src: scripts: add policy-node.lua to link port info session items

src/config/config.lua.d/10-session-item-support.lua

@@ -27,6 +27,9 @@ function session_item_support.enable()
   -- Create items for nodes that appear in the graph
   load_script("create-item.lua")
 
+  -- Link nodes to each other to make media flow in the graph
+  load_script("policy-node.lua")
+
   -- Link endpoints to each other to make media flow in the graph
   load_script("policy-endpoint.lua", session_item_support.policy)
 end

src/scripts/policy-node.lua

@@ -0,0 +1,176 @@
+-- WirePlumber
+--
+-- Copyright © 2020 Collabora Ltd.
+--    @author Julian Bouzas <julian.bouzas@collabora.com>
+--
+-- SPDX-License-Identifier: MIT
+
+target_class_assoc = {
+  ["Stream/Input/Audio"] = "Audio/Source",
+  ["Stream/Output/Audio"] = "Audio/Sink",
+  ["Stream/Input/Video"] = "Video/Source",
+  ["Stream/Output/Video"] = "Video/Sink",
+}
+
+default_audio_node_key = {
+  ["Audio/Sink"] = "default.configured.audio.sink",
+  ["Audio/Source"] = "default.configured.audio.source",
+}
+
+function createLink (si, si_target)
+  local node = si:get_associated_proxy ("node")
+  local target_node = si_target:get_associated_proxy ("node")
+  local media_class = node.properties["media.class"]
+  local target_media_class = target_node.properties["media.class"]
+  local out_item = nil
+  local out_context = nil
+  local in_item = nil
+  local in_context = nil
+
+  if string.find (media_class, "Input") or
+      string.find (media_class, "Sink") then
+    -- capture
+    out_item = si_target
+    in_item = si
+    if target_class_assoc[media_class] ~= target_media_class then
+      out_context = "reverse"
+    end
+  else
+    -- playback
+    out_item = si
+    in_item = si_target
+    if target_class_assoc[media_class] ~= target_media_class then
+      in_context = "reverse"
+    end
+  end
+
+  -- create and configure link
+  local si_link = SessionItem ( "si-standard-link" )
+  if not si_link:configure {
+    ["out-item"] = out_item,
+    ["in-item"] = in_item,
+    ["out-item-port-context"] = out_context,
+    ["in-item-port-context"] = in_context,
+    ["manage-lifetime"] = false,
+  } then
+    Log.warning (si_link, "failed to configure si-standard-link")
+  end
+
+  -- activate and register
+  si_link:activate (Feature.SessionItem.ACTIVE, function (link)
+    Log.info (link, "link activated")
+    link:register ()
+  end)
+end
+
+function findTarget (node, target_media_class)
+  local target = nil
+
+  -- honor node.target, if present
+  local target_id = node.properties["node.target"]
+  if target_id then
+    for candidate_si in siportinfos_om:iterate() do
+      local n = candidate_si:get_associated_proxy ("node")
+      if n and n['bound-id'] == tonumber(target_id) then
+        target = candidate_si
+        break
+      end
+    end
+  end
+
+  -- try to find the best target
+  if target == nil then
+    local metadata = metadatas_om:lookup()
+
+    for candidate_si in siportinfos_om:iterate() do
+      local n = candidate_si:get_associated_proxy ("node")
+      if n and n.properties["media.class"] == target_media_class then
+        -- honor default node, if present
+        if metadata then
+          local key = default_audio_node_key[target_media_class]
+          local value = metadata:find(0, key)
+          local n_id = n["bound-id"]
+          if value and n_id == tonumber(value) then
+            target = candidate_si
+            Log.debug (node, "choosing default node " .. n_id)
+            break
+          end
+        end
+
+        -- otherwise just use this candidate
+        if target == nil then
+          target = candidate_si
+        end
+      end
+    end
+  end
+
+  return target
+end
+
+function handleSiPortInfo (si)
+  -- only handle unlinked session items
+  for silink in silinks_om:iterate() do
+    if silink.properties["out-item-id"] == si.id or
+          silink.properties["in-item-id"] == si.id then
+      return
+    end
+  end
+
+  -- only handle session items that has a node associated proxy
+  local node = si:get_associated_proxy ("node")
+  if not node or not node.properties then
+    return
+  end
+
+  -- only handle session item that has a valid target media class
+  local media_class = node.properties["media.class"]
+  local target_media_class = target_class_assoc[media_class]
+  if not target_media_class then
+    return
+  end
+
+  -- find a suitable target and link
+  local si_target = findTarget (node, target_media_class)
+  if si_target then
+    createLink (si, si_target)
+  end
+end
+
+function reevaluateSiPortInfos ()
+  -- check port info session items and register new links
+  for si in siportinfos_om:iterate() do
+    handleSiPortInfo (si)
+  end
+end
+
+function reevaulateSiLinks ()
+  -- check link session items and unregister them if not used
+  for silink in silinks_om:iterate() do
+    local used = false
+    for si in siportinfos_om:iterate() do
+      if silink.properties["out-item-id"] == si.id or
+          silink.properties["in-item-id"] == si.id then
+        used = true
+        break
+      end
+    end
+    if not used then
+      silink:remove ()
+      Log.info (silink, "link removed")
+    end
+  end
+end
+
+metadatas_om = ObjectManager { Interest { type = "metadata" } }
+siportinfos_om = ObjectManager { Interest { type = "SiPortInfo" } }
+silinks_om = ObjectManager { Interest { type = "SiLink" } }
+
+siportinfos_om:connect("objects-changed", function (om)
+  reevaluateSiPortInfos ()
+  reevaulateSiLinks ()
+end)
+
+metadatas_om:activate()
+siportinfos_om:activate()
+silinks_om:activate()