Re: [PATCH v6 07/16] sequencer: refactor sequencer_add_exec_commands() to work on a todo_list

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Hi Alban

On 31/01/2019 20:37, Alban Gruin wrote:
Hi Phillip,

Le 31/01/2019 à 15:30, Phillip Wood a écrit :
Hi Alban

On 29/01/2019 15:01, Alban Gruin wrote:
This refactors sequencer_add_exec_commands() to work on a todo_list to
avoid redundant reads and writes to the disk.

Instead of inserting the `exec' commands between the other commands and
re-parsing the buffer at the end, they are 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.

todo_list_add_exec_commands() and sequencer_add_exec_commands() are
modified to take a string list instead of a string -- one item for each
command.  This makes it easier to insert a new command to the todo list
for each command to execute.

sequencer_add_exec_commands() still reads the todo list from the disk,
as it is needed by rebase -p.

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@xxxxxxxxx>
---
  builtin/rebase--interactive.c |  15 +++--
  sequencer.c                   | 110 +++++++++++++++++++++-------------
  sequencer.h                   |   5 +-
  3 files changed, 82 insertions(+), 48 deletions(-)

diff --git a/builtin/rebase--interactive.c
b/builtin/rebase--interactive.c
index df19ccaeb9..53056ee713 100644
--- a/builtin/rebase--interactive.c
+++ b/builtin/rebase--interactive.c
@@ -65,7 +65,7 @@ static int do_interactive_rebase(struct replay_opts
*opts, unsigned flags,
                   const char *onto, const char *onto_name,
                   const char *squash_onto, const char *head_name,
                   const char *restrict_revision, char *raw_strategies,
-                 const char *cmd, unsigned autosquash)
+                 struct string_list *commands, unsigned autosquash)
  {
      int ret;
      const char *head_hash = NULL;
@@ -116,7 +116,7 @@ static int do_interactive_rebase(struct
replay_opts *opts, unsigned flags,
          discard_cache();
          ret = complete_action(the_repository, opts, flags,
                        shortrevisions, onto_name, onto,
-                      head_hash, cmd, autosquash);
+                      head_hash, commands, autosquash);
      }
     free(revisions);
@@ -139,6 +139,7 @@ int cmd_rebase__interactive(int argc, const char
**argv, const char *prefix)
      const char *onto = NULL, *onto_name = NULL, *restrict_revision =
NULL,
          *squash_onto = NULL, *upstream = NULL, *head_name = NULL,
          *switch_to = NULL, *cmd = NULL;
+    struct string_list commands = STRING_LIST_INIT_DUP;
      char *raw_strategies = NULL;
      enum {
          NONE = 0, CONTINUE, SKIP, EDIT_TODO, SHOW_CURRENT_PATCH,
@@ -221,6 +222,12 @@ int cmd_rebase__interactive(int argc, const char
**argv, const char *prefix)
          warning(_("--[no-]rebase-cousins has no effect without "
                "--rebase-merges"));
+    if (cmd && *cmd) {
+        string_list_split(&commands, cmd, '\n', -1);

This whole splitting and later skipping 'exec ' is a bit of a shame - it
would be much nicer if we could just have one exec command per -x option
but I think that is outside the scope of this series (If I have time I'd
like to look at calling do_interactive_rebase() directly from
builtin/rebase.c without forking rebase--interactive).


Yes, I completely agree with you.  I thought to do this in preparation
to drop rebase -r.

+        if (strlen(commands.items[commands.nr - 1].string) == 0)

I'd be tempted just to test the string using !* rather than calling
strlen.


Right.  I’m still not used to this pattern.

Also is there ever a case where the last string isn't empty?

I don’t think so.  When rebase.c prepares the arguments for
rebase--interactive, it always add a newline at the end[1].  Do you want
me to drop this check?

I think that would be clearer



+            --commands.nr;
+    }
+
      switch (command) {
      case NONE:
          if (!onto && !upstream)
@@ -228,7 +235,7 @@ int cmd_rebase__interactive(int argc, const char
**argv, const char *prefix)
         ret = do_interactive_rebase(&opts, flags, switch_to,
upstream, onto,
                          onto_name, squash_onto, head_name,
restrict_revision,
-                        raw_strategies, cmd, autosquash);
+                        raw_strategies, &commands, autosquash);
          break;
      case SKIP: {
          struct string_list merge_rr = STRING_LIST_INIT_DUP;
@@ -262,7 +269,7 @@ int cmd_rebase__interactive(int argc, const char
**argv, const char *prefix)
          ret = rearrange_squash(the_repository);
          break;
      case ADD_EXEC:
-        ret = sequencer_add_exec_commands(the_repository, cmd);
+        ret = sequencer_add_exec_commands(the_repository, &commands);
          break;
      default:
          BUG("invalid command '%d'", command);
diff --git a/sequencer.c b/sequencer.c
index 266f80d704..3a90b419d7 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4446,25 +4446,27 @@ int sequencer_make_script(struct repository
*r, FILE *out,
      return 0;
  }
-/*
- * Add commands after pick and (series of) squash/fixup commands
- * in the todo list.
- */
-int sequencer_add_exec_commands(struct repository *r,
-                const char *commands)
+static void todo_list_add_exec_commands(struct todo_list *todo_list,
+                    struct string_list *commands)
  {
-    const char *todo_file = rebase_path_todo();
-    struct todo_list todo_list = TODO_LIST_INIT;
-    struct strbuf *buf = &todo_list.buf;
-    size_t offset = 0, commands_len = strlen(commands);
-    int i, insert;
+    struct strbuf *buf = &todo_list->buf;
+    size_t base_offset = buf->len;
+    int i, insert, nr = 0, alloc = 0;
+    struct todo_item *items = NULL, *base_items = NULL;
-    if (strbuf_read_file(&todo_list.buf, todo_file, 0) < 0)
-        return error(_("could not read '%s'."), todo_file);
+    base_items = xcalloc(commands->nr, sizeof(struct todo_item));
+    for (i = 0; i < commands->nr; ++i) {
+        size_t command_len = strlen(commands->items[i].string);
-    if (todo_list_parse_insn_buffer(r, todo_list.buf.buf, &todo_list)) {
-        todo_list_release(&todo_list);
-        return error(_("unusable todo list: '%s'"), todo_file);
+        strbuf_addstr(buf, commands->items[i].string);
+        strbuf_addch(buf, '\n');
+
+        base_items[i].command = TODO_EXEC;
+        base_items[i].offset_in_buf = base_offset;
+        base_items[i].arg_offset = base_offset + strlen("exec ");
+        base_items[i].arg_len = command_len - strlen("exec ");
+
+        base_offset += command_len + 1;
      }
     /*
@@ -4473,38 +4475,62 @@ int sequencer_add_exec_commands(struct
repository *r,
       * those chains if there are any.
       */
      insert = -1;
-    for (i = 0; i < todo_list.nr; i++) {
-        enum todo_command command = todo_list.items[i].command;
-
-        if (insert >= 0) {
-            /* skip fixup/squash chains */
-            if (command == TODO_COMMENT)
-                continue;
-            else if (is_fixup(command)) {
-                insert = i + 1;
-                continue;
-            }
-            strbuf_insert(buf,
-                      todo_list.items[insert].offset_in_buf +
-                      offset, commands, commands_len);

In a todo list that looks like
pick abc message
#pick cde empty commit
This inserts the exec command for the first pick above the commented out
pick. I think your translation puts it below the commented out pick as
it ignores the value of insert. I think it's probably easiest to add an
INSERT_ARRAY macro to insert it in the right place. An alternative might
be to track the last insert position and only copy commands across when
there is another exec to insert but that might get complicated in cases
such as

pick abc message
#squash cde squash! message //empty commit for rewording
fixup 123 fixup! message
#pick 456 empty commit


I could do this with MOVE_ARRAY(), no?

Yes, if you extend the array first then you could use MOVE_ARRAY() and COPY_ARRAY() to move the comment down and then insert the exec commands so maybe we don't need a new macro after all.

I've looked through most of the rest of this series (I think I've got three patches left to check) and they all look fine, I'll try and look at the rest tomorrow, but if not I'll get round to it next week.

Best Wishes

Phillip

Best Wishes

Phillip


[1] https://github.com/git/git/blob/master/builtin/rebase.c#L1182-L1191

Cheers,
Alban






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