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