Re: [PATCH v2 06/16] sequencer: refactor sequencer_add_exec_commands() to work on a todo_list
- From
- Phillip Wood <phillip.wood@talktalk.net>
- Date
- Oct 30, 2018, 16:47 UTC
- Message-ID
- <12e849d3-351b-7673-1f14-742d0fbb1ac1@talktalk.net>
- In-Reply-To
- <20181027212930.9303-7-alban.gruin@gmail.com>
On 27/10/2018 22:29, Alban Gruin wrote:
Show 10 quoted lines
> This refactors sequencer_add_exec_commands() to work on a todo_list to > avoid redundant reads and writes to the disk. > > An obvious way to do this would be to insert the `exec' command between > the other commands, and reparse it once this is done. This is not what > is done here. Instead, the command is appended to the buffer once, and > a new list of items is created. Items from the old list are copied to > it, and new `exec' items are appended when necessary. This eliminates > the need to reparse the todo list, but this also means its buffer cannot > be directly written to the disk, hence todo_list_write_to_disk().
I'd reword this slightly, maybe
Instead of just inserting the `exec' command between the other commands, and re-parsing the buffer at the end the exec command is appended to the buffer once, and a new list of items is created. Items from the old list are copied across and new `exec' items are appended when necessary. This eliminates the need to reparse the buffer, but this also means we have to use todo_list_write_to_disk() to write the file.
> sequencer_add_exec_commands() still reads the todo list from the disk, > as it is needed by rebase -p. todo_list_add_exec_commands() works on a > todo_list structure, and reparses it at the end.
I think the saying 'reparses' is confusing as that is what we're trying to avoid.
Show 23 quoted lines
> complete_action() still uses sequencer_add_exec_commands() for now.
> This will be changed in a future commit.
>
> Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
> ---
> sequencer.c | 69 +++++++++++++++++++++++++++++++++++++----------------
> 1 file changed, 49 insertions(+), 20 deletions(-)
>
> diff --git a/sequencer.c b/sequencer.c
> index e12860c047..12a3efeca8 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -4216,6 +4216,50 @@ int sequencer_make_script(FILE *out, int argc, const char **argv,
> return 0;
> }
>
> +static void todo_list_add_exec_commands(struct todo_list *todo_list,
> + const char *commands)
> +{
> + struct strbuf *buf = &todo_list->buf;
> + const char *old_buf = buf->buf;
> + size_t commands_len = strlen(commands + strlen("exec ")) - 1;
> + int i, first = 1, nr = 0, alloc = 0;Minor nit pick, I think it is clearer if first is initialized just before the loop as it is in the deleted code below.
Show 6 quoted lines
> + struct todo_item *items = NULL,
> + base_item = {TODO_EXEC, NULL, 0, 0, commands_len, 0};
> +
> + strbuf_addstr(buf, commands);
> + base_item.offset_in_buf = buf->len - commands_len - 1;
> + base_item.arg = buf->buf + base_item.offset_in_buf;I think if the user gives --exec more than once on the command line then commands will contain more than one exec command so this needs to parse commands and create one todo_item for each command.
Show 14 quoted lines
> +
> + /*
> + * Insert <commands> after every pick. Here, fixup/squash chains
> + * are considered part of the pick, so we insert the commands *after*
> + * those chains if there are any.
> + */
> + for (i = 0; i < todo_list->nr; i++) {
> + enum todo_command command = todo_list->items[i].command;
> + if (todo_list->items[i].arg)
> + todo_list->items[i].arg = todo_list->items[i].arg - old_buf + buf->buf;
> +
> + if (command == TODO_PICK && !first) {
> + ALLOC_GROW(items, nr + 1, alloc);
> + memcpy(items + nr++, &base_item, sizeof(struct todo_item));I think it would be clearer to say items[nr++] = base_item; rather than using memcpy. This applies below and to some of the other patches as well. Also this needs to loop over all the base_items if the user gave --exec more than once on the command line.
Best Wishes
Phillip
Show 61 quoted lines
> + }
> +
> + ALLOC_GROW(items, nr + 1, alloc);
> + memcpy(items + nr++, todo_list->items + i, sizeof(struct todo_item));
> + first = 0;
> + }
> +
> + /* insert or append final <commands> */
> + ALLOC_GROW(items, nr + 1, alloc);
> + memcpy(items + nr++, &base_item, sizeof(struct todo_item));
> +
> + FREE_AND_NULL(todo_list->items);
> + todo_list->items = items;
> + todo_list->nr = nr;
> + todo_list->alloc = alloc;
> +}
> +
> /*
> * Add commands after pick and (series of) squash/fixup commands
> * in the todo list.
> @@ -4224,10 +4268,7 @@ int sequencer_add_exec_commands(const char *commands)
> {
> const char *todo_file = rebase_path_todo();
> struct todo_list todo_list = TODO_LIST_INIT;
> - struct todo_item *item;
> - struct strbuf *buf = &todo_list.buf;
> - size_t offset = 0, commands_len = strlen(commands);
> - int i, first;
> + int res;
>
> if (strbuf_read_file(&todo_list.buf, todo_file, 0) < 0)
> return error(_("could not read '%s'."), todo_file);
> @@ -4237,23 +4278,11 @@ int sequencer_add_exec_commands(const char *commands)
> return error(_("unusable todo list: '%s'"), todo_file);
> }
>
> - first = 1;
> - /* insert <commands> before every pick except the first one */
> - for (item = todo_list.items, i = 0; i < todo_list.nr; i++, item++) {
> - if (item->command == TODO_PICK && !first) {
> - strbuf_insert(buf, item->offset_in_buf + offset,
> - commands, commands_len);
> - offset += commands_len;
> - }
> - first = 0;
> - }
> -
> - /* append final <commands> */
> - strbuf_add(buf, commands, commands_len);
> -
> - i = write_message(buf->buf, buf->len, todo_file, 0);
> + todo_list_add_exec_commands(&todo_list, commands);
> + res = todo_list_write_to_file(&todo_list, todo_file, NULL, NULL, 0, 0, -1, 0);
> todo_list_release(&todo_list);
> - return i;
> +
> + return res;
> }
>
> static void todo_list_to_strbuf(struct todo_list *todo_list, struct strbuf *buf,
>