Re: [RFA 3/3] PR python/19293 - invalidate frame cache when unwinders change

[Pedro Alves <palves at redhat dot com>]

On 06/11/2016 03:42 AM, Tom Tromey wrote:
> PR python/19293 notes that when a Python unwinder is disabled, the
> frame cache is not invalidated.  This means that disabling an unwinder
> doesn't have any immediate effect -- but in my experience it's often
> the case that I want to enable or disable an unwinder in order to see
> what happens.
> 
> This patch adds a new gdb.invalidate_cached_frames function and
> arranges for the relevant bits of library code to call it.  I've only
> partially documented this function, considering a warning sufficient
> without going into all the reasons ordinary code should not call it.
> The name of the new function was taken from a comment in frame.h next
> to reinit_frame_cache.

Seems reasonable to me.  Couple nits below.

> --- a/gdb/doc/python.texi
> +++ b/gdb/doc/python.texi
> @@ -3838,6 +3838,15 @@ frames, as expressed by the given @var{reason} code (an integer, see the
>  @code{unwind_stop_reason} method further down in this section).
>  @end defun
>  
> +@findex gdb.invalidate_cached_frames
> +@defun gdb.invalidate_cached_frames
> +@value{GDBN} internally keeps a cache of the frames that have been
> +unwound.  This function causes invalidates this cache.

s/causes// ?

> +
> +This function should not generally be called by ordinary Python code.
> +It is documented for the sake of completeness.
> +@end defun


> diff --git a/gdb/python/lib/gdb/unwinder.py b/gdb/python/lib/gdb/unwinder.py
> index 14b2758..67a37cb 100644
> --- a/gdb/python/lib/gdb/unwinder.py
> +++ b/gdb/python/lib/gdb/unwinder.py
> @@ -92,3 +92,4 @@ def register_unwinder(locus, unwinder, replace=False):
>                                     unwinder.name)
>          i += 1
>      locus.frame_unwinders.insert(0, unwinder)
> +    gdb.invalidate_cached_frames()
> diff --git a/gdb/python/python.c b/gdb/python/python.c
> index 9c4ddda..62c9bde 100644
> --- a/gdb/python/python.c
> +++ b/gdb/python/python.c
> @@ -884,6 +884,13 @@ gdbpy_find_pc_line (PyObject *self, PyObject *args)
>    return result;
>  }
>  
> +static PyObject *
> +gdbpy_invalidate_cached_frames (PyObject *self, PyObject *args)

Intro comment?

Thanks,
Pedro Alves