Window resize not always sent to clients

[AlanGriffiths]

Failing to notify the client of a window resize is the root cause of canonical/ubuntu-frame-osk#58

Tis can be reproduced (intermittently - around 1 in 4) with:

snap set frame-it osk=enable
MIR_SERVER_WINDOW_MANAGEMENT_TRACE=1 frame-it ./wayland-debug-wrapper wpe-webkit-mir-kiosk.cog

Here's an extract from a log of the messages received by the client and the Mir log with --window-management-trace.

Note that the only [email protected]() is to the smaller size of (1268, 741), and occurs before the advise_application_zone_update updated=(0, 0, (1268, 994)), original=(0, 0, (1268, 741)).

Following the advise_application_zone_update() the Frame window manager correctly resizes the window to new_size=(1268, 994) but there is no corresponding [email protected]() event. As a result the client continues to submit (1268, 741) buffers (which is interpreted as a resize request which is overruled by the WM)

[545592.862] [email protected](1268, 741, array)
[545592.873] [email protected](9)
[545592.877]  -> [email protected]_configure(9)
[545592.881] [email protected](11, wl_surface@13, array)
[545592.888] [email protected](wl_surface@13)
[545601.569] [email protected]_id(24)
[545601.618] [email protected](290107331)
[545601.765] [email protected]_id(15)
[545601.779] [email protected]_id(13)
[545601.784] [email protected]_id(14)
[545601.788] [email protected](0)
Cog-Core-Message: 16:14:06.299: <https://mir-server.io/> Loading...
[2023-09-14 16:14:06.362411] < -warning- > mirserver: Ignoring layer shell protocol violation: wl_surface destroyed before associated zwlr_layer_surface_v1@28
[2023-09-14 16:14:06.362501] <information> miral::Window Management: advise_delete_window window_info={name=, type=freestyle, state=attached, top_left=0, 741, size=(1268, 253), restore_rect=(634, 310, (0, 126)), children={}, depth_layer=4, attached_edges=11, exclusive_rect=1, preferred_orientation=0xf, confine_pointer=0, output_id=1}
[2023-09-14 16:14:06.362538] <information> miral::Window Management: place_and_size_for_state modifications={state=maximized} window_info={name=, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(320, 256, (640, 512)), children={}, depth_layer=0, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}
[2023-09-14 16:14:06.362551] <information> miral::Window Management: confirm_placement_on_display window_info={name=, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(320, 256, (640, 512)), children={}, depth_layer=0, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}, new_state= maximized, new_placement= (0, 0, (1268, 741)) -> (0, 0, (1268, 741))
[2023-09-14 16:14:06.362576] <information> miral::Window Management: confirm_placement_on_display window_info={name=, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(320, 256, (640, 512)), children={}, depth_layer=0, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}, new_state= fullscreen, new_placement= (0, 0, (1268, 994)) -> (0, 0, (1268, 741))
[2023-09-14 16:14:06.362585] <information> miral::Window Management: place_and_size_for_state modifications={state=maximized} window_info={name=Cog, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(317, 248, (634, 497)), children={}, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}
[2023-09-14 16:14:06.362593] <information> miral::Window Management: confirm_placement_on_display window_info={name=Cog, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(317, 248, (634, 497)), children={}, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}, new_state= maximized, new_placement= (0, 0, (1268, 741)) -> (0, 0, (1268, 741))
[2023-09-14 16:14:06.362601] <information> miral::Window Management: confirm_placement_on_display window_info={name=Cog, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(317, 248, (634, 497)), children={}, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}, new_state= fullscreen, new_placement= (0, 0, (1268, 994)) -> (0, 0, (1268, 741))
[2023-09-14 16:14:06.362609] <information> miral::Window Management: advise_application_zone_update updated=(0, 0, (1268, 994)), original=(0, 0, (1268, 741))
[2023-09-14 16:14:06.362633] <information> miral::Window Management: for_each_application
[2023-09-14 16:14:06.362640] <information> miral::Window Management: info_for -> 
[2023-09-14 16:14:06.362648] <information> miral::Window Management: place_and_size_for_state modifications={state=maximized} window_info={name=, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(320, 256, (640, 512)), children={}, depth_layer=0, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}
[2023-09-14 16:14:06.362656] <information> miral::Window Management: confirm_placement_on_display window_info={name=, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(320, 256, (640, 512)), children={}, depth_layer=0, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}, new_state= maximized, new_placement= (0, 0, (1268, 994)) -> (0, 0, (1268, 994))
[2023-09-14 16:14:06.362665] <information> miral::Window Management: modify_window window_info={name=, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(320, 256, (640, 512)), children={}, depth_layer=0, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}, modifications={top_left=0, 0, size=(1268, 994), state=fullscreen}
[2023-09-14 16:14:06.362673] <information> miral::Window Management: advise_resize window_info={name=, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(320, 256, (640, 512)), children={}, depth_layer=0, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}, new_size=(1268, 994)
[2023-09-14 16:14:06.362710] <information> miral::Window Management: info_for -> Cog
[2023-09-14 16:14:06.362719] <information> miral::Window Management: place_and_size_for_state modifications={state=maximized} window_info={name=Cog, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(317, 248, (634, 497)), children={}, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}
[2023-09-14 16:14:06.362728] <information> miral::Window Management: confirm_placement_on_display window_info={name=Cog, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(317, 248, (634, 497)), children={}, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}, new_state= maximized, new_placement= (0, 0, (1268, 994)) -> (0, 0, (1268, 994))
[2023-09-14 16:14:06.362735] <information> miral::Window Management: modify_window window_info={name=Cog, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(317, 248, (634, 497)), children={}, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}, modifications={top_left=0, 0, size=(1268, 994), state=fullscreen}
[2023-09-14 16:14:06.362743] <information> miral::Window Management: advise_resize window_info={name=Cog, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 741), restore_rect=(317, 248, (634, 497)), children={}, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}, new_size=(1268, 994)
[545827.949]  -> [email protected](new id wl_callback@13)
[545828.030] [email protected](0)
[545844.318]  -> [email protected](new id wl_callback@14)
[545844.361]  -> [email protected]_params(new id zwp_linux_buffer_params_v1@15)
[545844.391]  -> [email protected](fd 27, 0, 0, 5120, 16777216, 4)
[545844.407]  -> [email protected](fd 28, 1, 3932160, 256, 16777216, 4)
[545844.440]  -> [email protected]_immed(new id wl_buffer@17, 1268, 741, 875713089, 0)
[545844.453]  -> [email protected]()
[545844.457]  -> [email protected](wl_buffer@17, 0, 0)
[545844.466]  -> [email protected](0, 0, 2147483647, 2147483647)
[545845.076]  -> [email protected]()
[545845.269]  -> [email protected]_params(new id zwp_linux_buffer_params_v1@24)
[545845.318]  -> [email protected](fd 31, 0, 0, 5120, 16777216, 4)
[545845.334]  -> [email protected](fd 32, 1, 3932160, 256, 16777216, 4)
[545845.348]  -> [email protected]_immed(new id wl_buffer@22, 1268, 741, 875713089, 0)
[545845.360]  -> [email protected]()
[545845.363]  -> [email protected](wl_buffer@22, 0, 0)
[545845.371]  -> [email protected](0, 0, 1268, 741)
[545845.380]  -> [email protected](new id wl_callback@25)
[545845.385]  -> [email protected]()
[2023-09-14 16:14:06.534111] <information> miral::Window Management: handle_modify_window window_info={name=Cog, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 994), restore_rect=(317, 248, (634, 497)), children={}, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}, modifications={size=(1268, 741)}
[2023-09-14 16:14:06.534197] <information> miral::Window Management: place_and_size_for_state modifications={state=maximized} window_info={name=Cog, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 994), restore_rect=(317, 248, (634, 497)), children={}, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}
[2023-09-14 16:14:06.534245] <information> miral::Window Management: confirm_placement_on_display window_info={name=Cog, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 994), restore_rect=(317, 248, (634, 497)), children={}, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}, new_state= maximized, new_placement= (0, 0, (1268, 994)) -> (0, 0, (1268, 994))
[2023-09-14 16:14:06.534261] <information> miral::Window Management: modify_window window_info={name=Cog, type=freestyle, state=fullscreen, top_left=0, 0, size=(1268, 994), restore_rect=(317, 248, (634, 497)), children={}, exclusive_rect=0, preferred_orientation=0xf, confine_pointer=0}, modifications={top_left=0, 0, size=(1268, 994), state=fullscreen}
[2023-09-14 16:14:06.534275] <information> miral::Window Management: ====
[545846.131] [email protected]_id(24)
[545846.147] [email protected]_id(25)
[545846.154] [email protected]()
[545846.239]  -> [email protected]()
[545846.249] [email protected](290107576)
[545846.276] [email protected]_id(15)
[545846.335] [email protected]_id(13)
[545846.345] [email protected]_id(14)
[545846.353] [email protected](0)
[545862.622]  -> [email protected](new id wl_callback@13)
[545863.130] [email protected]()
[545863.139]  -> [email protected]()
[545863.143] [email protected](0)
[545866.277]  -> [email protected](new id wl_callback@14)

wpe-webkit-mir-kiosk.cog.log

$ cat wayland-debug-wrapper 
#!/bin/sh
WAYLAND_DEBUG=client exec "$@"

[AlanGriffiths]

OK, have traced the logic through to:

void mf::WaylandSurfaceObserver::content_resized_to(ms::Surface const*, geom::Size const& content_size)
{
    log_debug("mf::WaylandSurfaceObserver::content_resized_to({%d, %d})", content_size.width.as_int(), content_size.height.as_int());

    run_on_wayland_thread_unless_window_destroyed(
        [content_size](Impl* impl, WindowWlSurfaceRole* window)
        {
            log_debug("mf::WaylandSurfaceObserver::content_resized_to(...) content_size {%d, %d}, window_size {%d, %d}",
                      content_size.width.as_int(), content_size.height.as_int(), impl->window_size.width.as_int(), impl->window_size.height.as_int());
            if (content_size != impl->window_size)
            {
                impl->requested_size = content_size;
                window->handle_resize(std::nullopt, content_size);
            }
        });
}

Where we drop the resize because:

[2023-09-15 12:12:50.502459] < - debug - > mirserver: mf::WaylandSurfaceObserver::content_resized_to(...) content_size {1280, 1024}, window_size {1280, 1024}

Now to figure out how window_size is set to (1280, 1024) without notifying the client...

[AlanGriffiths]

OK, the sequence of events:

The client has submitted a (1280, 1024) and we have resized to (1280, 741) and sent a configure() (order doesn't matter).

Then, before the client sends another buffer we resize to (1280, 1024) and don't send a configure() because the size of the last buffer was right.

After which we get (1280, 741) buffers which we interpret as a resize attempt which we ignore, but don't send a configure because we're expecting the client to eventually submit a buffer of the right size. (In response to the configure we didn't send above.)