Reduce ChainDB memory usage

After some heap profiling, these bangs provided the most bang for the
buck (sorry for the pun).

For example, the memory usage of adding the first 30,000 blocks from disk (so
as fast as we can read them) to the ChainDB reduced from +240 MiB (and
growing) to 80 MiB. Note that these measurements were performed with block
validation disabled.

ouroboros-consensus/src/Ouroboros/Consensus/Ledger/Extended.hs

@@ -36,8 +36,8 @@ import           Ouroboros.Consensus.Util (repeatedlyM)
 --
 -- This is the combination of the ouroboros state and the ledger state proper.
 data ExtLedgerState blk = ExtLedgerState {
-      ledgerState         :: LedgerState blk
-    , ouroborosChainState :: ChainState (BlockProtocol blk)
+      ledgerState         :: !(LedgerState blk)
+    , ouroborosChainState :: !(ChainState (BlockProtocol blk))
     }
 
 data ExtValidationError blk =

ouroboros-consensus/src/Ouroboros/Storage/ChainDB/Impl/LgrDB.hs

@@ -330,7 +330,7 @@ getCurrentState LgrDB{..} = LedgerDB.ledgerDbCurrent <$> readTVar varDB
 -- 'LedgerDB'.
 setCurrent :: MonadSTM m
            => LgrDB m blk -> LedgerDB blk -> STM m ()
-setCurrent LgrDB{..} = writeTVar varDB
+setCurrent LgrDB{..} = writeTVar $! varDB
 
 currentPoint :: UpdateLedger blk
              => LedgerDB blk -> Point blk

ouroboros-consensus/src/Ouroboros/Storage/Common.hs

@@ -53,7 +53,7 @@ type SlotOffset = Word64
 -------------------------------------------------------------------------------}
 
 -- | Tip of the chain
-data Tip r = Tip r | TipGen
+data Tip r = Tip !r | TipGen
   deriving (Show, Eq, Generic)
 
 instance Condense r => Condense (Tip r) where

ouroboros-network/src/Ouroboros/Network/Point.hs

@@ -1,5 +1,5 @@
-{-# LANGUAGE DeriveFunctor     #-}
 {-# LANGUAGE DeriveFoldable    #-}
+{-# LANGUAGE DeriveFunctor     #-}
 {-# LANGUAGE DeriveGeneric     #-}
 {-# LANGUAGE DeriveTraversable #-}
 
@@ -11,9 +11,9 @@ module Ouroboros.Network.Point
   , block
   ) where
 
-import GHC.Generics (Generic)
+import           GHC.Generics (Generic)
 
-data WithOrigin t = Origin | At t
+data WithOrigin t = Origin | At !t
   deriving (Eq, Ord, Show, Generic, Functor, Foldable, Traversable)
 
 data Block slot hash = Block