From 937342955301e9820a9bcbafcf8922cc5dd1798d Mon Sep 17 00:00:00 2001
From: Sam Truzjan <pxqr.sta@gmail.com>
Date: Thu, 3 Apr 2014 01:35:32 +0400
Subject: [Exchange] Storage is not available during metadata exchange

---
 src/Network/BitTorrent/Exchange/Session.hs | 53 +++++++++++++++++++-----------
 1 file changed, 34 insertions(+), 19 deletions(-)

diff --git a/src/Network/BitTorrent/Exchange/Session.hs b/src/Network/BitTorrent/Exchange/Session.hs
index 4b9b0fdb..57d21579 100644
--- a/src/Network/BitTorrent/Exchange/Session.hs
+++ b/src/Network/BitTorrent/Exchange/Session.hs
@@ -97,12 +97,14 @@ data Session = Session
   , sessionLogger          :: !(LogFun)
   , sessionEvents          :: !(SendPort SessionEvent)
 
+------------------------------------------------------------------------
   , metadata               :: !(MVar Metadata.Status)
   , infodict               :: !(MVar (Cached InfoDict))
 
   , status                 :: !(MVar SessionStatus)
-  , storage                :: !(Storage)
+  , sessionStorage         :: !(MVar Storage)
 
+------------------------------------------------------------------------
   , connectionsPrefs       :: !ConnectionPrefs
 
     -- | Connections either waiting for TCP/uTP 'connect' or waiting
@@ -133,28 +135,32 @@ newSession :: LogFun
            -> IO Session          -- ^
 newSession logFun addr rootPath dict = do
   pid         <- maybe genPeerId return (peerId addr)
-  store       <- openInfoDict ReadWriteEx rootPath dict
-  statusVar   <- newMVar $ sessionStatus (BF.haveNone (totalPieces store))
+  let ih = idInfoHash dict
+  eventStream <- newSendPort
+
+  storage     <- openInfoDict ReadWriteEx rootPath dict
+  storageVar  <- newMVar storage
+
+  statusVar   <- newMVar $ sessionStatus (BF.haveNone (totalPieces storage))
                                          (piPieceLength (idPieceInfo dict))
+
   metadataVar <- newMVar (error "sessionMetadata")
   infodictVar <- newMVar (cache dict)
 
   pSetVar     <- newTVarIO S.empty
   eSetVar     <- newTVarIO M.empty
   chan        <- newChan
-  eventStream <- newSendPort
 
   return Session
     { sessionPeerId          = pid
-    , sessionTopic           = idInfoHash dict
+    , sessionTopic           = ih
     , sessionLogger          = logFun
     , sessionEvents          = eventStream
 
     , metadata               = metadataVar
     , infodict               = infodictVar
-
     , status                 = statusVar
-    , storage                = store
+    , sessionStorage         = storageVar
 
     , connectionsPrefs       = def
     , connectionsPending     = pSetVar
@@ -165,7 +171,8 @@ newSession logFun addr rootPath dict = do
 
 closeSession :: Session -> IO ()
 closeSession Session {..} = do
-  close storage
+  mstorage <- tryReadMVar sessionStorage
+  maybe (return ()) close mstorage
 {-
   hSet <- atomically $ do
     pSet <- swapTVar connectionsPending     S.empty
@@ -448,19 +455,27 @@ handleTransfer (Request bix) = do
   bitfield <- getThisBitfield
   upload   <- canUpload <$> use connStatus
   when (upload && ixPiece bix `BF.member` bitfield) $ do
-    blk <- liftIO $ readBlock bix storage
-    sendMessage (Message.Piece blk)
+    mstorage <- liftIO $ tryReadMVar sessionStorage
+    case mstorage of
+      Nothing -> return ()
+      Just storage -> do
+        blk <- liftIO $ readBlock bix storage
+        sendMessage (Message.Piece blk)
 
 handleTransfer (Message.Piece   blk) = do
   Session {..} <- asks connSession
-  isSuccess <- withStatusUpdates (SS.pushBlock blk storage)
-  case isSuccess of
-    Nothing -> liftIO $ throwIO $ userError "block is not requested"
-    Just isCompleted -> do
-      when isCompleted $ do
-        sendBroadcast (Have (blkPiece blk))
---        maybe send not interested
-      tryFillRequestQueue
+  mstorage <- liftIO $ tryReadMVar sessionStorage
+  case mstorage of
+    Nothing -> return () -- TODO (?) break connection
+    Just storage -> do
+      isSuccess <- withStatusUpdates (SS.pushBlock blk storage)
+      case isSuccess of
+        Nothing -> liftIO $ throwIO $ userError "block is not requested"
+        Just isCompleted -> do
+          when isCompleted $ do
+            sendBroadcast (Have (blkPiece blk))
+--            maybe send not interested
+            tryFillRequestQueue
 
 handleTransfer (Cancel  bix) = filterQueue (not . (transferResponse bix))
   where
@@ -546,7 +561,7 @@ mainWire :: Wire Session ()
 mainWire = do
   lift establishedConnection
   Session {..} <- asks connSession
-  lift $ resizeBitfield (totalPieces storage)
+--  lift $ resizeBitfield (totalPieces storage)
   logEvent "Connection established"
   iterM logMessage =$= exchange =$= iterM logMessage
   lift finishedConnection
-- 
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