scripts: use filter-utils to implement smart filter policy

src/config/wireplumber.conf

@@ -503,6 +503,11 @@ wireplumber.components = [
     provides = hooks.linking.target.find-defined
     requires = [ support.lua-scripting ]
   }
+  {
+    name = linking/find-filter-target.lua, type = script/lua
+    provides = hooks.linking.target.find-filter
+    requires = [ support.lua-scripting, metadata.filters ]
+  }
   {
     name = linking/find-default-target.lua, type = script/lua
     provides = hooks.linking.target.find-default
@@ -513,6 +518,11 @@ wireplumber.components = [
     provides = hooks.linking.target.find-best
     requires = [ support.lua-scripting ]
   }
+  {
+    name = linking/get-filter-from-target.lua, type = script/lua
+    provides = hooks.linking.target.get-filter-from
+    requires = [ support.lua-scripting, metadata.filters ]
+  }
   {
     name = linking/prepare-link.lua, type = script/lua
     provides = hooks.linking.target.prepare-link
@@ -530,8 +540,10 @@ wireplumber.components = [
                  hooks.linking.target.link ]
     wants = [ hooks.linking.move-follow,
               hooks.linking.target.find-defined,
+              hooks.linking.target.find-filter,
               hooks.linking.target.find-default,
-              hooks.linking.target.find-best ]
+              hooks.linking.target.find-best,
+              hooks.linking.target.get-filter-from ]
   }
 
   ## Linking: Role-based priority system

src/scripts/linking/find-best-target.lua

@@ -44,12 +44,19 @@ SimpleEventHook {
     } do
       local target_props = target.properties
       local target_node_id = target_props ["node.id"]
+      local si_target_node = si:get_associated_proxy ("node")
+      local si_target_link_group = si_target_node.properties ["node.link-group"]
       local priority = tonumber (target_props ["priority.session"]) or 0
 
       log:debug (string.format ("Looking at: %s (%s)",
         tostring (target_props ["node.name"]),
         tostring (target_node_id)))
 
+      if si_target_link_group ~= nil then
+        Log.debug ("... ignoring filter as best target")
+        goto skip_linkable
+      end
+
       if not putils.canLink (si_props, target) then
         log:debug ("... cannot link, skip linkable")
         goto skip_linkable

src/scripts/linking/find-default-target.lua

@@ -11,7 +11,7 @@ log = Log.open_topic ("s-linking")
 
 SimpleEventHook {
   name = "linking/find-default-target",
-  after = "linking/find-defined-target",
+  after = "linking/find-filter-target",
   interests = {
     EventInterest {
       Constraint { "event.type", "=", "select-target" },

src/scripts/linking/find-filter-target.lua

@@ -0,0 +1,72 @@
+-- WirePlumber
+--
+-- Copyright © 2023 Collabora Ltd.
+--
+-- SPDX-License-Identifier: MIT
+--
+-- Check if the target node is a filter target.
+
+local putils = require ("policy-utils")
+local cutils = require ("common-utils")
+local futils = require ("filter-utils")
+log = Log.open_topic ("s-linking")
+
+function findFilterTarget (si, om)
+  local node = si:get_associated_proxy ("node")
+  local direction = cutils.getTargetDirection (si.properties)
+  local link_group = node.properties ["node.link-group"]
+  local target_id = -1
+
+  -- return nil if si is not a filter node
+  if link_group == nil then
+    return nil
+  end
+
+  -- get the filter target
+  return futils.get_filter_target (direction, link_group)
+end
+
+SimpleEventHook {
+  name = "linking/find-filter-target",
+  after = "linking/find-defined-target",
+  interests = {
+    EventInterest {
+      Constraint { "event.type", "=", "select-target" },
+    },
+  },
+  execute = function (event)
+    local source, om, si, si_props, si_flags, target =
+        putils:unwrap_find_target_event (event)
+
+    -- bypass the hook if the target is already picked up
+    if target then
+      return
+    end
+
+    local target_picked = false
+
+    log:info (si, string.format ("handling item: %s (%s)",
+        tostring (si_props ["node.name"]), tostring (si_props ["node.id"])))
+
+    target = findFilterTarget (si, om)
+
+    local can_passthrough, passthrough_compatible
+    if target then
+      passthrough_compatible, can_passthrough =
+          putils.checkPassthroughCompatibility (si, target)
+      if putils.canLink (si_props, target) and passthrough_compatible then
+        target_picked = true;
+      end
+    end
+
+    if target_picked then
+      log:info (si,
+        string.format ("... filter target picked: %s (%s), can_passthrough:%s",
+          tostring (target.properties ["node.name"]),
+          tostring (target.properties ["node.id"]),
+          tostring (can_passthrough)))
+      si_flags.can_passthrough = can_passthrough
+      event:set_data ("target", target)
+    end
+  end
+}:register ()

src/scripts/linking/get-filter-from-target.lua

@@ -0,0 +1,64 @@
+-- WirePlumber
+--
+-- Copyright © 2023 Collabora Ltd.
+--
+-- SPDX-License-Identifier: MIT
+--
+-- Check if the target node is a filter target.
+
+local putils = require ("policy-utils")
+local cutils = require ("common-utils")
+local futils = require ("filter-utils")
+log = Log.open_topic ("s-linking")
+
+SimpleEventHook {
+  name = "linking/get-filter-from-target",
+  after = "linking/find-best-target",
+  interests = {
+    EventInterest {
+      Constraint { "event.type", "=", "select-target" },
+    },
+  },
+  execute = function (event)
+    local source, om, si, si_props, si_flags, target =
+        putils:unwrap_find_target_event (event)
+
+    -- bypass the hook if the target was not found
+    if target == nil then
+      return
+    end
+
+    -- bypass the hook if the session item is a filter
+    local node = si:get_associated_proxy ("node")
+    local link_group = node.properties ["node.link-group"]
+    if link_group ~= nil then
+      return
+    end
+
+    -- Get the filter from the given target, if any
+    local target_direction = cutils.getTargetDirection (si.properties)
+    local filter_target = futils.get_filter_from_target (target_direction, target)
+    if filter_target ~= nil then
+      target = filter_target
+    end
+
+    local can_passthrough, passthrough_compatible
+    if target ~= nil then
+      passthrough_compatible, can_passthrough =
+      putils.checkPassthroughCompatibility (si, target)
+      if putils.canLink (si_props, target) and passthrough_compatible then
+        target_picked = true;
+      end
+    end
+
+    if target_picked then
+      log:info (si,
+        string.format ("... filter target picked: %s (%s), can_passthrough:%s",
+          tostring (target.properties ["node.name"]),
+          tostring (target.properties ["node.id"]),
+          tostring (can_passthrough)))
+      si_flags.can_passthrough = can_passthrough
+      event:set_data ("target", target)
+    end
+  end
+}:register ()

src/scripts/linking/prepare-link.lua

@@ -14,7 +14,7 @@ log = Log.open_topic ("s-linking")
 
 SimpleEventHook {
   name = "linking/prepare-link",
-  after = "linking/find-best-target",
+  after = "linking/get-filter-from-target",
   interests = {
     EventInterest {
       Constraint { "event.type", "=", "select-target" },

src/scripts/linking/rescan.lua

@@ -12,8 +12,26 @@
 
 local putils = require ("policy-utils")
 local cutils = require ("common-utils")
+local futils = require ("filter-utils")
 log = Log.open_topic ("s-linking")
 
+function checkFilter (si, om, handle_nonstreams)
+  -- always handle filters if handle_nonstreams is true, even if it is disabled
+  if handle_nonstreams then
+    return true
+  end
+
+  -- always return true if this is not a filter
+  local node = si:get_associated_proxy ("node")
+  local link_group = node.properties["node.link-group"]
+  if link_group == nil then
+    return true
+  end
+
+  local direction = cutils.getTargetDirection (si.properties)
+  return futils.is_filter_enabled (direction, link_group)
+end
+
 function checkLinkable (si, om, handle_nonstreams)
   local si_props = si.properties
 
@@ -28,9 +46,48 @@ function checkLinkable (si, om, handle_nonstreams)
     return false, si_props
   end
 
+  -- check filters
+  if not checkFilter (si, om, handle_nonstreams) then
+    return false, si_props
+  end
+
   return true, si_props
 end
 
+function unhandleLinkable (si, om)
+  local si_id = si.id
+  local valid, si_props = checkLinkable (si, om, true)
+  if not valid then
+    return
+  end
+
+  log.info (si, string.format ("unhandling item: %s (%s)",
+      tostring (si_props ["node.name"]), tostring (si_props ["node.id"])))
+
+  -- iterate over all the links in the graph and
+  -- remove any links associated with this item
+  for silink in om:iterate { type = "SiLink" } do
+    local out_id = tonumber (silink.properties ["out.item.id"])
+    local in_id = tonumber (silink.properties ["in.item.id"])
+
+    if out_id == si_id or in_id == si_id then
+      local in_flags = putils:get_flags (in_id)
+      local out_flags = putils:get_flags (out_id)
+
+      if out_id == si_id and in_flags.peer_id == out_id then
+        in_flags.peer_id = nil
+      elseif in_id == si_id and out_flags.peer_id == in_id then
+        out_flags.peer_id = nil
+      end
+
+      silink:remove ()
+      log.info (silink, "... link removed")
+    end
+  end
+
+  putils:clear_flags (si_id)
+end
+
 SimpleEventHook {
   name = "linking/linkable-removed",
   interests = {
@@ -43,40 +100,34 @@ SimpleEventHook {
     local si = event:get_subject ()
     local source = event:get_source ()
     local om = source:call ("get-object-manager", "session-item")
-    local si_id = si.id
-    local valid, si_props = checkLinkable (si, om, true)
-    if not valid then
-      return
-    end
 
-    log:info (si, string.format ("unhandling item: %s (%s)",
-        tostring (si_props ["node.name"]), tostring (si_props ["node.id"])))
-
-    -- iterate over all the links in the graph and
-    -- remove any links associated with this item
-    for silink in om:iterate { type = "SiLink" } do
-      local out_id = tonumber (silink.properties ["out.item.id"])
-      local in_id = tonumber (silink.properties ["in.item.id"])
-
-      if out_id == si_id or in_id == si_id then
-        local in_flags = putils:get_flags (in_id)
-        local out_flags = putils:get_flags (out_id)
-
-        if out_id == si_id and in_flags.peer_id == out_id then
-          in_flags.peer_id = nil
-        elseif in_id == si_id and out_flags.peer_id == in_id then
-          out_flags.peer_id = nil
-        end
-
-        silink:remove ()
-        log:info (silink, "... link removed")
-      end
-    end
-
-    putils:clear_flags (si_id)
+    unhandleLinkable (si, om)
   end
 }:register ()
 
+function handleLinkables (source)
+  local om = source:call ("get-object-manager", "session-item")
+
+  for si in om:iterate { type = "SiLinkable" } do
+    local valid, si_props = checkLinkable (si, om)
+    if not valid then
+      goto skip_linkable
+    end
+
+    -- check if we need to link this node at all
+    local autoconnect = cutils.parseBool (si_props ["node.autoconnect"])
+    if not autoconnect then
+      log.debug (si, tostring (si_props ["node.name"]) .. " does not need to be autoconnected")
+      goto skip_linkable
+    end
+
+    -- push event to find target and link
+    source:call ("push-event", "select-target", si, nil)
+
+    ::skip_linkable::
+  end
+end
+
 SimpleEventHook {
   name = "linking/rescan",
   interests = {
@@ -86,28 +137,10 @@ SimpleEventHook {
   },
   execute = function (event)
     local source = event:get_source ()
-    local om = source:call ("get-object-manager", "session-item")
 
     log:info ("rescanning...")
 
-    for si in om:iterate { type = "SiLinkable" } do
-      local valid, si_props = checkLinkable (si, om)
-      if not valid then
-        goto skip_linkable
-      end
-
-      -- check if we need to link this node at all
-      local autoconnect = cutils.parseBool (si_props ["node.autoconnect"])
-      if not autoconnect then
-        log:debug (si, tostring (si_props ["node.name"]) .. " does not need to be autoconnected")
-        goto skip_linkable
-      end
-
-      -- push event to find target and link
-      source:call ("push-event", "select-target", si, nil)
-
-    ::skip_linkable::
-    end
+    handleLinkables (source)
   end
 }:register ()
 
@@ -131,3 +164,44 @@ SimpleEventHook {
     source:call ("schedule-rescan", "linking")
   end
 }:register ()
+
+SimpleEventHook {
+  name = "linking/rescan-trigger-before-filters-metadata-changed",
+  before = "lib/filter-utils/rescan-metadata-changed",
+  interests = {
+    EventInterest {
+      Constraint { "event.type", "=", "metadata-changed" },
+      Constraint { "metadata.name", "=", "filters" },
+    },
+  },
+  execute = function (event)
+    local source = event:get_source ()
+    local om = source:call ("get-object-manager", "session-item")
+
+    -- unlink all filters
+    for si in om:iterate {
+        type = "SiLinkable",
+        Constraint { "node.link-group", "+" },
+    } do
+      unhandleLinkable (si, om)
+    end
+
+  end
+}:register ()
+
+SimpleEventHook {
+  name = "linking/rescan-trigger-after-filters-metadata-changed",
+  after = "lib/filter-utils/rescan-metadata-changed",
+  interests = {
+    EventInterest {
+      Constraint { "event.type", "=", "metadata-changed" },
+      Constraint { "metadata.name", "=", "filters" },
+    },
+  },
+  execute = function (event)
+    local source = event:get_source ()
+    local om = source:call ("get-object-manager", "session-item")
+
+    source:call ("schedule-rescan", "linking")
+  end
+}:register ()

tests/script-tester.c

@@ -255,6 +255,8 @@ load_components (ScriptRunnerFixture *f, gconstpointer argv)
     load_component (f, "linking/find-best-target.lua", "script/lua");
     load_component (f, "linking/find-default-target.lua", "script/lua");
     load_component (f, "linking/find-defined-target.lua", "script/lua");
+    load_component (f, "linking/find-filter-target.lua", "script/lua");
+    load_component (f, "linking/get-filter-from-target.lua", "script/lua");
     load_component (f, "linking/link-target.lua", "script/lua");
     load_component (f, "linking/prepare-link.lua", "script/lua");
     load_component (f, "linking/rescan.lua", "script/lua");