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Diffstat (limited to 'src/Hakyll/Core/ResourceProvider/Modified.hs')
-rw-r--r-- | src/Hakyll/Core/ResourceProvider/Modified.hs | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/src/Hakyll/Core/ResourceProvider/Modified.hs b/src/Hakyll/Core/ResourceProvider/Modified.hs new file mode 100644 index 0000000..837bc8c --- /dev/null +++ b/src/Hakyll/Core/ResourceProvider/Modified.hs @@ -0,0 +1,83 @@ +-------------------------------------------------------------------------------- +module Hakyll.Core.ResourceProvider.Modified + ( resourceModified + , resourceModificationTime + ) where + + +-------------------------------------------------------------------------------- +import Control.Applicative ((<$>), (<*>)) +import Control.Monad (when) +import qualified Crypto.Hash.MD5 as MD5 +import qualified Data.ByteString as B +import qualified Data.ByteString.Lazy as BL +import Data.IORef +import qualified Data.Map as M +import Data.Time (UTCTime) +import System.Directory (getModificationTime) + + +-------------------------------------------------------------------------------- +import Hakyll.Core.Identifier +import Hakyll.Core.ResourceProvider.Internal +import Hakyll.Core.ResourceProvider.MetadataCache +import Hakyll.Core.Store (Store) +import qualified Hakyll.Core.Store as Store + + +-------------------------------------------------------------------------------- +-- | A resource is modified if it or its metadata has changed +resourceModified :: ResourceProvider -> Identifier a -> IO Bool +resourceModified rp r + | not exists = return False + | otherwise = do + cache <- readIORef cacheRef + case M.lookup normalized cache of + Just m -> return m + Nothing -> do + -- Check if the actual file was modified, and do a recursive + -- call to check if the metadata file was modified + m <- (||) + <$> fileDigestModified store (toFilePath r) + <*> resourceModified rp (resourceMetadataResource r) + modifyIORef cacheRef (M.insert normalized m) + + -- Important! (But ugly) + when m $ resourceInvalidateMetadataCache rp r + + return m + where + normalized = castIdentifier $ setGroup Nothing r + exists = resourceExists rp r + store = resourceStore rp + cacheRef = resourceModifiedCache rp + + +-------------------------------------------------------------------------------- +-- | Utility: Check if a the digest of a file was modified +fileDigestModified :: Store -> FilePath -> IO Bool +fileDigestModified store fp = do + -- Get the latest seen digest from the store, and calculate the current + -- digest for the + lastDigest <- Store.get store key + newDigest <- fileDigest fp + if Store.Found newDigest == lastDigest + -- All is fine, not modified + then return False + -- Resource modified; store new digest + else do + Store.set store key newDigest + return True + where + key = ["Hakyll.Core.Resource.Provider.fileModified", fp] + + +-------------------------------------------------------------------------------- +-- | Utility: Retrieve a digest for a given file +fileDigest :: FilePath -> IO B.ByteString +fileDigest = fmap MD5.hashlazy . BL.readFile + + +-------------------------------------------------------------------------------- +resourceModificationTime :: Identifier a -> IO UTCTime +resourceModificationTime = getModificationTime . toFilePath |