Make tasklist garbage-collectable

Again, instead of directly connecting to various signals for updating a
tasklist, this commit changes the code so that there is just a single, global
connections and based on this a weak table with all tasklist instances is used
do the updates.

Signed-off-by: Uli Schlachter <psychon@znc.in>

lib/awful/widget/tasklist.lua

@@ -23,6 +23,8 @@ local timer = require("gears.timer")
 
 local tasklist = { mt = {} }
 
+local instances
+
 -- Public structures
 tasklist.filter = {}
 
@@ -169,7 +171,7 @@ function tasklist.new(screen, filter, buttons, style, update_function, base_widg
     local data = setmetatable({}, { __mode = 'k' })
 
     local queued_update = false
-    local u = function ()
+    function w._do_tasklist_update()
         -- Add a delayed callback for the first update.
         if not queued_update then
             timer.delayed_call(function()
@@ -179,8 +181,24 @@ function tasklist.new(screen, filter, buttons, style, update_function, base_widg
             queued_update = true
         end
     end
-    tag.attached_connect_signal(screen, "property::selected", u)
-    tag.attached_connect_signal(screen, "property::activated", u)
+    if instances == nil then
+        instances = {}
+        local function us(s)
+            local i = instances[s]
+            if i then
+                for _, tlist in pairs(i) do
+                    tlist._do_tasklist_update()
+                end
+            end
+        end
+        local function u()
+            for s in ipairs(instances) do
+                us(s)
+            end
+        end
+
+        tag.attached_connect_signal(nil, "property::selected", u)
+        tag.attached_connect_signal(nil, "property::activated", u)
         capi.client.connect_signal("property::urgent", u)
         capi.client.connect_signal("property::sticky", u)
         capi.client.connect_signal("property::ontop", u)
@@ -195,9 +213,8 @@ function tasklist.new(screen, filter, buttons, style, update_function, base_widg
         capi.client.connect_signal("property::icon", u)
         capi.client.connect_signal("property::skip_taskbar", u)
         capi.client.connect_signal("property::screen", function(c, old_screen)
-        if screen == c.screen or screen == old_screen then
-            u()
-        end
+            us(c.screen)
+            us(old_screen)
         end)
         capi.client.connect_signal("property::hidden", u)
         capi.client.connect_signal("tagged", u)
@@ -206,7 +223,14 @@ function tasklist.new(screen, filter, buttons, style, update_function, base_widg
         capi.client.connect_signal("list", u)
         capi.client.connect_signal("focus", u)
         capi.client.connect_signal("unfocus", u)
-    u()
+    end
+    w._do_tasklist_update()
+    local list = instances[s]
+    if not list then
+        list = setmetatable({}, { __mode = "v" })
+        instances[screen] = list
+    end
+    table.insert(list, w)
     return w
 end
 

tests/test-leaks.lua

@@ -11,7 +11,8 @@ local errors = {}
 local prepare_for_collect = nil
 
 -- Test if some objects can be garbage collected
-local function collectable(a, b, c, d, e, f, g, h)
+local function collectable(a, b, c, d, e, f, g, h, last)
+    assert(last == nil, "got more arguments than supported")
     local objs = setmetatable({ a, b, c, d, e, f, g, h }, { __mode = "v" })
     a, b, c, d, e, f, g, h = nil, nil, nil, nil, nil, nil, nil, nil
     if prepare_for_collect then
@@ -37,12 +38,19 @@ collectable(awful.widget.launcher({ image = cairo.ImageSurface(cairo.Format.ARGB
 collectable(awful.widget.prompt())
 collectable(awful.widget.textclock())
 collectable(awful.widget.layoutbox(1))
+
 function prepare_for_collect()
     -- Only after doing the pending update can a taglist be GC'd.
     awesome.emit_signal("refresh")
 end
 collectable(awful.widget.taglist(1, awful.widget.taglist.filter.all))
 
+function prepare_for_collect()
+    -- Only after doing the pending update can a taglist be GC'd.
+    awesome.emit_signal("refresh")
+end
+collectable(awful.widget.tasklist(1, awful.widget.tasklist.filter.currenttags))
+
 -- And finally a full wibox
 function prepare_for_collect()
     -- Only after doing the pending repaint can a wibox be GC'd.