split up stats summing and evaluating, launch threads
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@ -19,7 +19,7 @@ import qualified Data.ByteString.Lazy.UTF8 as BSUL
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import qualified Data.ByteString.UTF8 as BSU
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import qualified Data.HashMap.Strict as HMap
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import qualified Data.HashSet as HSet
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import Data.Maybe (isJust, fromJust)
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import Data.Maybe (fromJust, isJust)
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import Data.String (fromString)
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import Data.Text.Lazy (Text)
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import qualified Data.Text.Lazy as Txt
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@ -54,9 +54,11 @@ data PostService d = PostService
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, relayInQueue :: TQueue (Hashtag, PostID, PostContent)
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-- ^ Queue for processing incoming posts of own instance asynchronously
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, postFetchQueue :: TQueue PostID
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-- ^ queue of posts to be fetched
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, migrationsInProgress :: TVar (HMap.HashMap NodeID (MVar ()))
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, httpMan :: HTTP.Manager
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, statsQueue :: TQueue StatsEvent
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, loadStats :: TVar RelayStats
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}
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deriving (Typeable)
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@ -86,6 +88,7 @@ instance DHT d => Service PostService d where
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migrationsInProgress' <- newTVarIO HMap.empty
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httpMan' <- HTTP.newManager HTTP.defaultManagerSettings
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statsQueue' <- newTQueueIO
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loadStats' <- newTVarIO emptyStats
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let
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thisService = PostService
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{ serviceConf = conf
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@ -99,6 +102,7 @@ instance DHT d => Service PostService d where
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, migrationsInProgress = migrationsInProgress'
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, httpMan = httpMan'
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, statsQueue = statsQueue'
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, loadStats = loadStats'
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}
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port' = fromIntegral (confServicePort conf)
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warpSettings = Warp.setPort port' . Warp.setHost (fromString . confServiceHost $ conf) $ Warp.defaultSettings
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@ -109,7 +113,11 @@ instance DHT d => Service PostService d where
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concurrently_
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-- web server
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(Warp.runSettings warpSettings $ postServiceApplication thisService)
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$ concurrently
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-- post queue processing
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(processIncomingPosts thisService)
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-- statistics/ measurements
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(launchStatsThreads thisService)
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-- update thread ID after fork
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atomically $ writeTVar threadVar servThreadID
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pure thisService
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@ -606,84 +614,14 @@ fetchTagPosts serv = forever $ do
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-- ======= statistics/measurement and logging =======
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data StatsEventType = PostPublishEvent
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-- ^ initial publishing of a post by an instance
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| RelayReceiveEvent
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-- ^ receiving of posts because of being the responsible relay, for estimation of \tau_t
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-- TODO: record for which hashtag
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| RelayDeliveryEvent
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-- ^ delivering (or at least attempt) a post to a subscriber
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| IncomingPostFetchEvent
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-- ^ another instance fetches a post from this instance
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deriving (Enum, Show, Eq)
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-- | Represents measurement event of a 'StatsEventType' with a count relevant for a certain key
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data StatsEvent = StatsEvent StatsEventType Int NodeID
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-- TODO: make delay configurable
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statsAccuDelay = 300000
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-- | periodically flush the stats queue and accumulate all events inside
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accumulateStatsThread :: TQueue StatsEvent -> IO ()
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accumulateStatsThread statsQ = getPOSIXTime >>= flushLoop
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where
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flushLoop previousRun = do
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now <- getPOSIXTime
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-- TODO: instead of letting the events accumulate in the queue and allocate linear memory, immediately fold the result
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-- but how to achieve the periodicity when blocking on a queue?
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-- idea: let another thread periodically exchange the RelayStats, modify it atomically (Konzept "unterm Arsch wegziehen")
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threadDelay statsAccuDelay
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latestEvents <- atomically $ flushTQueue statsQ
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-- accumulate the events
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-- and now what? write a log to file, probably as a forkIO
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-- persistently store in a TVar so it can be retrieved later by the DHT
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flushLoop now
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accumulateStats :: POSIXTime -> [StatsEvent] -> RelayStats
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accumulateStats timeInterval events =
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-- first sum all event numbers, then divide through number of seconds passed to
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-- get rate per second
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RelayStats
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{ relayReceiveRates = mapRMap (/ intervalSeconds) $ relayReceiveRates summedStats
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, relayDeliveryRates = mapRMap (/ intervalSeconds) $ relayDeliveryRates summedStats
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, postPublishRate = postPublishRate summedStats / intervalSeconds
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, postFetchRate = postFetchRate summedStats / intervalSeconds
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}
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where
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intervalSeconds = fromIntegral (fromEnum timeInterval) / 10^12
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summedStats = foldl (\stats event -> case event of
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StatsEvent PostPublishEvent num _ ->
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stats {postPublishRate = fromIntegral num + postPublishRate stats}
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StatsEvent RelayReceiveEvent num key ->
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stats {relayReceiveRates = sumIfEntryExists key (fromIntegral num) (relayReceiveRates stats)}
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StatsEvent RelayDeliveryEvent num key ->
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stats {relayDeliveryRates = sumIfEntryExists key (fromIntegral num) (relayDeliveryRates stats)}
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StatsEvent IncomingPostFetchEvent num _ ->
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stats {postFetchRate = fromIntegral num + postFetchRate stats}
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)
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emptyStats
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events
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sumIfEntryExists = addRMapEntryWith (\newVal oldVal ->
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let toInsert = fromJust $ extractRingEntry newVal
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in
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case oldVal of
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KeyEntry n -> KeyEntry (n + toInsert)
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ProxyEntry pointer (Just (KeyEntry n)) -> ProxyEntry pointer (Just (KeyEntry $ n + toInsert))
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ProxyEntry pointer Nothing -> ProxyEntry pointer (Just newVal)
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_ -> error "RingMap nested too deeply"
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)
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-- idea: first just sum with foldl, and then map the time division over all values
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emptyStats :: RelayStats
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emptyStats = RelayStats
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{ relayReceiveRates = emptyRMap
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, relayDeliveryRates = emptyRMap
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, postFetchRate = 0
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, postPublishRate = 0
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}
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-- | measured rates of relay performance
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-- TODO: maybe include other metrics in here as well, like number of subscribers?
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@ -697,3 +635,98 @@ data RelayStats = RelayStats
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, postPublishRate :: Double
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-- ^ rate of initially publishing posts through this instance
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}
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-- TODO: make delay configurable
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statsEvalDelay = 300000
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launchStatsThreads :: PostService d -> IO ()
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launchStatsThreads serv = do
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-- create shared accumulator
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sharedAccum <- newTVarIO emptyStats
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concurrently_
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(accumulateStatsThread sharedAccum $ statsQueue serv)
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(evaluateStatsThread serv sharedAccum)
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-- | Read stats events from queue and add them to a shared accumulator.
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-- Instead of letting the events accumulate in the queue and allocate linear memory, immediately fold the result.
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accumulateStatsThread :: TVar RelayStats -> TQueue StatsEvent -> IO ()
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accumulateStatsThread statsAccumulator statsQ = forever $ do
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-- blocks until stats event arrives
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event <- atomically $ readTQueue statsQ
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-- add the event number to current accumulator
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atomically $ modifyTVar' statsAccumulator $ statsAdder event
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-- | add incoming stats events to accumulator value
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statsAdder :: StatsEvent -> RelayStats -> RelayStats
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statsAdder event stats = case event of
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StatsEvent PostPublishEvent num _ ->
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stats {postPublishRate = fromIntegral num + postPublishRate stats}
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StatsEvent RelayReceiveEvent num key ->
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stats {relayReceiveRates = sumIfEntryExists key (fromIntegral num) (relayReceiveRates stats)}
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StatsEvent RelayDeliveryEvent num key ->
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stats {relayDeliveryRates = sumIfEntryExists key (fromIntegral num) (relayDeliveryRates stats)}
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StatsEvent IncomingPostFetchEvent num _ ->
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stats {postFetchRate = fromIntegral num + postFetchRate stats}
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where
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sumIfEntryExists = addRMapEntryWith (\newVal oldVal ->
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let toInsert = fromJust $ extractRingEntry newVal
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in
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case oldVal of
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KeyEntry n -> KeyEntry (n + toInsert)
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ProxyEntry pointer (Just (KeyEntry n)) -> ProxyEntry pointer (Just (KeyEntry $ n + toInsert))
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ProxyEntry pointer Nothing -> ProxyEntry pointer (Just newVal)
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_ -> error "RingMap nested too deeply"
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)
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-- Periodically exchange the accumulated statistics with empty ones, evaluate them
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-- and make them the current statistics of the service.
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evaluateStatsThread :: PostService d -> TVar RelayStats -> IO ()
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evaluateStatsThread serv statsAcc = getPOSIXTime >>= loop
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where
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loop previousTs = do
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threadDelay statsEvalDelay
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-- get and reset the stats accumulator
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summedStats <- atomically $ do
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stats <- readTVar statsAcc
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writeTVar statsAcc emptyStats
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pure stats
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-- as the transaction might retry several times, current time needs to
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-- be read afterwards
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now <- getPOSIXTime
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-- evaluate stats rate and replace server stats
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atomically . writeTVar (loadStats serv) . evaluateStats (now - previousTs) $ summedStats
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-- idea: let another thread periodically exchange the RelayStats, modify it atomically (Konzept "unterm Arsch wegziehen")
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-- and now what? write a log to file, probably as a forkIO
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-- persistently store in a TVar so it can be retrieved later by the DHT
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loop now
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-- | Evaluate the accumulated statistic events: Currently mostly calculates the event
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-- rates by dividing through the collection time frame
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evaluateStats :: POSIXTime -> RelayStats -> RelayStats
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evaluateStats timeInterval summedStats =
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-- first sum all event numbers, then divide through number of seconds passed to
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-- get rate per second
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RelayStats
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{ relayReceiveRates = mapRMap (/ intervalSeconds) $ relayReceiveRates summedStats
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, relayDeliveryRates = mapRMap (/ intervalSeconds) $ relayDeliveryRates summedStats
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, postPublishRate = postPublishRate summedStats / intervalSeconds
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, postFetchRate = postFetchRate summedStats / intervalSeconds
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}
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where
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-- TODO: take speedup into account
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intervalSeconds = fromIntegral (fromEnum timeInterval) / 10^12
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emptyStats :: RelayStats
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emptyStats = RelayStats
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{ relayReceiveRates = emptyRMap
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, relayDeliveryRates = emptyRMap
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, postFetchRate = 0
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, postPublishRate = 0
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}
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