-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | Cache for HXT XML Documents and other binary data
--   
--   Extension for caching XML documents and other binary data in cache
--   directory of the local filesystem. The module exports a version of
--   readDocument with the additional cache functionality.
@package hxt-cache
@version 0.0.4

module Control.Concurrent.ResourceTable
type ResourceTable a = MVar (Map a ResourceLock)
type ResourceLock = (MVar (), Int)
requestResource :: (Ord a) => ResourceTable a -> a -> IO ()
releaseResource :: (Ord a) => ResourceTable a -> a -> IO ()
newResourceTable :: IO (ResourceTable a)


-- | Caching of XML document trees and other binary data
module Text.XML.HXT.Arrow.XmlCache

-- | This readDocument is a wrapper for the
--   <tt>Text.XML.HXT.Arrow.ReadDocument.readDocument</tt> function. The
--   function is controlled by the options <a>a_cache</a>,
--   <a>a_compress</a> and <a>a_document_age</a>.
--   
--   <ul>
--   <li><a>a_cache</a>: the document tree of the document read is cached
--   in the directory given by this option, or, if it is read before and it
--   is not out of date, see <a>a_document_age</a>, it is read from the
--   cache. The document is stored in binary format (used package:
--   binary).</li>
--   <li><a>a_compress</a> : controls whether the cache contents is
--   compressed with the bzip2 lib for saving space</li>
--   <li><a>a_document_age</a>: determines the maximum age of the document
--   in seconds. If this time is exceeded, the cache entry is ignored, the
--   original is re-read and cached again. Default for the document age is
--   1 day.</li>
--   </ul>
readDocument :: Attributes -> String -> IOStateArrow s b XmlTree
a_cache :: String
a_compress :: String
a_document_age :: String
lookupCache :: (NFData b, Binary b) => CacheConfig -> String -> IOStateArrow s a b
writeCache :: (Binary b) => CacheConfig -> String -> IOStateArrow s b ()

-- | Compute the SHA1 hash is hexadecimal format for an arbitray
--   serializable value
sha1HashValue :: (Arrow a, Binary b) => a b Integer
sha1HashString :: (Arrow a, Binary b) => a b String
data CacheConfig
CC :: FilePath -> Bool -> Integer -> CacheConfig
c_dir :: CacheConfig -> FilePath
c_compress :: CacheConfig -> Bool
c_age :: CacheConfig -> Integer

-- | Arrow for checking if a document is in the cache. The arrow fails if
--   document not there, else the file modification time is returned.
isInCache :: Attributes -> IOStateArrow s String ClockTime
isInCache' :: CacheConfig -> String -> IO (Maybe ClockTime)