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{-# LANGUAGE MultiParamTypeClasses, TypeSynonymInstances #-}
{-# LANGUAGE PatternGuards #-}
-----------------------------------------------------------------------------
-- |
-- Module : XMonad.Layout.Stoppable
-- Copyright : (c) Anton Vorontsov <anton@enomsg.org> 2014
-- License : BSD-style (as xmonad)
--
-- Maintainer : Anton Vorontsov <anton@enomsg.org>
-- Stability : unstable
-- Portability : unportable
--
-- This module implements a special kind of layout modifier, which when
-- applied to a layout, causes xmonad to stop all non-visible processes.
-- In a way, this is a sledge-hammer for applications that drain power.
-- For example, given a web browser on a stoppable workspace, once the
-- workspace is hidden the web browser will be stopped.
--
-- Note that the stopped application won't be able to communicate with X11
-- clipboard. For this, the module actually stops applications after a
-- certain delay, giving a chance for a user to complete copy-paste
-- sequence. By default, the delay equals to 15 seconds, it is
-- configurable via 'Stoppable' constructor.
--
-- The stoppable modifier prepends a mark (by default equals to
-- \"Stoppable\") to the layout description (alternatively, you can choose
-- your own mark and use it with 'Stoppable' constructor). The stoppable
-- layout (identified by a mark) spans to multiple workspaces, letting you
-- to create groups of stoppable workspaces that only stop processes when
-- none of the workspaces are visible, and conversely, unfreezing all
-- processes even if one of the stoppable workspaces are visible.
--
-- To stop the process we use signals, which works for most cases. For
-- processes that tinker with signal handling (debuggers), another
-- (Linux-centric) approach may be used. See
-- <https://www.kernel.org/doc/Documentation/cgroups/freezer-subsystem.txt>
--
-----------------------------------------------------------------------------
module XMonad.Layout.Stoppable
( -- $usage
Stoppable(..)
, stoppable
) where
import XMonad
import XMonad.Actions.WithAll
import XMonad.Util.WindowProperties
import XMonad.Util.RemoteWindows
import XMonad.Util.Timer
import XMonad.StackSet hiding (filter)
import XMonad.Layout.LayoutModifier
import System.Posix.Signals
import Data.Maybe
import Control.Monad
-- $usage
-- You can use this module with the following in your @~\/.xmonad\/xmonad.hs@:
--
-- > import XMonad
-- > import XMonad.Layout.Stoppable
-- >
-- > main = xmonad def
-- > { layoutHook = layoutHook def ||| stoppable (layoutHook def) }
--
-- Note that the module has to distinguish between local and remote
-- proccesses, which means that it needs to know the hostname, so it looks
-- for environment variables (e.g. HOST).
--
-- Environment variables will work for most cases, but won't work if the
-- hostname changes. To cover dynamic hostnames case, in addition to
-- layoutHook you have to provide manageHook from
-- "XMonad.Util.RemoteWindows" module.
--
-- For more detailed instructions on editing the layoutHook see:
--
-- "XMonad.Doc.Extending#Editing_the_layout_hook"
signalWindow :: Signal -> Window -> X ()
signalWindow s w = do
pid <- getProp32s "_NET_WM_PID" w
io $ (signalProcess s . fromIntegral) `mapM_` fromMaybe [] pid
signalLocalWindow :: Signal -> Window -> X ()
signalLocalWindow s w = isLocalWindow w >>= flip when (signalWindow s w)
withAllOn :: (a -> X ()) -> Workspace i l a -> X ()
withAllOn f wspc = f `mapM_` integrate' (stack wspc)
withAllFiltered :: (Workspace i l a -> Bool)
-> [Workspace i l a]
-> (a -> X ()) -> X ()
withAllFiltered p wspcs f = withAllOn f `mapM_` filter p wspcs
sigStoppableWorkspacesHook :: String -> X ()
sigStoppableWorkspacesHook k = do
ws <- gets windowset
withAllFiltered isStoppable (hidden ws) (signalLocalWindow sigSTOP)
where
isStoppable ws = k `elem` words (description $ layout ws)
-- | Data type for ModifiedLayout. The constructor lets you to specify a
-- custom mark/description modifier and a delay. You can also use
-- 'stoppable' helper function.
data Stoppable a = Stoppable
{ mark :: String
, delay :: Rational
, timer :: Maybe TimerId
} deriving (Show,Read)
instance LayoutModifier Stoppable Window where
modifierDescription = mark
hook _ = withAll $ signalLocalWindow sigCONT
handleMess (Stoppable m _ (Just tid)) msg
| Just ev <- fromMessage msg = handleTimer tid ev run
where run = sigStoppableWorkspacesHook m >> return Nothing
handleMess (Stoppable m d _) msg
| Just Hide <- fromMessage msg =
(Just . Stoppable m d . Just) `liftM` startTimer d
| otherwise = return Nothing
-- | Convert a layout to a stoppable layout using the default mark
-- (\"Stoppable\") and a delay of 15 seconds.
stoppable :: l a -> ModifiedLayout Stoppable l a
stoppable = ModifiedLayout (Stoppable "Stoppable" 15 Nothing)
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