bittorrent: Expire old peer announcements.

1 files changed, 18 insertions, 2 deletions

diff --git a/src/Network/BitTorrent/MainlineDHT.hs b/src/Network/BitTorrent/MainlineDHT.hs
index f43b070c..63e67ad3 100644
--- a/src/Network/BitTorrent/MainlineDHT.hs
+++ b/src/Network/BitTorrent/MainlineDHT.hs
@@ -47,7 +47,7 @@ import Data.Monoid
 import Data.Ord
 import qualified Data.Serialize               as S
 import Data.Set                               (Set)
-import Data.Time.Clock.POSIX                  (POSIXTime)
+import Data.Time.Clock.POSIX                  (POSIXTime, getPOSIXTime)
 import Data.Torrent
 import Data.Typeable
 import Data.Word
@@ -631,7 +631,7 @@ newClient swarms addr = do
             , clientResponseId    = return
             }
 
-    -- TODO: Provide some means of shutting down these four auxillary threads:
+    -- TODO: Provide some means of shutting down these five auxillary threads:
 
     fork $ fix $ \again -> do
         myThreadId >>= flip labelThread "addr4"
@@ -656,8 +656,24 @@ newClient swarms addr = do
     refresh_thread4 <- forkPollForRefresh $ refresher4 routing
     refresh_thread6 <- forkPollForRefresh $ refresher6 routing
 
+    forkAnnouncedInfohashesGC (contactInfo swarms)
+
     return (client, routing, bootstrap (refresher4 routing), bootstrap (refresher6 routing))
 
+-- Note that you should call .put() every hour for content that you want to
+-- keep alive, since nodes may discard data nodes older than 2 hours. (source:
+-- https://www.npmjs.com/package/bittorrent-dht)
+--
+-- This function will discard records between 3 and 6 hours old.
+forkAnnouncedInfohashesGC :: TVar PeerStore -> IO ThreadId
+forkAnnouncedInfohashesGC vpeers = fork $ do
+    myThreadId >>= flip labelThread "gc:bt-peers"
+    fix $ \loop -> do
+        cutoff <- getPOSIXTime
+        threadDelay 10800000000 -- 3 hours
+        atomically $ modifyTVar' vpeers $ deleteOlderThan cutoff
+        loop
+
 -- | Modifies a purely random 'NodeId' to one that is related to a given
 -- routable address in accordance with BEP 42.
 --