On Thu, 16 Dec 2004 08:56:15 -0500, Robert Dockins
Return the high level value to the user; when the enclosed ForeignPtr is garbage collected deRefWeak on the weak pointer will return Nothing. Then the clean-up thread can begin polling the song object to see if it is finished.
But if the ForeignPtr has been garbage collected, it's too late! The sound data is *gone* and the channel can no longer play the sound. I need to catch it just before the *channel* gets garbage collected and extract the vital information from the channel so that I can keep them alive long enough to finish playback. One of the vital pieces of information is a reference to the sound data and the other is the physical channel (CInt). Using those two pieces of information I *should* be able to poll the channel to see if it is playing, and also keep the sound data alive (touchForeignPtr). Once the channel has finished playing I just need to return and let the GC take care of the sound data (which may or may not have additional references from other channels), since ITS finalizer properly releases its resources. However this doesn't work. Strangely I do this (see other post for additional code) main = do hSetBuffering stdout NoBuffering x <- fsound_Init 44100 32 0 c <- callStuff threadDelay 1000000 putStrLn "Performing GC!" performGC threadDelay 1000000 b <- isPlaying c print b getLine return () callStuff = do s <- sampleLoad "test.mp3" c <- samplePlay s threadDelay 3000000 b <- isPlaying c print b threadDelay 1000000 return c And expect to get output along the lines of: True Performing GC Starting keep-alive loop for sample playback Keeping channel alive! Keeping channel alive! Keeping channel alive! Keeping channel alive! Finished keeping sample alive Freeing up sample! False Instead I get: True Performing GC! Freeing up sample Starting keep-alive loop for sample playback Keeping channel alive! Finished keeping sample alive False In other words after the GC the first thing that happens is that the _sound_data_ is being garbage collected! That's extremly freaky since the channel (which is used later on to produce the "False" value from isPlaying) contains a reference to this sound data! THEN the keep-alive loop starts (and since isPlaying naturally returns False since there is no sound data anymore, it immediatly returns). I don't understand this behaviour. /S -- Sebastian Sylvan +46(0)736-818655 UIN: 44640862