From: Ramakrishnan Muthukrishnan <ram@rkrishnan.org>
Date: Sun, 13 Sep 2015 07:15:35 +0000 (+0530)
Subject: wip: Use reader to pass around metainfo
X-Git-Url: https://git.rkrishnan.org/pf/content/%22news.html/running.html?a=commitdiff_plain;h=24489a350fcb60839546aaa0d127c563746839e6;p=functorrent.git

wip: Use reader to pass around metainfo
---

diff --git a/functorrent.cabal b/functorrent.cabal
index b663ef9..31cbbdb 100644
--- a/functorrent.cabal
+++ b/functorrent.cabal
@@ -45,7 +45,8 @@ library
                        QuickCheck,
                        safe,
                        tasty,
-                       tasty-hunit
+                       tasty-hunit,
+                       transformers
 
 executable functorrent
   main-is:             Main.hs
diff --git a/src/FuncTorrent/Tracker.hs b/src/FuncTorrent/Tracker.hs
index 206e1b8..aac578c 100644
--- a/src/FuncTorrent/Tracker.hs
+++ b/src/FuncTorrent/Tracker.hs
@@ -8,6 +8,8 @@ module FuncTorrent.Tracker
 
 import Prelude hiding (lookup, splitAt)
 
+import Control.Monad.IO.Class (liftIO)
+import Control.Monad.Reader (ReaderT, ask, runReaderT)
 import Data.ByteString (ByteString)
 import Data.ByteString.Char8 as BC (pack, unpack, splitAt)
 import Data.Char (chr)
@@ -65,14 +67,18 @@ mkTrackerResponse resp =
           where (ip', port') = splitAt 4 peer
 
 -- | Connect to a tracker and get peer info
-tracker :: String -> Metainfo -> IO ByteString
-tracker peer_id m = get (head . announceList $ m) $ mkArgs peer_id m
+tracker :: String -> ReaderT Metainfo IO ByteString
+tracker peer_id = do
+  m <- ask
+  let args = mkArgs peer_id m
+  liftIO $ get (head . announceList $ m) $ args
 
-getTrackerResponse ::  String -> Metainfo -> IO (Either ByteString TrackerResponse)
-getTrackerResponse peerId m = do
-  resp <- tracker peerId m
+getTrackerResponse ::  String -> ReaderT Metainfo IO (Either ByteString TrackerResponse)
+getTrackerResponse peerId = do
+  m <- ask
+  resp <- liftIO $ runReaderT (tracker peerId) m
   case decode resp of
-   Right trackerInfo -> return $ mkTrackerResponse trackerInfo
+   Right trackerInfo -> liftIO $ return $ mkTrackerResponse trackerInfo
    Left e -> return $ Left (pack (show e))
 
 --- | URL encode hash as per RFC1738
@@ -100,3 +106,5 @@ mkArgs peer_id m = [("info_hash", pack . urlEncodeHash . B16.encode . infoHash $
                     ("left", pack . show . lengthInBytes $ info m),
                     ("compact", "1"),
                     ("event", "started")]
+
+
diff --git a/src/main/Main.hs b/src/main/Main.hs
index b86f2e4..b82d27a 100644
--- a/src/main/Main.hs
+++ b/src/main/Main.hs
@@ -2,6 +2,8 @@
 module Main where
 
 import Prelude hiding (log, length, readFile, getContents)
+
+import Control.Monad.Reader(runReaderT)
 import Data.ByteString.Char8 (ByteString, getContents, readFile, unpack)
 import System.Environment (getArgs)
 import System.Exit (exitSuccess)
@@ -49,7 +51,7 @@ main = do
        log "Trying to fetch peers"
 
        log $ "Trackers: " ++ head (announceList m)
-       trackerResp <- getTrackerResponse peerId m
+       trackerResp <- runReaderT (getTrackerResponse peerId) m
        case  trackerResp of
         Left e -> log $ "Error" ++ unpack e
         Right peerList -> do