System.Log.Heavy.Backends

This module contains implementation of most commonly used logging backends. You can write your own backends, by implementing an instance of IsLogBackend type class.

Documentation

This module contains several implementation of logging backend. A backend is some kind of target, where your messages will go. Each backend has its own specific settings.

Backends provided are:

• Fast-logger backend. It allows to write messages to stdout, stderr or arbitrary file.
• Syslog backend.
• Chan backend.
• Null backend. This discards all messages. Can be used to disable logging.

There are also some backend combinators:

• Filtering - passes messages, that match specified filter, to underlying backend.
• FilteringM - similar to Filtering, but allows to change the filter in runtime.
• Parallel - writes messages to several backends in parallel.
• Dynamic - allows to change underlying backend or its settings in runtime.

data FastLoggerBackend

Fast-logger logging backend.

Instances

IsLogBackend FastLoggerBackend

Defined in System.Log.Heavy.Backends

Associated Types

data LogBackendSettings FastLoggerBackend :: Type

Methods

makeLogger :: Logger FastLoggerBackend

initLogBackend :: LogBackendSettings FastLoggerBackend -> IO FastLoggerBackend

wouldWriteMessage :: FastLoggerBackend -> LogMessage -> IO Bool

cleanupLogBackend :: FastLoggerBackend -> IO ()

withLoggingB :: (MonadBaseControl IO m, MonadIO m) => LogBackendSettings FastLoggerBackend -> (FastLoggerBackend -> m a) -> m a

data LogBackendSettings FastLoggerBackend

Defined in System.Log.Heavy.Backends

data LogBackendSettings FastLoggerBackend = FastLoggerSettings {

• lsFormat :: Format
• lsType :: LogType

}

data SyslogBackend

Syslog logging backend.

Instances

IsLogBackend SyslogBackend

Defined in System.Log.Heavy.Backends

Associated Types

data LogBackendSettings SyslogBackend :: Type

Methods

makeLogger :: Logger SyslogBackend

initLogBackend :: LogBackendSettings SyslogBackend -> IO SyslogBackend

wouldWriteMessage :: SyslogBackend -> LogMessage -> IO Bool

cleanupLogBackend :: SyslogBackend -> IO ()

withLoggingB :: (MonadBaseControl IO m, MonadIO m) => LogBackendSettings SyslogBackend -> (SyslogBackend -> m a) -> m a

data LogBackendSettings SyslogBackend

Defined in System.Log.Heavy.Backends

data LogBackendSettings SyslogBackend = SyslogSettings {

• ssFormat :: Format
• ssIdent :: String
• ssOptions :: [Option]
• ssFacility :: Facility

}

data ChanLoggerBackend

Logging backend which writes all messages to the Chan

Instances

IsLogBackend ChanLoggerBackend

Defined in System.Log.Heavy.Backends

Associated Types

data LogBackendSettings ChanLoggerBackend :: Type

Methods

makeLogger :: Logger ChanLoggerBackend

initLogBackend :: LogBackendSettings ChanLoggerBackend -> IO ChanLoggerBackend

wouldWriteMessage :: ChanLoggerBackend -> LogMessage -> IO Bool

cleanupLogBackend :: ChanLoggerBackend -> IO ()

withLoggingB :: (MonadBaseControl IO m, MonadIO m) => LogBackendSettings ChanLoggerBackend -> (ChanLoggerBackend -> m a) -> m a

data LogBackendSettings ChanLoggerBackend

Defined in System.Log.Heavy.Backends

data LogBackendSettings ChanLoggerBackend = ChanLoggerSettings (Chan LogMessage)

data ParallelBackend

Logging backend that writes log messages to several other backends in parallel.

Instances

IsLogBackend ParallelBackend

Defined in System.Log.Heavy.Backends

Associated Types

data LogBackendSettings ParallelBackend :: Type

Methods

makeLogger :: Logger ParallelBackend

initLogBackend :: LogBackendSettings ParallelBackend -> IO ParallelBackend

wouldWriteMessage :: ParallelBackend -> LogMessage -> IO Bool

cleanupLogBackend :: ParallelBackend -> IO ()

withLoggingB :: (MonadBaseControl IO m, MonadIO m) => LogBackendSettings ParallelBackend -> (ParallelBackend -> m a) -> m a

data LogBackendSettings ParallelBackend

Defined in System.Log.Heavy.Backends

data LogBackendSettings ParallelBackend = ParallelLogSettings [LoggingSettings]

data NullBackend

Null logging backend, which discards all messages (passes them to devnull, if you wish). This can be used to disable logging.

Instances

IsLogBackend NullBackend

Defined in System.Log.Heavy.Backends

Associated Types

data LogBackendSettings NullBackend :: Type

Methods

makeLogger :: Logger NullBackend

initLogBackend :: LogBackendSettings NullBackend -> IO NullBackend

wouldWriteMessage :: NullBackend -> LogMessage -> IO Bool

cleanupLogBackend :: NullBackend -> IO ()

withLoggingB :: (MonadBaseControl IO m, MonadIO m) => LogBackendSettings NullBackend -> (NullBackend -> m a) -> m a

data LogBackendSettings NullBackend

Defined in System.Log.Heavy.Backends

data LogBackendSettings NullBackend = NullLogSettings

data Filtering b

Messages filtering backend. This backend passes a message to underlying backend, if this message conforms to specified filter.

Instances

IsLogBackend b => IsLogBackend (Filtering b)

Defined in System.Log.Heavy.Backends

Associated Types

data LogBackendSettings (Filtering b) :: Type

Methods

makeLogger :: Logger (Filtering b)

initLogBackend :: LogBackendSettings (Filtering b) -> IO (Filtering b)

wouldWriteMessage :: Filtering b -> LogMessage -> IO Bool

cleanupLogBackend :: Filtering b -> IO ()

withLoggingB :: (MonadBaseControl IO m, MonadIO m) => LogBackendSettings (Filtering b) -> (Filtering b -> m a) -> m a

data LogBackendSettings (Filtering b)

Defined in System.Log.Heavy.Backends

data LogBackendSettings (Filtering b) = Filtering (LogMessage -> Bool) (LogBackendSettings b)

filtering :: IsLogBackend b => LogFilter -> LogBackendSettings b -> LogBackendSettings (Filtering b)

Specify filter as LogFilter.

excluding :: IsLogBackend b => LogFilter -> LogBackendSettings b -> LogBackendSettings (Filtering b)

Exclude messages by filter.

data family LogBackendSettings b

Logging backend settings data type

Instances

data LogBackendSettings AnyLogBackend

Defined in System.Log.Heavy.Types

data LogBackendSettings AnyLogBackend = AnyLogBackendSettings LoggingSettings

data LogBackendSettings DynamicBackend

Defined in System.Log.Heavy.Backends.Dynamic

data LogBackendSettings DynamicBackend = DynamicSettings DynamicBackendHandle

data LogBackendSettings NullBackend

Defined in System.Log.Heavy.Backends

data LogBackendSettings NullBackend = NullLogSettings

data LogBackendSettings ParallelBackend

Defined in System.Log.Heavy.Backends

data LogBackendSettings ParallelBackend = ParallelLogSettings [LoggingSettings]

data LogBackendSettings ChanLoggerBackend

Defined in System.Log.Heavy.Backends

data LogBackendSettings ChanLoggerBackend = ChanLoggerSettings (Chan LogMessage)

data LogBackendSettings SyslogBackend

Defined in System.Log.Heavy.Backends

data LogBackendSettings SyslogBackend = SyslogSettings {

• ssFormat :: Format
• ssIdent :: String
• ssOptions :: [Option]
• ssFacility :: Facility

}

data LogBackendSettings FastLoggerBackend

Defined in System.Log.Heavy.Backends

data LogBackendSettings FastLoggerBackend = FastLoggerSettings {

• lsFormat :: Format
• lsType :: LogType

}

data LogBackendSettings (FilteringM b)

Defined in System.Log.Heavy.Backends.Dynamic

data LogBackendSettings (FilteringM b) = FilteringM (MVar (LogMessage -> Bool)) (LogBackendSettings b)

data LogBackendSettings (Filtering b)

Defined in System.Log.Heavy.Backends

data LogBackendSettings (Filtering b) = Filtering (LogMessage -> Bool) (LogBackendSettings b)

Default settings

defStdoutSettings :: LogBackendSettings FastLoggerBackend

Default settings for fast-logger stdout output

defStderrSettings :: LogBackendSettings FastLoggerBackend

Default settings for fast-logger stderr output

defFileSettings :: FilePath -> LogBackendSettings FastLoggerBackend

Default settings for fast-logger file output. This implies log rotation when log file size reaches 10Mb.

defaultSyslogSettings :: LogBackendSettings SyslogBackend

Default settings for syslog backend

defaultSyslogFormat :: Format

Default log message format fof syslog backend: [{level}] {source}: {message}