rebase -i: rearrange fixup/squash lines using the rebase--helper

This operation has quadratic complexity, which is especially painful
on Windows, where shell scripts are *already* slow (mainly due to the
overhead of the POSIX emulation layer).

Let's reimplement this with linear complexity (using a hash map to
match the commits' subject lines) for the common case; Sadly, the
fixup/squash feature's design neglected performance considerations,
allowing arbitrary prefixes (read: `fixup! hell` will match the
commit subject `hello world`), which means that we are stuck with
quadratic performance in the worst case.

The reimplemented logic also happens to fix a bug where commented-out
lines (representing empty patches) were dropped by the previous code.

While at it, clarify how the fixup/squash feature works in `git rebase
-i`'s man page.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Johannes Schindelin
2017-07-14 16:45:31 +02:00
committed by Junio C Hamano
parent b174ae7df2
commit c44a4c650c
6 changed files with 213 additions and 98 deletions

View File

@ -15,7 +15,7 @@ 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, SKIP_UNNECESSARY_PICKS
CHECK_TODO_LIST, SKIP_UNNECESSARY_PICKS, REARRANGE_SQUASH
} command = 0;
struct option options[] = {
OPT_BOOL(0, "ff", &opts.allow_ff, N_("allow fast-forward")),
@ -34,6 +34,8 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
N_("check the todo list"), CHECK_TODO_LIST),
OPT_CMDMODE(0, "skip-unnecessary-picks", &command,
N_("skip unnecessary picks"), SKIP_UNNECESSARY_PICKS),
OPT_CMDMODE(0, "rearrange-squash", &command,
N_("rearrange fixup/squash lines"), REARRANGE_SQUASH),
OPT_END()
};
@ -60,5 +62,7 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
return !!check_todo_list();
if (command == SKIP_UNNECESSARY_PICKS && argc == 1)
return !!skip_unnecessary_picks();
if (command == REARRANGE_SQUASH && argc == 1)
return !!rearrange_squash();
usage_with_options(builtin_rebase_helper_usage, options);
}