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Today's Topics:
1. Re: ODP: howto Pipe (PICCA Frederic-Emmanuel)
2. Re: ODP: howto Pipe (Marcin Mrotek)
----------------------------------------------------------------------
Message: 1
Date: Sat, 20 Feb 2016 14:18:46 +0000
From: PICCA Frederic-Emmanuel
<frederic-emmanuel.pi...@synchrotron-soleil.fr>
To: "The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell" <beginners@haskell.org>
Subject: Re: [Haskell-beginners] ODP: howto Pipe
Message-ID:
<a2a20ec3b8560d408356cac2fc148e53b303b...@sun-dag3.synchrotron-soleil.fr>
Content-Type: text/plain; charset="us-ascii"
In fact I got the segfault also with the P.print...
So I rewrote the solve function like this
withDiffractometer :: Diffractometer -> (Ptr HklEngineList -> IO b) -> IO b
withDiffractometer d fun = do
let f_engines = difEngineList d
withForeignPtr f_engines fun
solveTrajPipe' :: Diffractometer -> Pipe Engine Geometry IO ()
solveTrajPipe' dif = flip evalStateT dif $ forever $ do
-- Inside here we are using `StateT Int (Consumer a IO) r`
e <- lift await
dif <- get
let name = engineName e
solutions <- lift . lift $ withDiffractometer dif $ \engines ->
withCString name $ \cname -> do
engine <- c_hkl_engine_list_engine_get_by_name engines cname nullPtr
n <- c_hkl_engine_pseudo_axis_names_get engine >>= darrayStringLen
solve' engine n e >>= getSolution0
put dif
lift $ yield solutions
using the evalStateT. It works with million of evaluations :)
but now if I remove the get and put lines, I get the segfault.
This segfault is located in the solve' method
solve' :: Ptr HklEngine -> CSize -> Engine -> IO (ForeignPtr HklGeometryList)
solve' engine n (Engine _ ps _) = do
let positions = [v | (Parameter _ v _) <- ps]
withArray positions $ \values ->
c_hkl_engine_pseudo_axis_values_set engine values n unit nullPtr
>>= newForeignPtr c_hkl_geometry_list_free
so to my opinion I do not manage correctly the life time of my dif object, but
I do not understand how I can ensure this life time in until the solve' method
proceed.
Cheers
Frederic
------------------------------
Message: 2
Date: Sun, 21 Feb 2016 10:25:31 +0100
From: Marcin Mrotek <marcin.jan.mro...@gmail.com>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <beginners@haskell.org>
Subject: Re: [Haskell-beginners] ODP: howto Pipe
Message-ID:
<cajcfpzn+zjovsutvmnnynddrihgtbwd+mjfb-cc3ny4by78...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
First of all, (StateT Diffractometer (Pipe Engine Geometry IO) ())
isn't the same as (Pipe Engine Geometry (StateT Diffractometer IO)
()), although I'm not sure what exactly the difference will be, as
I've never used it the former way. This might be again a question for
the Pipes mailing list.
Secondly:
> but now if I remove the get and put lines, I get the segfault.
Okay, I have no idea. As I see it, this shouldn't happen, as you're
getting and putting the same pointer all the time. What if you remove
the StateT altogether and just use the `dif` from the function
argument, are you still getting segfaults? Also what about writting
the function without using pipes, and using Pipes.mapM to make it a
pipe like I mentioned? (if the only Pipes operation you're doing are
an `await` in the beginning and a `yield` at the end, Pipes.mapM
covers it)
Best regards,
Marcin Mrotek
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