Re: [PATCH v2] Don't add window duplicates to tui_windows

[Hannes Domani <ssbssa@yahoo.de>]

 Am Montag, 25. Januar 2021, 17:19:16 MEZ hat Andrew Burgess <andrew.burgess@embecosm.com> Folgendes geschrieben:

> * Hannes Domani via Gdb-patches <gdb-patches@sourceware.org> [2021-01-05 14:55:49 +0100]:
>
> > Otherwise, each time a window size is changed with 'winheight', all windows
> > are duplicated, and when done multiple times, slows down redrawing.
> >
> > gdb/ChangeLog:
> >
> > 2021-01-05  Hannes Domani  <ssbssa@yahoo.de>
> >
> >     * tui/tui-layout.c (tui_apply_current_layout): Add add_window
> >     argument to apply function.
> >     (tui_layout_window::apply): Likewise.
> >     (tui_layout_split::adjust_size): Likewise.
> >     (tui_layout_split::apply): Likewise.
> >     * tui/tui-layout.h (class tui_layout_base): Likewise.
> >     (class tui_layout_window): Likewise.
> >     (class tui_layout_split): Likewise.
> > ---
> > v2:
> > - Use new add_window argument to decide if window should be added to
> >  tui_windows.
> > ---
> >  gdb/tui/tui-layout.c | 19 ++++++++++++-------
> >  gdb/tui/tui-layout.h |  7 ++++---
> >  2 files changed, 16 insertions(+), 10 deletions(-)
> >
> > diff --git a/gdb/tui/tui-layout.c b/gdb/tui/tui-layout.c
> > index d6e299b00f1..fc1b65d8799 100644
> > --- a/gdb/tui/tui-layout.c
> > +++ b/gdb/tui/tui-layout.c
> > @@ -85,7 +85,7 @@ tui_apply_current_layout ()
> >    for (tui_win_info *win_info : saved_tui_windows)
> >      win_info->make_visible (false);
> >
> > -  applied_layout->apply (0, 0, tui_term_width (), tui_term_height ());
> > +  applied_layout->apply (0, 0, tui_term_width (), tui_term_height (), true);
> >
> >    /* Keep the list of internal windows up-to-date.  */
> >    for (int win_type = SRC_WIN; (win_type < MAX_MAJOR_WINDOWS); win_type++)
> > @@ -416,7 +416,8 @@ tui_layout_window::clone () const
> >  /* See tui-layout.h.  */
> >
> >  void
> > -tui_layout_window::apply (int x_, int y_, int width_, int height_)
> > +tui_layout_window::apply (int x_, int y_, int width_, int height_,
> > +              bool add_window)
> >  {
> >    x = x_;
> >    y = y_;
> > @@ -424,7 +425,8 @@ tui_layout_window::apply (int x_, int y_, int width_, int height_)
> >    height = height_;
> >    gdb_assert (m_window != nullptr);
> >    m_window->resize (height, width, x, y);
> > -  tui_windows.push_back (m_window);
> > +  if (add_window)
> > +    tui_windows.push_back (m_window);
> >  }
>
> I wondered if there was a solution to this problem that would remove
> the need to update some global state from the ::apply function.
>
> I came up with the patch below.  What do you think?

I think this is fine, I only have one question below.


> This also includes a test that covers this issue, when I run the test
> under valgrind it highlights that GDB tries to free the same object
> multiple times.
>
> Thanks,
> Andrew
>
>
> ---
>
> commit 3d47fcb70e234d08ab2e47c1527bca081846b8ee
> Author: Andrew Burgess <andrew.burgess@embecosm.com>
> Date:  Mon Jan 25 15:46:58 2021 +0000
>
>     gdb/tui: don't add windows to global list from tui_layout:window::apply
>    
>     This commit was inspired by this mailing list patch:
>    
>       https://sourceware.org/pipermail/gdb-patches/2021-January/174713.html
>    
>     Currently, calling tui_layout_window::apply will add the window from
>     the layout object to the global tui_windows list.
>    
>     Unfortunately, when the user runs the 'winheight' command, this calls
>     tui_adjust_window_height, which calls the tui_layout_base::adjust_size
>     function, which can then call tui_layout_base::apply.  The consequence
>     of this is that when the user does 'winheight' duplicate copies of a
>     window can be added to the global tui_windows list.
>    
>     The original patch fixed this by changing the apply function to only
>     update the global list some of the time.
>    
>     This patch takes a different approach.  The apply function no longer
>     updates the global tui_windows list.  Instead a new virtual function
>     is added to tui_layout_base which is used to gather all the currently
>     applied windows into a vector.  Finally tui_apply_current_layout is
>     updated to make use of this new function to update the tui_windows
>     list.
>    
>     The benefits I see in this approach are, (a) the apply function now no
>     longer touches global state, this solves the immediate problem,
>     and (b) now that tui_windows is updated directly in the function
>     tui_apply_current_layout, we can drop the saved_tui_windows global.
>    
>     gdb/ChangeLog:
>    
>             * tui-layout.c (saved_tui_windows): Delete.
>             (tui_apply_current_layout): Don't make use of saved_tui_windows,
>             call new get_windows member function instead.
>             (tui_get_window_by_name): Check in tui_windows.
>             (tui_layout_window::apply): Don't add to tui_windows.
>             * tui-layout.h (tui_layout_base::get_windows): New member function.
>             (tui_layout_window::get_windows): Likewise.
>             (tui_layout_split::get_windows): Likewise.
>    
>     gdb/testsuite/ChangeLog:
>    
>             * gdb.tui/winheight.exp: Add more tests.
>
> diff --git a/gdb/testsuite/gdb.tui/winheight.exp b/gdb/testsuite/gdb.tui/winheight.exp
> index 38fb29c3829..04de35d2f45 100644
> --- a/gdb/testsuite/gdb.tui/winheight.exp
> +++ b/gdb/testsuite/gdb.tui/winheight.exp
> @@ -36,3 +36,17 @@ Term::check_box "smaller source box" 0 0 80 10
>
> Term::command "winheight cmd -5"
> Term::check_box "larger source box" 0 0 80 15
> +
> +Term::command "winheight src -5"
> +Term::check_box "smaller source box again" 0 0 80 10
> +
> +Term::command "winheight src +5"
> +Term::check_box "larger source box again" 0 0 80 15
> +
> +# At one point we had a bug where adjusting the winheight would result
> +# in GDB keeping hold of duplicate window pointers, which it might
> +# then try to delete when the layout was changed.  Running this test
> +# under valgrind would expose that bug.
> +Term::command "layout asm"
> +Term::check_box "check for asm window" 0 0 80 15
> +
> diff --git a/gdb/tui/tui-layout.c b/gdb/tui/tui-layout.c
> index d6e299b00f1..adb99852da2 100644
> --- a/gdb/tui/tui-layout.c
> +++ b/gdb/tui/tui-layout.c
> @@ -64,11 +64,6 @@ static tui_layout_split *asm_regs_layout;
> /* See tui-data.h.  */
> std::vector<tui_win_info *> tui_windows;
>
> -/* When applying a layout, this is the list of all windows that were
> -  in the previous layout.  This is used to re-use windows when
> -  changing a layout.  */
> -static std::vector<tui_win_info *> saved_tui_windows;
> -
> /* See tui-layout.h.  */
>
> void
> @@ -79,10 +74,7 @@ tui_apply_current_layout ()
>
>   extract_display_start_addr (&gdbarch, &addr);
>
> -  saved_tui_windows = std::move (tui_windows);
> -  tui_windows.clear ();
> -
> -  for (tui_win_info *win_info : saved_tui_windows)
> +  for (tui_win_info *win_info : tui_windows)
>     win_info->make_visible (false);
>
>   applied_layout->apply (0, 0, tui_term_width (), tui_term_height ());
> @@ -96,25 +88,33 @@ tui_apply_current_layout ()
>   /* This should always be made visible by a layout.  */
>   gdb_assert (TUI_CMD_WIN->is_visible ());
>
> +  /* Get the new list of currently visible windows.  */
> +  std::vector<tui_win_info *> new_tui_windows;
> +  applied_layout->get_windows (&new_tui_windows);
> +
>   /* Now delete any window that was not re-applied.  */
>   tui_win_info *focus = tui_win_with_focus ();
>   tui_win_info *locator = tui_locator_win_info_ptr ();
> -  for (tui_win_info *win_info : saved_tui_windows)
> +  for (tui_win_info *win_info : tui_windows)
>     {
>       if (!win_info->is_visible ())
>     {
> +      /* If we're about to delete the window with focus then don't.
> +        This will be deleted later once we have selected an
> +        alternative window to focus on.  */
>       if (focus == win_info)
> -        tui_set_win_focus_to (tui_windows[0]);
> +        tui_set_win_focus_to (new_tui_windows[0]);
>       if (win_info != locator)
>         delete win_info;
>     }
>     }
>
> +  tui_windows.clear ();

Isn't this clear() redundant?


> +  tui_windows = std::move (new_tui_windows);
> +
>   if (gdbarch == nullptr && TUI_DISASM_WIN != nullptr)
>     tui_get_begin_asm_address (&gdbarch, &addr);
>   tui_update_source_windows_with_addr (gdbarch, addr);
> -
> -  saved_tui_windows.clear ();
> }
>
> /* See tui-layout.  */
> @@ -354,7 +354,7 @@ static std::unordered_map<std::string, window_factory> *known_window_types;
> static tui_win_info *
> tui_get_window_by_name (const std::string &name)
> {
> -  for (tui_win_info *window : saved_tui_windows)
> +  for (tui_win_info *window : tui_windows)
>     if (name == window->name ())
>       return window;
>
> @@ -424,7 +424,6 @@ tui_layout_window::apply (int x_, int y_, int width_, int height_)
>   height = height_;
>   gdb_assert (m_window != nullptr);
>   m_window->resize (height, width, x, y);
> -  tui_windows.push_back (m_window);
> }
>
> /* See tui-layout.h.  */
> diff --git a/gdb/tui/tui-layout.h b/gdb/tui/tui-layout.h
> index 193f42de420..f89166eae37 100644
> --- a/gdb/tui/tui-layout.h
> +++ b/gdb/tui/tui-layout.h
> @@ -91,6 +91,9 @@ class tui_layout_base
>       depth of this layout in the hierarchy (zero-based).  */
>   virtual void specification (ui_file *output, int depth) = 0;
>
> +  /* Add all windows to the WINDOWS vector.  */
> +  virtual void get_windows (std::vector<tui_win_info *> *windows) = 0;
> +
>   /* The most recent space allocation.  */
>   int x = 0;
>   int y = 0;
> @@ -141,6 +144,12 @@ class tui_layout_window : public tui_layout_base
>
>   void specification (ui_file *output, int depth) override;
>
> +  /* See tui_layout_base::get_windows.  */
> +  void get_windows (std::vector<tui_win_info *> *windows) override
> +  {
> +    windows->push_back (m_window);
> +  }
> +
> protected:
>
>   void get_sizes (bool height, int *min_value, int *max_value) override;
> @@ -195,6 +204,13 @@ class tui_layout_split : public tui_layout_base
>
>   void specification (ui_file *output, int depth) override;
>
> +  /* See tui_layout_base::get_windows.  */
> +  void get_windows (std::vector<tui_win_info *> *windows) override
> +  {
> +    for (auto &item : m_splits)
> +      item.layout->get_windows (windows);
> +  }
> +
> protected:
>
>   void get_sizes (bool height, int *min_value, int *max_value) override;