Use MVar over IORef

Prevents race conditions when updating the Maps
This commit is contained in:
1computer1 2019-07-12 02:53:10 -04:00
parent b9ae32c4c0
commit 08a1f272c6
3 changed files with 45 additions and 42 deletions

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@ -8,6 +8,7 @@ module Myriad.Core
, LanguageConfig(..)
, MyriadT
, MonadWithIO
, MyriadIO
, runMyriadT
, initEnv
) where
@ -23,8 +24,8 @@ import qualified Data.Text as T
import Dhall
import GHC.Generics (Generic)
import Control.Concurrent.MVar
import Control.Concurrent.QSem
import Data.IORef.Lifted
import Data.Snowflake
type Language = T.Text
@ -35,9 +36,9 @@ data EvalResult = EvalOk BL.ByteString | EvalTimedOut | EvalErrored
data Env = Env
{ config :: MyriadConfig
, containers :: IORef (M.Map Language ContainerName)
, containerSems :: IORef (M.Map Language QSem)
, evalSems :: IORef (M.Map Language QSem)
, containers :: MVar (M.Map Language ContainerName)
, containerSems :: MVar (M.Map Language QSem)
, evalSems :: MVar (M.Map Language QSem)
, snowflakeGen :: SnowflakeGen
}
@ -66,6 +67,8 @@ type MyriadT m = ReaderT Env (LoggingT m)
type MonadWithIO m = (MonadIO m, MonadBase IO m, MonadBaseControl IO m)
type MyriadIO a = forall m. MonadWithIO m => MyriadT m a
readConfig :: T.Text -> IO MyriadConfig
readConfig = input auto
@ -73,9 +76,9 @@ initEnv :: T.Text -> IO Env
initEnv configInput =
Env
<$> readConfig configInput
<*> newIORef M.empty
<*> newIORef M.empty
<*> newIORef M.empty
<*> newMVar M.empty
<*> newMVar M.empty
<*> newMVar M.empty
<*> newSnowflakeGen defaultConfig 0
runMyriadT :: MonadIO m => Env -> MyriadT m a -> m a

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@ -16,21 +16,21 @@ import Control.Monad.Reader
import qualified Data.Map.Strict as M
import Control.Concurrent.Lifted (fork, threadDelay)
import Control.Concurrent.Async.Lifted
import Control.Concurrent.Lifted (fork, threadDelay)
import Control.Concurrent.MVar.Lifted
import Control.Concurrent.QSem.Lifted
import Control.Exception.Lifted
import Data.IORef.Lifted
import Data.Snowflake
import System.Process.Typed
import Myriad.Core
import Myriad.Util
exec :: MonadWithIO m => String -> MyriadT m ()
exec :: String -> MyriadIO ()
exec = runProcess_ . shell
buildImage :: MonadWithIO m => LanguageConfig -> MyriadT m ()
buildImage :: LanguageConfig -> MyriadIO ()
buildImage lang@LanguageConfig { name, concurrent } = do
logInfoN $ mconcat ["Building image ", cvs $ imageName lang]
let cmd = mconcat ["docker build -t ", imageName lang, " ./languages/", cvs name]
@ -39,35 +39,35 @@ buildImage lang@LanguageConfig { name, concurrent } = do
Env { config = MyriadConfig { prepareContainers }, containerSems, evalSems } <- ask
csem <- newQSem 1 -- We only want one container to be set up at a time
esem <- newQSem $ fromIntegral concurrent
modifyIORef' containerSems $ M.insert name csem
modifyIORef' evalSems $ M.insert name esem
modifyMVar_ containerSems $ pure . M.insert name csem
modifyMVar_ evalSems $ pure . M.insert name esem
when_ prepareContainers $ setupContainer lang
buildAllImages :: MonadWithIO m => MyriadT m ()
buildAllImages :: MyriadIO ()
buildAllImages = do
MyriadConfig { languages, buildConcurrently } <- asks config
if buildConcurrently
then forConcurrently_ languages buildImage
else forM_ languages buildImage
startCleanup :: MonadWithIO m => MyriadT m ()
startCleanup :: MyriadIO ()
startCleanup = do
MyriadConfig { cleanupInterval } <- asks config
when_ (cleanupInterval > 0) do
let t = fromIntegral cleanupInterval * 60000000
fork $ timer t
where
timer :: MonadWithIO m => Int -> MyriadT m ()
timer :: Int -> MyriadIO ()
timer t = forever do
threadDelay t
n <- killAllContainersMaybe
logInfoN $ mconcat ["Cleaned up ", cvs $ show n, " containers"]
timer t
setupContainer :: MonadWithIO m => LanguageConfig -> MyriadT m ContainerName
setupContainer :: LanguageConfig -> MyriadIO ContainerName
setupContainer lang@LanguageConfig { name, memory, cpus } = do
ref <- asks containers
cnts <- readIORef ref
cnts <- readMVar ref
case cnts M.!? name of
Just x -> pure x
Nothing -> do
@ -91,60 +91,60 @@ setupContainer lang@LanguageConfig { name, memory, cpus } = do
-- 711 so that users can't traverse into other people's code
exec $ mconcat ["docker exec ", cnt, " mkdir eval"]
exec $ mconcat ["docker exec ", cnt, " chmod 711 eval"]
modifyIORef' ref $ M.insert name cnt
modifyMVar_ ref $ pure . M.insert name cnt
logInfoN $ mconcat ["Started container ", cvs cnt]
pure cnt
killContainer :: MonadWithIO m => Language -> MyriadT m ()
killContainer :: Language -> MyriadIO ()
killContainer lang = do
ref <- asks containers
containers <- readIORef ref
containers <- readMVar ref
case containers M.!? lang of
Nothing -> pure ()
Just cnt -> do
modifyIORef' ref $ M.delete lang
modifyMVar_ ref $ pure . M.delete lang
let cmd = mconcat ["docker kill ", cnt]
runProcess_ . setStderr nullStream . setStdout nullStream $ shell cmd
logInfoN $ mconcat ["Killed container ", cvs cnt]
killContainerMaybe :: MonadWithIO m => Language -> MyriadT m Bool
killContainerMaybe :: Language -> MyriadIO Bool
killContainerMaybe lang = do
containers <- asks containers >>= readIORef
containers <- asks containers >>= readMVar
case containers M.!? lang of
Nothing -> pure False
Just cnt -> do
res :: Either SomeException () <- try $ killContainer lang
res <- try @_ @SomeException $ killContainer lang
case res of
Left err -> do
logErrorN $ mconcat ["An exception occured when killing ", cvs cnt, ":\n", cvs $ show err]
pure False
Right _ -> pure True
killAllContainers :: MonadWithIO m => MyriadT m ()
killAllContainers :: MyriadIO ()
killAllContainers = do
containers <- asks containers >>= readIORef
containers <- asks containers >>= readMVar
forConcurrently_ (M.keys containers) $ killContainer
killAllContainersMaybe :: MonadWithIO m => MyriadT m [ContainerName]
killAllContainersMaybe :: MyriadIO [ContainerName]
killAllContainersMaybe = do
containers <- asks containers >>= readIORef
containers <- asks containers >>= readMVar
xs <- forConcurrently (M.toList containers) \(k, v) -> (v,) <$> killContainerMaybe k
pure . map fst $ filter snd xs
evalCode :: MonadWithIO m => LanguageConfig -> Int -> String -> MyriadT m EvalResult
evalCode :: LanguageConfig -> Int -> String -> MyriadIO EvalResult
evalCode lang@LanguageConfig { name, timeout, retries } numRetries code = do
Env { containerSems, evalSems } <- ask
csem <- (M.! name) <$> readIORef containerSems
esem <- (M.! name) <$> readIORef evalSems
csem <- (M.! name) <$> readMVar containerSems
esem <- (M.! name) <$> readMVar evalSems
bracket_ (waitQSem esem) (signalQSem esem) $ do
cnt <- bracket_ (waitQSem csem) (signalQSem csem) $ setupContainer lang
doneRef <- newIORef False -- For keeping track of if the evaluation is done, i.e. succeeded or timed out.
doneRef <- newMVar False -- For keeping track of if the evaluation is done, i.e. succeeded or timed out.
void . fork $ timer doneRef -- `race` could not have been used here since some evals can't be cancelled.
res <- try $ eval cnt
case res of
Left (SomeException err) -> do
void $ killContainerMaybe name
done <- readIORef doneRef
done <- readMVar doneRef
if done
-- If we find the eval is done from an exception, then it was timed out.
then do
@ -152,25 +152,25 @@ evalCode lang@LanguageConfig { name, timeout, retries } numRetries code = do
pure EvalTimedOut
-- Otherwise, the container was killed from another eval, so we should retry.
else do
writeIORef doneRef True
modifyMVar_ doneRef $ pure . const True
if numRetries < fromIntegral retries
then evalCode lang (numRetries + 1) code
else do
logErrorN $ mconcat ["An exception occured when evaluating in ", cvs cnt, ":\n", cvs $ show err]
pure EvalErrored
Right x -> do
writeIORef doneRef True
modifyMVar_ doneRef $ pure . const True
pure x
where
timer :: MonadWithIO m => IORef Bool -> MyriadT m ()
timer :: MVar Bool -> MyriadIO ()
timer doneRef = do
threadDelay $ fromIntegral timeout * 1000000
done <- readIORef doneRef
done <- readMVar doneRef
unless_ done do
writeIORef doneRef True
modifyMVar_ doneRef $ pure . const True
killContainerMaybe name
eval :: MonadWithIO m => ContainerName -> MyriadT m EvalResult
eval :: ContainerName -> MyriadIO EvalResult
eval cnt = do
logInfoN $ mconcat ["Running code in container ", cvs cnt, ":\n", cvs code]
snowflakeGen <- asks snowflakeGen

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@ -15,7 +15,7 @@ import qualified Data.Text as T
import GHC.Generics
import Control.Concurrent.Async.Lifted
import Data.IORef.Lifted
import Control.Concurrent.MVar.Lifted
import Servant
import Myriad.Core
@ -62,7 +62,7 @@ serverT = handleLanguages :<|> handleEval :<|> handleContainers :<|> handleClean
handleContainers :: MyriadT m [T.Text]
handleContainers = do
logInfoN $ mconcat ["GET /containers"]
containers <- asks containers >>= readIORef
containers <- asks containers >>= readMVar
pure . map cvs $ M.elems containers
handleCleanup :: MyriadT m [T.Text]