Peer: refactor pickPiece function

Use the headMay from the Safe package to get a Maybe list head and
lift fst to Maybe to get the key.

diff --git a/functorrent.cabal b/functorrent.cabal
index 2db111915a66b7e9e43b1e89a8ebd6bfd696f2f0..2ec81bb1dfa020d9f04fe30acc52b0b2d4d4d233 100644 (file)
--- a/functorrent.cabal
+++ b/functorrent.cabal
@@ -42,6 +42,7 @@ library
                        network-uri,
                        parsec,
                        QuickCheck,
                        network-uri,
                        parsec,
                        QuickCheck,

+                       safe,

                        tasty,
                        tasty-hunit
 
                        tasty,
                        tasty-hunit
 


@@ -63,7 +64,8 @@ executable functorrent
                        network,
                        network-uri,
                        parsec,
                        network,
                        network-uri,
                        parsec,

-                       QuickCheck
+                       QuickCheck,
+                       safe

 
 test-suite functorrent-test
   type:              exitcode-stdio-1.0
 
 test-suite functorrent-test
   type:              exitcode-stdio-1.0

diff --git a/src/FuncTorrent/Peer.hs b/src/FuncTorrent/Peer.hs
index 5e23fa112574c0ca07f6ddfbde0f36212a932720..0b9ece75bc9cc88db2fc5783255ea5cc103fb436 100644 (file)
--- a/src/FuncTorrent/Peer.hs
+++ b/src/FuncTorrent/Peer.hs
@@ -4,7 +4,7 @@ module FuncTorrent.Peer
      handlePeerMsgs
     ) where
 
      handlePeerMsgs
     ) where
 

-import Prelude hiding (lookup, concat, replicate, splitAt, take)
+import Prelude hiding (lookup, concat, replicate, splitAt, take, filter)

 
 import System.IO (Handle, BufferMode(..), hSetBuffering)
 import Data.ByteString (ByteString, unpack, concat, hGet, hPut, take, empty)
 
 import System.IO (Handle, BufferMode(..), hSetBuffering)
 import Data.ByteString (ByteString, unpack, concat, hGet, hPut, take, empty)


@@ -13,8 +13,9 @@ import Network (connectTo, PortID(..))
 import Control.Monad.State
 import Data.Bits
 import Data.Word (Word8)
 import Control.Monad.State
 import Data.Bits
 import Data.Word (Word8)

-import Data.Map (Map, fromList, toList, (!), mapWithKey, adjust)
+import Data.Map (Map, fromList, toList, (!), mapWithKey, adjust, filter)

 import qualified Crypto.Hash.SHA1 as SHA1 (hash)
 import qualified Crypto.Hash.SHA1 as SHA1 (hash)

+import Safe (headMay)

 
 import FuncTorrent.Metainfo (Info(..), Metainfo(..))
 import FuncTorrent.Utils (splitN, splitNum)
 
 import FuncTorrent.Metainfo (Info(..), Metainfo(..))
 import FuncTorrent.Utils (splitN, splitNum)


@@ -102,13 +103,8 @@ toPeerState h p meCh meIn heCh heIn =
 -- simple algorithm to pick piece.
 -- pick the first piece from 0 that is not downloaded yet.
 pickPiece :: PieceMap -> Maybe Integer
 -- simple algorithm to pick piece.
 -- pick the first piece from 0 that is not downloaded yet.
 pickPiece :: PieceMap -> Maybe Integer

-pickPiece m =
-  let pieceList = toList m
-      allPending = filter (\(_, v) -> dlstate v == Pending) pieceList
-  in
-   case allPending of
-    [] -> Nothing
-    ((i, _):_) -> Just i
+pickPiece =
+  (fst `liftM`) . headMay . toList . filter (\v -> dlstate v == Pending)

 
 updatePieceAvailability :: PieceMap -> Peer -> [Integer] -> PieceMap
 updatePieceAvailability pieceStatus p pieceList =
 
 updatePieceAvailability :: PieceMap -> Peer -> [Integer] -> PieceMap
 updatePieceAvailability pieceStatus p pieceList =