gameServer/Store.hs
author nemo
Sun, 03 Jun 2012 23:04:21 -0400
changeset 7174 80480d21e6ed
parent 6805 097289be7200
child 7751 8c7f5c43ea5e
permissions -rw-r--r--
Workaround for bug #144. This workaround had occurred to me a while ago, but wasn't sure if placing them unfairly was better than not placing them at all. Argument for not placing at all is people should probably abort the game when they notice it. Argument for placing unfairly is people can still abort, and if we really wanted them to abort, we should probably just have halted launch if all hogs failed to spawn. This way at least play can continue.

{-# LANGUAGE BangPatterns, GeneralizedNewtypeDeriving #-}
module Store(
    ElemIndex(),
    MStore(),
    IStore(),
    newStore,
    addElem,
    removeElem,
    readElem,
    writeElem,
    modifyElem,
    elemExists,
    firstIndex,
    indicesM,
    withIStore,
    withIStore2,
    (!),
    indices
    ) where

import qualified Data.Array.IArray as IA
import qualified Data.Array.IO as IOA
import qualified Data.IntSet as IntSet
import Data.IORef
import Control.Monad
import Control.DeepSeq


newtype ElemIndex = ElemIndex Int
    deriving (Eq, Show, Read, Ord, NFData)
newtype MStore e = MStore (IORef (IntSet.IntSet, IntSet.IntSet, IOA.IOArray Int e))
newtype IStore e = IStore (IntSet.IntSet, IA.Array Int e)


firstIndex :: ElemIndex
firstIndex = ElemIndex 0

-- MStore code
initialSize :: Int
initialSize = 16


growFunc :: Int -> Int
growFunc a = a * 3 `div` 2

truncFunc :: Int -> Int
truncFunc a | a > growFunc initialSize = (a `div` 2)
            | otherwise = a


newStore :: IO (MStore e)
newStore = do
    newar <- IOA.newArray_ (0, initialSize - 1)
    new <- newIORef (IntSet.empty, IntSet.fromAscList [0..initialSize - 1], newar)
    return (MStore new)


growStore :: MStore e -> IO ()
growStore (MStore ref) = do
    (busyElems, freeElems, arr) <- readIORef ref
    (_, m') <- IOA.getBounds arr
    let newM' = growFunc (m' + 1) - 1
    newArr <- IOA.newArray_ (0, newM')
    sequence_ [IOA.readArray arr i >>= IOA.writeArray newArr i | i <- [0..m']]
    writeIORef ref (busyElems, freeElems `IntSet.union` IntSet.fromAscList [m'+1..newM'], newArr)


growIfNeeded :: MStore e -> IO ()
growIfNeeded m@(MStore ref) = do
    (_, freeElems, _) <- readIORef ref
    when (IntSet.null freeElems) $ growStore m


truncateIfNeeded :: MStore e -> IO ()
truncateIfNeeded (MStore ref) = do
    (busyElems, _, arr) <- readIORef ref
    (_, m') <- IOA.getBounds arr
    let newM' = truncFunc (m' + 1) - 1
    when (newM' < m' && (not $ IntSet.null busyElems) && IntSet.findMax busyElems <= newM') $ do
        newArr <- IOA.newArray_ (0, newM')
        sequence_ [IOA.readArray arr i >>= IOA.writeArray newArr i | i <- IntSet.toList busyElems]
        writeIORef ref (busyElems, IntSet.fromAscList [0..newM'] `IntSet.difference` busyElems, newArr)


addElem :: MStore e -> e -> IO ElemIndex
addElem m@(MStore ref) element = do
    growIfNeeded m
    (busyElems, freeElems, arr) <- readIORef ref
    let (!n, freeElems') = IntSet.deleteFindMin freeElems
    IOA.writeArray arr n element
    writeIORef ref (IntSet.insert n busyElems, freeElems', arr)
    return $ ElemIndex n


removeElem :: MStore e -> ElemIndex -> IO ()
removeElem m@(MStore ref) (ElemIndex n) = do
    (busyElems, freeElems, arr) <- readIORef ref
    IOA.writeArray arr n (error $ "Store: no element " ++ show n)
    writeIORef ref (IntSet.delete n busyElems, IntSet.insert n freeElems, arr)
    truncateIfNeeded m


readElem :: MStore e -> ElemIndex -> IO e
readElem (MStore ref) (ElemIndex n) = readIORef ref >>= \(_, _, arr) -> IOA.readArray arr n


writeElem :: MStore e -> ElemIndex -> e -> IO ()
writeElem (MStore ref) (ElemIndex n) el = readIORef ref >>= \(_, _, arr) -> IOA.writeArray arr n el


modifyElem :: MStore e -> (e -> e) -> ElemIndex -> IO ()
modifyElem (MStore ref) f (ElemIndex n) = do
    (_, _, arr) <- readIORef ref
    IOA.readArray arr n >>= IOA.writeArray arr n . f

elemExists :: MStore e -> ElemIndex -> IO Bool
elemExists (MStore ref) (ElemIndex n) = do
    (_, !free, _) <- readIORef ref
    return $ n `IntSet.notMember` free

indicesM :: MStore e -> IO [ElemIndex]
indicesM (MStore ref) = do
    (!busy, _, _) <- readIORef ref
    return $ map ElemIndex $ IntSet.toList busy


-- A way to see MStore elements in pure code via IStore
m2i :: MStore e -> IO (IStore e)
m2i (MStore ref) = do
    (a, _, c') <- readIORef ref
    c <- IOA.unsafeFreeze c'
    return $ IStore (a, c)

i2m :: MStore e -> IStore e -> IO ()
i2m (MStore ref) (IStore (_, arr)) = do
    (b, e, _) <- readIORef ref
    a <- IOA.unsafeThaw arr
    writeIORef ref (b, e, a)

withIStore :: MStore e -> (IStore e -> a) -> IO a
withIStore m f = do
    i <- m2i m
    let res = f i
    res `seq` i2m m i
    return res


withIStore2 :: MStore e1 -> MStore e2 -> (IStore e1 -> IStore e2 -> a) -> IO a
withIStore2 m1 m2 f = do
    i1 <- m2i m1
    i2 <- m2i m2
    let res = f i1 i2
    res `seq` i2m m1 i1
    i2m m2 i2
    return res


-- IStore code
(!) :: IStore e -> ElemIndex -> e
(!) (IStore (_, arr)) (ElemIndex i) = (IA.!) arr i

indices :: IStore e -> [ElemIndex]
indices (IStore (busy, _)) = map ElemIndex $ IntSet.toList busy