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

[Patrick Palka <patrick@parcs.ath.cx>]

On Mon, Jun 15, 2015 at 11:09 AM, Pedro Alves <palves@redhat.com> wrote:
> 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.

Okay.

>
> 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.  :-)

Good idea.

>
> Thanks,
> Pedro Alves
>