miniplex (empty) → 0.2.1

raw patch · 9 files changed

+922/−0 lines, 9 filesdep +basedep +mtldep +networkbuild-type:Customsetup-changed

Dependencies added: base, mtl, network, stm, unix

Files

• LICENSE +504/−0
• Setup.lhs +3/−0
• bin/plox-read.hs +24/−0
• bin/plox-write.hs +34/−0
• lib/System/Miniplex.hs +41/−0
• lib/System/Miniplex/Sekrit.hs +69/−0
• lib/System/Miniplex/Sink.hs +144/−0
• lib/System/Miniplex/Source.hs +73/−0
• miniplex.cabal +30/−0

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@@ -0,0 +1,3 @@+#!/usr/bin/env runhaskell+> import Distribution.Simple+> main = defaultMain

@@ -0,0 +1,24 @@+import qualified System.Miniplex as MP+import System.Environment+import System.Exit+import System.IO++usage :: IO ()+usage = do+    self <- getProgName+    hPutStr stderr $ "Usage: " ++ self ++ " TAG\n"+    exitFailure++main :: IO ()+main = do+    args <- getArgs+    case args of+        [tag] -> do+            hSetBuffering stdout LineBuffering+            MP.withSource tag service+        _ -> usage++service :: MP.Source -> IO ()+service s = do+    msgs <- MP.getMsgs s+    mapM_ putStrLn msgs

@@ -0,0 +1,34 @@+import qualified System.Miniplex as MP+import System.Environment+import System.Exit+import System.IO+import System.Posix.Process+import System.Posix.Signals++usage :: IO ()+usage = do+    self <- getProgName+    hPutStr stderr $ "Usage: " ++ self ++ " TAG\n"+    exitFailure++main :: IO ()+main = do+    installHandler floatingPointException (Catch (raiseSignal internalAbort)) Nothing+    installHandler openEndedPipe Ignore Nothing+    args <- getArgs+    case args of+        [tag] -> MP.withSink tag service+        _ -> usage++service :: MP.Sink -> IO ()+service s = do+    mapM_ (\x -> installHandler x (Catch (hdl x)) Nothing) signals+    t <- getContents+    mapM_ (MP.write s) (lines t)+    where+    hdl sig = do+        MP.destroy s+        installHandler sig Default Nothing+        raiseSignal sig+        exitImmediately (ExitFailure 127)+    signals = [sigINT, sigALRM, sigTERM, sigUSR1, sigUSR2]

@@ -0,0 +1,41 @@+-- | Semisynchronous interprocess communication.+module System.Miniplex (+	module System.Miniplex.Sink,+	module System.Miniplex.Source+-- * Overview+--+-- $over++-- * Implementation+--+-- $impl+) where++import System.Miniplex.Sink+import System.Miniplex.Source++-- $over+-- This module provides interprocess communication channels. This is meant+-- to be used by logger-like programs that want to send status reports to+-- N listeners (where N >= 0).+--+-- Such a logger would 'create' a 'Sink' with a certain tag and just start+-- writing messages to it. Then, at any point a client knowing the tag can+-- 'attach' a 'Source' and receive those messages -- until it disconnects.+-- This is all completely transparent to the logger.+--+-- Because each message is intended to be a complete status update, 'write'+-- does not buffer unsent messages: A client that is not ready to read when+-- a new message arrives will simply skip it (and hopefully continue+-- processing with the next message). However, there is one exception to+-- this rule: A 'Sink' remembers the last message sent and repeats it+-- to newly connected clients. Therefore a client will always receive a+-- message immediately after connecting unless the logger hasn't sent+-- anything so far.++-- $impl+-- The implementation is based on named sockets. Specifically, @'create'+-- \"tag\"@ creates the socket @~\/.miniplex\/tag@. It also spawns a thread+-- to watch it, which in turn spawns one thread per connected client.+-- 'attach' simply connects to this socket; no threads are spawned by+-- "System.Miniplex.Source".

@@ -0,0 +1,69 @@+module System.Miniplex.Sekrit (+    pathFromTag+    , reallySend+    , reallyRecv+    , bytesFromInt+    , intFromBytes+    , closeOnExec+) where++import Foreign.C.Error+import Network.Socket+import Data.Bits+import System.Directory+import System.Posix.IO+import System.Posix.Types++good :: String -> Bool+good s = not (null s) && head s /= '.' && all (`elem` chs) s+    where+    chs =+        ['a' .. 'z'] ++ ['A' .. 'Z'] ++ ['0' .. '9'] ++ ",$=-#%.+_^&'@~()[]{}"++pathFromTag :: String -> String -> IO String+pathFromTag context what+    | not $ good what =+        ioError $ errnoToIOError context eADDRNOTAVAIL Nothing (Just what)+    | otherwise = do+        dir <- getAppUserDataDirectory "miniplex"+        createDirectoryIfMissing False dir+        return $ dir ++ "/" ++ what++reallySend :: Socket -> String -> IO ()+reallySend sock str = step (length str) str+    where+    step n msg+        | n <= 0 = return ()+        | otherwise = do+            w <- send sock msg+            step (n - w) (drop w msg)++reallyRecv :: Socket -> Int -> IO String+reallyRecv sock = step+    where+    step n+        | n <= 0 = return ""+        | otherwise = do+            (s, r) <- recvLen sock n+            t <- step (n - r)+            return (s ++ t)++bytesFromInt :: Int -> String+bytesFromInt n = map (toEnum . (.&.) 255 . shiftR n . (*) 8) . reverse $ [0 .. 3]++intFromBytes :: String -> Int+intFromBytes = sum . zipWith (\n c -> fromEnum c `shiftL` (8 * n)) (reverse [0 .. 3])++closeOnExec :: Socket -> IO ()+closeOnExec (MkSocket fd _ _ _ _) =+    setFdOption (Fd fd) CloseOnExec True++{-+killSocket :: Socket -> IO ()+killSocket s = do+    bracket+        (openFd "/dev/null" WriteOnly Nothing defaultFileFlags)+        closeFd+        (`dupTo` Fd (fdSocket s))+    return ()+-}

@@ -0,0 +1,144 @@+{-# OPTIONS_GHC -fglasgow-exts #-}++-- | Asynchronous message broadcasting.+module System.Miniplex.Sink (+-- * Caveat+--+-- | This module performs writes on sockets that may be closed at any time,+-- triggering @SIGPIPE@ signals. It is therefore recommended that you call+-- @'System.Posix.Signals.installHandler' 'System.Posix.Signals.openEndedPipe'+-- 'System.Posix.Signals.Ignore' 'Nothing'@ at the beginning of your+-- program.+    Sink,+    create,+    write,+    destroy,+    withSink+) where++import System.Miniplex.Sekrit+import Prelude hiding (catch)+import Data.Typeable+import Data.List+import Control.Concurrent+import Control.Concurrent.STM+import Control.Exception+import Control.Monad+import Control.Monad.Fix+import System.Directory+import qualified Network as N+import Network.Socket++data Rend a = EOF | Empty | Some a++data Sink = Sink {+    name :: !String,+    sock :: !Socket,+    ctrl :: !(TVar [TVar (Rend String)]),+    acct :: !ThreadId,+    zmsg :: !(TVar (Maybe String))+} deriving (Typeable)++loop :: (Monad m) => m Bool -> m ()+loop m = fix $ \self -> m >>= flip when self++xsend :: Socket -> String -> IO ()+xsend s str =+    {- bracket+        (installHandler openEndedPipe Ignore Nothing)+        (\h -> installHandler openEndedPipe h Nothing)+        (\_ -> -} reallySend s (bytesFromInt (length str) ++ str) {- ) -}++finallyClose :: Socket -> IO a -> IO a+finallyClose s x = x `finally` sClose s++forkClose :: Socket -> IO () -> IO ThreadId+forkClose s x =+    forkIO $ finallyClose s $ handleJust ioErrors (const $ return ()) x++barghest :: Socket -> TVar [TVar (Rend String)] -> TVar (Maybe String) -> IO ()+barghest s cp zp = loop conn+    where+    conn = block $ do+        (t, _) <- accept s+        forkClose t $ unblock $ do+            v <- atomically (newTVar Empty)+            spawn t v+        return True+    spawn t v = do+        shutdown t ShutdownReceive+        z <- atomically $ readTVar zp+        maybe  (return ()) (xsend t) z+        block $ do+            atomically $ do+                vs <- readTVar cp+                writeTVar cp (v : vs)+            unblock (loop body) `finally`+                atomically (readTVar cp >>= writeTVar cp . delete v)+        where+        body = join . atomically $ do+            x <- readTVar v+            case x of+                EOF -> return (return False)+                Empty -> retry+                Some str -> do+                    writeTVar v Empty+                    return $ xsend t str >> return True++-- | @'create' tag@ creates a message sink. @tag@ is used to uniquely+-- identify this sink. The set of allowed characters for @tag@ includes+-- letters, digits, @_@, @-@ and @+@.+--+-- (Implementation detail: This function actually creates a named socket+-- in your @~\/.miniplex\/@.)+create :: String -> IO Sink+create what = do+    n <- pathFromTag "System.Miniplex.Sink.create" what+    s <- N.listenOn (N.UnixSocket n)+    closeOnExec s+    vs <- atomically $ newTVar []+    z <- atomically $ newTVar Nothing+    t <- forkClose s (barghest s vs z)+    return $ Sink+        { name = n+        , sock = s+        , ctrl = vs+        , acct = t+        , zmsg = z+        }++-- | @'write' si msg@ asynchronously writes @msg@ to @si@, where it will be+-- received by all currently connected readers.+write :: Sink -> String -> IO ()+write si str =+    atomically $ do+        writeTVar (zmsg si) (Just str)+        vs <- readTVar (ctrl si)+        mapM_ (flip writeTVar msg) vs+    where+    msg = Some str++-- | Deallocates a sink. The destroyed sink must not be used again.+--+-- (Implementation detail: This function closes and removes the socket from+-- the file system. If you forget to call it, you'll leave a stale entry in+-- @~\/.miniplex\/@, which will cause calls to 'create' with the same tag to+-- fail.)+destroy :: Sink -> IO ()+destroy si = do+    removeFile (name si)+    killThread (acct si)+    atomically $ do+        vs <- readTVar c+        mapM_ (flip writeTVar EOF) vs+        writeTVar c []+    where+    c = ctrl si++-- | Helper function to simplify resource handling. @'withSink' tag body@+-- creates a sink, calls @body@, then destroys the sink, even if @body@+-- throws an exception.+withSink :: String -> (Sink -> IO a) -> IO a+withSink t f = block $ do+    si <- create t+    unblock (f si) `finally` destroy si

@@ -0,0 +1,73 @@+{-# OPTIONS_GHC -fglasgow-exts #-}++-- | Synchronous message receiving.+module System.Miniplex.Source (+    Source,+    attach,+    read,+    getMsgs,+    detach,+    withSource+) where++import System.Miniplex.Sekrit++import Prelude hiding (read)++import Control.Exception+import Control.Monad+import Control.Monad.Reader ()++import Data.Typeable++import Network.Socket++import System.IO.Unsafe++newtype Source = Source {+    sock :: Socket+} deriving (Typeable)++-- | @'attach' tag@ returns a message source connected to the sink created by+-- a call to @'System.Miniplex.Sink.create' tag@. If no such sink exists, an+-- exception is thrown.+attach :: String -> IO Source+attach what = do+    n <- pathFromTag "System.Miniplex.Source.attach" what+    bracketOnError+        (socket AF_UNIX Stream 0)+        sClose+        $ \s -> do+            closeOnExec s+            connect s (SockAddrUnix n)+            shutdown s ShutdownSend+            return $ Source {sock = s}++-- | Synchronously reads a message from a source (i.e. it blocks if there is+-- currently no message available).+read :: Source -> IO String+read so = do+    n <- liftM intFromBytes $ reallyRecv s 4+    reallyRecv s n+    where+    s = sock so++-- | Returns a lazy list of all messages arriving at a source (like+-- @'System.IO.hGetContents'@).+getMsgs :: Source -> IO [String]+getMsgs so = unsafeInterleaveIO . handle (\_ -> detach so >> return []) $+    liftM2 (liftM2 (:)) read getMsgs so++-- | Disconnects from a message sink. The detached source becomes invalid+-- and must not be used again.+detach :: Source -> IO ()+detach so = do+    sClose (sock so)++-- | Helper function to simplify resource handling. @'withSource' tag body@+-- creates a source, calls @body@, then disconnects the source, even if+-- @body@ throws an exception.+withSource :: String -> (Source -> IO a) -> IO a+withSource tag f = block $ do+    so <- attach tag+    unblock (f so) `finally` detach so

@@ -0,0 +1,30 @@+name: miniplex+version: 0.2.1+license: LGPL+license-file: LICENSE+author: Lukas Mai+maintainer: Lukas Mai <l.mai@web.de>+stability: experimental+category: System+synopsis: simple 1-to-N interprocess communication+description:+    This module provides interprocess communication channels. This is meant+    to be used by logger-like programs that want to send status reports to+    N listeners (where N >= 0).+exposed-modules: System.Miniplex, System.Miniplex.Source, System.Miniplex.Sink+other-modules: System.Miniplex.Sekrit+hs-source-dirs: lib+build-depends: base, network, stm, unix, mtl+ghc-options: -Wall++executable: plox-read+hs-source-dirs: bin, lib+main-is: plox-read.hs+other-modules: System.Miniplex+ghc-options: -Wall++executable: plox-write+hs-source-dirs: bin, lib+main-is: plox-write.hs+other-modules: System.Miniplex+ghc-options: -Wall