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[PATCH v5 08/10] rebase -i: skip unnecessary picks using the rebase--helper

From
Johannes Schindelin <johannes.schindelin@gmx.de>
Date
Jun 14, 2017, 13:08 UTC
Message-ID
<72bbfcae2abcb14f6b1288051a244faadbee29e0.1497444257.git.johannes.schindelin@gmx.de>
In-Reply-To
<cover.1497444257.git.johannes.schindelin@gmx.de>

In particular on Windows, where shell scripts are even more expensive than on MacOSX or Linux, it makes sense to move a loop that forks Git at least once for every line in the todo list into a builtin.

Note: The original code did not try to skip unnecessary picks of root
commits but punts instead (probably --root was not considered common
enough of a use case to bother optimizing). We do the same, for now.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 builtin/rebase--helper.c   |   6 ++-
 git-rebase--interactive.sh |  41 ++---------------
 sequencer.c                | 107 +++++++++++++++++++++++++++++++++++++++++++++
 sequencer.h                |   1 +
 4 files changed, 116 insertions(+), 39 deletions(-)
diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index 0deba9d1945..fdc933dc64a 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -14,7 +14,7 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 	int keep_empty = 0;
 	enum {
 		CONTINUE = 1, ABORT, MAKE_SCRIPT, SHORTEN_SHA1S, EXPAND_SHA1S,
-		CHECK_TODO_LIST
+		CHECK_TODO_LIST, SKIP_UNNECESSARY_PICKS
 	} command = 0;
 	struct option options[] = {
 		OPT_BOOL(0, "ff", &opts.allow_ff, N_("allow fast-forward")),
@@ -31,6 +31,8 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 			N_("expand SHA-1s in the todo list"), EXPAND_SHA1S),
 		OPT_CMDMODE(0, "check-todo-list", &command,
 			N_("check the todo list"), CHECK_TODO_LIST),
+		OPT_CMDMODE(0, "skip-unnecessary-picks", &command,
+			N_("skip unnecessary picks"), SKIP_UNNECESSARY_PICKS),
 		OPT_END()
 	};
 
@@ -55,5 +57,7 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		return !!transform_todo_ids(0);
 	if (command == CHECK_TODO_LIST && argc == 1)
 		return !!check_todo_list();
+	if (command == SKIP_UNNECESSARY_PICKS && argc == 1)
+		return !!skip_unnecessary_picks();
 	usage_with_options(builtin_rebase_helper_usage, options);
 }
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index c8cad318fa4..af8d7bd77fb 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -713,43 +713,6 @@ do_rest () {
 	done
 }
 
-# skip picking commits whose parents are unchanged
-skip_unnecessary_picks () {
-	fd=3
-	while read -r command rest
-	do
-		# fd=3 means we skip the command
-		case "$fd,$command" in
-		3,pick|3,p)
-			# pick a commit whose parent is current $onto -> skip
-			sha1=${rest%% *}
-			case "$(git rev-parse --verify --quiet "$sha1"^)" in
-			"$onto"*)
-				onto=$sha1
-				;;
-			*)
-				fd=1
-				;;
-			esac
-			;;
-		3,"$comment_char"*|3,)
-			# copy comments
-			;;
-		*)
-			fd=1
-			;;
-		esac
-		printf '%s\n' "$command${rest:+ }$rest" >&$fd
-	done <"$todo" >"$todo.new" 3>>"$done" &&
-	mv -f "$todo".new "$todo" &&
-	case "$(peek_next_command)" in
-	squash|s|fixup|f)
-		record_in_rewritten "$onto"
-		;;
-	esac ||
-		die "$(gettext "Could not skip unnecessary pick commands")"
-}
-
 expand_todo_ids() {
 	git rebase--helper --expand-ids
 }
@@ -1149,7 +1112,9 @@ git rebase--helper --check-todo-list || {
 
 expand_todo_ids
 
-test -d "$rewritten" || test -n "$force_rebase" || skip_unnecessary_picks
+test -d "$rewritten" || test -n "$force_rebase" ||
+onto="$(git rebase--helper --skip-unnecessary-picks)" ||
+die "Could not skip unnecessary pick commands"
 
 checkout_onto
 if test -z "$rebase_root" && test ! -d "$rewritten"
diff --git a/sequencer.c b/sequencer.c
index a697906d463..a0e020dab09 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -2640,3 +2640,110 @@ int check_todo_list(void)
 
 	return res;
 }
+
+/* skip picking commits whose parents are unchanged */
+int skip_unnecessary_picks(void)
+{
+	const char *todo_file = rebase_path_todo();
+	struct strbuf buf = STRBUF_INIT;
+	struct todo_list todo_list = TODO_LIST_INIT;
+	struct object_id onto_oid, *oid = &onto_oid, *parent_oid;
+	int fd, i;
+
+	if (!read_oneliner(&buf, rebase_path_onto(), 0))
+		return error(_("could not read 'onto'"));
+	if (get_sha1(buf.buf, onto_oid.hash)) {
+		strbuf_release(&buf);
+		return error(_("need a HEAD to fixup"));
+	}
+	strbuf_release(&buf);
+
+	fd = open(todo_file, O_RDONLY);
+	if (fd < 0) {
+		return error_errno(_("could not open '%s'"), todo_file);
+	}
+	if (strbuf_read(&todo_list.buf, fd, 0) < 0) {
+		close(fd);
+		return error(_("could not read '%s'."), todo_file);
+	}
+	close(fd);
+	if (parse_insn_buffer(todo_list.buf.buf, &todo_list) < 0) {
+		todo_list_release(&todo_list);
+		return -1;
+	}
+
+	for (i = 0; i < todo_list.nr; i++) {
+		struct todo_item *item = todo_list.items + i;
+
+		if (item->command >= TODO_NOOP)
+			continue;
+		if (item->command != TODO_PICK)
+			break;
+		if (parse_commit(item->commit)) {
+			todo_list_release(&todo_list);
+			return error(_("could not parse commit '%s'"),
+				oid_to_hex(&item->commit->object.oid));
+		}
+		if (!item->commit->parents)
+			break; /* root commit */
+		if (item->commit->parents->next)
+			break; /* merge commit */
+		parent_oid = &item->commit->parents->item->object.oid;
+		if (hashcmp(parent_oid->hash, oid->hash))
+			break;
+		oid = &item->commit->object.oid;
+	}
+	if (i > 0) {
+		int offset = i < todo_list.nr ?
+			todo_list.items[i].offset_in_buf : todo_list.buf.len;
+		const char *done_path = rebase_path_done();
+
+		fd = open(done_path, O_CREAT | O_WRONLY | O_APPEND, 0666);
+		if (fd < 0) {
+			error_errno(_("could not open '%s' for writing"),
+				    done_path);
+			todo_list_release(&todo_list);
+			return -1;
+		}
+		if (write_in_full(fd, todo_list.buf.buf, offset) < 0) {
+			error_errno(_("could not write to '%s'"), done_path);
+			todo_list_release(&todo_list);
+			close(fd);
+			return -1;
+		}
+		close(fd);
+
+		fd = open(rebase_path_todo(), O_WRONLY, 0666);
+		if (fd < 0) {
+			error_errno(_("could not open '%s' for writing"),
+				    rebase_path_todo());
+			todo_list_release(&todo_list);
+			return -1;
+		}
+		if (write_in_full(fd, todo_list.buf.buf + offset,
+				todo_list.buf.len - offset) < 0) {
+			error_errno(_("could not write to '%s'"),
+				    rebase_path_todo());
+			close(fd);
+			todo_list_release(&todo_list);
+			return -1;
+		}
+		if (ftruncate(fd, todo_list.buf.len - offset) < 0) {
+			error_errno(_("could not truncate '%s'"),
+				    rebase_path_todo());
+			todo_list_release(&todo_list);
+			close(fd);
+			return -1;
+		}
+		close(fd);
+
+		todo_list.current = i;
+		if (is_fixup(peek_command(&todo_list, 0)))
+			record_in_rewritten(oid, peek_command(&todo_list, 0));
+	}
+
+	todo_list_release(&todo_list);
+	printf("%s\n", oid_to_hex(oid));
+
+	return 0;
+}
diff --git a/sequencer.h b/sequencer.h
index 878dd296f8c..04a57e09a1d 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -50,6 +50,7 @@ int sequencer_make_script(int keep_empty, FILE *out,
 
 int transform_todo_ids(int shorten_ids);
 int check_todo_list(void);
+int skip_unnecessary_picks(void);
 
 extern const char sign_off_header[];
 

-- 
2.13.1.windows.1.1.ga36e14b3aaa
Previous: Johannes SchindelinNext: Liam Beguin
Message 9 of 20 in “The final building block for a faster rebase -i”
  1. 00/10 The final building block for a faster rebase -iJohannes Schindelin, Jun 14, 2017
  2. 02/10 rebase -i: generate the script via rebase--helperJohannes Schindelin, Jun 14, 2017
  3. 01/10 t3415: verify that an empty instructionFormat is handled as beforeJohannes Schindelin, Jun 14, 2017
  4. 03/10 rebase -i: remove useless indentationJohannes Schindelin, Jun 14, 2017
  5. 04/10 rebase -i: do not invent onelines when expanding/collapsing SHA-1sJohannes Schindelin, Jun 14, 2017
  6. 05/10 rebase -i: also expand/collapse the SHA-1s via the rebase--helperJohannes Schindelin, Jun 14, 2017
  7. 06/10 t3404: relax rebase.missingCommitsCheck testsJohannes Schindelin, Jun 14, 2017
  8. 07/10 rebase -i: check for missing commits in the rebase--helperJohannes Schindelin, Jun 14, 2017
  9. 08/10 rebase -i: skip unnecessary picks using the rebase--helperJohannes Schindelin, Jun 14, 2017
  10. Liam BeguinJun 16, 2017
  11. Johannes SchindelinJun 16, 2017
  12. Liam BeguinJun 17, 2017
  13. Johannes SchindelinJun 19, 2017
  14. Jeff KingJun 19, 2017
  15. Junio C HamanoJun 19, 2017
  16. Liam BeguinJun 20, 2017
  17. 09/10 t3415: test fixup with wrapped onelineJohannes Schindelin, Jun 14, 2017
  18. 10/10 rebase -i: rearrange fixup/squash lines using the rebase--helperJohannes Schindelin, Jun 14, 2017
  19. Junio C HamanoJun 15, 2017
  20. Johannes SchindelinJun 16, 2017

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