System.Log.Heavy.Backends.Dynamic

This module incldues logging backend combinators that allow to change underlying backend or it's settings in runtime.

Dynamic backend

data DynamicBackend

Dynamic logging backend allows to change logging backend or it's settings in runtime. When it sees new backend settings, it deinitializes old backend and initializes new one.

How to use it:

• Before creating DynamicSettings, you have to select some initial LoggingSettings and create DynamicBackendHandle with it.
• When you decide that you want to use new backend settings, call updateDynamicBackendSettings on existing DynamicBackendHandle. DynamicBackend will use new settings for the next logging function call.
• It is responsibility of caller code to do not change backends too frequently; for example, if you are checking your config file for updates of logging settings each 10s, you have to check that settings actually changed since last time.

It is possible to create one instance of DynamicBackendHandle and pass it to multiple threads.

Instances

IsLogBackend DynamicBackend

Associated Types

data LogBackendSettings DynamicBackend :: *

Methods

makeLogger :: Logger DynamicBackend

initLogBackend :: LogBackendSettings DynamicBackend -> IO DynamicBackend

wouldWriteMessage :: DynamicBackend -> LogMessage -> IO Bool

cleanupLogBackend :: DynamicBackend -> IO ()

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

data LogBackendSettings DynamicBackend

data LogBackendSettings DynamicBackend = DynamicSettings DynamicBackendHandle

data DynamicBackendHandle

Abstract handle, that is used to control DynamicBackend.

newDynamicBackendHandle

Arguments

:: LoggingSettings

Initial logging settings. This can be changed later with updateDynamicBackendSettings.

-> IO DynamicBackendHandle

Create an instance of DynamicBackendHandle.

updateDynamicBackendSettings

Arguments

:: DynamicBackendHandle

Handle of DynamicBackend.

-> LoggingSettings

New logging settings.

-> IO ()

Update settings of DynamicBackend, which was created by provided handle.

Dynamic filtering

data FilteringM b

Filtering backend with mutable filter.

Instances

IsLogBackend b => IsLogBackend (FilteringM b)

Associated Types

data LogBackendSettings (FilteringM b) :: *

Methods

makeLogger :: Logger (FilteringM b)

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

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

cleanupLogBackend :: FilteringM b -> IO ()

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

data LogBackendSettings (FilteringM b)

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

filteringM :: IsLogBackend b => LogFilter -> LogBackendSettings b -> IO (LogBackendSettings (FilteringM b))

Specify filter as LogFilter. This filter can be changed later.

excludingM :: IsLogBackend b => LogFilter -> LogBackendSettings b -> IO (LogBackendSettings (FilteringM b))

Exclude messages by filter. This filter can be changed later.