits outside the specified rev-list-args range by their sha1sum. Such a stream will only be useful in a repository which already contains the necessary commits (much like the restriction imposed when using --no-data). Note from Peff: I think we might be able to do a little more optimization here. If we're exporting HEAD^..HEAD and there's an object in HEAD^ which is unchanged in HEAD, I think we'd still print it (because it would not be marked SHOWN), but we could omit it (by walking the tree of the boundary commits and marking them shown). I don't think it's a blocker for what you're doing here, but just a possible future optimization. Signed-off-by: Elijah Newren <newren@gmail.com> Acked-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Elijah Newren committed Nov 15, 2018 at 23:59 UTC 530ca19c02b1fa1d13195d24fc76c2926ceecdc2

3 files changed +58 -12

Documentation/git-fast-export.txt

+15 -2

@@ -110,6 +110,18 @@ marks the same across runs.

110 the shape of the history and stored tree. See the section on

111 `ANONYMIZING` below.

112

113 +--reference-excluded-parents::

114 + By default, running a command such as `git fast-export

115 + master~5..master` will not include the commit master{tilde}5

116 + and will make master{tilde}4 no longer have master{tilde}5 as

117 + a parent (though both the old master{tilde}4 and new

118 + master{tilde}4 will have all the same files). Use

119 + --reference-excluded-parents to instead have the the stream

120 + refer to commits in the excluded range of history by their

121 + sha1sum. Note that the resulting stream can only be used by a

122 + repository which already contains the necessary parent

123 + commits.

124 +

125 --refspec::

126 Apply the specified refspec to each ref exported. Multiple of them can

127 be specified.

@@ -119,8 +131,9 @@ marks the same across runs.

131 'git rev-list', that specifies the specific objects and references

132 to export. For example, `master~10..master` causes the

133 current master reference to be exported along with all objects

122 - added since its 10th ancestor commit and all files common to

123 - master{tilde}9 and master{tilde}10.

134 + added since its 10th ancestor commit and (unless the

135 + --reference-excluded-parents option is specified) all files

136 + common to master{tilde}9 and master{tilde}10.

137

138 EXAMPLES

139 --------

builtin/fast-export.c

+32 -10

@@ -37,6 +37,7 @@ static int fake_missing_tagger;

37 static int use_done_feature;

38 static int no_data;

39 static int full_tree;

40 +static int reference_excluded_commits;

41 static struct string_list extra_refs = STRING_LIST_INIT_NODUP;

42 static struct string_list tag_refs = STRING_LIST_INIT_NODUP;

43 static struct refspec refspecs = REFSPEC_INIT_FETCH;

@@ -597,7 +598,8 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,

598 message += 2;

599

600 if (commit->parents &&

600 - get_object_mark(&commit->parents->item->object) != 0 &&

601 + (get_object_mark(&commit->parents->item->object) != 0 ||

602 + reference_excluded_commits) &&

603 !full_tree) {

604 parse_commit_or_die(commit->parents->item);

605 diff_tree_oid(get_commit_tree_oid(commit->parents->item),

@@ -645,13 +647,21 @@ static void handle_commit(struct commit *commit, struct rev_info *rev,

647 unuse_commit_buffer(commit, commit_buffer);

648

649 for (i = 0, p = commit->parents; p; p = p->next) {

648 - int mark = get_object_mark(&p->item->object);

649 - if (!mark)

650 + struct object *obj = &p->item->object;

651 + int mark = get_object_mark(obj);

652 +

653 + if (!mark && !reference_excluded_commits)

654 continue;

655 if (i == 0)

652 - printf("from :%d\n", mark);

656 + printf("from ");

657 + else

658 + printf("merge ");

659 + if (mark)

660 + printf(":%d\n", mark);

661 else

654 - printf("merge :%d\n", mark);

662 + printf("%s\n", oid_to_hex(anonymize ?

663 + anonymize_oid(&obj->oid) :

664 + &obj->oid));

665 i++;

666 }

667

@@ -932,13 +942,22 @@ static void handle_tags_and_duplicates(struct string_list *extras)

942 /*

943 * Getting here means we have a commit which

944 * was excluded by a negative refspec (e.g.

935 - * fast-export ^master master). If the user

945 + * fast-export ^master master). If we are

946 + * referencing excluded commits, set the ref

947 + * to the exact commit. Otherwise, the user

948 * wants the branch exported but every commit

937 - * in its history to be deleted, that sounds

938 - * like a ref deletion to me.

949 + * in its history to be deleted, which basically

950 + * just means deletion of the ref.

951 */

940 - printf("reset %s\nfrom %s\n\n",

941 - name, oid_to_hex(&null_oid));

952 + if (!reference_excluded_commits) {

953 + /* delete the ref */

954 + printf("reset %s\nfrom %s\n\n",

955 + name, oid_to_hex(&null_oid));

956 + continue;

957 + }

958 + /* set ref to commit using oid, not mark */

959 + printf("reset %s\nfrom %s\n\n", name,

960 + oid_to_hex(&commit->object.oid));

961 continue;

962 }

963

@@ -1075,6 +1094,9 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)

1094 OPT_STRING_LIST(0, "refspec", &refspecs_list, N_("refspec"),

1095 N_("Apply refspec to exported refs")),

1096 OPT_BOOL(0, "anonymize", &anonymize, N_("anonymize output")),

1097 + OPT_BOOL(0, "reference-excluded-parents",

1098 + &reference_excluded_commits, N_("Reference parents which are not in fast-export stream by object id")),

1099 +

1100 OPT_END()

1101 };

1102

t/t9350-fast-export.sh

+11

@@ -66,6 +66,17 @@ test_expect_success 'fast-export master~2..master' '

67 '

69 +test_expect_success 'fast-export --reference-excluded-parents master~2..master' '

70 +

71 + git fast-export --reference-excluded-parents master~2..master >actual &&

72 + grep commit.refs/heads/master actual >commit-count &&

73 + test_line_count = 2 commit-count &&

74 + sed "s/master/rewrite/" actual |

75 + (cd new &&

76 + git fast-import &&

77 + test $MASTER = $(git rev-parse --verify refs/heads/rewrite))

78 +'

79 +

80 test_expect_success 'iso-8859-1' '

82 git config i18n.commitencoding ISO8859-1 &&