agl-shell: Add bound_ok and bound_fail events and a default destructor

As we're increasing the amount of combinations we could have in the AGL
platforms, in which we're mixing various platforms, we require a way
to tell clients that there's already a shell client which in charge.

We can't really have multiple shell clients managing the windows and
surfaces, but in the same time we don't want to sever the wayland
connection the way it happens currently. Racy alternatives might exist,
which  avoid advertising the interface altogether once a
client did bind to the interface but that's not really a
viable solution.

So instead of doing that, this patch introduces two new events which
tells the client that it was either successful, and it can continue
issue requests and receive events or a that it the bind failed. The
client can chose to wait and try later and abandon to bind to the
agl_shell intefface, and behave like a regular client.

While doing an update to protocol to add those two events this patch add
also a default destructor for the protocol.

Bug-AGL: SPEC-4502
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Change-Id: Iacb86a668d1c4630724eecdb18e4b4c2d4e8e34a

1 files changed, 46 insertions, 3 deletions

diff --git a/protocol/agl-shell.xml b/protocol/agl-shell.xml
index 11a65a1..4ab71af 100644
--- a/protocol/agl-shell.xml
+++ b/protocol/agl-shell.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <protocol name="agl_shell">
   <copyright>
-    Copyright © 2019 Collabora, Ltd.
+    Copyright © 2019, 2022 Collabora, Ltd.
 
     Permission is hereby granted, free of charge, to any person obtaining a
     copy of this software and associated documentation files (the "Software"),
@@ -22,8 +22,29 @@
     FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
     DEALINGS IN THE SOFTWARE.
   </copyright>
-  <interface name="agl_shell" version="1">
-    <description summary="user interface for weston-ivi">
+  <interface name="agl_shell" version="2">
+    <description summary="user interface for Automotive Grade Linux platform">
+      Starting with version 2 of the protocol, the client is required to wait
+      for the 'bound_ok' or 'bound_fail' events in order to proceed further.
+
+      In case the client gets a 'bound_fail' event then it should consider that
+      there's another client already bound to the agl_shell protocol.
+      A client that receives a 'bound_ok' event should consider that there's
+      no other client already bound to the interface and can proceed further.
+
+      If the client uses an older version of the protocol it will receive
+      automatically an error and the compositor will terminate the connection,
+      if there's another client already bound the interface.
+
+      If the client receives the 'bound_fail' event and attempts to use the
+      interface further it will receive an error and the compositor will
+      terminate the connection. After the 'bound_fail' event was received the
+      client should call the destructor, which has been added with version 2
+      of the protocol. The client is free to try at a later point in time to
+      see if it will receive the 'bound_ok' event, but there's no explicit way
+      of finding out when that event will be delivered.
+      It is assumed that it can infer that information through other
+      means/other channels.
     </description>
 
     <enum name="error">
@@ -113,5 +134,27 @@
       <arg name="app_id" type="string"/>
       <arg name="output" type="object" interface="wl_output"/>
     </request>
+
+    <event name="bound_ok" since="2">
+     <description summary="event sent if binding was ok">
+        Informs the client that it was able to bind the agl_shell
+        interface succesfully. Clients are required to wait for this
+        event before continuing further.
+     </description>
+    </event>
+
+    <event name="bound_fail" since="2">
+      <description summary="event sent if binding was nok">
+        Informs the client that binding to the agl_shell interface was
+        unsuccesfull. Clients are required to wait for this event for
+        continuing further.
+      </description>
+    </event>
+
+    <request name="destroy" type="destructor" since="2">
+      <description summary="destroys the factory object">
+      </description>
+    </request>
+
   </interface>
 </protocol>