diff --git a/Data/CacheStructure.hs b/Data/CacheStructure.hs new file mode 100644 --- /dev/null +++ b/Data/CacheStructure.hs @@ -0,0 +1,56 @@ +----------------------------------------------------------------------------- +-- | +-- Module : Data.CacheStructure +-- Copyright : Peter Robinson 2009 +-- License : LGPL +-- +-- Maintainer : Peter Robinson +-- Stability : experimental +-- Portability : non-portable (requires STM) +-- +-- A type class for implementing different caching policies (e.g. LRU, LFU,... ). +-- Should be imported qualified. +----------------------------------------------------------------------------- + +module Data.CacheStructure( CacheStructure(..), CacheException(..) ) +where +import Control.Exception +import Data.Typeable + +data CacheException = CacheException String + deriving (Show,Eq,Typeable) + +instance Exception CacheException + +-- | A type class for implementing a caching policy (e.g. LRU) +class CacheStructure c a where + -- | A new element is added to the cache or an already existing element + -- was accessed. + hit :: a -> c a -> c a + -- | Returns the \"last\" element w.r.t. the caching policy. + last :: c a -> a + -- | Removes and returns the \"last\" element w.r.t. the caching policy. + pop :: c a -> (c a,a) + -- | Creates an empty cache structure. + empty :: c a + -- | Checks for emptyness. + null :: c a -> Bool + -- | Transforms the cache structure to a list. + toList :: c a -> [a] + -- | An element is deleted. + delete :: a -> c a -> c a + -- | Checks if an element is in the cache structure. + member :: a -> c a -> Bool + -- | Returns the size. Should be /O(1)/. + size :: c a -> Int + -- | Runs 'pop' a number of times. Has a default implementation. + popMany :: Int -> c a -> (c a,[a]) + popMany = popMany' [] + where + popMany' del 0 cs = (cs,del) + popMany' del i cs + | i < 0 = throw $ CacheException "Invalid size for cache structure!" + | otherwise = let (cs',a) = pop cs + in popMany' (a:del) (i-1) cs' + + diff --git a/Data/CacheStructure/LRU.hs b/Data/CacheStructure/LRU.hs new file mode 100644 --- /dev/null +++ b/Data/CacheStructure/LRU.hs @@ -0,0 +1,35 @@ +----------------------------------------------------------------------------- +-- | +-- Module : Data.Policy.LRU +-- Copyright : Peter Robinson 2009 +-- License : LGPL +-- +-- Maintainer : Peter Robinson +-- Stability : experimental +-- Portability : non-portable (requires STM) +-- +-- Provides a least recently used caching policy. +-- Note: This module is simply a wrapper around the LRU-package. +----------------------------------------------------------------------------- + +module Data.CacheStructure.LRU( L.LRU ) +where +import Control.Exception +import Data.CacheStructure +import qualified Data.LRU as L + +instance Ord a => CacheStructure L.LRU a where + hit = L.hit + pop l = case L.last l of + Nothing -> throw $ CacheException "Cache structure is empty!" + Just a -> (L.pop l,a) + last l = case L.last l of + Nothing -> throw $ CacheException "Cache structure is empty!" + Just a -> a + empty = L.empty + null = L.null + toList = L.toList + delete = L.delete + member = L.member + size = L.size + diff --git a/Data/TMap.hs b/Data/TMap.hs new file mode 100644 --- /dev/null +++ b/Data/TMap.hs @@ -0,0 +1,260 @@ +----------------------------------------------------------------------------- +-- | +-- Module : Data.TMap +-- Copyright : Peter Robinson 2009 +-- License : LGPL +-- +-- Maintainer : Peter Robinson +-- Stability : experimental +-- Portability : non-portable (requires STM) +-- +-- Provides a thread-safe STM interface for finite map types with optional persistent +-- storage. +-- +----------------------------------------------------------------------------- + +module Data.TMap( -- * TMap + TMap, + -- * Creating a new TMap + newTMapIO, + -- * Finite Map Interace + lookup, + insert, + delete, + member, + adjust, + -- * Handling the size of the TMap + purgeTMap, + purgeTMapIO, + getMaximumSize, + setMaximumSize, + getCurrentSize, + -- * Flushing the backend + flushBackend, + -- * Exception Type + TMapException(..), + ) +where + +import Control.Concurrent.AdvSTM +import Control.Concurrent.AdvSTM.TVar +-- import Control.Monad.CatchIO +import Control.Monad( liftM, when ) +import Control.Monad.Trans( MonadIO, liftIO ) + +import qualified Control.Exception as Exc +import Data.Maybe( isJust ) +import Prelude hiding (lookup,catch) + +import qualified Data.TMap.Backend as B +import qualified Data.CacheStructure as C +import Data.TMap.Exception( TMapException(..) ) + +import qualified Data.Edison.Assoc as M + + +-------------------------------------------------------------------------------- + + +data Entry a = Entry a -- ^ Cache hit + | NotInTMap -- ^ Cache miss + | NotInBackend -- ^ Element exists neither in backend nor in cache + deriving (Show,Eq) + +instance Functor Entry where + fmap _ NotInBackend = NotInBackend + fmap _ NotInTMap = NotInTMap + fmap f (Entry a) = Entry (f a) + + +data TMap map k a b c = TMap + { backend :: B.Backend k a b => b k a + , sizeTVar :: TVar (Maybe Int) + , tmapTVar :: (M.FiniteMapX map k, C.CacheStructure c k) + => TVar (map (Entry a),c k) + } + + +-------------------------------------------------------------------------------- + +-- | Creates a new TMap. You will need to use an apropriate backend and specify +-- the caching policy, e.g., +-- +-- @ +-- import Data.TMap.Backend.StdoutBackend( newStdoutBackend ) +-- import Data.TMap.CacheStructure.LRU +-- @ +-- +-- will simply log all backend operations to Stdout and use a \"least recently +-- used\" cache algorithm. +-- +-- Now, to create an unbounded map that uses the 'FM Int String' (see package EdisonCore) +-- as the map type, you can write +-- +-- @ +-- tmap = newTMapIO newStdoutBackend Nothing :: IO (TMap (FM Int) Int String StdoutBackend LRU) +-- @ +newTMapIO :: (M.FiniteMapX map k, Ord k, B.Backend k a b,C.CacheStructure c k) + => b k a -- ^ the backend + -> Maybe Int -- ^ maximum-size: Use 'Nothing' for unbounded size. + -> IO (TMap map k a b c) +newTMapIO b maxsize = do + tvar <- newTVarIO (M.empty,C.empty) + tvarSize <- newTVarIO maxsize + B.initialize b + return $ TMap b tvarSize tvar + +{- + - Deactivated --- Can cause a non-terminating retry-loop when used with lookup k: + - When key 'k' is not found lookup retries. (Cond 1) + - But this causes the creation of the tmap to be rolled back too, and so + - (Cond 1) holds forever. +newTMap :: (M.FiniteMapX map k, Ord k, B.Backend k a b, MonadAdvSTM m) + => b -> m (TMap map k a b) +newTMap b = do + tvar <- newTVar M.empty + return $ TMap b tvar +-} + + +-- | Looks for a given key in the map and (if necessary) in the persistent storage +-- and updates the map if necessary. +lookup :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b,C.CacheStructure c k) + => k -> TMap map k a b c -> m (Maybe a) +lookup k tmap = do + (themap,accSeq) <- readTVar (tmapTVar tmap) + case M.lookupWithDefault NotInTMap k themap of + Entry v -> do + writeTVar (tmapTVar tmap) (themap,C.hit k accSeq) +-- onCommit $ print ("OldAccess List: ",C.toList accSeq) +-- onCommit $ print ("NewAccess List: ",C.toList $ C.hit k accSeq) + return $ Just v + NotInBackend -> return Nothing + NotInTMap -> retryWith $ do +-- print $ "Lookup: Didn't find " ++ show k ++ ", retrying lookup..." + result <- B.lookup (backend tmap) k + case result of + Nothing -> do +-- print "Entry not in backend" + atomically $ do + (themap',accSeq') <- readTVar (tmapTVar tmap) + writeTVar (tmapTVar tmap) (M.insert k (NotInBackend) themap', accSeq') + Just v -> do +-- print "Found entry in backend" + atomically $ do + (themap',accSeq') <- readTVar (tmapTVar tmap) + writeTVar (tmapTVar tmap) ( M.insert k (Entry v) themap' + , C.hit k accSeq') +-- onCommit $ print ("Access List: ",C.toList $ C.hit k accSeq') + +-- | Checks whether the given key is in the map. +member :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b,C.CacheStructure c k) + => k -> TMap map k a b c -> m Bool +member k tmap = liftM isJust (lookup k tmap) + + +-- | Adds a key-value mapping to the map. Can throw a 'DuplicateEntry' +-- exception. +insert :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b, C.CacheStructure c k) + => k -> a -> TMap map k a b c -> m () +insert k a tmap = do + res <- lookup k tmap + case res of + Just _ -> Exc.throw $ DuplicateEntry -- (show (k,v)) + Nothing -> do + (themap,accSeq) <- readTVar (tmapTVar tmap) + writeTVar (tmapTVar tmap) ( M.insert k (Entry a) themap + , C.hit k accSeq) + onCommit $ B.insert (backend tmap) k a + + +-- | Applies a function to the element identified by the key. Can throw an 'EntryNotFound' exception. +adjust :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b, C.CacheStructure c k) + => (a -> a) -> k -> TMap map k a b c -> m () +adjust f k tmap = do + res <- lookup k tmap + case res of + Nothing -> Exc.throw EntryNotFound + Just _ -> do + (themap,accSeq) <- readTVar (tmapTVar tmap) + writeTVar (tmapTVar tmap) (M.adjust (fmap f) k themap, C.hit k accSeq) + onCommit $ B.adjust (backend tmap) f k + + +-- | Removes a key from the map. Can throw an 'EntryNotFound' exception. +delete :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b,C.CacheStructure c k) + => k -> TMap map k a b c -> m () +delete k tmap = do + res <- lookup k tmap + case res of + Nothing -> Exc.throw EntryNotFound + Just _ -> do + (themap,accSeq) <- readTVar (tmapTVar tmap) + writeTVar (tmapTVar tmap) (M.insert k NotInBackend themap, accSeq) + onCommit $ B.delete (backend tmap) k + +-------------------------------------------------------------------------------- + +-- | Reduces the map to the appropriate size if the maximum size was exceeded. +-- Calls /Data.TMap.Backend.flush/ if the map is purged. +-- Runs in /O(1)/ if the map size is within bounds, otherwise /O(n)/. +purgeTMapIO :: (M.FiniteMapX map k, MonadIO m, Ord k, B.Backend k a b, C.CacheStructure c k) + => TMap map k a b c -> m () +purgeTMapIO tmap = liftIO . atomically $ purgeTMap tmap + + +-- | Reduces the map to the appropriate size if the maximum size was exceeded. +-- Calls /Data.TMap.Backend.flush/ if the map is purged. +-- Runs in /O(1)/ if the map size is within bounds, otherwise /O(n)/. +-- /Warning:/ This function should always be called at the end of a transaction to +-- prevent nonterminating retry-loops! +purgeTMap :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b, C.CacheStructure c k) + => TMap map k a b c -> m () +purgeTMap tmap = do + mSize <- readTVar (sizeTVar tmap) + case mSize of + Just maxSize -> do + (themap,accSeq) <- readTVar (tmapTVar tmap) +-- onCommit $ print ("Old List: ",C.toList accSeq) + when (C.size accSeq > maxSize) $ do + let (restSeq,delSeq) = C.popMany (C.size accSeq - maxSize) accSeq + writeTVar (tmapTVar tmap) (foldr M.delete themap delSeq, restSeq) + onCommit $ B.flush (backend tmap) +-- onCommit $ print ("Purged List: ",C.toList restSeq) + Nothing -> return () + +-------------------------------------------------------------------------------- + +-- | Sets the maximum size of the map. /O(1)/. Note that the size of the TMap needs +-- to be reduced manually to the maximum size by calling /purgeTMap/. +setMaximumSize :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b, C.CacheStructure c k) + => TMap map k a b c -> Int -> m () +setMaximumSize tmap maxSize + | maxSize <= 0 = Exc.throw $ TMapDefaultExc "setMaximumSize: Invalid size specified." + | otherwise = writeTVar (sizeTVar tmap) $ Just maxSize + +-- | Gets the maximum size of the map. /O(1)/. +getMaximumSize :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b, C.CacheStructure c k) + => TMap map k a b c + -> m (Maybe Int) +getMaximumSize tmap + | otherwise = readTVar (sizeTVar tmap) + + +-- | Gets the current size of the map. /O(1)/. +getCurrentSize :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b, C.CacheStructure c k) + => TMap map k a b c + -> m Int +getCurrentSize tmap = do + (_,accSeq) <- readTVar (tmapTVar tmap) + return $ C.size accSeq + + +-------------------------------------------------------------------------------- + +-- | Sends a /B.flush/ request to the backend. Useful for asynchronous backend +-- implementations. +flushBackend :: (M.FiniteMapX map k, MonadIO m, Ord k, B.Backend k a b, C.CacheStructure c k) + => TMap map k a b c -> m () +flushBackend tmap = B.flush (backend tmap) + diff --git a/Data/TMap/Backend.hs b/Data/TMap/Backend.hs new file mode 100644 --- /dev/null +++ b/Data/TMap/Backend.hs @@ -0,0 +1,46 @@ +----------------------------------------------------------------------------- +-- | +-- Module : Data.TMap.Backend +-- Copyright : Peter Robinson 2009 +-- License : LGPL +-- +-- Maintainer : Peter Robinson +-- Stability : experimental +-- Portability : non-portable (requires STM) +-- +-- Provides a type class for backend instantiations. To avoid data +-- inconsistencies, these functions should not be used directly but only by +-- means of the TMap interface. +-- +----------------------------------------------------------------------------- + +module Data.TMap.Backend( Backend(..) ) +where +import Control.Monad.Trans( MonadIO ) + +-- | This class needs to be instantiated when developing a new +-- backend. The backend is expected to be able to handle concurrent +-- (non-conflicting) requests. +class Backend k a b | a -> k where + + -- | Called when a new element was inserted. + insert :: MonadIO m => b k a -> k -> a -> m () + + -- | Called when an element was updated. + adjust :: MonadIO m => b k a-> (a -> a) -> k -> m () + + -- | Called when an element was deleted from the map. + delete :: MonadIO m => b k a-> k -> m () + + -- | Called when an element is not found in the map. + lookup :: MonadIO m => b k a -> k -> m (Maybe a) + + -- | Called by /flushBackend/ and /purgeTMap/. + flush :: MonadIO m => b k a -> m () + + -- | Called in 'newTMapIO' + initialize :: MonadIO m => b k a -> m () + + flush _ = return () + initialize _ = return () + diff --git a/Data/TMap/Backend/NoBackend.hs b/Data/TMap/Backend/NoBackend.hs new file mode 100644 --- /dev/null +++ b/Data/TMap/Backend/NoBackend.hs @@ -0,0 +1,26 @@ +----------------------------------------------------------------------------- +-- | +-- Module : Data.TMap.Backend.NoBackend +-- Copyright : Peter Robinson 2009 +-- License : LGPL +-- +-- Maintainer : Peter Robinson +-- Stability : experimental +-- Portability : non-portable (requires STM) +-- +-- A backend instantiation that ignores all requests. +-- +-- +----------------------------------------------------------------------------- +module Data.TMap.Backend.NoBackend( NoBackend(..) ) +where +import Data.TMap.Backend( Backend(..) ) + +data NoBackend k a = NoBackend + +instance Backend k a NoBackend where + insert _ _ _ = return () + adjust _ _ _ = return () + lookup _ _ = return Nothing + delete _ _ = return () + diff --git a/Data/TMap/Backend/StdoutBackend.hs b/Data/TMap/Backend/StdoutBackend.hs new file mode 100644 --- /dev/null +++ b/Data/TMap/Backend/StdoutBackend.hs @@ -0,0 +1,32 @@ +----------------------------------------------------------------------------- +-- | +-- Module : Data.TMap.Backend.StdoutBackend +-- Copyright : Peter Robinson 2009 +-- License : LGPL +-- +-- Maintainer : Peter Robinson +-- Stability : experimental +-- Portability : non-portable (requires STM) +-- +-- Simply prints out all backend requests to stdout. +-- +----------------------------------------------------------------------------- + +module Data.TMap.Backend.StdoutBackend( StdoutBackend + , newStdoutBackend ) +where +import Data.TMap.Backend +import Control.Monad.Trans( MonadIO, liftIO ) + +data StdoutBackend k a = StdoutBackend + +instance (Show a,Show k) => Backend k a StdoutBackend where + insert _ _ a = liftIO (print ("inserting: ",a)) >> return () + adjust _ _ k = liftIO (print ("adjusting: ",k)) >> return () + lookup _ k = liftIO (print ("looking up: ",k)) >> return Nothing + delete _ k = liftIO (print ("deleting: ",k)) >> return () + +-- | Creates a new 'StdoutBackend'. +newStdoutBackend :: StdoutBackend k a +newStdoutBackend = StdoutBackend + diff --git a/Data/TMap/Exception.hs b/Data/TMap/Exception.hs new file mode 100644 --- /dev/null +++ b/Data/TMap/Exception.hs @@ -0,0 +1,29 @@ +----------------------------------------------------------------------------- +-- | +-- Module : Data.TMap.Exception +-- Copyright : Peter Robinson 2009 +-- License : LGPL +-- +-- Maintainer : Peter Robinson +-- Stability : experimental +-- Portability : non-portable (requires STM) +-- +-- +-- +----------------------------------------------------------------------------- + +module Data.TMap.Exception( TMapException(..) ) +where +import Control.Exception +import Data.Typeable + +data TMapException = DuplicateEntry + | EntryNotFound + | TMapNotFound + | TMapDefaultExc String + | BackendException String + deriving (Show,Eq,Typeable) + +instance Exception TMapException + + diff --git a/Data/TStorage.hs b/Data/TStorage.hs new file mode 100644 --- /dev/null +++ b/Data/TStorage.hs @@ -0,0 +1,95 @@ +----------------------------------------------------------------------------- +-- | +-- Module : Data.TStorage +-- Copyright : Peter Robinson 2009 +-- License : LGPL +-- +-- Maintainer : Peter Robinson +-- Stability : experimental +-- Portability : non-portable (requires STM) +-- +-- Provides a high level interface to 'Data.TMap'. This module was inspired +-- by the TCache package, (C) Alberto Gomez Corona. +-- +-- The essential difference to the low level functions in 'Data.TMap' is +-- that this interface assumes that the stored type is an instance of +-- 'HasKey', allowing partially filled (i.e. complete enough for deducing +-- the key) values to be passed to the interface functions. +----------------------------------------------------------------------------- + +module Data.TStorage( TMap, + HasKey(..), + newTMapIO, + add, + tryComplete, + complete, + remove, + removeKey, + apply, + purgeTMap, + purgeTMapIO, + ) + +where +import Control.Concurrent.AdvSTM +import Control.Exception +import Prelude hiding (lookup,catch) + +import qualified Data.TMap.Backend as B +import qualified Data.CacheStructure as C + +import qualified Data.Edison.Assoc as M + +import Data.TMap + +-- | Instantiated by types where values have a unique key. +class HasKey a k | a -> k where + key :: a -> k + +-- | Adds a new element to the map. The key is automatically deduced by the +-- 'HasKey' instantiation. +add :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b, C.CacheStructure c k + , HasKey a k) + => a -> TMap map k a b c -> m () +add a = insert (key a) a + + +-- | Tries to fill a partially initialized value with data from the TMap. Returns +-- 'Nothing' if the TMap does not contain a corresponding entry. +tryComplete :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b, C.CacheStructure c k + , HasKey a k) + => a -> TMap map k a b c -> m (Maybe a) +tryComplete a = lookup (key a) + +-- | Fills a partially initialized value with data from the TMap. Throws +-- a 'TMapNotFound' exception if there is no corresponding entry. +complete :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b, C.CacheStructure c k + , HasKey a k) + => a -> TMap map k a b c -> m a +complete a tmap = do + mval <- tryComplete a tmap + case mval of + Just val -> return val + Nothing -> throw TMapNotFound + +-- | Removes the element from the map. +remove :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b, C.CacheStructure c k + , HasKey a k) + => a -> TMap map k a b c -> m () +remove a = delete (key a) + +-- | Removes the entry that has the supplied key. +removeKey :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b, C.CacheStructure c k + , HasKey a k) + => k -> TMap map k a b c -> m () +removeKey = delete + +-- | Applies a function to an element that might be only partially initialized. +apply :: (M.FiniteMapX map k, MonadAdvSTM m, Ord k, B.Backend k a b, C.CacheStructure c k + , HasKey a k) + => (a -> a) -> a -> TMap map k a b c -> m a +apply f a tmap = do + adjust f (key a) tmap + complete a tmap + + diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,508 @@ +Copyright 2008-2009, Peter Robinson . 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Here is a sample; alter the names: + + Yoyodyne, Inc., hereby disclaims all copyright interest in the + library `Frob' (a library for tweaking knobs) written by James Random Hacker. + + , 1 April 1990 + Ty Coon, President of Vice + +That's all there is to it! + + + diff --git a/Sample.hs b/Sample.hs new file mode 100644 --- /dev/null +++ b/Sample.hs @@ -0,0 +1,58 @@ +module Sample +where +import Control.Monad( when ) +import Data.TStorage +import Data.TMap +import Data.TMap.Backend.StdoutBackend +import qualified Data.CacheStructure.LRU as C +import Control.Concurrent.AdvSTM +import qualified Control.Exception as Exc +import qualified Data.Edison.Assoc.StandardMap as M +import Prelude hiding( lookup ) + +data Sometype = Sometype { theid :: Int, name :: String } + deriving (Show,Eq,Ord) + +instance HasKey Sometype Int where + key = theid + +sample :: IO () +sample = Exc.handle (\(e::Exc.SomeException) -> print e) $ do + tmap <- newTMapIO newStdoutBackend (Just 4) + :: IO (TMap (M.FM Int) Int Sometype StdoutBackend C.LRU) + -- First the low level TMap interface: + res <- atomically $ do + insert 1 (Sometype 1 "somename") tmap + insert 2 (Sometype 2 "somename2") tmap + insert 3 (Sometype 3 "somename3") tmap + insert 4 (Sometype 4 "somename4") tmap + insert 5 (Sometype 5 "somename5") tmap + insert 6 (Sometype 6 "somename6") tmap + lookup 2 tmap + delete 2 tmap + lookup 2 tmap + atomically $ purgeTMap tmap + print ("Result1: ",res) + + -- Let's try the high-level TStorage interface: + res2 <- atomically $ do + add (Sometype 7 "somename7") tmap + v1 <- apply (\s -> s{name="_"}) (Sometype {theid = 4}) tmap + v2 <- complete (Sometype {theid = 5}) tmap + return (v1,v2) + print ("Result2: ",res2) + +test :: IO () +test = do + tmap <- newTMapIO newStdoutBackend (Just 4) + :: IO (TMap (M.FM Int) Int String StdoutBackend C.LRU) + atomically $ do + isMemb <- member 1 tmap + when (not isMemb) $ + insert 1 "john doe" tmap + + atomically $ do + v <- lookup 1 tmap + -- ... doing something here with 'v' + adjust (\_ -> "jd") 1 tmap + diff --git a/Setup.lhs b/Setup.lhs new file mode 100644 --- /dev/null +++ b/Setup.lhs @@ -0,0 +1,4 @@ +#! /usr/bin/env runhaskell + +> import Distribution.Simple +> main = defaultMain diff --git a/persistent-map.cabal b/persistent-map.cabal new file mode 100644 --- /dev/null +++ b/persistent-map.cabal @@ -0,0 +1,100 @@ +Name: persistent-map +Synopsis: A thread-safe interface for finite map types with optional persistency support. +Description: + This library provides a thread-safe (STM) frontend for finite map types together with a + backend interface for persistent storage. The /TMap/ data type + is thread-safe, since all access functions run inside an STM monad . Any type + instantiating 'Data.Edison.Assoc.FiniteMapX' + (see EdisonAPI) can be used as a map type. + . + When a TMap is modified within an STM transaction, a corresponding + backend IO-request is added using the onCommit hook (cf. stm-io-hooks + package). To ensure consistency, + the (Adv)STM monad runs these requests iff the transaction commits. + Additional backends (e.g. HDBC) can be added by instantiating the class + 'Backend'. + . + /Example:/ + . + Thread 1: + . + > atomically $ do + > isMemb <- member 1 tmap + > when (not isMemb) $ + > insert 1 "john doe" tmap + . + Thread 2: + . + > atomically $ do + > v <- lookup 1 tmap + > -- ... do something with 'v' + > adjust (\_ -> "jd") 1 tmap + . + The function 'member' will first check whether the key value '1' is in the map; + if not, it sends a lookup-request to the persistent backend + and then retries the transaction. Note that \"sending a lookup-request\" + essentially means adding a call to the corresponding IO-function of the backend + to the list of retry-IO actions. (This is done using the 'retryWith' + IO hook of the stm-io-package.) + . + If the value does not exist yet, function 'insert' adds the key-value mapping to the + TMap and sends an insert-request to the backend using the + 'onCommit' hook of the stm-io-package. Note that 'onCommit' guarantees that + the backend IO action is only executed iff the transaction commits. Any + changes that were made to the TMap are invisible to other threads until + the onCommit actions are run. Therefore, the threads will always observe a + consistent state. + . + The module 'Data.TStorage' provides a high level interface to TMap inspired + by the TCache package ((C) Alberto Gomez Corona). It + can store any type that has a key (i.e. is an instance of type class 'HasKey'). + See file Sample.hs for an example on how to use it. + . + /Warning:/ This package is very experimental and the interface will + probably change. + +Author: Peter Robinson +Maintainer: thaldyron@gmail.com +License: LGPL +License-file: LICENSE +Version: 0.0.0 +Category: Data, Concurrency +Stability: experimental +Homepage: http://darcs.monoid.at/persistent-map + +build-type: Simple +cabal-version: >= 1.2.3 +library + ghc-options: -Wall -fno-ignore-asserts + + exposed-modules: Data.TMap + Data.TStorage +-- Data.TMap.Exception + Data.TMap.Backend + Data.TMap.Backend.NoBackend + Data.TMap.Backend.StdoutBackend + Data.CacheStructure + Data.CacheStructure.LRU + + other-modules: Sample + Data.TMap.Exception + + build-depends: base >= 4 && < 5, + EdisonAPI >= 1.2.1 && < 1.3, + LRU >= 0.1.1 && < 0.2, + EdisonCore >= 1.2.1.3 && < 1.3, +-- binary, + stm-io-hooks >= 0.2.0 && < 0.3, +-- HDBC >= 2.0 && < 2.1, + mtl >= 1.1.0.2 && < 1.2 +-- MonadCatchIO-mtl + + extensions: MultiParamTypeClasses, + RankNTypes, + FunctionalDependencies, + FlexibleContexts, + FlexibleInstances, + UndecidableInstances, + DeriveDataTypeable, + ScopedTypeVariables +