From afcb91f59b7951ac7e455d260f10cb11024d10fc Mon Sep 17 00:00:00 2001
From: Julian Bouzas <julian.bouzas@collabora.com>
Date: Thu, 20 Jun 2024 08:42:27 -0400
Subject: [PATCH] rescan: Stop rescan for 2s if BT node is removed

The intention here is to fix a Bluetooth bug where changing between different
profiles momentarily causes streams to be linked to an internal speaker.
Unfortunately, this case is not handled by the event dispatcher because some
signals are emitted using idle callbacks, and therefore we have to rely on
extra logic in rescan.lua to solve the problem.
---
 src/scripts/linking/rescan.lua | 61 +++++++++++++++++++++++++++++++++-
 1 file changed, 60 insertions(+), 1 deletion(-)

diff --git a/src/scripts/linking/rescan.lua b/src/scripts/linking/rescan.lua
index bdc01268..368d824b 100644
--- a/src/scripts/linking/rescan.lua
+++ b/src/scripts/linking/rescan.lua
@@ -15,6 +15,8 @@ cutils = require ("common-utils")
 futils = require ("filter-utils")
 log = Log.open_topic ("s-linking")
 handles = {}
+handles.rescan_enabled = true
+handles.timeout_source = nil
 
 function checkFilter (si, om, handle_nonstreams)
   -- always handle filters if handle_nonstreams is true, even if it is disabled
@@ -192,8 +194,65 @@ SimpleEventHook {
     },
   },
   execute = function (event)
+    if handles.rescan_enabled then
+      local source = event:get_source ()
+      source:call ("schedule-rescan", "linking")
+    end
+  end
+}:register ()
+
+SimpleEventHook {
+  name = "linking/session-item-added",
+  before = "linking/rescan-trigger",
+  interests = {
+    EventInterest {
+      Constraint { "event.type", "=", "session-item-added" },
+    },
+  },
+  execute = function (event)
+    -- clear timeout source, if any
+    if handles.timeout_source ~= nil then
+      handles.timeout_source:destroy ()
+      handles.timeout_source = nil
+    end
+
+    -- Always enable rescan when any node is added
+    handles.rescan_enabled = true
+  end
+}:register ()
+
+-- Stop rescan for 2 seconds if BT item was removed. This avoids audio
+-- being played on internal nodes for a few seconds while the BT device is
+-- switching profiles.
+SimpleEventHook {
+  name = "linking/bluez-session-item-removed",
+  before = "linking/rescan-trigger",
+  interests = {
+    EventInterest {
+      Constraint { "event.type", "=", "session-item-removed" },
+      Constraint { "device.api", "=", "bluez5" },
+    },
+  },
+  execute = function (event)
+    local si = event:get_subject ()
+    local si_props = si.properties
     local source = event:get_source ()
-    source:call ("schedule-rescan", "linking")
+
+    -- clear timeout source, if any
+    if handles.timeout_source ~= nil then
+      handles.timeout_source:destroy ()
+      handles.timeout_source = nil
+    end
+
+    -- disable rescan
+    handles.rescan_enabled = false
+
+    -- re-enable rescan after 2 seconds
+    handles.timeout_source = Core.timeout_add (2000, function()
+      handles.timeout_source = nil
+      handles.rescan_enabled = true
+      source:call ("schedule-rescan", "linking")
+    end)
   end
 }:register ()