059daf4 · distributed-process

50-- [4] "Delivery of Messages", post on erlang-questions

51-- http://erlang.org/pipermail/erlang-questions/2012-February/064767.html

52module Control.Distributed.Process

53− ( -- * Cloud Haskell API

53+ ( -- * Basic cloud Haskell API

54 ProcessId

55 , Process

56 , expect

57 , send

58 , getSelfPid

59+ , monitorProcess

60+ , linkProcess

61+ -- * Monitoring

62+ , MonitorAction(..)

63+ , ProcessMonitorException(..)

64+ , SignalReason(..)

59 -- * Initialization

65 -- * Initialization

60 , newLocalNode

66 , newLocalNode

61 , forkProcess

67 , forkProcess

68 , fromChunks

74 , fromChunks

69 , splitAt

75 , splitAt

70 )

76 )

71−import Data.Binary (Binary, decode, encode, put, get)

77+import Data.Binary (Binary, decode, encode, put, get, getWord8, putWord8)

72import Data.Map (Map)

78import Data.Map (Map)

73import qualified Data.Map as Map (empty, lookup, insert, delete)

79import qualified Data.Map as Map (empty, lookup, insert, delete)

74import qualified Data.List as List (delete)

80import qualified Data.List as List (delete)

75import Data.Int (Int32)

81import Data.Int (Int32)

76import Data.Typeable (Typeable)

82import Data.Typeable (Typeable)

77−import Control.Monad (void, liftM2)

83+import Control.Monad (void, liftM, liftM2)

78import Control.Monad.Reader (MonadReader(..), ReaderT, runReaderT)

84import Control.Monad.Reader (MonadReader(..), ReaderT, runReaderT)

79import Control.Monad.IO.Class (MonadIO, liftIO)

85import Control.Monad.IO.Class (MonadIO, liftIO)

80import Control.Applicative ((<$>))

86import Control.Applicative ((<$>))

81import Control.Category ((>>>))

87import Control.Category ((>>>))

82−import Control.Exception (throwIO)

88+import Control.Exception (Exception, throwIO)

83import Control.Concurrent (forkIO)

89import Control.Concurrent (forkIO)

84import Control.Concurrent.MVar ( MVar

90import Control.Concurrent.MVar ( MVar

85 , newMVar

91 , newMVar

168 deriving (Functor, Monad, MonadIO, MonadReader ProcessState)

174 deriving (Functor, Monad, MonadIO, MonadReader ProcessState)

169

175

170--------------------------------------------------------------------------------

176--------------------------------------------------------------------------------

171−-- Cloud Haskell API --

177+-- Basic Cloud Haskell API --

172--------------------------------------------------------------------------------

178--------------------------------------------------------------------------------

173

179

174expect :: forall a. Serializable a => Process a

180expect :: forall a. Serializable a => Process a

192getSelfPid :: Process ProcessId

198getSelfPid :: Process ProcessId

193getSelfPid = processId <$> ask

199getSelfPid = processId <$> ask

194

200

201+monitorProcess :: ProcessId -> ProcessId -> MonitorAction -> Process ()

202+monitorProcess = undefined

203+

204+linkProcess :: ProcessId -> Process ()

205+linkProcess = undefined

206+

207+--------------------------------------------------------------------------------

208+-- Monitoring --

209+-- --

210+-- TODO: Many of these definitions are not available in the paper, and are --

211+-- taken from 'remote'. Do we want to stick to them precisely? --

212+--------------------------------------------------------------------------------

213+

214+-- | The different kinds of monitoring available between processes.

215+data MonitorAction =

216+ -- ^ MaMonitor means that the monitor process will be sent a

217+ -- ProcessMonitorException message when the monitee terminates for any

218+ -- reason.

219+ MaMonitor

220+ -- ^ MaLink means that the monitor process will receive an asynchronous

221+ -- exception of type ProcessMonitorException when the monitee terminates

222+ -- for any reason

223+ | MaLink

224+ -- ^ MaLinkError means that the monitor process will receive an

225+ -- asynchronous exception of type ProcessMonitorException when the monitee

226+ -- terminates abnormally

227+ | MaLinkError

228+ deriving (Typeable, Show, Ord, Eq)

229+

230+-- | The main form of notification to a monitoring process that a monitored

231+-- process has terminated. This data structure can be delivered to the monitor

232+-- either as a message (if the monitor is of type 'MaMonitor') or as an

233+-- asynchronous exception (if the monitor is of type 'MaLink' or

234+-- 'MaLinkError'). It contains the PID of the monitored process and the reason

235+-- for its nofication.

236+data ProcessMonitorException = ProcessMonitorException ProcessId SignalReason

237+ deriving (Typeable)

238+

239+-- | Part of the notification system of process monitoring, indicating why the

240+-- monitor is being notified.

241+data SignalReason =

242+ -- ^ the monitee terminated normally

243+ SrNormal

244+ -- ^ the monitee terminated with an uncaught exception, which is given as a

245+ -- string

246+ | SrException String

247+ -- ^ the monitee is believed to have ended or be inaccessible, as the node

248+ -- on which its running is not responding to pings. This may indicate a

249+ -- network bisection or that the remote node has crashed.

250+ | SrNoPing

251+ -- ^ SrInvalid: the monitee was not running at the time of the attempt to

252+ -- establish monitoring

253+ | SrInvalid

254+ deriving (Typeable,Show)

255+

256+instance Binary MonitorAction where

257+ put MaMonitor = putWord8 0

258+ put MaLink = putWord8 1

259+ put MaLinkError = putWord8 2

260+

261+ get = do x <- getWord8

262+ case x of

263+ 0 -> return MaMonitor

264+ 1 -> return MaLink

265+ 2 -> return MaLinkError

266+ _ -> fail "Invalid MonitorAction"

267+

268+instance Binary ProcessMonitorException where

269+ put (ProcessMonitorException pid sr) = put pid >> put sr

270+ get = liftM2 ProcessMonitorException get get

271+

272+instance Binary SignalReason where

273+ put SrNormal = putWord8 0

274+ put (SrException s) = putWord8 1 >> put s

275+ put SrNoPing = putWord8 2

276+ put SrInvalid = putWord8 3

277+

278+ get = do a <- getWord8

279+ case a of

280+ 0 -> return SrNormal

281+ 1 -> liftM SrException get

282+ 2 -> return SrNoPing

283+ 3 -> return SrInvalid

284+ _ -> fail "Invalid SignalReason"

285+

286+instance Exception ProcessMonitorException

287+

288+instance Show ProcessMonitorException where

289+ show (ProcessMonitorException pid why) =

290+ "ProcessMonitorException: "

291+ ++ show pid

292+ ++ " has terminated because "

293+ ++ show why

294+

195--------------------------------------------------------------------------------

295--------------------------------------------------------------------------------

196-- Initialization --

296-- Initialization --

197--------------------------------------------------------------------------------

297--------------------------------------------------------------------------------