Re: [PATCH] Call target_terminal_ours() before refreshing TUI's frame info

[Pedro Alves <palves@redhat.com>]

On 06/02/2015 04:52 PM, Patrick Palka wrote:
> In some cases tui_show_frame_info() may get called while the inferior's
> terminal settings are still in effect.  But when we call this function
> we absolutely need to have our terminal settings in effect because the
> function is responsible for redrawing TUI's windows following a change
> in the selected frame or a change in the PC.  If our terminal settings
> are not in effect, the screen does not get redrawn properly, causing
> temporary display artifacts (which can be fixed via ^L).
> 
> This scenario happens most prominently when stepping through a program
> in TUI while a watchpoint is in effect.
> 
> Here is an example backtrace for when tui_show_frame_info() gets called
> while target_terminal_is_inferior() == 1:
> 
>   #1  0x00000000004988ee in tui_selected_frame_level_changed_hook (level=0)
>   #2  0x0000000000617b99 in select_frame (fi=0x18c9820)
>   #3  0x0000000000617c3f in get_selected_frame (message=message@entry=0x0)
>   #4  0x00000000004ce534 in update_watchpoint (b=b@entry=0x2d9a760,
>       reparse=reparse@entry=0)
>   #5  0x00000000004d625e in insert_breakpoints ()
>   #6  0x0000000000531cfe in keep_going (ecs=ecs@entry=0x7ffea7884ac0)
>   #7  0x00000000005326d7 in process_event_stop_test (ecs=ecs@entry=0x7ffea7884ac0)
>   #8  0x000000000053596e in handle_inferior_event_1 (ecs=0x7ffea7884ac0)
> 
> The fix is simple: call target_terminal_ours() before calling
> tui_show_frame_info() in TUI's frame-changed hook, making sure to
> restore the original terminal settings afterwards.
> 
> gdb/ChangeLog:
> 
> 	* tui/tui-hooks.c (tui_selected_frame_level_changed_hook): Call
> 	target_terminal_ours() before calling tui_show_frame_info(), and
> 	restore the original terminal settings afterwards.


OK, though please try/use target_terminal_ours_for_output instead.

I think we should get rid of this hook entirely, and refresh
the window at some higher level point.  Refreshing the window for
each internal stop and/or selected frame save/restore results in
lots of pointless flicker...  I'm sure you've noticed.  :-)

Thanks,
Pedro Alves