On Tue, May 2, 2023 at 10:50 PM Simon Marchi via Gdb-patches <
gdb-patches@sourceware.org> wrote:

> Instead of having the interpreter code registering observers for the
> signal_received observable, add a "signal_received" virtual method to
> struct interp.  Add a interps_notify_signal_received function that loops
> over all UIs and calls the signal_received method on the interpreter.
> Finally, add a notify_signal_received function that calls
> interps_notify_signal_received and then notifies the observers.  Replace
> all existing notifications to the signal_received observers with calls
> to notify_signal_received.
>
> Before this patch, the CLI and MI code both register a signal_received
> observer.  These observer go over all UIs, and, for those that have a
> interpreter of the right kind, print the stop notifiation.
>
> After this patch, we have just one "loop over all UIs", inside
> interps_notify_signal_received.  Since the interp::on_signal_received
> method gets called once for each interpreter, the implementations only
> need to deal with the current interpreter (the "this" pointer).
>
> The motivation for this patch comes from a future patch, that makes the
> amdgpu code register an observer to print a warning after the CLI's
> signal stop message.  Since the amdgpu and the CLI code both use
> observers, the order of the two messages is not stable, unless we define
> the priority using the observer dependency system.  However, the
> approach of using virtual methods on the interpreters seems like a good
> change anyway, I think it's more straightforward and simple to
> understand than the current solution that uses observers.  We are sure
> that the amdgpu message gets printed after the CLI message, since
> observers are notified after interpreters.
>
> Keep the signal_received, even if nothing uses if, because we will be
> using it in the upcoming amdgpu patch implementing the warning described
> above.
>
> Change-Id: I4d8614bb8f6e0717f4bfc2a59abded3702f23ac4
> ---
>  gdb/cli/cli-interp.c | 17 +++--------------
>  gdb/cli/cli-interp.h |  2 ++
>  gdb/infrun.c         | 14 ++++++++++++--
>  gdb/infrun.h         |  4 ++++
>  gdb/interps.c        | 23 +++++++++++++++++++++++
>  gdb/interps.h        |  8 ++++++++
>  gdb/mi/mi-interp.c   | 20 ++++----------------
>  gdb/mi/mi-interp.h   |  2 ++
>  gdb/remote.c         |  2 +-
>  9 files changed, 59 insertions(+), 33 deletions(-)
>
> I can confirm this causes no regressions when tested on Fedora-Rawhide,
> ppc64le.
>