git-annex/Utility/Batch.hs
Joey Hess 1ffb3bb0ba add remote fsck interface
Currently only implemented for local git remotes. May try to add support
to git-annex-shell for ssh remotes later. Could concevably also be
supported by some special remote, although that seems unlikely.

Cronner user this when available, and when not falls back to
fsck --fast --from remote

git annex fsck --from does not itself use this interface.
To do so, I would need to pass --fast and all other options that influence
fsck on to the git annex fsck that it runs inside the remote. And that
seems like a lot of work for a result that would be no better than
cd remote; git annex fsck
This may need to be revisited if git-annex-shell gets support, since it
may be the case that the user cannot ssh to the server to run git-annex
fsck there, but can run git-annex-shell there.

This commit was sponsored by Damien Diederen.
2013-10-11 16:03:18 -04:00

68 lines
2 KiB
Haskell

{- Running a long or expensive batch operation niced.
-
- Copyright 2013 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Utility.Batch where
import Common
import qualified Build.SysConfig
#if defined(linux_HOST_OS) || defined(__ANDROID__)
import Control.Concurrent.Async
import System.Posix.Process
#endif
import qualified Control.Exception as E
{- Runs an operation, at batch priority.
-
- This is done by running it in a bound thread, which on Linux can be set
- to have a different nice level than the rest of the program. Note that
- due to running in a bound thread, some operations may be more expensive
- to perform. Also note that if the action calls forkIO or forkOS itself,
- that will make a new thread that does not have the batch priority.
-
- POSIX threads do not support separate nice levels, so on other operating
- systems, the action is simply ran.
-}
batch :: IO a -> IO a
#if defined(linux_HOST_OS) || defined(__ANDROID__)
batch a = wait =<< batchthread
where
batchthread = asyncBound $ do
setProcessPriority 0 maxNice
a
#else
batch a = a
#endif
maxNice :: Int
maxNice = 19
{- Runs a command in a way that's suitable for batch jobs.
- The command is run niced. If the calling thread receives an async
- exception, it sends the command a SIGTERM, and after the command
- finishes shuttting down, it re-raises the async exception. -}
batchCommand :: String -> [CommandParam] -> IO Bool
batchCommand command params = do
(_, _, _, pid) <- createProcess $ proc "sh"
[ "-c"
, "exec " ++ nicedcommand
]
r <- E.try (waitForProcess pid) :: IO (Either E.SomeException ExitCode)
case r of
Right ExitSuccess -> return True
Right _ -> return False
Left asyncexception -> do
terminateProcess pid
void $ waitForProcess pid
E.throwIO asyncexception
where
commandline = unwords $ map shellEscape $ command : toCommand params
nicedcommand
| Build.SysConfig.nice = "nice " ++ commandline
| otherwise = commandline