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|
-----------------------------------------------------------------------------
-- |
-- Module : Plugins.Monitors.Alsa
-- Copyright : (c) 2018 Daniel Schüssler
-- License : BSD-style (see LICENSE)
--
-- Maintainer : Jose A. Ortega Ruiz <jao@gnu.org>
-- Stability : unstable
-- Portability : unportable
--
-- Event-based variant of the Volume plugin.
--
-----------------------------------------------------------------------------
{-# LANGUAGE PatternGuards #-}
module Xmobar.Plugins.Monitors.Alsa
( startAlsaPlugin
, withMonitorWaiter
, parseOptsIncludingMonitorArgs
, AlsaOpts(aoAlsaCtlPath)
) where
import Control.Concurrent
import Control.Concurrent.Async
import Control.Exception
import Control.Monad
import Data.IORef
import Data.Time.Clock
import Xmobar.Plugins.Monitors.Common
import qualified Xmobar.Plugins.Monitors.Volume as Volume;
import System.Console.GetOpt
import System.Directory
import System.Exit
import System.IO
import System.IO.Error
import System.Process
alsaCtlRestartRateLimit :: NominalDiffTime
alsaCtlRestartRateLimit = 3 -- 'Num NominalDiffTime' assumes seconds
data AlsaOpts = AlsaOpts
{ aoVolumeOpts :: Volume.VolumeOpts
, aoAlsaCtlPath :: Maybe FilePath
}
defaultOpts :: AlsaOpts
defaultOpts = AlsaOpts Volume.defaultOpts Nothing
alsaCtlOptionName :: String
alsaCtlOptionName = "alsactl"
options :: [OptDescr (AlsaOpts -> AlsaOpts)]
options =
Option "" [alsaCtlOptionName] (ReqArg (\x o ->
o { aoAlsaCtlPath = Just x }) "") ""
: fmap (fmap modifyVolumeOpts) Volume.options
where
modifyVolumeOpts f o = o { aoVolumeOpts = f (aoVolumeOpts o) }
-- | Drop generic Monitor args first, then apply 'parseOptsWith' in order to
-- parse everything.
parseOptsIncludingMonitorArgs :: [String] -> IO AlsaOpts
parseOptsIncludingMonitorArgs args =
case getOpt Permute [] args of
(_, args', _) -> parseOptsWith options defaultOpts args'
startAlsaPlugin :: String -> String -> [String] -> (String -> IO ()) -> IO ()
startAlsaPlugin mixerName controlName args cb = do
opts <- parseOptsIncludingMonitorArgs args
let run args2 = do
-- Replicating the reparsing logic used by other plugins for now,
-- but it seems the option parsing could be floated out (actually,
-- GHC could in principle do it already since getOpt is pure, but
-- it would have to inline 'runMBD', 'doArgs' and 'parseOpts' to see
-- it, which probably isn't going to happen with the default
-- optimization settings).
opts2 <- io $ parseOptsWith options defaultOpts args2
Volume.runVolumeWith (aoVolumeOpts opts2) mixerName controlName
withMonitorWaiter mixerName (aoAlsaCtlPath opts) cb $ \wait_ ->
runMB args Volume.volumeConfig run wait_ cb
withMonitorWaiter :: String -> Maybe FilePath -> (String -> IO ()) -> (IO () -> IO a) -> IO a
withMonitorWaiter mixerName alsaCtlPathOverride outputCallback cont = do
mvar <- newMVar ()
effectivePath <- determineAlsaCtlPath
bracket (async $ alsaReaderThread mixerName effectivePath outputCallback mvar) cancel $ \a -> do
-- Throw on this thread if there's an exception
-- on the reader thread.
link a
cont $ takeMVar mvar
where
defaultPath = "/usr/sbin/alsactl"
determineAlsaCtlPath =
case alsaCtlPathOverride of
Just path -> do
found <- doesFileExist path
if found
then pure path
else throwIO . ErrorCall $
"Specified alsactl file " ++ path ++ " does not exist"
Nothing -> do
(ec, path, err) <- readProcessWithExitCode "which" ["alsactl"] ""
unless (null err) $ hPutStrLn stderr err
case ec of
ExitSuccess -> pure $ trimTrailingNewline path
ExitFailure _ -> do
found <- doesFileExist defaultPath
if found
then pure defaultPath
else throwIO . ErrorCall $
"alsactl not found in PATH or at " ++
show defaultPath ++
"; please specify with --" ++
alsaCtlOptionName ++ "=/path/to/alsactl"
alsaReaderThread :: String -> String -> (String -> IO a) -> MVar () -> IO b
alsaReaderThread mixerName alsaCtlPath outputCallback mvar =
let createProc = (proc "stdbuf" ["-oL", alsaCtlPath, "monitor", mixerName])
{std_out = CreatePipe}
runAlsaOnce =
withCreateProcess createProc $ \_ (Just alsaOut) _ _ -> do
hSetBuffering alsaOut LineBuffering
tryPutMVar mvar () -- Refresh immediately after restarting alsactl
forever $ do
c <- hGetChar alsaOut
when (c == '\n') $
-- This uses 'tryPutMVar' because 'putMVar' would make 'runVolume' run
-- once for each event. But we want it to run only once after a burst
-- of events.
void $ tryPutMVar mvar ()
in do
limiter <- createRateLimiter alsaCtlRestartRateLimit
forever $ do
limiter
catchJust
(guard . isEOFError)
runAlsaOnce
pure
outputCallback "Restarting alsactl..."
-- This is necessarily very inefficient on 'String's
trimTrailingNewline :: String -> String
trimTrailingNewline x =
case reverse x of
'\n' : '\r' : y -> reverse y
'\n' : y -> reverse y
_ -> x
-- |
-- Returns an IO action that completes at most once per @interval@.
-- The returned cation is not safe for concurrent use.
createRateLimiter :: NominalDiffTime -> IO (IO ())
createRateLimiter interval = do
prevTimeRef <- newIORef Nothing
let
limiter = do
prevTime0 <- readIORef prevTimeRef
curTime <- getCurrentTime
case prevTime0 of
Just prevTime | diff <- interval - (curTime `diffUTCTime` prevTime),
diff > 0
-> do
threadDelayNDT diff
writeIORef prevTimeRef . Just =<< getCurrentTime
_ -> writeIORef prevTimeRef (Just curTime)
pure limiter
threadDelayNDT :: NominalDiffTime -> IO ()
threadDelayNDT ndt =
threadDelay (round (realToFrac ndt * 1e6 :: Double))
|
