rebase -i: also expand/collapse the SHA-1s via the rebase--helper

This is crucial to improve performance on Windows, as the speed is now
mostly dominated by the SHA-1 transformation (because it spawns a new
rev-parse process for *every* line, and spawning processes is pretty
slow from Git for Windows' MSYS2 Bash).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

builtin/rebase--helper.c

@@ -13,7 +13,7 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 	struct replay_opts opts = REPLAY_OPTS_INIT;
 	int keep_empty = 0;
 	enum {
-		CONTINUE = 1, ABORT, MAKE_SCRIPT
+		CONTINUE = 1, ABORT, MAKE_SCRIPT, SHORTEN_SHA1S, EXPAND_SHA1S
 	} command = 0;
 	struct option options[] = {
 		OPT_BOOL(0, "ff", &opts.allow_ff, N_("allow fast-forward")),
@@ -24,6 +24,10 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 				ABORT),
 		OPT_CMDMODE(0, "make-script", &command,
 			N_("make rebase script"), MAKE_SCRIPT),
+		OPT_CMDMODE(0, "shorten-sha1s", &command,
+			N_("make rebase script"), SHORTEN_SHA1S),
+		OPT_CMDMODE(0, "expand-sha1s", &command,
+			N_("make rebase script"), EXPAND_SHA1S),
 		OPT_END()
 	};
 
@@ -42,5 +46,9 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		return sequencer_remove_state(&opts);
 	if (command == MAKE_SCRIPT && argc > 1)
 		return sequencer_make_script(keep_empty, stdout, argc, argv);
+	if (command == SHORTEN_SHA1S && argc == 1)
+		return transform_todo_ids(1);
+	if (command == EXPAND_SHA1S && argc == 1)
+		return transform_todo_ids(0);
 	usage_with_options(builtin_rebase_helper_usage, options);
 }

git-rebase--interactive.sh

@@ -743,11 +743,11 @@ transform_todo_ids () {
 }
 
 expand_todo_ids() {
-	transform_todo_ids
+	git rebase--helper --expand-sha1s
 }
 
 collapse_todo_ids() {
-	transform_todo_ids --short
+	git rebase--helper --shorten-sha1s
 }
 
 # Rearrange the todo list that has both "pick sha1 msg" and

sequencer.c

@@ -1152,7 +1152,7 @@ struct todo_item *append_todo(struct todo_list *todo_list)
 }
 
 static int parse_insn_line(struct todo_item *item,
-	const char *bol, char *eol, struct replay_opts *opts)
+	const char *bol, char *eol)
 {
 	unsigned char commit_sha1[20];
 	char *end_of_object_name;
@@ -1226,7 +1226,7 @@ static int parse_insn_buffer(char *buf, struct todo_list *todo_list,
 
 		item = append_todo(todo_list);
 		item->offset_in_buf = p - todo_list->buf.buf;
-		if (parse_insn_line(item, p, eol, opts))
+		if (parse_insn_line(item, p, eol))
 			return error(_("Could not parse line %d."), i);
 		if (fixup_okay)
 			; /* do nothing */
@@ -2206,3 +2206,56 @@ int sequencer_make_script(int keep_empty, FILE *out,
 	strbuf_release(&buf);
 	return 0;
 }
+
+
+int transform_todo_ids(int shorten_sha1s)
+{
+	const char *todo_file = git_path_rebase_todo();
+	struct todo_list todo_list = TODO_LIST_INIT;
+	struct replay_opts opts;
+	int fd, res, i;
+	FILE *out;
+
+	strbuf_reset(&todo_list.buf);
+	fd = open(todo_file, O_RDONLY);
+	if (fd < 0)
+		return error(_("Could not open %s (%s)"),
+			todo_file, strerror(errno));
+	if (strbuf_read(&todo_list.buf, fd, 0) < 0) {
+		close(fd);
+		return error(_("Could not read %s."), todo_file);
+	}
+	close(fd);
+
+	memset(&opts, 0, sizeof(opts));
+	opts.action = REPLAY_INTERACTIVE_REBASE;
+	res = parse_insn_buffer(todo_list.buf.buf, &todo_list, &opts);
+	if (res)
+		return error(_("Unusable instruction sheet: %s"), todo_file);
+
+	out = fopen(todo_file, "w");
+	if (!out)
+		return error(_("Unable to open '%s' for writing"), todo_file);
+	for (i = 0; i < todo_list.nr; i++) {
+		struct todo_item *item = todo_list.items + i;
+		int bol = item->offset_in_buf;
+		const char *p = todo_list.buf.buf + bol;
+		int eol = i + 1 < todo_list.nr ?
+			todo_list.items[i + 1].offset_in_buf :
+			todo_list.buf.len;
+
+		if (item->command >= TODO_EXEC && item->command != TODO_DROP)
+			fwrite(p, eol - bol, 1, out);
+		else {
+			int eoc = strcspn(todo_list.buf.buf + bol, " \t");
+			const char *sha1 = shorten_sha1s ?
+				short_commit_name(item->commit) :
+				oid_to_hex(&item->commit->object.oid);
+
+			fprintf(out, "%.*s %s %.*s\n",
+				eoc, p, sha1, item->arg_len, item->arg);
+		}
+	}
+	fclose(out);
+	return 0;
+}

sequencer.h

@@ -49,6 +49,8 @@ int sequencer_commit(const char *defmsg, struct replay_opts *opts,
 int sequencer_make_script(int keep_empty, FILE *out,
 		int argc, const char **argv);
 
+int transform_todo_ids(int shorten_sha1s);
+
 extern const char sign_off_header[];
 
 void append_signoff(struct strbuf *msgbuf, int ignore_footer, unsigned flag);