git-annex/CmdLine/Action.hs
Joey Hess b6642dde8a
avoid interleaving command stages with Concurrency 1
Before, -J1 was different than no -J: It makes concurrent-output be used
for display, and it actually can run concurrent jobs in some situations.
Eg, a perform stage and a cleanup stage can both run.

dupState is used in several places, and changes NonConcurrent to
Concurrent 1. My concern is that this might, in some case, enable
that concurrent behavior. And in particular, that it might get enabled in
--batch mode, when the user is not expecting concurrent output because
they did not pass -J.

While I don't have a test case where that happens and causes out of
order output, it looks like it could, and so prudent to make this change.
2020-09-16 12:10:45 -04:00

282 lines
8.7 KiB
Haskell

{- git-annex command-line actions and concurrency
-
- Copyright 2010-2020 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE CPP, BangPatterns #-}
module CmdLine.Action where
import Annex.Common
import qualified Annex
import Annex.Concurrent
import Types.Command
import Types.Concurrency
import Messages.Concurrent
import Types.Messages
import Types.WorkerPool
import Control.Concurrent
import Control.Concurrent.Async
import Control.Concurrent.STM
import GHC.Conc
import qualified Data.Map.Strict as M
import qualified System.Console.Regions as Regions
{- Runs a command, starting with the check stage, and then
- the seek stage. Finishes by running the continutation, and
- then showing a count of any failures. -}
performCommandAction :: Command -> CommandSeek -> Annex () -> Annex ()
performCommandAction Command { cmdcheck = c, cmdname = name } seek cont = do
mapM_ runCheck c
Annex.changeState $ \s -> s { Annex.errcounter = 0 }
seek
finishCommandActions
cont
showerrcount =<< Annex.getState Annex.errcounter
where
showerrcount 0 = noop
showerrcount cnt = giveup $ name ++ ": " ++ show cnt ++ " failed"
commandActions :: [CommandStart] -> Annex ()
commandActions = mapM_ commandAction
{- Runs one of the actions needed to perform a command.
- Individual actions can fail without stopping the whole command,
- including by throwing non-async exceptions.
-
- When concurrency is enabled, a thread is forked off to run the action
- in the background, as soon as a free worker slot is available.
- This should only be run in the seek stage.
-}
commandAction :: CommandStart -> Annex ()
commandAction start = getConcurrency >>= \case
NonConcurrent -> runnonconcurrent
Concurrent n
| n > 1 -> runconcurrent
| otherwise -> runnonconcurrent
ConcurrentPerCpu -> runconcurrent
where
runnonconcurrent = void $ includeCommandAction start
runconcurrent = Annex.getState Annex.workers >>= \case
Nothing -> runnonconcurrent
Just tv ->
liftIO (atomically (waitStartWorkerSlot tv)) >>=
maybe runnonconcurrent (runconcurrent' tv)
runconcurrent' tv (workerst, workerstage) = do
aid <- liftIO $ async $ snd <$> Annex.run workerst
(concurrentjob workerst)
liftIO $ atomically $ do
pool <- takeTMVar tv
let !pool' = addWorkerPool (ActiveWorker aid workerstage) pool
putTMVar tv pool'
void $ liftIO $ forkIO $ debugLocks $ do
-- accountCommandAction will usually catch
-- exceptions. Just in case, fall back to the
-- original workerst.
workerst' <- either (const workerst) id
<$> waitCatch aid
atomically $ do
pool <- takeTMVar tv
let !pool' = deactivateWorker pool aid workerst'
putTMVar tv pool'
concurrentjob workerst = start >>= \case
Nothing -> noop
Just (startmsg, perform) ->
concurrentjob' workerst startmsg perform
concurrentjob' workerst startmsg perform = case mkActionItem startmsg of
OnlyActionOn k _ -> ensureOnlyActionOn k $
-- If another job performed the same action while we
-- waited, there may be nothing left to do, so re-run
-- the start stage to see if it still wants to do
-- something.
start >>= \case
Just (startmsg', perform') ->
case mkActionItem startmsg' of
OnlyActionOn k' _ | k' /= k ->
concurrentjob' workerst startmsg' perform'
_ -> beginjob workerst startmsg' perform'
Nothing -> noop
_ -> beginjob workerst startmsg perform
beginjob workerst startmsg perform =
inOwnConsoleRegion (Annex.output workerst) $ do
enteringInitialStage
void $ accountCommandAction startmsg $
performconcurrent startmsg perform
-- Like performCommandAction' but the worker thread's stage
-- is changed before starting the cleanup action.
performconcurrent startmsg perform = do
showStartMessage startmsg
perform >>= \case
Just cleanup -> enteringStage CleanupStage $ do
r <- cleanup
showEndMessage startmsg r
return r
Nothing -> do
showEndMessage startmsg False
return False
{- Waits for all worker threads to finish and merges their AnnexStates
- back into the current Annex's state.
-}
finishCommandActions :: Annex ()
finishCommandActions = Annex.getState Annex.workers >>= \case
Nothing -> noop
Just tv -> do
Annex.changeState $ \s -> s { Annex.workers = Nothing }
sts <- liftIO $ atomically $ do
pool <- readTMVar tv
if allIdle pool
then return (spareVals pool)
else retry
mapM_ mergeState sts
{- Waits for all worker threads that have been started so far to finish. -}
waitForAllRunningCommandActions :: Annex ()
waitForAllRunningCommandActions = Annex.getState Annex.workers >>= \case
Nothing -> noop
Just tv -> liftIO $ atomically $ do
pool <- readTMVar tv
unless (allIdle pool)
retry
{- Like commandAction, but without the concurrency. -}
includeCommandAction :: CommandStart -> CommandCleanup
includeCommandAction start =
start >>= \case
Nothing -> return True
Just (startmsg, perform) -> do
showStartMessage startmsg
accountCommandAction startmsg $
performCommandAction' startmsg perform
accountCommandAction :: StartMessage -> CommandCleanup -> CommandCleanup
accountCommandAction startmsg cleanup = tryNonAsync cleanup >>= \case
Right True -> return True
Right False -> incerr
Left err -> case fromException err of
Just exitcode -> liftIO $ exitWith exitcode
Nothing -> do
toplevelWarning True (show err)
showEndMessage startmsg False
incerr
where
incerr = do
Annex.incError
return False
{- Runs a single command action through the start, perform and cleanup
- stages, without catching errors and without incrementing error counter.
- Useful if one command wants to run part of another command. -}
callCommandAction :: CommandStart -> CommandCleanup
callCommandAction start = start >>= \case
Just (startmsg, perform) -> do
showStartMessage startmsg
performCommandAction' startmsg perform
Nothing -> return True
performCommandAction' :: StartMessage -> CommandPerform -> CommandCleanup
performCommandAction' startmsg perform =
perform >>= \case
Nothing -> do
showEndMessage startmsg False
return False
Just cleanup -> do
r <- cleanup
showEndMessage startmsg r
return r
{- Start concurrency when that has been requested.
- Should be run wrapping the seek stage of a command.
-
- Note that a duplicate of the Annex state is made here, and worker
- threads use that state. While the worker threads are not actually
- started here, that has the same effect.
-}
startConcurrency :: UsedStages -> Annex a -> Annex a
startConcurrency usedstages a = do
fromcmdline <- getConcurrency
fromgitcfg <- annexJobs <$> Annex.getGitConfig
let usegitcfg = setConcurrency (ConcurrencyGitConfig fromgitcfg)
case (fromcmdline, fromgitcfg) of
(NonConcurrent, NonConcurrent) -> a
(Concurrent n, _) ->
goconcurrent n
(ConcurrentPerCpu, _) ->
goconcurrentpercpu
(NonConcurrent, Concurrent n) -> do
usegitcfg
goconcurrent n
(NonConcurrent, ConcurrentPerCpu) -> do
usegitcfg
goconcurrentpercpu
where
goconcurrent n = do
raisecapabilitiesto n
withMessageState $ \s -> case outputType s of
NormalOutput -> ifM (liftIO concurrentOutputSupported)
( Regions.displayConsoleRegions $
goconcurrent' n True
, goconcurrent' n False
)
_ -> goconcurrent' n False
goconcurrent' n b = bracket_ (setup n b) cleanup a
goconcurrentpercpu = goconcurrent =<< liftIO getNumProcessors
setup n b = do
setconcurrentoutputenabled b
initworkerpool n
cleanup = do
finishCommandActions
setconcurrentoutputenabled False
setconcurrentoutputenabled b = Annex.changeState $ \s ->
s { Annex.output = (Annex.output s) { concurrentOutputEnabled = b } }
raisecapabilitiesto n = do
c <- liftIO getNumCapabilities
when (n > c) $
liftIO $ setNumCapabilities n
initworkerpool n = do
tv <- liftIO newEmptyTMVarIO
Annex.changeState $ \s -> s { Annex.workers = Just tv }
st <- dupState
liftIO $ atomically $ putTMVar tv $
allocateWorkerPool st (max n 1) usedstages
{- Ensures that only one thread processes a key at a time.
- Other threads will block until it's done.
-
- May be called repeatedly by the same thread without blocking. -}
ensureOnlyActionOn :: Key -> Annex a -> Annex a
ensureOnlyActionOn k a = debugLocks $
go =<< getConcurrency
where
go NonConcurrent = a
go (Concurrent _) = goconcurrent
go ConcurrentPerCpu = goconcurrent
goconcurrent = do
tv <- Annex.getState Annex.activekeys
bracket (setup tv) id (const a)
setup tv = liftIO $ do
mytid <- myThreadId
atomically $ do
m <- readTVar tv
case M.lookup k m of
Just tid
| tid /= mytid -> retry
| otherwise -> return $ return ()
Nothing -> do
writeTVar tv $! M.insert k mytid m
return $ liftIO $ atomically $
modifyTVar tv $ M.delete k