5a9842d7ed
I couldn't find a way to avoid the deadlock w/o rewriting it to clearly not have one. I'm not quite sure what was the actual cause of the deadlock. This makes me unsure how I now know it clearly doesn't have a deadlock. But, it was easy to reproduce before (just call it twice in a row) and doesn't happen now.
334 lines
11 KiB
Haskell
334 lines
11 KiB
Haskell
{- git-annex command-line actions and concurrency
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-
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- Copyright 2010-2019 Joey Hess <id@joeyh.name>
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-
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- Licensed under the GNU AGPL version 3 or higher.
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-}
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{-# LANGUAGE CPP, BangPatterns #-}
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module CmdLine.Action where
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import Annex.Common
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import qualified Annex
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import Annex.Concurrent
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import Types.Command
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import Types.Concurrency
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import Messages.Concurrent
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import Types.Messages
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import Types.WorkerPool
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import Remote.List
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import Control.Concurrent
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import Control.Concurrent.Async
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import Control.Concurrent.STM
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import GHC.Conc
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import qualified Data.Map.Strict as M
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import qualified System.Console.Regions as Regions
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{- Runs a command, starting with the check stage, and then
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- the seek stage. Finishes by running the continutation, and
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- then showing a count of any failures. -}
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performCommandAction :: Command -> CommandSeek -> Annex () -> Annex ()
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performCommandAction Command { cmdcheck = c, cmdname = name } seek cont = do
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mapM_ runCheck c
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Annex.changeState $ \s -> s { Annex.errcounter = 0 }
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seek
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finishCommandActions
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cont
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showerrcount =<< Annex.getState Annex.errcounter
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where
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showerrcount 0 = noop
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showerrcount cnt = giveup $ name ++ ": " ++ show cnt ++ " failed"
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commandActions :: [CommandStart] -> Annex ()
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commandActions = mapM_ commandAction
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{- Runs one of the actions needed to perform a command.
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- Individual actions can fail without stopping the whole command,
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- including by throwing non-async exceptions.
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-
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- When concurrency is enabled, a thread is forked off to run the action
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- in the background, as soon as a free worker slot is available.
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- This should only be run in the seek stage.
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-}
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commandAction :: CommandStart -> Annex ()
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commandAction start = Annex.getState Annex.concurrency >>= \case
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NonConcurrent -> void $ includeCommandAction start
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Concurrent n -> runconcurrent n
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ConcurrentPerCpu -> runconcurrent =<< liftIO getNumProcessors
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where
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runconcurrent n = do
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tv <- Annex.getState Annex.workers
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workerst <- waitWorkerSlot n PerformStage tv
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aid <- liftIO $ async $ snd <$> Annex.run workerst
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(concurrentjob workerst)
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liftIO $ atomically $ do
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pool <- takeTMVar tv
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let !pool' = addWorkerPool (ActiveWorker aid PerformStage) pool
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putTMVar tv pool'
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void $ liftIO $ forkIO $ debugLocks $ do
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-- accountCommandAction will usually catch
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-- exceptions. Just in case, fall back to the
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-- original workerst.
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workerst' <- either (const workerst) id
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<$> waitCatch aid
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atomically $ do
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pool <- takeTMVar tv
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let !pool' = deactivateWorker pool aid workerst'
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putTMVar tv pool'
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concurrentjob workerst = start >>= \case
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Nothing -> noop
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Just (startmsg, perform) ->
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concurrentjob' workerst startmsg perform
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concurrentjob' workerst startmsg perform = case mkActionItem startmsg of
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OnlyActionOn k _ -> ensureOnlyActionOn k $
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-- If another job performed the same action while we
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-- waited, there may be nothing left to do, so re-run
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-- the start stage to see if it still wants to do
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-- something.
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start >>= \case
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Just (startmsg', perform') ->
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case mkActionItem startmsg' of
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OnlyActionOn k' _ | k' /= k ->
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concurrentjob' workerst startmsg' perform'
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_ -> mkjob workerst startmsg' perform'
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Nothing -> noop
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_ -> mkjob workerst startmsg perform
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mkjob workerst startmsg perform =
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inOwnConsoleRegion (Annex.output workerst) $
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void $ accountCommandAction startmsg $
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performconcurrent startmsg perform
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-- Like performCommandAction' but the worker thread's stage
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-- is changed before starting the cleanup action.
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performconcurrent startmsg perform = do
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showStartMessage startmsg
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perform >>= \case
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Just cleanup -> do
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changeStageTo CleanupStage
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r <- cleanup
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showEndMessage startmsg r
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return r
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Nothing -> do
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showEndMessage startmsg False
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return False
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-- | Wait until there's an idle worker in the pool, remove it from the
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-- pool, and return its state.
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--
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-- If the pool is unallocated, it will be allocated to the specified size.
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waitWorkerSlot :: Int -> WorkerStage -> TMVar (WorkerPool Annex.AnnexState) -> Annex Annex.AnnexState
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waitWorkerSlot n wantstage tv = debugLocks $
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join $ liftIO $ atomically $ waitWorkerSlot' wantstage tv >>= \case
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Nothing -> return $ do
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-- Generate the remote list now, to avoid
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-- each thread generating it, which would
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-- be more expensive and could cause
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-- threads to contend over eg, calls to
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-- setConfig.
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_ <- remoteList
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st <- dupState
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liftIO $ atomically $ do
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let (WorkerPool l) = allocateWorkerPool st (max n 1)
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let (st', pool) = findidle st [] l
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void $ swapTMVar tv pool
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return st'
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Just st -> return $ return st
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where
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findidle st _ [] = (st, WorkerPool [])
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findidle _ c ((IdleWorker st stage):rest)
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| stage == wantstage = (st, WorkerPool (c ++ rest))
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findidle st c (w:rest) = findidle st (w:c) rest
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-- | STM action that waits until there's an idle worker in the worker pool,
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-- removes it from the pool, and returns its state.
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--
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-- If the worker pool is not already allocated, returns Nothing.
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waitWorkerSlot' :: WorkerStage -> TMVar (WorkerPool Annex.AnnexState) -> STM (Maybe (Annex.AnnexState))
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waitWorkerSlot' wantstage tv =
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takeTMVar tv >>= \case
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UnallocatedWorkerPool -> do
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putTMVar tv UnallocatedWorkerPool
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return Nothing
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WorkerPool l -> do
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(st, pool') <- waitWorkerSlot'' wantstage l
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putTMVar tv pool'
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return $ Just st
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waitWorkerSlot'' :: WorkerStage -> [Worker Annex.AnnexState] -> STM (Annex.AnnexState, WorkerPool Annex.AnnexState)
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waitWorkerSlot'' wantstage = findidle []
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where
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findidle _ [] = retry
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findidle c ((IdleWorker st stage):rest)
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| stage == wantstage = return (st, WorkerPool (c ++ rest))
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findidle c (w:rest) = findidle (w:c) rest
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{- Waits for all worker threads to finish and merges their AnnexStates
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- back into the current Annex's state.
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-}
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finishCommandActions :: Annex ()
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finishCommandActions = do
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tv <- Annex.getState Annex.workers
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pool <- liftIO $ atomically $
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swapTMVar tv UnallocatedWorkerPool
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case pool of
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UnallocatedWorkerPool -> noop
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WorkerPool l -> forM_ (mapMaybe workerAsync l) $ \aid ->
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liftIO (waitCatch aid) >>= \case
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Left _ -> noop
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Right st -> mergeState st
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{- Changes the current thread's stage in the worker pool.
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-
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- The pool needs to continue to contain the same number of worker threads
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- for each stage. So, an idle worker with the desired stage is found in
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- the pool (waiting if necessary for one to become idle), and the stages
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- of it and the current thread are swapped.
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-
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- Noop if the current thread already has the requested stage, or if the
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- current thread is not in the worker pool, or if concurrency is not
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- enabled.
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-}
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changeStageTo :: WorkerStage -> Annex ()
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changeStageTo newstage = debugLocks $ do
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mytid <- liftIO myThreadId
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tv <- Annex.getState Annex.workers
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liftIO $ atomically $ do
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pool <- takeTMVar tv
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case removeThreadIdWorkerPool mytid pool of
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Just ((myaid, oldstage), WorkerPool l)
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| oldstage /= newstage -> do
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(idlest, restpool) <- waitWorkerSlot'' newstage l
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let pool' = addWorkerPool (IdleWorker idlest oldstage) $
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addWorkerPool (ActiveWorker myaid newstage) restpool
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putTMVar tv pool'
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_ -> putTMVar tv pool
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{- Like commandAction, but without the concurrency. -}
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includeCommandAction :: CommandStart -> CommandCleanup
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includeCommandAction start =
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start >>= \case
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Nothing -> return True
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Just (startmsg, perform) -> do
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showStartMessage startmsg
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accountCommandAction startmsg $
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performCommandAction' startmsg perform
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accountCommandAction :: StartMessage -> CommandCleanup -> CommandCleanup
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accountCommandAction startmsg cleanup = tryNonAsync cleanup >>= \case
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Right True -> return True
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Right False -> incerr
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Left err -> case fromException err of
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Just exitcode -> liftIO $ exitWith exitcode
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Nothing -> do
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toplevelWarning True (show err)
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showEndMessage startmsg False
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incerr
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where
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incerr = do
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Annex.incError
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return False
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{- Runs a single command action through the start, perform and cleanup
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- stages, without catching errors and without incrementing error counter.
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- Useful if one command wants to run part of another command. -}
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callCommandAction :: CommandStart -> CommandCleanup
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callCommandAction = fromMaybe True <$$> callCommandAction'
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{- Like callCommandAction, but returns Nothing when the command did not
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- perform any action. -}
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callCommandAction' :: CommandStart -> Annex (Maybe Bool)
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callCommandAction' start =
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start >>= \case
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Nothing -> return Nothing
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Just (startmsg, perform) -> do
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showStartMessage startmsg
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Just <$> performCommandAction' startmsg perform
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performCommandAction' :: StartMessage -> CommandPerform -> CommandCleanup
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performCommandAction' startmsg perform =
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perform >>= \case
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Nothing -> do
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showEndMessage startmsg False
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return False
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Just cleanup -> do
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r <- cleanup
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showEndMessage startmsg r
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return r
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{- Do concurrent output when that has been requested. -}
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allowConcurrentOutput :: Annex a -> Annex a
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allowConcurrentOutput a = do
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fromcmdline <- Annex.getState Annex.concurrency
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fromgitcfg <- annexJobs <$> Annex.getGitConfig
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let usegitcfg = Annex.changeState $
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\c -> c { Annex.concurrency = fromgitcfg }
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case (fromcmdline, fromgitcfg) of
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(NonConcurrent, NonConcurrent) -> a
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(Concurrent n, _) -> do
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raisecapabilitiesto n
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goconcurrent
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(ConcurrentPerCpu, _) -> goconcurrent
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(NonConcurrent, Concurrent n) -> do
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usegitcfg
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raisecapabilitiesto n
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goconcurrent
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(NonConcurrent, ConcurrentPerCpu) -> do
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usegitcfg
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goconcurrent
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where
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goconcurrent = do
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withMessageState $ \s -> case outputType s of
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NormalOutput -> ifM (liftIO concurrentOutputSupported)
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( Regions.displayConsoleRegions $
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goconcurrent' True
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, goconcurrent' False
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)
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_ -> goconcurrent' False
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goconcurrent' b = bracket_ (setup b) cleanup a
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setup = setconcurrentoutputenabled
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cleanup = do
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finishCommandActions
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setconcurrentoutputenabled False
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setconcurrentoutputenabled b = Annex.changeState $ \s ->
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s { Annex.output = (Annex.output s) { concurrentOutputEnabled = b } }
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raisecapabilitiesto n = do
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c <- liftIO getNumCapabilities
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when (n > c) $
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liftIO $ setNumCapabilities n
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{- Ensures that only one thread processes a key at a time.
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- Other threads will block until it's done.
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-
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- May be called repeatedly by the same thread without blocking. -}
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ensureOnlyActionOn :: Key -> Annex a -> Annex a
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ensureOnlyActionOn k a = debugLocks $
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go =<< Annex.getState Annex.concurrency
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where
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go NonConcurrent = a
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go (Concurrent _) = goconcurrent
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go ConcurrentPerCpu = goconcurrent
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goconcurrent = do
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tv <- Annex.getState Annex.activekeys
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bracket (setup tv) id (const a)
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setup tv = liftIO $ do
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mytid <- myThreadId
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atomically $ do
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m <- readTVar tv
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case M.lookup k m of
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Just tid
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| tid /= mytid -> retry
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| otherwise -> return $ return ()
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Nothing -> do
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writeTVar tv $! M.insert k mytid m
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return $ liftIO $ atomically $
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modifyTVar tv $ M.delete k
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