[mutter/wip/carlosg/input-refactors-pt1: 6/28] backends/native: Assign unique ranges of slots to virtual devices

[Carlos Garnacho <carlosg src gnome org>]

commit bfe322983f73a6ebb523ae07d6599f0d833436b8
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Oct 22 11:23:03 2020 +0200

    backends/native: Assign unique ranges of slots to virtual devices
    
    We are moving to seat-wide touch slot accounting, so move these virtual
    devices to using their own range each.
    
    There's the theoretical case of overflow/rollover, if enough virtual
    devices are created/destroyed in the session lifetime. In that case the
    slots are prevented from colliding with real touch devices, although there's
    no prevention for newer virtual devices colliding with older persisting ones.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1486

 src/backends/native/meta-seat-native.c             | 38 ++++++++++++++++++++++
 src/backends/native/meta-seat-native.h             |  5 +++
 .../native/meta-virtual-input-device-native.c      | 29 +++++++++++++++--
 3 files changed, 69 insertions(+), 3 deletions(-)
---
diff --git a/src/backends/native/meta-seat-native.c b/src/backends/native/meta-seat-native.c
index 222acbd0bf..0280a89444 100644
--- a/src/backends/native/meta-seat-native.c
+++ b/src/backends/native/meta-seat-native.c
@@ -2603,6 +2603,7 @@ meta_seat_native_finalize (GObject *object)
     }
   g_slist_free (seat->devices);
   g_free (seat->touch_states);
+  g_hash_table_destroy (seat->reserved_virtual_slots);
 
   g_object_unref (seat->udev_client);
 
@@ -2700,16 +2701,51 @@ meta_seat_native_apply_kbd_a11y_settings (ClutterSeat            *seat,
                                                       settings);
 }
 
+static guint
+bump_virtual_touch_slot_base (MetaSeatNative *seat_native)
+{
+  while (TRUE)
+    {
+      if (seat_native->virtual_touch_slot_base < 0x100)
+        seat_native->virtual_touch_slot_base = 0x100;
+
+      seat_native->virtual_touch_slot_base +=
+        CLUTTER_VIRTUAL_INPUT_DEVICE_MAX_TOUCH_SLOTS;
+
+      if (!g_hash_table_lookup (seat_native->reserved_virtual_slots,
+                               GUINT_TO_POINTER (seat_native->virtual_touch_slot_base)))
+        break;
+    }
+
+  return seat_native->virtual_touch_slot_base;
+}
+
 static ClutterVirtualInputDevice *
 meta_seat_native_create_virtual_device (ClutterSeat            *seat,
                                         ClutterInputDeviceType  device_type)
 {
+  MetaSeatNative *seat_native = META_SEAT_NATIVE (seat);
+  guint slot_base;
+
+  slot_base = bump_virtual_touch_slot_base (seat_native);
+  g_hash_table_add (seat_native->reserved_virtual_slots,
+                    GUINT_TO_POINTER (slot_base));
+
   return g_object_new (META_TYPE_VIRTUAL_INPUT_DEVICE_NATIVE,
                        "seat", seat,
+                       "slot-base", slot_base,
                        "device-type", device_type,
                        NULL);
 }
 
+void
+meta_seat_native_relinquish_touch_slots (MetaSeatNative *seat,
+                                         guint           slots)
+{
+  g_hash_table_remove (seat->reserved_virtual_slots,
+                       GUINT_TO_POINTER (slots));
+}
+
 static ClutterVirtualDeviceType
 meta_seat_native_get_supported_virtual_device_types (ClutterSeat *seat)
 {
@@ -2854,6 +2890,8 @@ meta_seat_native_init (MetaSeatNative *seat)
   seat->repeat = TRUE;
   seat->repeat_delay = 250;     /* ms */
   seat->repeat_interval = 33;   /* ms */
+
+  seat->reserved_virtual_slots = g_hash_table_new (NULL, NULL);
 }
 
 void
diff --git a/src/backends/native/meta-seat-native.h b/src/backends/native/meta-seat-native.h
index 7945603758..eddf204b0d 100644
--- a/src/backends/native/meta-seat-native.h
+++ b/src/backends/native/meta-seat-native.h
@@ -90,6 +90,8 @@ struct _MetaSeatNative
 
   MetaTouchState **touch_states;
   int n_alloc_touch_states;
+  guint virtual_touch_slot_base;
+  GHashTable *reserved_virtual_slots;
 
   struct xkb_state *xkb;
   xkb_led_index_t caps_lock_led;
@@ -288,4 +290,7 @@ void meta_seat_native_set_keyboard_repeat (MetaSeatNative *seat,
                                            uint32_t        delay,
                                            uint32_t        interval);
 
+void meta_seat_native_relinquish_touch_slots (MetaSeatNative *seat,
+                                              guint           slots);
+
 #endif /* META_SEAT_NATIVE_H */
diff --git a/src/backends/native/meta-virtual-input-device-native.c 
b/src/backends/native/meta-virtual-input-device-native.c
index 510414bde8..465a5543e0 100644
--- a/src/backends/native/meta-virtual-input-device-native.c
+++ b/src/backends/native/meta-virtual-input-device-native.c
@@ -34,6 +34,7 @@ enum
   PROP_0,
 
   PROP_SEAT,
+  PROP_SLOT_BASE,
 
   PROP_LAST
 };
@@ -46,6 +47,7 @@ struct _MetaVirtualInputDeviceNative
 
   ClutterInputDevice *device;
   MetaSeatNative *seat;
+  guint slot_base;
   int button_count[KEY_CNT];
 };
 
@@ -547,14 +549,16 @@ meta_virtual_input_device_native_notify_touch_down (ClutterVirtualInputDevice *v
   MetaInputDeviceNative *device_evdev =
     META_INPUT_DEVICE_NATIVE (virtual_evdev->device);
   MetaTouchState *touch_state;
+  guint seat_slot;
 
   g_return_if_fail (virtual_evdev->device != NULL);
 
   if (time_us == CLUTTER_CURRENT_TIME)
     time_us = g_get_monotonic_time ();
 
+  seat_slot = virtual_evdev->slot_base + (guint) device_slot;
   touch_state = meta_input_device_native_acquire_touch_state (device_evdev,
-                                                              device_slot);
+                                                              seat_slot);
   if (!touch_state)
     return;
 
@@ -582,14 +586,16 @@ meta_virtual_input_device_native_notify_touch_motion (ClutterVirtualInputDevice
   MetaInputDeviceNative *device_evdev =
     META_INPUT_DEVICE_NATIVE (virtual_evdev->device);
   MetaTouchState *touch_state;
+  guint seat_slot;
 
   g_return_if_fail (virtual_evdev->device != NULL);
 
   if (time_us == CLUTTER_CURRENT_TIME)
     time_us = g_get_monotonic_time ();
 
+  seat_slot = virtual_evdev->slot_base + (guint) device_slot;
   touch_state = meta_input_device_native_lookup_touch_state (device_evdev,
-                                                             device_slot);
+                                                             seat_slot);
   if (!touch_state)
     return;
 
@@ -615,14 +621,16 @@ meta_virtual_input_device_native_notify_touch_up (ClutterVirtualInputDevice *vir
   MetaInputDeviceNative *device_evdev =
     META_INPUT_DEVICE_NATIVE (virtual_evdev->device);
   MetaTouchState *touch_state;
+  guint seat_slot;
 
   g_return_if_fail (virtual_evdev->device != NULL);
 
   if (time_us == CLUTTER_CURRENT_TIME)
     time_us = g_get_monotonic_time ();
 
+  seat_slot = virtual_evdev->slot_base + (guint) device_slot;
   touch_state = meta_input_device_native_lookup_touch_state (device_evdev,
-                                                             device_slot);
+                                                             seat_slot);
   if (!touch_state)
     return;
 
@@ -651,6 +659,9 @@ meta_virtual_input_device_native_get_property (GObject    *object,
     case PROP_SEAT:
       g_value_set_pointer (value, virtual_evdev->seat);
       break;
+    case PROP_SLOT_BASE:
+      g_value_set_uint (value, virtual_evdev->slot_base);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -671,6 +682,9 @@ meta_virtual_input_device_native_set_property (GObject      *object,
     case PROP_SEAT:
       virtual_evdev->seat = g_value_get_pointer (value);
       break;
+    case PROP_SLOT_BASE:
+      virtual_evdev->slot_base = g_value_get_uint (value);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -726,6 +740,9 @@ meta_virtual_input_device_native_dispose (GObject *object)
       g_clear_object (&virtual_evdev->device);
     }
 
+  meta_seat_native_relinquish_touch_slots (virtual_evdev->seat,
+                                           virtual_evdev->slot_base);
+
   object_class->dispose (object);
 }
 
@@ -762,5 +779,11 @@ meta_virtual_input_device_native_class_init (MetaVirtualInputDeviceNativeClass *
                                                "Seat",
                                                CLUTTER_PARAM_READWRITE |
                                                G_PARAM_CONSTRUCT_ONLY);
+  obj_props[PROP_SLOT_BASE] = g_param_spec_uint ("slot-base",
+                                                 "Slot base",
+                                                 "Base for touch slots",
+                                                 0, G_MAXUINT, 0,
+                                                 CLUTTER_PARAM_READWRITE |
+                                                 G_PARAM_CONSTRUCT_ONLY);
   g_object_class_install_properties (object_class, PROP_LAST, obj_props);
 }