System.Log.FastLogger

This module provides a fast logging system which scales on multicore environments (i.e. +RTS -N<x>).

Note: This library does not guarantee correct ordering of log messages when program is run on more than one core thus users should rely more on message timestamps than on their order in the log.

FastLogger

type FastLogger = LogStr -> IO ()

FastLogger simply log logStr.

type LogType = LogType' LogStr

data LogType' a where

Logger Type.

Constructors

LogNone

Fields

• :: LogType' LogStr

  No logging.

LogStdout

Fields

• :: BufSize
• -> LogType' LogStr

  Logging to stdout. BufSize is a buffer size for each capability.

LogStderr

Fields

• :: BufSize
• -> LogType' LogStr

  Logging to stderr. BufSize is a buffer size for each capability.

LogFileNoRotate

Fields

• :: FilePath
• -> BufSize
• -> LogType' LogStr

  Logging to a file. BufSize is a buffer size for each capability.

LogFile

Fields

• :: FileLogSpec
• -> BufSize
• -> LogType' LogStr

  Logging to a file. BufSize is a buffer size for each capability. File rotation is done on-demand.

LogFileTimedRotate

Fields

• :: TimedFileLogSpec
• -> BufSize
• -> LogType' LogStr

  Logging to a file. BufSize is a buffer size for each capability. Rotation happens based on check specified in TimedFileLogSpec.

LogCallback

Fields

• :: (v -> IO ())
• -> IO ()
• -> LogType' v

  Logging with a log and flush action. run flush after log each message.

newFastLogger :: LogType' v -> IO (v -> IO (), IO ())

Initialize a FastLogger without attaching timestamp a tuple of logger and clean up action are returned. This type signature should be read as:

newFastLogger :: LogType -> IO (FastLogger, IO ())

This logger uses numCapabilities many buffers, and thus does not provide time-ordered output. For time-ordered output, use newFastLogger1.

newFastLogger1 :: LogType' v -> IO (v -> IO (), IO ())

Like newFastLogger, but creating a logger that uses only 1 capability. This scales less well on multi-core machines, but provides time-ordered output.

withFastLogger :: LogType -> (FastLogger -> IO a) -> IO a

bracket version of newFastLogger

Timed FastLogger

type TimedFastLogger = (FormattedTime -> LogStr) -> IO ()

TimedFastLogger pass FormattedTime to callback and simply log its result. this can be used to customize how to log timestamp.

Usually, one would write a wrapper on top of TimedFastLogger, for example:

{-# LANGUAGE OverloadedStrings #-}

log :: TimedFastLogger -> LogStr -> IO ()
log logger msg = logger (\time -> toLogStr (show time) <> " " <> msg <> "\n")

newTimedFastLogger

Arguments

:: IO FormattedTime

How do we get FormattedTime? System.Log.FastLogger.Date provide cached formatted time.

-> LogType

-> IO (TimedFastLogger, IO ())

Initialize a FastLogger with timestamp attached to each message. a tuple of logger and clean up action are returned.

withTimedFastLogger :: IO FormattedTime -> LogType -> (TimedFastLogger -> IO a) -> IO a

bracket version of newTimeFastLogger

Log messages

data LogStr

Log message builder. Use (<>) to append two LogStr in O(1).

Instances

IsString LogStr

Defined in System.Log.FastLogger.LogStr

Methods

fromString :: String -> LogStr

Monoid LogStr

Defined in System.Log.FastLogger.LogStr

Methods

mempty :: LogStr

mappend :: LogStr -> LogStr -> LogStr

mconcat :: [LogStr] -> LogStr

Semigroup LogStr

Defined in System.Log.FastLogger.LogStr

Methods

(<>) :: LogStr -> LogStr -> LogStr

sconcat :: NonEmpty LogStr -> LogStr

stimes :: Integral b => b -> LogStr -> LogStr

Show LogStr

Defined in System.Log.FastLogger.LogStr

Methods

showsPrec :: Int -> LogStr -> ShowS

show :: LogStr -> String

showList :: [LogStr] -> ShowS

ToLogStr LogStr

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: LogStr -> LogStr

Eq LogStr

Defined in System.Log.FastLogger.LogStr

Methods

(==) :: LogStr -> LogStr -> Bool

(/=) :: LogStr -> LogStr -> Bool

class ToLogStr msg where

Types that can be converted to a LogStr. Instances for types from the text library use a UTF-8 encoding. Instances for numerical types use a decimal encoding.

Methods

toLogStr :: msg -> LogStr

Instances

ToLogStr Int16

Since: 2.4.14

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Int16 -> LogStr

ToLogStr Int32

Since: 2.4.14

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Int32 -> LogStr

ToLogStr Int64

Since: 2.4.14

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Int64 -> LogStr

ToLogStr Int8

Since: 2.4.14

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Int8 -> LogStr

ToLogStr Word16

Since: 2.4.14

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Word16 -> LogStr

ToLogStr Word32

Since: 2.4.14

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Word32 -> LogStr

ToLogStr Word64

Since: 2.4.14

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Word64 -> LogStr

ToLogStr Word8

Since: 2.4.14

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Word8 -> LogStr

ToLogStr Builder

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Builder -> LogStr

ToLogStr ByteString

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: ByteString -> LogStr

ToLogStr ByteString

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: ByteString -> LogStr

ToLogStr ShortByteString

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: ShortByteString -> LogStr

ToLogStr LogStr

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: LogStr -> LogStr

ToLogStr Text

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Text -> LogStr

ToLogStr Text

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Text -> LogStr

ToLogStr String

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: String -> LogStr

ToLogStr Integer

Since: 2.4.14

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Integer -> LogStr

ToLogStr Double

Since: 2.4.14

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Double -> LogStr

ToLogStr Float

Since: 2.4.14

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Float -> LogStr

ToLogStr Int

Since: 2.4.14

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Int -> LogStr

ToLogStr Word

Since: 2.4.14

Defined in System.Log.FastLogger.LogStr

Methods

toLogStr :: Word -> LogStr

fromLogStr :: LogStr -> ByteString

Converting LogStr to ByteString.

logStrLength :: LogStr -> Int

Obtaining the length of LogStr.

Buffer size

type BufSize = Int

The type for buffer size of each core.

defaultBufSize :: BufSize

The default buffer size (4,096 bytes).

LoggerSet

module System.Log.FastLogger.LoggerSet

Date cache

module System.Log.FastLogger.Date

File rotation

module System.Log.FastLogger.File

Types

module System.Log.FastLogger.Types