Initial commit

.gitignore

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+*cabal.config
+*cabal.sandbox.config
+.cabal-sandbox/*
+*dist/

LICENSE

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+Copyright (c) 2015, Anchor Systems
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Anchor Systems nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Setup.hs

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+import           Distribution.Simple
+main = defaultMain

ekg-servant.cabal

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+name:                ekg-servant
+version:             0.1.0.0
+synopsis:            Helpers for using ekg with servant
+description:         Helpers for using ekg with servant
+license:             BSD3
+license-file:        LICENSE
+author:              Anchor Engineering <engineering@lists.anchor.net.au>
+maintainer:          Anchor Engineering <engineering@lists.anchor.net.au>
+category:            System
+build-type:          Simple
+cabal-version:       >=1.10
+
+source-repository HEAD
+  type: git
+  location: https://github.com/anchor/ekg-servant.git
+
+library
+  exposed-modules:     Servant.Ekg
+  build-depends:       base >=4.7 && <4.9
+                     , ekg-core
+                     , http-types
+                     , time
+                     , wai
+  default-language:    Haskell2010

lib/Servant/Ekg.hs

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+module Servant.Ekg where
+
+import           Control.Exception
+import           Data.Time.Clock
+import           Network.HTTP.Types
+import           Network.Wai
+import qualified System.Metrics.Counter      as Counter
+import qualified System.Metrics.Distribution as Distribution
+import qualified System.Metrics.Gauge        as Gauge
+
+
+gaugeInflight :: Gauge.Gauge -> Middleware
+gaugeInflight inflight application request respond =
+    bracket_ (Gauge.inc inflight)
+             (Gauge.dec inflight)
+             (application request respond)
+
+-- | Count responses with 2XX, 4XX, 5XX, and XXX response codes.
+countResponseCodes
+    :: (Counter.Counter, Counter.Counter, Counter.Counter, Counter.Counter)
+    -> Middleware
+countResponseCodes (c2XX, c4XX, c5XX, cXXX) application request respond =
+    application request respond'
+  where
+    respond' res = count (responseStatus res) >> respond res
+    count Status{statusCode = sc }
+        | 200 <= sc && sc < 300 = Counter.inc c2XX
+        | 400 <= sc && sc < 500 = Counter.inc c4XX
+        | 500 <= sc && sc < 600 = Counter.inc c5XX
+        | otherwise             = Counter.inc cXXX
+
+responseTimeDistribution :: Distribution.Distribution -> Middleware
+responseTimeDistribution dist application request respond =
+    bracket getCurrentTime stop $ const $ application request respond
+  where
+    stop t1 = do
+        t2 <- getCurrentTime
+        let dt = diffUTCTime t2 t1
+        Distribution.add dist $ fromRational $ toRational dt