Hello.
I am writing an application which uses Haskell threads to execute some
long tasks.
I have tried to isolate the issue in a small program which is attached
to this message.
When updating a sorted tree model in a separate thread, most of the time
the application crashes with a critical error:
(TreeSort:15588): Gtk-CRITICAL **:
IA__gtk_tree_model_sort_convert_iter_to_child_iter: assertion `VALID_ITER
(sorted_iter, tree_model_sort)' failed
TreeSort: user error (ListStore.getRow: iter does not refer to a valid entry)
There are two buttons in the application: only one uses a separate
thread. Keep pressing it and soon the application will crash. With the
other button it does not crash.
Is this a known bug?
What would be a fix or an workaround for this issue?
Romildo
import Graphics.UI.Gtk
import Control.Concurrent (yield, forkIO)
import Control.Monad (forM_)
import Data.IORef (newIORef, readIORef, writeIORef)
sortFunc rawmodel selector iter1 iter2 =
do x1 <- treeModelGetRow rawmodel iter1
x2 <- treeModelGetRow rawmodel iter2
return (compare (selector x1) (selector x2))
mkSortCol view model rawmodel maybeSort title mkCellRenderer attribs f =
do col <- treeViewColumnNew
treeViewColumnSetTitle col title
treeViewColumnSetResizable col True
treeViewColumnSetSizing col TreeViewColumnAutosize
rend <- mkCellRenderer
treeViewColumnPackStart col rend True
set rend attribs
cellLayoutSetAttributeFunc col rend model $ \iter ->
do putStrLn (">>> DEBUG attributeFunc " ++ title)
cIter <- treeModelSortConvertIterToChildIter model iter
row <- treeModelGetRow rawmodel cIter
set rend (f row)
putStrLn ("<<< DEBUG attributeFunc " ++ title)
treeViewAppendColumn view col
case maybeSort of
Just (id,selector) ->
do treeSortableSetSortFunc model id $ sortFunc rawmodel selector
treeViewColumnSetSortColumnId col id
Nothing ->
return ()
return rend
main =
do ref <- newIORef 0
initGUI
timeoutAddFull (yield >> return True) priorityDefaultIdle 50
win <- windowNew
rawmodel <- listStoreNew []
model <- treeModelSortNewWithModel rawmodel
treeSortableSetDefaultSortFunc model $ Just $ sortFunc rawmodel fst
view <- treeViewNewWithModel model
let nothing = Nothing :: Maybe (SortColumnId, a -> ())
mkSortCol view model rawmodel nothing "Name" cellRendererTextNew [] $ \(x,_) -> [cellText := x]
mkSortCol view model rawmodel (Just (2,snd)) "Number" cellRendererTextNew [] $ \(_,y) -> [cellText := show y]
box <- vBoxNew False 2
containerAdd win box
boxPackStart box view PackGrow 2
let flushModel =
do listStoreClear rawmodel
treeViewSetCursor view [0] Nothing
forM_ [1..10] $ \_ ->
do counter <- readIORef ref
putStrLn (show counter)
writeIORef ref (counter + 1)
listStoreAppend rawmodel (":" ++ show counter,counter)
button1 <- buttonNewWithMnemonic "_Flush within forkIO"
boxPackStart box button1 PackGrow 2
on button1 buttonActivated $ forkIO flushModel >> return ()
button2 <- buttonNewWithMnemonic "_Flush without forkIO"
boxPackStart box button2 PackGrow 2
on button2 buttonActivated $ flushModel
widgetShowAll win
onDestroy win mainQuit
mainGUI
------------------------------------------------------------------------------
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