From 453cf2bd0f276862d434f37a7943047425881a5a Mon Sep 17 00:00:00 2001
From: Dimitri Lozeve <dimitri.lozeve@gmail.com>
Date: Mon, 20 Nov 2017 17:01:52 +0000
Subject: [PATCH] Parallelise body updating

---
 orbit.cabal |  4 +++-
 src/Lib.hs  | 23 +++++++++++++++++++++--
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/orbit.cabal b/orbit.cabal
index 7216b81..6999c49 100644
--- a/orbit.cabal
+++ b/orbit.cabal
@@ -19,12 +19,14 @@ library
   build-depends:       base >= 4.7 && < 5
                      , linear
                      , lens
+                     , parallel
+                     , deepseq
   default-language:    Haskell2010
 
 executable orbit-exe
   hs-source-dirs:      app
   main-is:             Main.hs
-  ghc-options:         -threaded -rtsopts -with-rtsopts=-N
+  ghc-options:         -threaded -rtsopts -with-rtsopts=-N -eventlog
   build-depends:       base
                      , orbit
                      , linear
diff --git a/src/Lib.hs b/src/Lib.hs
index 490bd82..c034929 100644
--- a/src/Lib.hs
+++ b/src/Lib.hs
@@ -43,6 +43,9 @@ import Linear.Metric
 
 import Control.Lens hiding (Empty)
 
+import Control.Parallel.Strategies
+import Control.DeepSeq
+
 --------------------------------------------------------------------------------
 -- CONSTANTS
 --------------------------------------------------------------------------------
@@ -66,6 +69,10 @@ data Body = Body {
 
 makeLenses ''Body
 
+instance NFData Body where
+  rnf (Body name radius mass pos speed) =
+    rnf name `seq` rnf radius `seq` rnf mass `seq` rnf pos `seq` rnf speed
+
 
 -- | Distance between two bodies
 bodyDistance :: Body -> Body -> Double
@@ -87,12 +94,23 @@ data Region = Region {
 
 makeLenses ''Region
 
+instance NFData Region where
+  rnf (Region c cm m d) =
+    rnf c `seq` rnf cm `seq` rnf m `seq` rnf d
+
 -- | Main data structure for the Octree
 data Octree = Empty Region
             | Single Region Body
             | Node Region Octree Octree Octree Octree Octree Octree Octree Octree
   deriving (Show, Eq)
 
+instance NFData Octree where
+  rnf (Empty r) = rnf r
+  rnf (Single r b) = rnf r `seq` rnf b
+  rnf (Node r o1 o2 o3 o4 o5 o6 o7 o8) =
+    rnf r `seq` rnf o1 `seq` rnf o2 `seq` rnf o3 `seq` rnf o4
+    `seq` rnf o5 `seq` rnf o6 `seq` rnf o7 `seq` rnf o8
+
 -- | One of the 8 octants from a given reference point
 data Octant = NED | NWD | SWD | SED
             | NEU | NWU | SWU | SEU
@@ -254,8 +272,9 @@ updateAll :: Double -- ^ The time step
   -> [Body] -- ^ A list of Bodies
   -> [Body] -- ^ The updated list of Bodies
 updateAll dt theta bs =
-  map (update dt theta tree) bs
-  where tree = buildTree bs
+  let
+    tree = buildTree bs
+  in parMap (rparWith rdeepseq) (update dt theta tree) bs