Settings.hs

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-- |
-- Module : Database.EventStore.Internal.Settings
-- Copyright : (C) 2017 Yorick Laupa
-- License : (see the file LICENSE)
--
-- Maintainer : Yorick Laupa <yo.eight@gmail.com>
-- Stability : provisional
-- Portability : non-portable
--
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module Database.EventStore.Internal.Settings where

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import Network.Connection (TLSSettings)
import System.Metrics (Store)

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import Database.EventStore.Internal.Logger
import Database.EventStore.Internal.Prelude

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-- Flag
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-- | Indicates either a 'Package' contains 'Credentials' data or not.
data Flag
    = None
    | Authenticated
    deriving Show

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-- | Maps a 'Flag' into a 'Word8' understandable by the server.
flagWord8 :: Flag -> Word8
flagWord8 None          = 0x00
flagWord8 Authenticated = 0x01

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-- Credentials
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-- | Holds login and password information.
data Credentials
    = Credentials
      { credLogin    :: !ByteString
      , credPassword :: !ByteString
      }
    deriving (Eq, Show)

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-- | Creates a 'Credentials' given a login and a password.
credentials :: ByteString -- ^ Login
            -> ByteString -- ^ Password
            -> Credentials
credentials = Credentials

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-- | Represents reconnection strategy.
data Retry
    = AtMost Int
    | KeepRetrying

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-- | Indicates how many times we should try to reconnect to the server. A value
--   less than or equal to 0 means no retry.
atMost :: Int -> Retry
atMost = AtMost

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-- | Indicates we should try to reconnect to the server until the end of the
--   Universe.
keepRetrying :: Retry
keepRetrying = KeepRetrying

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-- | Global 'Connection' settings
data Settings
    = Settings
      { s_heartbeatInterval :: NominalDiffTime
        -- ^ Maximum delay of inactivity before the client sends a heartbeat
        --   request.
      , s_heartbeatTimeout :: NominalDiffTime
        -- ^ Maximum delay the server has to issue a heartbeat response.
      , s_requireMaster :: Bool
        -- ^ On a cluster settings. Requires the master node when performing a
        --   write operation.
      , s_credentials :: Maybe Credentials
        -- ^ 'Credentials' used for an authenticated communication.
      , s_retry :: Retry
        -- ^ Retry strategy when failing to connect.
      , s_reconnect_delay :: NominalDiffTime
        -- ^ Delay before issuing a new connection request.
      , s_ssl :: Maybe TLSSettings
        -- ^ SSL settings.
      , s_loggerType :: LogType
        -- ^ Type of logging to use.
      , s_loggerFilter :: LoggerFilter
        -- ^ Restriction of what would be logged.
      , s_loggerDetailed :: Bool
        -- ^ Detailed logging output. Currently, it also indicates the location
        --   where the log occurred.
      , s_operationTimeout :: NominalDiffTime
        -- ^ Delay in which an operation will be retried if no response arrived.
      , s_operationRetry :: Retry
        -- ^ Retry strategy when an operation timeout.
      , s_monitoring :: Maybe Store
        -- ^ EKG metric store.
      }

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-- | Default global settings.
--
--   * 's_heartbeatInterval' = 750 ms
--   * 's_heartbeatTimeout'  = 1500 ms
--   * 's_requireMaster'     = 'True'
--   * 's_credentials'       = 'Nothing'
--   * 's_retry'             = 'atMost' 3
--   * 's_reconnect_delay'   = 3 seconds
--   * 's_ssl'               = 'Nothing'
--   * 's_loggerType'        = 'LogNone'
--   * 's_loggerFilter'      = 'LoggerLevel' 'LevelInfo'
--   * 's_loggerDetailed'    = 'False'
--   * 's_operationTimeout'  = 10 seconds
--   * 's_operationRetry'    = 'atMost' 3
--   * 's_monitoring'        = 'Nothing'
defaultSettings :: Settings
defaultSettings  = Settings
                   { s_heartbeatInterval = msDiffTime 750  -- 750ms
                   , s_heartbeatTimeout  = msDiffTime 1500 -- 1500ms
                   , s_requireMaster     = True
                   , s_credentials       = Nothing
                   , s_retry             = atMost 3
                   , s_reconnect_delay   = 3
                   , s_ssl               = Nothing
                   , s_loggerType        = LogNone
                   , s_loggerFilter      = LoggerLevel LevelInfo
                   , s_loggerDetailed    = False
                   , s_operationTimeout  = 10 -- secs
                   , s_operationRetry    = atMost 3
                   , s_monitoring        = Nothing
                   }

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-- | Default SSL settings based on 'defaultSettings'.
defaultSSLSettings :: TLSSettings -> Settings
defaultSSLSettings tls = defaultSettings { s_ssl = Just tls }

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-- | Millisecond timespan
msDiffTime :: Float -> NominalDiffTime
msDiffTime n = fromRational $ toRational (n / 1000)