Expose distribution internals for use in ekg-json

Author: tibbe

System/Metrics.hs

@@ -517,7 +517,7 @@ data Value = Counter {-# UNPACK #-} !Int64
            | Gauge {-# UNPACK #-} !Int64
            | Label {-# UNPACK #-} !T.Text
            | Distribution !Distribution.Stats
-           deriving Show
+           deriving (Eq, Show)
 
 sampleOne :: MetricSampler -> IO Value
 sampleOne (CounterS m)      = Counter <$> m

System/Metrics/Distribution.hsc

@@ -37,6 +37,7 @@ import Foreign.Storable (Storable(alignment, peek, poke, sizeOf), peekByteOff,
 import Prelude hiding (max, min, read, sum)
 
 import Data.Array
+import System.Metrics.Distribution.Internal (Stats(..))
 import System.Metrics.ThreadId
 
 -- | An metric for tracking events.
@@ -162,13 +163,3 @@ read distrib = do
         , min   = cMin
         , max   = cMax
         }
-
--- | Distribution statistics
-data Stats = Stats
-    { mean     :: !Double  -- ^ Sample mean
-    , variance :: !Double  -- ^ Biased sample variance
-    , count    :: !Int64   -- ^ Event count
-    , sum      :: !Double  -- ^ Sum of values
-    , min      :: !Double  -- ^ Min value seen
-    , max      :: !Double  -- ^ Max value seen
-    } deriving Show

System/Metrics/Distribution/Internal.hs

@@ -0,0 +1,19 @@
+{-# OPTIONS_GHC -funbox-strict-fields #-}
+
+-- | Internal module used to share implementation details between the
+-- family of ekg packages. DO NOT DEPEND ON THIS MODULE.
+module System.Metrics.Distribution.Internal
+    ( Stats(..)
+    ) where
+
+import Data.Int (Int64)
+
+-- | Distribution statistics
+data Stats = Stats
+    { mean     :: !Double  -- ^ Sample mean
+    , variance :: !Double  -- ^ Biased sample variance
+    , count    :: !Int64   -- ^ Event count
+    , sum      :: !Double  -- ^ Sum of values
+    , min      :: !Double  -- ^ Min value seen
+    , max      :: !Double  -- ^ Max value seen
+    } deriving (Eq, Show)

ekg-core.cabal

@@ -19,6 +19,7 @@ library
     System.Metrics
     System.Metrics.Counter
     System.Metrics.Distribution
+    System.Metrics.Distribution.Internal
     System.Metrics.Gauge
     System.Metrics.Label