module Main where
import ZHelpers (setId)
import Control.Concurrent (forkIO, threadDelay)
import Control.Concurrent.MVar (withMVar, newMVar, MVar)
import Data.ByteString.Char8 (pack, unpack)
import Control.Monad (replicateM_)
nbrWorkers :: Int
nbrWorkers = 10
-- In general, although locks are an antipattern in ZeroMQ, we need a lock
-- for the stdout handle, otherwise we will get jumbled text. We don't //
-- use the lock for anything zeroMQ related, just output to screen.//
workerThread :: Context -> MVar () -> IO ()
workerThread ctx lock = withSocket ctx Req $ \worker -> do
connect worker "ipc://routing.ipc"
let work_func val = do
send worker (pack "ready") 
workload <- receive worker 
if unpack workload == "END"
then withMVar lock $ \_ -> putStrLn $ "Processed: " ++ show val ++ " tasks"
else work_func (val+1)
main :: IO ()
main = withContext 1 $ \context -> do
withSocket context XRep $ \client -> do
bind client "ipc://routing.ipc"
-- We only Need the MVar For Printing the Output (so output doesn't become interleaved)
-- The alternative is to Make an ipc channel, but that distracts from the example.
lock <- newMVar ()
replicateM_ nbrWorkers (forkIO (workerThread context lock))
let generalProc a = do
address <- receive client 
empty <- receive client 
ready <- receive client 
send client address [SndMore]
send client (pack "") [SndMore]
send client (pack a) 
replicateM_ (nbrWorkers * 10) (generalProc "This is the workload")
replicateM_ nbrWorkers (generalProc "END")
threadDelay $ 1 * 1000 * 1000