Add new version tracking implementation #53

ChangeLog.md

@@ -1,5 +1,17 @@
 # ChangeLog
 
+## 0.2.1.0
+
+Release notes:
+
+* Adds `Data.Store.Version` and deprecates `Data.Store.TypeHash`.
+  The new functionality is similar to TypeHash, but there are much fewer false
+  positives of hashes changing.
+
+Other enhancements:
+
+* Now exports types related to generics
+
 ## 0.2.0.0
 
 Release notes:

package.yaml

@@ -29,7 +29,7 @@ dependencies:
   - store-core >=0.2 && <0.3
 
   # Utilities package tightly coupled to the TH code
-  - th-utilities >=0.1.1.0
+  - th-utilities >=0.2
 
   # Due to removal of 'internal' from MonadPrim in 0.6
   - primitive >=0.6
@@ -42,12 +42,15 @@ dependencies:
 # Added to appease at least the lower part of the PvP
   - array >=0.5.0.0
   - base-orphans >=0.4.3
+  - base64-bytestring >= 0.1.1
   - bytestring >=0.10.4.0
   - conduit >=1.2.3.1
   - containers >=0.5.5.1
   - cryptohash >=0.11.6
   - deepseq >=1.3.0.2
+  - directory >= 1.2
   - fail >=4.9.0.0
+  - filepath >= 1.3
   - ghc-prim >=0.3.1.0
   - hashable >=1.2.3.1
   - hspec >=2.1.2

src/Data/Store/TH/Internal.hs

@@ -45,7 +45,7 @@ import           Language.Haskell.TH.Syntax (lift)
 import           Prelude
 import           Safe (headMay)
 import           TH.Derive (Deriver(..))
-import           TH.ReifyDataType
+import           TH.ReifySimple
 import           TH.Utilities (expectTyCon1, dequalify, plainInstanceD)
 
 instance Deriver (Store a) where

src/Data/Store/TypeHash/Internal.hs

@@ -30,6 +30,10 @@ import           Language.Haskell.TH.ReifyMany (reifyMany)
 import           Language.Haskell.TH.Syntax (Lift(lift))
 import           Prelude
 
+{-# DEPRECATED mkManyHasTypeHash, mkHasTypeHash
+    "Use of Data.Store.TypeHash isn't recommended, as the hashes are too unstable for most uses.  Please instead consider using Data.Store.Version.  See https://github.com/fpco/store/issues/53"
+  #-}
+
 newtype Tagged a = Tagged { unTagged :: a }
     deriving (Eq, Ord, Show, Data, Typeable, Generic)
 

src/Data/Store/Version.hs

@@ -0,0 +1,280 @@
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TemplateHaskell #-}
+-- | This module provides utilities which help ensure that we aren't
+-- attempting to de-serialize data that is an older or newer version.
+-- The 'WithVersion' utility wraps up a datatype along with a version
+-- tag. This version tag can either be provided by the user
+-- ('namedVersionConfig'), or use a computed hash
+-- ('hashedVersionConfig').
+--
+-- The magic here is using an SYB traversal ('Data') to get the
+-- structure of all the data-types involved. This info is rendered to
+-- text and hashed to yield a hash which describes it.
+module Data.Store.Version
+    ( StoreVersion(..)
+    , WithVersion(..)
+    , VersionConfig(..)
+    , hashedVersionConfig
+    , namedVersionConfig
+    , wrapVersion
+    , checkVersion
+    , VersionCheckException(..)
+    ) where
+
+import           Control.Exception
+import           Control.Monad
+import           Control.Monad.Trans.State
+import qualified Crypto.Hash.SHA1 as SHA1
+import qualified Data.ByteString as BS
+import qualified Data.ByteString.Base64.URL as B64Url
+import qualified Data.ByteString.Char8 as BS8
+import           Data.Generics hiding (DataType, Generic)
+import qualified Data.Map as M
+import qualified Data.Set as S
+import           Data.Store.Internal
+import qualified Data.Text as T
+import           Data.Text.Encoding (encodeUtf8, decodeUtf8, decodeUtf8With)
+import           Data.Text.Encoding.Error (lenientDecode)
+import qualified Data.Text.IO as T
+import           Data.Typeable.Internal (TypeRep(..))
+import           GHC.Generics (Generic)
+import           Language.Haskell.TH
+import           System.Directory
+import           System.Environment
+import           System.FilePath
+import           TH.RelativePaths
+import           TH.Utilities
+
+newtype StoreVersion = StoreVersion { unStoreVersion :: BS.ByteString }
+    deriving (Eq, Show, Ord, Data, Typeable, Generic, Store)
+
+data WithVersion a = WithVersion a StoreVersion
+    deriving (Eq, Show, Ord, Data, Typeable, Generic)
+
+instance Store a => Store (WithVersion a)
+
+-- | Configuration for the version checking of a particular type.
+data VersionConfig a = VersionConfig
+    { vcExpectedHash :: Maybe String
+      -- ^ When set, specifies the hash which is expected to be computed.
+    , vcManualName :: Maybe String
+      -- ^ When set, specifies the name to instead use to tag the data.
+    , vcIgnore :: S.Set String
+      -- ^ DataTypes to ignore.
+    } deriving (Eq, Show, Data, Typeable, Generic)
+
+hashedVersionConfig :: String -> VersionConfig a
+hashedVersionConfig hash = VersionConfig
+    { vcExpectedHash = Just hash
+    , vcManualName = Nothing
+    , vcIgnore = S.empty
+    }
+
+namedVersionConfig :: String -> String -> VersionConfig a
+namedVersionConfig name hash = VersionConfig
+    { vcExpectedHash = Just hash
+    , vcManualName = Just name
+    , vcIgnore = S.empty
+    }
+
+wrapVersion :: Data a => VersionConfig a -> Q Exp
+wrapVersion = impl Wrap
+
+checkVersion :: Data a => VersionConfig a -> Q Exp
+checkVersion = impl Check
+
+data WhichFunc = Wrap | Check
+
+impl :: forall a. Data a => WhichFunc -> VersionConfig a -> Q Exp
+impl wf vc = do
+    let proxy = Proxy :: Proxy a
+        info = encodeUtf8 (T.pack (getStructureInfo (vcIgnore vc) proxy))
+        hash = SHA1.hash info
+        hashb64 = BS8.unpack (B64Url.encode hash)
+        version = case vcManualName vc of
+            Nothing -> [e| StoreVersion hash |]
+            Just name -> [e| StoreVersion name |]
+    case vcExpectedHash vc of
+        Nothing -> return ()
+        Just expectedHash -> do
+            let shownType = showsQualTypeRep 0 (typeRep proxy) ""
+            -- FIXME: sanitize expected and handle null
+            path <- storeVersionedPath expectedHash
+            if hashb64 == expectedHash
+                then writeVersionInfo path shownType info
+                else do
+                    newPath <- storeVersionedPath hashb64
+                    writeVersionInfo newPath shownType info
+                    exists <- runIO $ doesFileExist path
+                    extraMsg <- if not exists
+                        then return ", but no file found with previously stored structural info."
+                        else return (", use something like the following to compare with the old structural info:\n\n" ++
+                                     "diff -u " ++ show path ++ " " ++ show newPath)
+                    error $
+                        "\nData.Store.Version computed hash " ++ show hashb64 ++
+                        ", but expected hash " ++ show expectedHash ++ " is specified.\n" ++
+                        "The data used to construct the hash has been written to " ++ show newPath ++
+                        extraMsg ++ "\n"
+    case wf of
+        Wrap -> [e| (\x -> (x :: $(typeRepToType (typeRep proxy))) `WithVersion` $(version)) |]
+        Check -> [e| (\(WithVersion x gotVersion) ->
+                        if gotVersion /= $(version)
+                            then Left (VersionCheckException
+                                { expectedVersion = $(version)
+                                , receivedVersion = gotVersion
+                                })
+                            else Right x) |]
+
+{-
+                            txtWithComments <- runIO $ T.readFile path
+                            let txt = T.unlines $ dropWhile ("--" `T.isPrefixOf`) $ T.lines txtWithComments
+                                storedHash = BS8.unpack (B64Url.encode (SHA1.hash (encodeUtf8 txt)))
+                            if storedHash == expectedHash
+                                then return (", compare with the structural info that matches the hash, found in " ++ show path)
+                                else return (", but the old file found also doesn't match the hash.")
+-}
+
+writeVersionInfo :: FilePath -> String -> BS.ByteString -> Q ()
+writeVersionInfo path shownType info = runIO $ do
+    createDirectoryIfMissing True (takeDirectory path)
+    T.writeFile path $ T.unlines $
+        [ T.pack ("-- Structural info for type " ++ shownType)
+        , "-- Generated by an invocation of functions in Data.Store.Version"
+        ] ++ T.lines (decodeUtf8 info)
+
+storeVersionedPath :: String -> Q FilePath
+storeVersionedPath filename = do
+    mstack <- runIO (lookupEnv "STACK_EXE")
+    let dirName = case mstack of
+            Just _ -> ".stack-work"
+            Nothing -> "dist"
+    pathRelativeToCabalPackage (dirName </> "store-versioned" </> filename)
+
+-- Implementation details
+
+data S = S
+    { sResults :: M.Map String String
+    , sCurResult :: String
+    , sFieldNames :: [String]
+    }
+
+getStructureInfo :: forall a. Data a => S.Set String -> Proxy a -> String
+getStructureInfo ignore = renderResults . sResults . flip execState (S M.empty "" []) . getStructureInfo' ignore
+  where
+    renderResults = unlines . map (\(k, v) -> k ++ v) . M.toAscList
+
+getStructureInfo' :: forall a. Data a => S.Set String -> Proxy a -> State S ()
+getStructureInfo' ignore _ = do
+    s0 <- get
+    when (M.notMember label (sResults s0)) $
+        if S.member shownType ignore
+            then setResult " ignored\n"
+            else case dataTypeRep (dataTypeOf (undefined :: a)) of
+                AlgRep cs -> do
+                    setResult ""
+                    mapM_ goConstr (zip (True : repeat False) cs)
+                    result <- gets sCurResult
+                    setResult (if null cs then result ++ "\n" else result)
+                IntRep -> setResult " has IntRep\n"
+                FloatRep -> setResult " has FloatRep\n"
+                CharRep -> setResult " has CharRep\n"
+                NoRep
+                    | S.member shownType ignore -> setResult " has NoRep\n"
+                    | otherwise -> error $
+                        "\nNoRep in Data.Store.Version for " ++ show shownType ++
+                        ".\nIn the future it will be possible to statically " ++
+                        "declare a global serialization version for this type. " ++
+                        "\nUntil then you will need to use 'vcIgnore', and " ++
+                        "understand that serialization changes for affected types " ++
+                        "will not be detected.\n"
+  where
+    setResult x =
+         modify (\s -> S
+             { sResults = M.insert label x (sResults s)
+             , sCurResult = ""
+             , sFieldNames = []
+             })
+    label = "data-type " ++ shownType
+    shownType = showsQualTypeRep 0 (typeRep (Proxy :: Proxy a)) ""
+    goConstr :: (Bool, Constr) -> State S ()
+    goConstr (isFirst, c) = do
+        modify (\s -> s
+            { sFieldNames = constrFields c ++ map (\ix -> "slot " ++ show (ix :: Int)) [0..]
+            , sCurResult = sCurResult s ++ (if isFirst then "\n  = " else "  | ") ++ showConstr c ++ " {\n"
+            })
+        void (fromConstrM goField c :: State S a)
+        modify (\s -> s { sCurResult = sCurResult s ++ "  }\n" })
+    goField :: forall b. Data b => State S b
+    goField = do
+        s <- get
+        case sFieldNames s of
+            [] -> fail "impossible case in getStructureInfo'"
+            (name:names) -> do
+                getStructureInfo' ignore (Proxy :: Proxy b)
+                s' <- get
+                put s
+                    { sResults = sResults s'
+                    , sCurResult = sCurResult s ++ "    " ++ name ++ " :: " ++ showsQualTypeRep 0 (typeRep (Proxy :: Proxy b)) "\n"
+                    , sFieldNames = names
+                    }
+                return (error "unexpected evaluation")
+
+showsQualTypeRep :: Int -> TypeRep -> ShowS
+showsQualTypeRep p (TypeRep _ tycon kinds tys) =
+    case tys of
+        [] -> showsQualTyCon tycon
+        [x] | tycon == tcList -> showChar '[' . showsQualTypeRep 0 x . showChar ']'
+          where
+        [a,r] | tycon == tcFun  -> showParen (p > 8) $
+                                     showsQualTypeRep 9 a .
+                                     showString " -> " .
+                                     showsQualTypeRep 8 r
+        xs | isTupleTyCon tycon -> showTuple xs
+           | otherwise         ->
+                showParen (p > 9) $
+                showsQualTyCon tycon .
+                showChar ' '      .
+                showArgs (showChar ' ') (kinds ++ tys)
+
+showsQualTyCon :: TyCon -> ShowS
+showsQualTyCon tc = showString (tyConModule tc ++ "." ++ tyConName tc)
+
+isTupleTyCon :: TyCon -> Bool
+isTupleTyCon tc
+  | ('(':',':_) <- tyConName tc = True
+  | otherwise                   = False
+
+showArgs :: ShowS -> [TypeRep] -> ShowS
+showArgs _   []     = id
+showArgs _   [a]    = showsQualTypeRep 10 a
+showArgs sep (a:as) = showsQualTypeRep 10 a . sep . showArgs sep as
+
+showTuple :: [TypeRep] -> ShowS
+showTuple args = showChar '('
+               . showArgs (showChar ',') args
+               . showChar ')'
+
+tcList :: TyCon
+tcList = tyConOf (Proxy :: Proxy [()])
+
+tcFun :: TyCon
+tcFun = tyConOf (Proxy :: Proxy (Int -> Int))
+
+tyConOf :: Typeable a => Proxy a -> TyCon
+tyConOf = typeRepTyCon . typeRep
+
+data VersionCheckException = VersionCheckException
+    { expectedVersion :: StoreVersion
+    , receivedVersion :: StoreVersion
+    } deriving (Typeable, Show)
+
+instance Exception VersionCheckException where
+    displayException VersionCheckException{..} =
+        "Mismatch detected by Data.Store.Version - expected " ++
+        T.unpack (decodeUtf8With lenientDecode (unStoreVersion expectedVersion)) ++ " but got " ++
+        T.unpack (decodeUtf8With lenientDecode (unStoreVersion receivedVersion))

stack.yaml

@@ -6,5 +6,5 @@ packages:
   extra-dep: true
 extra-deps:
 - th-lift-instances-0.1.7
-- th-utilities-0.1.1.0
+- th-utilities-0.2.0.0
 - th-reify-many-0.1.6