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|
{-# LANGUAGE CPP #-}
------------------------------------------------------------------------------
-- |
-- Module: Xmobar.Run.Loop
-- Copyright: (c) 2022 Jose Antonio Ortega Ruiz
-- License: BSD3-style (see LICENSE)
--
-- Maintainer: jao@gnu.org
-- Stability: unstable
-- Portability: unportable
-- Created: Fri Jan 28, 2022 03:20
--
--
-- Running a thread for each defined Command in a loop
--
------------------------------------------------------------------------------
module Xmobar.Run.Loop (LoopFunction, loop) where
import Control.Concurrent (forkIO)
import Control.Exception (bracket_, bracket, handle, SomeException(..))
import Control.Concurrent.STM
import Control.Concurrent.Async (Async, async, cancel)
import Control.Monad (guard, void, unless)
import Data.Maybe (isJust)
import Data.Foldable (for_)
import Xmobar.System.Signal
import Xmobar.Config.Types
import Xmobar.Run.Runnable (Runnable)
import Xmobar.Run.Exec (start, trigger, alias)
import Xmobar.Run.Template
import Xmobar.Run.Timer (withTimer)
#ifdef DBUS
import Xmobar.System.DBus
#endif
newRefreshLock :: IO (TMVar ())
newRefreshLock = newTMVarIO ()
refreshLock :: TMVar () -> IO a -> IO a
refreshLock var = bracket_ lock unlock
where
lock = atomically $ takeTMVar var
unlock = atomically $ putTMVar var ()
refreshLockT :: TMVar () -> STM a -> STM a
refreshLockT var action = do
takeTMVar var
r <- action
putTMVar var ()
return r
type LoopFunction = TMVar SignalType -> TVar [String] -> IO ()
loop :: Config -> LoopFunction -> IO ()
loop conf looper = withDeferSignals $ do
cls <- mapM (parseTemplate (commands conf) (sepChar conf))
(splitTemplate (alignSep conf) (template conf))
let confSig = unSignalChan (signal conf)
sig <- maybe newEmptyTMVarIO pure confSig
unless (isJust confSig) $ setupSignalHandler sig
refLock <- newRefreshLock
withTimer (refreshLock refLock) $
bracket (mapM (mapM $ startCommand sig) cls)
cleanupThreads
$ \vars -> do
tv <- initLoop sig refLock vars
looper sig tv
cleanupThreads :: [[([Async ()], a)]] -> IO ()
cleanupThreads vars =
for_ (concat vars) $ \(asyncs, _) ->
for_ asyncs cancel
-- | Initialises context for an event loop, returning a TVar that
-- will hold the current list of values computed by commands.
initLoop :: TMVar SignalType -> TMVar () -> [[([Async ()], TVar String)]]
-> IO (TVar [String])
initLoop sig lock vs = do
tv <- newTVarIO ([] :: [String])
_ <- forkIO (handle (handler "checker") (checker tv [] vs sig lock))
#ifdef DBUS
runIPC sig
#endif
return tv
where
handler thing (SomeException e) =
void $ putStrLn ("Thread " ++ thing ++ " failed: " ++ show e)
-- | Runs a command as an independent thread and returns its Async handles
-- and the TVar the command will be writing to.
startCommand :: TMVar SignalType
-> (Runnable,String,String)
-> IO ([Async ()], TVar String)
startCommand sig (com,s,ss)
| alias com == "" = do var <- newTVarIO is
atomically $ writeTVar var (s ++ ss)
return ([], var)
| otherwise = do var <- newTVarIO is
let cb str = atomically $ writeTVar var (s ++ str ++ ss)
a1 <- async $ start com cb
a2 <- async $ trigger com $ maybe (return ())
(atomically . putTMVar sig)
return ([a1, a2], var)
where is = s ++ "Updating..." ++ ss
-- | Send signal to eventLoop every time a var is updated
checker :: TVar [String]
-> [String]
-> [[([Async ()], TVar String)]]
-> TMVar SignalType
-> TMVar ()
-> IO ()
checker tvar ov vs sig pauser = do
nval <- atomically $ refreshLockT pauser $ do
nv <- mapM concatV vs
guard (nv /= ov)
writeTVar tvar nv
return nv
atomically $ putTMVar sig Wakeup
checker tvar nval vs sig pauser
where
concatV = fmap concat . mapM (readTVar . snd)
|
