Minor refactoring.

1 files changed, 63 insertions, 71 deletions

diff --git a/src/Network/Kademlia/Bootstrap.hs b/src/Network/Kademlia/Bootstrap.hs
index 42bff665..92a20ca5 100644
--- a/src/Network/Kademlia/Bootstrap.hs
+++ b/src/Network/Kademlia/Bootstrap.hs
@@ -45,41 +45,6 @@ import Network.Kademlia.Search
 import Control.Concurrent.Tasks
 import Network.Kademlia
 
--- From BEP 05:
---
--- Each bucket should maintain a "last changed" property to indicate how
--- "fresh" the contents are.
---
--- Note: We will use a "time to next refresh" property instead and store it in
--- a priority search queue.
---
--- When...
---
--- >>> data BucketTouchEvent = RoutingStatus :--> RoutingStatus
--- >>> bucketEvents =
--- >>>  [ Applicant :--> Stranger -- a node in a bucket is pinged and it responds,
--- >>>
--- >>>  , Stranger  :--> Accepted -- or a node is added to a bucket,
--- >>>
--- >>>  , Accepted  :--> Stranger -- or a node in a bucket is replaced
--- >>>  , Applicant :--> Accepted -- with another node,
--- >>>  ]
---
--- the bucket's last changed property should be updated. Buckets
--- that have not been changed in 15 minutes should be "refreshed." This is done
--- by picking a random ID in the range of the bucket and performing a
--- find_nodes search on it.
---
--- The only other possible BucketTouchEvents are as follows:
---
--- >>> not_handled =
--- >>>   , Stranger :--> Applicant -- A ping is pending, it's result is covered:
--- >>>                             --     (Applicant :--> Stranger)
--- >>>                             --     (Applicant :--> Accepted)
--- >>>   , Accepted :--> Applicant -- Never happens
--- >>>   ]
---
-
 type SensibleNodeId nid ni =
                  ( Show nid
                  , Ord nid
@@ -199,7 +164,10 @@ refreshBucket sch var n = do
     return rcount
 
 bootstrap :: (Ord ni, Ord nid, Hashable nid, Hashable ni, Foldable t, Foldable t1, Show nid) =>
-             BucketRefresher nid ni -> t1 ni -> t ni -> IO ()
+             BucketRefresher nid ni
+             -> t1 ni -- ^ Nodes to bootstrap from.
+             -> t ni  -- ^ Fallback nodes; used only if the others are unresponsive.
+             -> IO ()
 bootstrap BucketRefresher { refreshSearch  = sch
                           , refreshBuckets = var
                           , refreshPing    = ping } ns ns0 = do
@@ -223,60 +191,84 @@ bootstrap BucketRefresher { refreshSearch  = sch
             forkTask g (show $ kademliaLocation (searchSpace sch) n)
                        (void $ ping n)
     hPutStrLn stderr "Finished bootstrap pings."
-
-    -- Now run searches until all the buckets are full.  On a small network,
-    -- this may never quit.
+    -- Now search our own Id by refreshing the last bucket.
+    last <- atomically $ bktCount <$> readTVar var
+    void $ refreshBucket sch var last
+    -- That's it.
     --
-    -- TODO: For small networks, we should give up on filling a nearby bucket
-    -- at some point and move on to one farther away.
-    flip fix 1 $ \again cnt -> do
-        when (cnt==0) $ do
-            -- Force a delay in case the search returns too quickly
-            hPutStrLn stderr $ "Zero results, forcing 1 minute delay"
-            threadDelay (60 * 1000000)
-        tbl <- atomically $ readTVar var
-        let shp    = zip (R.shape tbl) [0 .. ]
-            unfull = filter ( (< R.defaultBucketSize) . fst ) shp
-        case dropWhile ((> R.defaultBucketCount - 1) . snd) unfull of
-            [] -> do
-                when (length shp < R.defaultBucketCount) $ do
-                    -- Not enough buckets, keep trying.
-                    hPutStrLn stderr
-                        $ "Not enough buckets, refresh " ++ show (R.defaultBucketCount - 1)
-                    cnt <- refreshBucket sch var
-                        (R.defaultBucketCount - 1)
-                    again cnt
-            (size,num):_ -> do
-                hPutStrLn stderr $ "Bucket too small, refresh "++ show (size,num,shp)
-                cnt <- refreshBucket sch var num
-                again cnt
+    -- Hopefully 'forkPollForRefresh' was invoked and can take over
+    -- maintenance.
+
 
 -- | Reschedule a bucket's refresh-time.  It should be called whenever a bucket
 -- changes.  This will typically be invoked from 'tblTransition'.
 --
--- XXX: This will be redundantly triggered twice upon every node replacement
--- because we do not currently distinguish between standalone
+-- From BEP 05:
+--
+-- > Each bucket should maintain a "last changed" property to indicate how
+-- > "fresh" the contents are.
+--
+-- We will use a "time to next refresh" property instead and store it in
+-- a priority search queue.
+--
+-- In detail using an expository (not actually implemented) type
+-- 'BucketTouchEvent'...
+--
+-- >>> data BucketTouchEvent = RoutingStatus :--> RoutingStatus
+-- >>> bucketEvents =
+-- >>>  [ Applicant :--> Stranger -- a node in a bucket is pinged and it responds,
+-- >>>
+-- >>>  , Stranger  :--> Accepted -- or a node is added to a bucket,
+-- >>>
+-- >>>  , Accepted  :--> Stranger -- or a node in a bucket is replaced
+-- >>>  , Applicant :--> Accepted -- with another node,
+-- >>>  ]
+--
+-- the bucket's last changed property should be updated. Buckets that have not
+-- been changed in 15 minutes (see 'refreshInterval') should be "refreshed."
+-- This is done by picking a random ID in the range of the bucket and
+-- performing a find_nodes search on it.
+--
+-- The only other possible BucketTouchEvents are as follows:
+--
+-- >>> not_handled =
+-- >>>   , Stranger :--> Applicant -- A ping is pending, it's result is covered:
+-- >>>                             --     (Applicant :--> Stranger)
+-- >>>                             --     (Applicant :--> Accepted)
+-- >>>   , Accepted :--> Applicant -- Never happens
+-- >>>   ]
+--
+-- Because this BucketTouchEvent type is not actually implemented and we only
+-- receive notifications of a node's new state, it suffices to reschedule the
+-- bucket refresh 'touchBucket' on every transition to a state other than
+-- 'Applicant'.
+--
+-- XXX: Unfortunately, this means redundantly triggering twice upon every node
+-- replacement because we do not currently distinguish between standalone
 -- insertion/deletion events and an insertion/deletion pair constituting
 -- replacement.
 --
 -- It might also be better to pass the timestamp of the transition here and
 -- keep the refresh queue in better sync with the routing table by updating it
 -- within the STM monad.
+--
+-- We embed the result in the STM monad but currently, no STM state changes
+-- occur until the returned IO action is invoked.  TODO: simplify?
 touchBucket :: BucketRefresher nid ni
             -> RoutingTransition ni     -- ^ What happened to the bucket?
             -> STM (IO ())
 touchBucket BucketRefresher{ refreshSearch
                            , refreshInterval
                            , refreshBuckets
-                           , refreshQueue
-                           }
-            tr
-    | (transitionedTo tr == Applicant)
-                = return $ return ()
-    | otherwise = return $ do
+                           , refreshQueue    }
+            RoutingTransition{ transitionedTo
+                             , transitioningNode }
+    = case transitionedTo of
+        Applicant -> return $ return () -- Ignore transition to applicant.
+        _         -> return $ do        -- Reschedule for any other transition.
          now <- getPOSIXTime
          atomically $ do
             let space = searchSpace refreshSearch
-                nid = kademliaLocation space (transitioningNode tr)
+                nid = kademliaLocation space transitioningNode
             num <- R.bucketNumber space nid <$> readTVar refreshBuckets
             modifyTVar' refreshQueue $ Int.insert num (now + refreshInterval)