Re: [Haskell-cafe] Re: POSIX AIO (asych I/O) ...
On 2008 Jul 2, at 1:42, Galchin, Vasili wrote: errno - throwErrnoIfMinus1 aioError (c_aio_error p_aiocb) ghc thinks that Errno should be an instance of Num: System/Posix/Aio.hsc:117:15: No instance for (Num Errno) I expect so it can compare it to -1(throwErrnoIfMinusOne). But if the return value is actually an errno and not -1 to indicate error (which it is if I read the manpage correctly), you don't want throwErrnoIfMinus1 anyway; I suspect you want to wrap the return value of c_aio_return (which should be IO CInt) in an Errno constructor, then use errnoToIOError if you really want to raise an IOError. (What were you expecting for count? I see none, just an errno.) Note that it *never* returns -1; it returns 0 for successful completion for the aiocb, EINPROGRESS if it's still working, and the appropriate errno if it failed. You might want to decide if you want to use the aio_return style interface or something more Haskell-ish before designing this part of the API. If you want to stick close to the C interface: aioReturn :: AIOCB - IO (AIOCB, Errno) aioReturn aiocb = do allocaBytes (#const sizeof(struct aiocb)) $ \ p_aiocb - do poke p_aiocb aiocb err - c_aio_return p_aiocb aiocb - peek p_aiocb return (aiocb, Errno err) I'd actually consider something more Haskellish, e.g. a variant of StateT IO where the state is the aiocb and errno, the errno initialized to eINPROGRESS and set by aioReturn and aioError (and once aioReturn is called, it can't be called again so return the cached value if needed). -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: POSIX AIO (asych I/O) ...
On Wed, 2008-07-02 at 02:07 -0400, Brandon S. Allbery KF8NH wrote: On 2008 Jul 2, at 1:42, Galchin, Vasili wrote: errno - throwErrnoIfMinus1 aioError (c_aio_error p_aiocb) ghc thinks that Errno should be an instance of Num: System/Posix/Aio.hsc:117:15: No instance for (Num Errno) I expect so it can compare it to -1(throwErrnoIfMinusOne). But if the return value is actually an errno and not -1 to indicate error (which it is if I read the manpage correctly), you don't want throwErrnoIfMinus1 anyway; I suspect you want to wrap the return value of c_aio_return (which should be IO CInt) in an Errno constructor, then use errnoToIOError if you really want to raise an IOError. (What were you expecting for count? I see none, just an errno.) Note that it *never* returns -1; it returns 0 for successful completion for the aiocb, EINPROGRESS if it's still working, and the appropriate errno if it failed. It seems as though it can return -1 if given non-sensical input. But in that case, the nicely type-correct thing to do would still be to have the C binding return a CInt, and wrap that after the call to throwErrnoIfMinus1 (in this case, `errno' still refers to the global errno, set to EINVAL). jcc ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: POSIX AIO (asych I/O) ...
On 2008 Jul 2, at 2:15, Jonathan Cast wrote: It seems as though it can return -1 if given non-sensical input. But in The POSIX spec says it returns EINVAL in that case. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: POSIX AIO (asych I/O) ...
On Wed, 2008-07-02 at 02:17 -0400, Brandon S. Allbery KF8NH wrote: On 2008 Jul 2, at 2:15, Jonathan Cast wrote: It seems as though it can return -1 if given non-sensical input. But in The POSIX spec says it returns EINVAL in that case. Are you sure? A little googling picks up e.g. HP docs [1] that state RETURN VALUE If the aiocb is invalid or if no asynchronous I/O operation is enqueued for the aiocb, aio_error() returns -1 and errno is set to indicate the error It may be non-POSIX, but I'd like to see some verbiage for which HP/UX's behavior isn't the most natural interpretation. jcc [1] http://docs.hp.com/en/B9106-90009/aio_error.2.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: POSIX AIO (asych I/O) ...
Thanks, Brandon!! I understand most of what you say but let me ponder! Kind regards, Vasili On Wed, Jul 2, 2008 at 1:07 AM, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote: On 2008 Jul 2, at 1:42, Galchin, Vasili wrote: errno - throwErrnoIfMinus1 aioError (c_aio_error p_aiocb) ghc thinks that Errno should be an instance of Num: System/Posix/Aio.hsc:117:15: No instance for (Num Errno) I expect so it can compare it to -1(throwErrnoIfMinusOne). But if the return value is actually an errno and not -1 to indicate error (which it is if I read the manpage correctly), you don't want throwErrnoIfMinus1 anyway; I suspect you want to wrap the return value of c_aio_return (which should be IO CInt) in an Errno constructor, then use errnoToIOError if you really want to raise an IOError. (What were you expecting for count? I see none, just an errno.) Note that it *never* returns -1; it returns 0 for successful completion for the aiocb, EINPROGRESS if it's still working, and the appropriate errno if it failed. You might want to decide if you want to use the aio_return style interface or something more Haskell-ish before designing this part of the API. If you want to stick close to the C interface: aioReturn :: AIOCB - IO (AIOCB, Errno) aioReturn aiocb = do allocaBytes (#const sizeof(struct aiocb)) $ \ p_aiocb - do poke p_aiocb aiocb err - c_aio_return p_aiocb aiocb - peek p_aiocb return (aiocb, Errno err) I'd actually consider something more Haskellish, e.g. a variant of StateT IO where the state is the aiocb and errno, the errno initialized to eINPROGRESS and set by aioReturn and aioError (and once aioReturn is called, it can't be called again so return the cached value if needed). -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: POSIX AIO (asych I/O) ...
On 2008 Jul 2, at 2:32, Jonathan Cast wrote: On Wed, 2008-07-02 at 02:17 -0400, Brandon S. Allbery KF8NH wrote: On 2008 Jul 2, at 2:15, Jonathan Cast wrote: It seems as though it can return -1 if given non-sensical input. But in The POSIX spec says it returns EINVAL in that case. Are you sure? A little googling picks up e.g. HP docs [1] that state Hm. I think the manuals I was looking at are ambiguous on the point, and I can't get at the actual standard right now. Probably best to assume -1/EINVAL is a possible return value, then. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: POSIX AIO (asych I/O) ...
Hi Brandon, Most of what you say makes sense. However, at some places in your narrative aren't you mixing up my aioError and aioReturn?(or aio_error and aio_return, respectively). E.g. aioReturn should return the byte count and not errno? If you want to stick close to the C interface: aioReturn :: AIOCB - IO (AIOCB, Errno) aioReturn aiocb = do allocaBytes (#const sizeof(struct aiocb)) $ \ p_aiocb - do poke p_aiocb aiocb err - c_aio_return p_aiocb aiocb - peek p_aiocb return (aiocb, Errno err) Vasili On Wed, Jul 2, 2008 at 1:07 AM, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote: On 2008 Jul 2, at 1:42, Galchin, Vasili wrote: errno - throwErrnoIfMinus1 aioError (c_aio_error p_aiocb) ghc thinks that Errno should be an instance of Num: System/Posix/Aio.hsc:117:15: No instance for (Num Errno) I expect so it can compare it to -1(throwErrnoIfMinusOne). But if the return value is actually an errno and not -1 to indicate error (which it is if I read the manpage correctly), you don't want throwErrnoIfMinus1 anyway; I suspect you want to wrap the return value of c_aio_return (which should be IO CInt) in an Errno constructor, then use errnoToIOError if you really want to raise an IOError. (What were you expecting for count? I see none, just an errno.) Note that it *never* returns -1; it returns 0 for successful completion for the aiocb, EINPROGRESS if it's still working, and the appropriate errno if it failed. You might want to decide if you want to use the aio_return style interface or something more Haskell-ish before designing this part of the API. If you want to stick close to the C interface: aioReturn :: AIOCB - IO (AIOCB, Errno) aioReturn aiocb = do allocaBytes (#const sizeof(struct aiocb)) $ \ p_aiocb - do poke p_aiocb aiocb err - c_aio_return p_aiocb aiocb - peek p_aiocb return (aiocb, Errno err) I'd actually consider something more Haskellish, e.g. a variant of StateT IO where the state is the aiocb and errno, the errno initialized to eINPROGRESS and set by aioReturn and aioError (and once aioReturn is called, it can't be called again so return the cached value if needed). -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: POSIX AIO (asych I/O) ...
Hello, Haskell 101 question! I discovered that aio_error returns errno rather -1. Of course, my aio_error binding is called before my aio_return binding (aio calling sequence protocol). I have worked on Posix OS's for quite a while but am unhappy with non-consistent errno handling ;^(. In any case, I modified my aio_error binding implementation to have a AIOCB - IO Errno signature: aioError :: AIOCB - IO Errno aioError aiocb = do allocaBytes (#const sizeof(struct aiocb)) $ \ p_aiocb - do poke p_aiocb aiocb errno - throwErrnoIfMinus1 aioError (c_aio_error p_aiocb) return (errno) foreign import ccall safe aio.h aio_error c_aio_error :: Ptr AIOCB - IO Errno ghc thinks that Errno should be an instance of Num: System/Posix/Aio.hsc:117:15: No instance for (Num Errno) Why? Vasili On Tue, Jul 1, 2008 at 2:42 AM, Galchin, Vasili [EMAIL PROTECTED] wrote: Hello, I am also testing my aio support. The aio_write binding seems to work ok .. as well as aio_error, Aio_return is a problem child. I think I wrote a really simple binding. I always receive nbytes as 0. I have been staring at the code hoping to catch a stupid mistake. I put putStrLn's in the code. .Here is the code ... aioReturn :: AIOCB - IO (AIOCB, ByteCount) aioReturn aiocb = do allocaBytes (#const sizeof(struct aiocb)) $ \ p_aiocb - do poke p_aiocb aiocb count - throwErrnoIfMinus1 aioReturn (c_aio_return p_aiocb) aiocb - peek p_aiocb return (aiocb, fromIntegral count) foreign import ccall safe aio.h aio_return c_aio_return :: Ptr AIOCB - IO CInt Maybe someone can spot something that I haven't. Thanks, Vasili ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
