On Wed, 26 Feb 2003, Sigbjorn Finne wrote:

wait3() or getrusage()? (Neither of which are supported by the posix library.)

--sigbjorn

Thanks, Sigbjorn. I drafted a Haskell wrapping of wait4(), modeled on code I found in CVS. See attached. I'd like a bit of help in two respects: 1. I found it difficult to satisfy the code requirements because I'm building the module outside the RTS build environment. Some issues: a. I don't know how to make a .hsc file, which would be the appropriate form for the file, I think. This meant I couldn't use #const, and may also explain why I couldn't find the __hsunix_* routines. b. I had to duplicate some helper functions, including `waitOptions` and `decipherWaitStatus`, because they didn't seem to be exported from the module in which they're defined. c. I'm not sure how to define `struct timeval` and `struct rusage` so I can avoid the kludgy code in `makeProcessResourceUsage`. It seems that maybe I should be building in the RTS environment (and maybe even extending the System.Posix.Process module itself) to clean up all of the above problems. That seems a bit daunting to me, however. 2. Having gotten my module to compile cleanly, it--not surprisingly--fails at runtime: invalid argument Action: reapChildProcess Reason: Invalid argument Maybe a few minutes of your eyes (or those of anyone else who has delved in the RTS) would spot the problem(s) quickly. I tried gdb and saw what appear to me to be reasonable arguments to wait4(), but I'm over my head here. Thanks in advance. Dean

----- Original Message ----- From: "Dean Herington" To: Sent: Wednesday, February 26, 2003 16:17 Subject: child process statistics

...

Does anyone know how to get the process statistics (cputime, page faults, etc.) for a child process? When the child process has terminated, before doing getAnyProcessStatus on it, I'd like to get its statistics.

Browsing the libraries documentation didn't turn anything up. I couldn't even find what I want at the Unix level among man pages. (I'm happy to write some FFI code to access system routines if I can locate the right ones.)

Dean

{-# OPTIONS -fglasgow-exts #-} -- Posix extras -- $Id$ module PosixExtras ( ProcessResourceUsage(..), reapChildProcess ) where import Ratio import System import Posix hiding (userTime, systemTime) import System.IO.Error import Foreign import Foreign.C data ProcessResourceUsage = ProcessResourceUsage { userTime, systemTime :: Rational } deriving (Show, Read) reapChildProcess :: Bool -> Bool -> ProcessID -> IO (Maybe (ProcessID, ProcessStatus, ProcessResourceUsage)) reapChildProcess block stopped pid = alloca $ \p_wstat -> allocaBytes structRusageSize $ \p_sru -> do pid' <- throwErrnoIfMinus1 "reapChildProcess" (c_wait4 (fromIntegral pid) p_wstat (waitOptions block stopped) p_sru) case pid' of 0 -> return Nothing _ -> do ps <- decipherWaitStatus p_wstat pru <- makeProcessResourceUsage p_sru return (Just (fromIntegral pid', ps, pru)) type CPid = CInt structRusageSize = 144 -- I think it's 72. Include 100% slop. type CRusage = CLong -- cheat makeProcessResourceUsage :: Ptr CLong -> IO ProcessResourceUsage makeProcessResourceUsage p_sru = do -- Assume that ru_utime and ru_stime are at the beginning of struct rusage. [uhi, ulo, shi, slo] <- mapM get [0..3] let u = time uhi ulo s = time shi slo return $ ProcessResourceUsage{ userTime = u, systemTime = s } where get n = fmap fromIntegral $ peekElemOff p_sru n time hi lo = toRational hi + (lo % 1000000) foreign import ccall unsafe "wait4" c_wait4 :: CPid -> Ptr CInt -> CInt -> Ptr CRusage -> IO CPid -- The following was scarfed from -- fptools/libraries/unix/System/Posix/Process.hsc?rev=1.4 waitOptions :: Bool -> Bool -> CInt -- block stopped waitOptions False False = 1 -- (#const WNOHANG) waitOptions False True = 3 -- (#const (WNOHANG|WUNTRACED)) waitOptions True False = 0 waitOptions True True = 2 -- (#const WUNTRACED) -- Turn a (ptr to a) wait status into a ProcessStatus decipherWaitStatus :: Ptr CInt -> IO ProcessStatus decipherWaitStatus wstatp = do wstat <- peek wstatp if c_WIFEXITED wstat /= 0 then do let exitstatus = c_WEXITSTATUS wstat if exitstatus == 0 then return (Exited ExitSuccess) else return (Exited (ExitFailure (fromIntegral exitstatus))) else do if c_WIFSIGNALED wstat /= 0 then do let termsig = c_WTERMSIG wstat return (Terminated (fromIntegral termsig)) else do if c_WIFSTOPPED wstat /= 0 then do let stopsig = c_WSTOPSIG wstat return (Stopped (fromIntegral stopsig)) else do ioError (mkIOError illegalOperationErrorType "waitStatus" Nothing Nothing) {- foreign import ccall unsafe "__hsunix_wifexited" c_WIFEXITED :: CInt -> CInt foreign import ccall unsafe "__hsunix_wexitstatus" c_WEXITSTATUS :: CInt -> CInt foreign import ccall unsafe "__hsunix_wifsignaled" c_WIFSIGNALED :: CInt -> CInt foreign import ccall unsafe "__hsunix_wtermsig" c_WTERMSIG :: CInt -> CInt foreign import ccall unsafe "__hsunix_wifstopped" c_WIFSTOPPED :: CInt -> CInt foreign import ccall unsafe "__hsunix_wstopsig" c_WSTOPSIG :: CInt -> CInt -} c_WIFEXITED :: CInt -> CInt c_WIFEXITED c = h2c $ fromEnum $ low7 (c2h c) == 0 c_WEXITSTATUS :: CInt -> CInt c_WEXITSTATUS c = h2c $ high8 $ c2h c c_WIFSIGNALED :: CInt -> CInt c_WIFSIGNALED c = h2c $ fromEnum $ c_WIFSTOPPED c /= 0 && c_WIFEXITED c /= 0 c_WTERMSIG :: CInt -> CInt c_WTERMSIG c = h2c $ low7 $ c2h c c_WIFSTOPPED :: CInt -> CInt c_WIFSTOPPED c = h2c $ fromEnum $ low8 (c2h c) == 127 c_WSTOPSIG :: CInt -> CInt c_WSTOPSIG c = h2c $ high8 $ c2h c low7 x = x `rem` 128 low8 x = x `rem` 256 high8 x = x `div` 256 c2h = fromIntegral h2c = fromIntegral