Add memoHits to sigma profiling framework.

Summary: Integrate counts of memoized computation access into the profiling framework. Every call to `cachedComputation` logs one hit, including the first one.

Reviewed By: simonmar

Differential Revision: D3430491

fbshipit-source-id: a799c0e603c7bc94813da9801d7f4931a011131d

Haxl/Core/Monad.hs

@@ -379,6 +379,12 @@ modifyProfileData env label allocs =
         updCaller _ old =
           old { profileAllocs = profileAllocs old - allocs }
 
+incrementMemoHitCounterFor :: ProfileLabel -> Profile -> Profile
+incrementMemoHitCounterFor lbl p =
+  p { profile = HashMap.adjust incrementMemoHitCounter lbl (profile p) }
+
+incrementMemoHitCounter :: ProfileData -> ProfileData
+incrementMemoHitCounter pd = pd { profileMemoHits = succ (profileMemoHits pd) }
 -- -----------------------------------------------------------------------------
 -- Exceptions
 
@@ -919,6 +925,8 @@ cachedComputation
 
 cachedComputation req haxl = GenHaxl $ \env ref -> do
   cache <- readIORef (memoRef env)
+  ifProfiling (flags env) $
+    modifyIORef' (profRef env) (incrementMemoHitCounterFor (profLabel env))
   case DataCache.lookup req cache of
     Nothing -> do
       memovar <- newIORef (MemoInProgress ref haxl)

Haxl/Core/Types.hs

@@ -49,6 +49,7 @@ module Haxl.Core.Types (
   ProfileData(..),
   emptyProfileData,
   AllocCount,
+  MemoHitCount,
 
   -- * Data fetching
   DataSource(..),
@@ -223,6 +224,7 @@ numFetches (Stats rs) = sum (map fetchesInRound rs)
 
 type ProfileLabel = Text
 type AllocCount = Int64
+type MemoHitCount = Int64
 
 data Profile = Profile
   { profileRound :: {-# UNPACK #-} !Round
@@ -243,11 +245,13 @@ data ProfileData = ProfileData
      -- ^ labels that this label depends on
   , profileFetches :: Map Round (HashMap Text Int)
      -- ^ map from round to {datasource name => fetch count}
+  , profileMemoHits :: {-# UNPACK #-} !MemoHitCount
+    -- ^ number of hits to memoized computation at this label
   }
   deriving Show
 
 emptyProfileData :: ProfileData
-emptyProfileData = ProfileData 0 HashSet.empty Map.empty
+emptyProfileData = ProfileData 0 HashSet.empty Map.empty 0
 
 -- ---------------------------------------------------------------------------
 -- DataCache