Std.IO.Logger

Simple, high performance logger. The design choice of this logger is biased towards simplicity instead of generlization:

• All log functions lives in IO.
• A logger connected to stderr, setStdLogger are always available.
• Each logging thread are responsible for building log Builders into a small Bytes with line buffer instead of leaving all Builders to the flushing thread so that:
• We won't keep garbage for too long simply because they're referenced by log's Builder.
• Each logging thread only need perform a CAS to prepend log Bytes into a list, which reduces contention.
• Each log is atomic, Logging order is preserved under concurrent settings.

Flushing is automatic and throttled for debug, info, warn to boost performance, while a fatal log always flush logger's buffer, This also lead to a problem that if main thread exits too early logs may missed, to add a flushing when program exits, use withLogger like:

import Std.IO.Logger

main :: IO ()
main = withStdLogger $ do
    ....

A simple Logger type

data Logger

data LoggerConfig

Logger configuration.

Constructors

LoggerConfig

Fields

• loggerBufferSize :: !Int

  Buffer size used when creating logger's BufferedOutput

• loggerMinFlushInterval :: !Int

  Minimal flush interval, see Notes on debug

• loggerTsCache :: IO (Builder ())

  A IO action return a formatted date/time string

• loggerLineBufSize :: !Int

  Buffer size to build each log/line

• loggerShowDebug :: Bool

  Set to False to filter debug logs

• loggerShowTS :: Bool

  Set to False to disable auto data/time string prepending

newLogger :: Output o => LoggerConfig -> o -> IO Logger

Make a new logger

loggerFlush :: Logger -> IO ()

flush logger's buffer to output device

setStdLogger :: Logger -> IO ()

Change stderr logger.

getStdLogger :: IO Logger

withStdLogger :: IO () -> IO ()

Flush stderr logger when program exits.

logging functions

debug :: Builder () -> IO ()

info :: Builder () -> IO ()

warn :: Builder () -> IO ()

fatal :: Builder () -> IO ()

otherLevel

Arguments

:: Builder ()

log level

-> Bool

flush immediately?

-> Builder ()

log content

-> IO ()

logging functions with specific logger

debugWith :: Logger -> Builder () -> IO ()

infoWith :: Logger -> Builder () -> IO ()

warnWith :: Logger -> Builder () -> IO ()

fatalWith :: Logger -> Builder () -> IO ()

otherLevelWith

Arguments

:: Logger

-> Builder ()

log level

-> Bool

flush immediately?

-> Builder ()

log content

-> IO ()