Re: [Haskell-iPhone] Automatically freeing function pointers

David, I hadn't quite grasped your code. The problem with your code is that these two lines...

func <- funky freeHaskellFunPtr func

...allocate then deallocate a function pointer, with a net result of nothing useful, and no effect on the function pointer you allocated on the third line. If you use this trick, however... {-# LANGUAGE DoRec #-} foreign import ccall safe "wrapper" mkInit :: (Ptr WorkerThread -> CInt -> IO ()) -> IO (FunPtr (Ptr WorkerThread -> CInt -> IO ())) applicationMain init dealloc = mdo fInit <- mkInit $ \callbackWorker fd -> do freeHaskellFunPtr fInit ... ... ...then you can do it quite painlessly. Note that DoRec is correct for ghc 6.10, but its name has changed in later ghc versions. The compiler will tell you. Steve On 21/06/11 05:00, David Pollak wrote:

On Sun, Jun 19, 2011 at 1:32 PM, Stephen Blackheath [to GHC-iPhone] mailto:likeliest.complexions.stephen@blacksapphire.com> wrote:

David,

In GHC-iPhone the number of function pointers that are allowed to be active for a given function is limited, but you can change the size of the limit. This is documented in

Steve,

Yep... I understand that there are not an unlimited number of function pointers. However, the function that I wrote was "supposed" to automatically release the function:

runOnMain :: IO () -> IO () runOnMain todo = do func <- funky dispatchFunc func where funky = mkStrCB $ \v -> do todo func <- funky freeHaskellFunPtr func

Note the freeHaskellFunPtr function call at the end of the lambda.

I'm thinking that the "func <- funky" line is being treated as a recursive call and I'm also thinking that this is a limitation of my understanding the magic of lazy evaluation.

So, please let me rephrase my question:

How do I get the pointer to a wrapper function so that the pointer can be used within the wrapped function itself?

I have worked around the particular issue by making a call to freeHaskellFunPtr in the Objective-C code that invokes the function. It's less optimal that being able to have the Haskell code be able to auto-free the function pointer after the function is invoked.

Thanks,

David

http://projects.haskell.org/__ghc-iphone/downloads/GHC-__iPhone.pdf http://projects.haskell.org/ghc-iphone/downloads/GHC-iPhone.pdf

on p5 under 'Pool sizes for foreign function "wrapper" callbacks'.

Steve

On 18/06/11 11:29, David Pollak wrote:

Howdy,

I tried to build a function that would create an auto-freeing function pointer:

runOnMain :: IO () -> IO () runOnMain todo = do func <- funky dispatchFunc func where funky = mkStrCB $ \v -> do todo func <- funky freeHaskellFunPtr func

Unfortunately, I wind up getting: internal error: iPhoneCreateAdjustor - adjustor pool 'Main_d2K2' is empty (capacity 32) (GHC version 6.10.4-iphone-simulator for i386_apple_darwin)

I'm not sure why, but I suspect that funky is being called recursively and thus stuff is never being freed.

Any hints as to the issue and solutions?

Thanks,

David

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