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2+{-# LANGUAGE DefaultSignatures #-}
3+{-# LANGUAGE DeriveFunctor #-}
4+{-# LANGUAGE DeriveGeneric #-}
5+{-# LANGUAGE ExistentialQuantification #-}
6+{-# LANGUAGE FlexibleContexts #-}
7+{-# LANGUAGE FlexibleInstances #-}
9+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
10+{-# LANGUAGE MultiParamTypeClasses #-}
11+{-# LANGUAGE OverloadedStrings #-}
12+{-# LANGUAGE RankNTypes #-}
13+{-# LANGUAGE RecordWildCards #-}
14+{-# LANGUAGE TemplateHaskell #-}
15+{-# LANGUAGE TypeFamilies #-}
16+{-# LANGUAGE UndecidableInstances #-}
17+#if MIN_VERSION_base(4, 9, 0)
18+{-# OPTIONS_GHC -fno-warn-redundant-constraints #-}
20+-- | This module is not meant to be imported directly and may contain
21+-- internal mechanisms that will change without notice.
22+module Katip.Core where
24+-------------------------------------------------------------------------------
25+import Control.Applicative as A
26+import Control.AutoUpdate
27+import Control.Concurrent
28+import qualified Control.Concurrent.Async as Async
29+import Control.Concurrent.STM
30+import qualified Control.Concurrent.STM.TBQueue as BQ
31+import Control.Exception.Safe
32+import Control.Monad (unless, void, when)
33+import Control.Monad.Base
34+#if MIN_VERSION_base(4, 9, 0)
35+import qualified Control.Monad.Fail as MF
37+import Control.Monad.IO.Class
38+import Control.Monad.IO.Unlift
39+import Control.Monad.Trans.Class
40+import Control.Monad.Trans.Control
41+#if !MIN_VERSION_either(4, 5, 0)
42+import Control.Monad.Trans.Either
44+import Control.Monad.Trans.Except
45+import Control.Monad.Trans.Maybe
46+import Control.Monad.Trans.Reader
47+import Control.Monad.Trans.Resource (MonadResource, ResourceT,
49+import Control.Monad.Trans.RWS.Lazy (RWST, mapRWST)
50+import qualified Control.Monad.Trans.RWS.Strict as Strict (RWST, mapRWST)
51+import Control.Monad.Trans.State.Lazy (StateT, mapStateT)
52+import qualified Control.Monad.Trans.State.Strict as Strict (StateT, mapStateT)
53+import Control.Monad.Trans.Writer.Lazy (WriterT, mapWriterT)
54+import qualified Control.Monad.Trans.Writer.Strict as Strict (WriterT,
56+import Data.Aeson (FromJSON (..), ToJSON (..),
58+import qualified Data.Aeson as A
59+import Data.Foldable as FT
60+import qualified Data.HashMap.Strict as HM
62+import qualified Data.Map.Strict as M
63+import Data.Maybe (fromMaybe)
64+import Data.Semigroup as SG
66+import Data.String.Conv
67+import Data.Text (Text)
68+import qualified Data.Text as T
69+import qualified Data.Text.Lazy.Builder as B
71+import GHC.Generics hiding (to)
72+#if MIN_VERSION_base(4, 8, 0)
73+#if !MIN_VERSION_base(4, 9, 0)
78+import Language.Haskell.TH
79+import qualified Language.Haskell.TH.Syntax as TH
82+import Network.HostName
89+-------------------------------------------------------------------------------
92+readMay :: Read a => String -> Maybe a
93+readMay s = case [x | (x,t) <- reads s, ("","") <- lex t] of
95+ [] -> Nothing -- no parse
96+ _ -> Nothing -- Ambiguous parse
99+-------------------------------------------------------------------------------
100+-- | Represents a heirarchy of namespaces going from general to
101+-- specific. For instance: ["processname", "subsystem"]. Note that
102+-- single-segment namespaces can be created using
103+-- IsString/OverloadedStrings, so "foo" will result in Namespace
105+newtype Namespace = Namespace { unNamespace :: [Text] }
106+ deriving (Eq,Show,Read,Ord,Generic,ToJSON,FromJSON,SG.Semigroup,Monoid)
108+instance IsString Namespace where
109+ fromString s = Namespace [fromString s]
112+-------------------------------------------------------------------------------
113+-- | Ready namespace for emission with dots to join the segments.
114+intercalateNs :: Namespace -> [Text]
115+intercalateNs (Namespace xs) = intersperse "." xs
118+-------------------------------------------------------------------------------
119+-- | Application environment, like @prod@, @devel@, @testing@.
120+newtype Environment = Environment { getEnvironment :: Text }
121+ deriving (Eq,Show,Read,Ord,Generic,ToJSON,FromJSON,IsString)
124+-------------------------------------------------------------------------------
126+ = DebugS -- ^ Debug messages
127+ | InfoS -- ^ Information
128+ | NoticeS -- ^ Normal runtime Conditions
129+ | WarningS -- ^ General Warnings
130+ | ErrorS -- ^ General Errors
131+ | CriticalS -- ^ Severe situations
132+ | AlertS -- ^ Take immediate action
133+ | EmergencyS -- ^ System is unusable
134+ deriving (Eq, Ord, Show, Read, Generic, Enum, Bounded)
137+-------------------------------------------------------------------------------
138+-- | Verbosity controls the amount of information (columns) a 'Scribe'
139+-- emits during logging.
141+-- The convention is:
142+-- - 'V0' implies no additional payload information is included in message.
143+-- - 'V3' implies the maximum amount of payload information.
144+-- - Anything in between is left to the discretion of the developer.
145+data Verbosity = V0 | V1 | V2 | V3
146+ deriving (Eq, Ord, Show, Read, Generic, Enum, Bounded)
149+-------------------------------------------------------------------------------
150+renderSeverity :: Severity -> Text
151+renderSeverity s = case s of
155+ WarningS -> "Warning"
157+ CriticalS -> "Critical"
159+ EmergencyS -> "Emergency"
162+-------------------------------------------------------------------------------
163+textToSeverity :: Text -> Maybe Severity
164+textToSeverity = go . T.toLower
166+ go "debug" = Just DebugS
167+ go "info" = Just InfoS
168+ go "notice" = Just NoticeS
169+ go "warning" = Just WarningS
170+ go "error" = Just ErrorS
171+ go "critical" = Just CriticalS
172+ go "alert" = Just AlertS
173+ go "emergency" = Just EmergencyS
177+instance ToJSON Severity where
178+ toJSON s = A.String (renderSeverity s)
180+instance FromJSON Severity where
181+ parseJSON = A.withText "Severity" parseSeverity
183+ parseSeverity t = case textToSeverity t of
185+ Nothing -> fail $ "Invalid Severity " ++ toS t
187+instance ToJSON Verbosity where
188+ toJSON s = A.String $ case s of
194+instance FromJSON Verbosity where
195+ parseJSON = A.withText "Verbosity" $ \s -> case s of
200+ _ -> fail $ "Invalid Verbosity " ++ toS s
203+-------------------------------------------------------------------------------
204+-- | Log message with Builder underneath; use '<>' to concat in O(1).
205+newtype LogStr = LogStr { unLogStr :: B.Builder }
206+ deriving (Generic, Show, Eq)
208+instance IsString LogStr where
209+ fromString = LogStr . B.fromString
212+instance Semigroup LogStr where
213+ (LogStr a) <> (LogStr b) = LogStr (a <> b)
216+instance Monoid LogStr where
218+ mempty = LogStr mempty
221+instance FromJSON LogStr where
222+ parseJSON = A.withText "LogStr" parseLogStr
224+ parseLogStr = return . LogStr . B.fromText
226+-------------------------------------------------------------------------------
227+-- | Pack any string-like thing into a 'LogStr'. This will
228+-- automatically work on 'String', 'ByteString', 'Text' and any of the
230+logStr :: StringConv a Text => a -> LogStr
231+logStr t = LogStr (B.fromText $ toS t)
234+-------------------------------------------------------------------------------
235+-- | Shorthand for 'logStr'
236+ls :: StringConv a Text => a -> LogStr
240+-------------------------------------------------------------------------------
241+-- | Convert any showable type into a 'LogStr'.
242+showLS :: Show a => a -> LogStr
246+-------------------------------------------------------------------------------
247+newtype ThreadIdText = ThreadIdText {
248+ getThreadIdText :: Text
249+ } deriving (ToJSON, FromJSON, Show, Eq, Ord)
252+mkThreadIdText :: ThreadId -> ThreadIdText
253+mkThreadIdText = ThreadIdText . stripPrefix' "ThreadId " . T.pack . show
255+ stripPrefix' pfx t = fromMaybe t (T.stripPrefix pfx t)
258+-------------------------------------------------------------------------------
259+-- | This has everything each log message will contain.
261+ _itemApp :: Namespace
262+ , _itemEnv :: Environment
263+ , _itemSeverity :: Severity
264+ , _itemThread :: ThreadIdText
265+ , _itemHost :: HostName
266+ , _itemProcess :: ProcessID
268+ , _itemMessage :: LogStr
269+ , _itemTime :: UTCTime
270+ , _itemNamespace :: Namespace
271+ , _itemLoc :: Maybe Loc
272+ } deriving (Generic, Functor)
275+-- Manual instance because 'Loc' has no 'Eq' and 'Show' instances in old
276+-- versions of template-haskell (< 2.10)
277+instance Eq a => Eq (Item a) where
278+ a == b = FT.and [ _itemApp a == _itemApp b
279+ , _itemEnv a == _itemEnv b
280+ , _itemSeverity a == _itemSeverity b
281+ , _itemThread a == _itemThread b
282+ , _itemHost a == _itemHost b
283+ , _itemProcess a == _itemProcess b
284+ , _itemPayload a == _itemPayload b
285+ , _itemMessage a == _itemMessage b
286+ , _itemTime a == _itemTime b
287+ , _itemNamespace a == _itemNamespace b
288+ , case (_itemLoc a, _itemLoc b) of
289+ (Nothing, Nothing) -> True
290+ (Just l1, Just l2) -> FT.and [ loc_filename l1 == loc_filename l2
291+ , loc_package l1 == loc_package l2
292+ , loc_module l1 == loc_module l2
293+ , loc_start l1 == loc_start l2
294+ , loc_end l1 == loc_end l2
299+instance Show a => Show (Item a) where
300+ showsPrec d Item{..} = showParen (d >= 11) ( showString "Item {"
301+ . field "_itemApp" _itemApp
302+ . field "_itemEnv" _itemEnv
303+ . field "_itemSeverity" _itemSeverity
304+ . field "_itemThread" _itemThread
305+ . field "_itemHost" _itemHost
306+ . field "_itemProcess" _itemProcess
307+ . field "_itemPayload" _itemPayload
308+ . field "_itemMessage" _itemMessage
309+ . field "_itemTime" _itemTime
310+ . field "_itemNamespace" _itemNamespace
311+ . showString "_itemLoc = " . shows (LocShow <$> _itemLoc)
315+ field n v = showString n . showString " = " . shows v . showString ", "
317+newtype LocShow = LocShow Loc
320+instance Show LocShow where
321+ showsPrec d (LocShow Loc{..}) = showParen (d >= 11) ( showString "Loc {"
322+ . field "loc_filename" loc_filename
323+ . field "loc_package" loc_package
324+ . field "loc_module" loc_module
325+ . field "loc_start" loc_start
326+ . showString "loc_end = " . shows loc_end
330+ field n v = showString n . showString " = " . shows v . showString ", "
333+instance ToJSON a => ToJSON (Item a) where
334+ toJSON Item{..} = A.object
335+ [ "app" A..= _itemApp
336+ , "env" A..= _itemEnv
337+ , "sev" A..= _itemSeverity
338+ , "thread" A..= getThreadIdText _itemThread
339+ , "host" A..= _itemHost
340+ , "pid" A..= ProcessIDJs _itemProcess
341+ , "data" A..= _itemPayload
342+ , "msg" A..= (B.toLazyText $ unLogStr _itemMessage)
343+ , "at" A..= _itemTime
344+ , "ns" A..= _itemNamespace
345+ , "loc" A..= fmap LocJs _itemLoc
348+newtype LocJs = LocJs { getLocJs :: Loc }
351+instance ToJSON LocJs where
352+ toJSON (LocJs (Loc fn p m (l, c) _)) = A.object
361+instance FromJSON LocJs where
362+ parseJSON = A.withObject "LocJs" parseLocJs
365+ fn <- o A..: "loc_fn"
366+ p <- o A..: "loc_pkg"
367+ m <- o A..: "loc_mod"
368+ l <- o A..: "loc_ln"
369+ c <- o A..: "loc_col"
370+ return $ LocJs $ Loc fn p m (l, c) (l, c)
373+instance FromJSON a => FromJSON (Item a) where
374+ parseJSON = A.withObject "Item" parseItem
382+ <*> (getProcessIDJs <$> o A..: "pid")
387+ <*> (fmap getLocJs <$> o A..: "loc")
390+processIDToText :: ProcessID -> Text
391+processIDToText = toS . show
394+textToProcessID :: Text -> Maybe ProcessID
395+textToProcessID = readMay . toS
398+newtype ProcessIDJs = ProcessIDJs {
399+ getProcessIDJs :: ProcessID
403+instance ToJSON ProcessIDJs where
404+ toJSON (ProcessIDJs p) = A.String (processIDToText p)
407+instance FromJSON ProcessIDJs where
408+ parseJSON = A.withText "ProcessID" parseProcessID
410+ parseProcessID t = case textToProcessID t of
411+ Just p -> return $ ProcessIDJs p
412+ Nothing -> fail $ "Invalid ProcessIDJs " ++ toS t
415+-------------------------------------------------------------------------------
416+-- | Field selector by verbosity within JSON payload.
417+data PayloadSelection
422+instance Semigroup PayloadSelection where
423+ AllKeys <> _ = AllKeys
424+ _ <> AllKeys = AllKeys
425+ SomeKeys as <> SomeKeys bs = SomeKeys (as <> bs)
428+instance Monoid PayloadSelection where
429+ mempty = SomeKeys []
433+-------------------------------------------------------------------------------
434+-- | Katip requires JSON objects to be logged as context. This
435+-- typeclass provides a default instance which uses ToJSON and
436+-- produces an empty object if 'toJSON' results in any type other than
437+-- object. If you have a type you want to log that produces an Array
438+-- or Number for example, you'll want to write an explicit instance
439+-- here. You can trivially add a ToObject instance for something with
440+-- a ToJSON instance like:
442+-- > instance ToObject Foo
443+class ToObject a where
444+ toObject :: a -> A.Object
445+ default toObject :: ToJSON a => a -> A.Object
446+ toObject v = case toJSON v of
451+instance ToObject A.Object
453+-------------------------------------------------------------------------------
454+-- | Payload objects need instances of this class. LogItem makes it so
455+-- that you can have very verbose items getting logged with lots of
456+-- extra fields but under normal circumstances, if your scribe is
457+-- configured for a lower verbosity level, it will only log a
458+-- selection of those keys. Furthermore, each 'Scribe' can be
459+-- configured with a different 'Verbosity' level. You could even use
460+-- 'registerScribe', 'unregisterScribe', and 'clearScribes' to at
461+-- runtime swap out your existing scribes for more verbose debugging
462+-- scribes if you wanted to.
464+-- When defining 'payloadKeys', don't redundantly declare the same
465+-- keys for higher levels of verbosity. Each level of verbosity
466+-- automatically and recursively contains all keys from the level
468+class ToObject a => LogItem a where
470+ -- | List of keys in the JSON object that should be included in message.
471+ payloadKeys :: Verbosity -> a -> PayloadSelection
474+instance LogItem () where payloadKeys _ _ = SomeKeys []
477+data AnyLogPayload = forall a. ToJSON a => AnyLogPayload a
479+newtype SimpleLogPayload = SimpleLogPayload {
480+ unSimpleLogPayload :: [(Text, AnyLogPayload)]
483+-------------------------------------------------------------------------------
484+-- | A built-in convenience log payload that won't log anything on 'V0',
485+-- but will log everything in any other level of verbosity. Intended
486+-- for easy in-line usage without having to define new log types.
488+-- Construct using 'sl' and combine multiple tuples using '<>' from
490+instance ToJSON SimpleLogPayload where
491+ toJSON (SimpleLogPayload as) = object $ map go as
492+ where go (k, AnyLogPayload v) = k A..= v
495+instance ToObject SimpleLogPayload
498+instance LogItem SimpleLogPayload where
499+ payloadKeys V0 _ = SomeKeys []
500+ payloadKeys _ _ = AllKeys
503+instance Semigroup SimpleLogPayload where
504+ SimpleLogPayload a <> SimpleLogPayload b = SimpleLogPayload (a <> b)
507+instance Monoid SimpleLogPayload where
508+ mempty = SimpleLogPayload []
512+-------------------------------------------------------------------------------
513+-- | Construct a simple log from any JSON item.
514+sl :: ToJSON a => Text -> a -> SimpleLogPayload
515+sl a b = SimpleLogPayload [(a, AnyLogPayload b)]
518+-------------------------------------------------------------------------------
519+-- | Constrain payload based on verbosity. Backends should use this to
520+-- automatically bubble higher verbosity levels to lower ones.
521+payloadObject :: LogItem a => Verbosity -> a -> A.Object
522+payloadObject verb a = case FT.foldMap (flip payloadKeys a) [(V0)..verb] of
523+ AllKeys -> toObject a
524+ SomeKeys ks -> HM.filterWithKey (\ k _ -> k `FT.elem` ks) $ toObject a
527+-------------------------------------------------------------------------------
528+-- | Convert log item to its JSON representation while trimming its
529+-- payload based on the desired verbosity. Backends that push JSON
530+-- messages should use this to obtain their payload.
531+itemJson :: LogItem a => Verbosity -> Item a -> A.Value
532+itemJson verb a = toJSON $ a & itemPayload %~ payloadObject verb
535+-------------------------------------------------------------------------------
536+-- | Scribes are handlers of incoming items. Each registered scribe
537+-- knows how to push a log item somewhere.
539+-- = Guidelines for writing your own 'Scribe'
541+-- Scribes should always take a 'Severity' and 'Verbosity'.
543+-- Severity is used to __exclude log messages__ that are lower than
544+-- the provided Severity. For instance, if the user passes InfoS,
545+-- DebugS items should be ignored. Katip provides the 'permitItem'
546+-- utility for this. The user or the scribe may use 'permitAND' and
547+-- 'permitOR' to further customize this filtering, even dynamically if
550+-- Verbosity is used to select keys from the log item's payload. Each
551+-- 'LogItem' instance describes what keys should be retained for each
552+-- Verbosity level. Use the 'payloadObject' utility for extracting the keys
553+-- that should be written.
555+-- Scribes provide a finalizer IO action ('scribeFinalizer') that is
556+-- meant to synchronously flush any remaining writes and clean up any
557+-- resources acquired when the scribe was created. Internally, katip
558+-- keeps a buffer for each scribe's writes. When 'closeScribe' or
559+-- 'closeScribes' is called, that buffer stops accepting new log
560+-- messages and after the last item in its buffer is sent to 'liPush',
561+-- calls the finalizer. Thus, when the finalizer returns, katip can
562+-- assume that all resources are cleaned up and all log messages are
565+-- While katip internally buffers messages per 'ScribeSettings', it
566+-- sends them one at a time to the scribe. Depending on the scribe
567+-- itself, it may make sense for that scribe to keep its own internal
568+-- buffer to batch-send logs if writing items one at a time is not
569+-- efficient. The scribe implementer must be sure that on
570+-- finalization, all writes are committed synchronously.
572+-- | Signature of a function passed to `Scribe` constructor and
573+-- mkScribe* functions that decides which messages to be
574+-- logged. Typically filters based on 'Severity', but can be
575+-- combined with other, custom logic with 'permitAND' and 'permitOR'
576+type PermitFunc = forall a. Item a -> IO Bool
579+-- | AND together 2 permit functions
580+permitAND :: PermitFunc -> PermitFunc -> PermitFunc
581+permitAND f1 f2 = \a -> liftA2 (&&) (f1 a) (f2 a)
583+-- | OR together 2 permit functions
584+permitOR :: PermitFunc -> PermitFunc -> PermitFunc
585+permitOR f1 f2 = \a -> liftA2 (||) (f1 a) (f2 a)
588+data Scribe = Scribe {
589+ liPush :: forall a. LogItem a => Item a -> IO ()
590+ -- ^ How do we write an item to the scribe's output?
591+ , scribeFinalizer :: IO ()
592+ -- ^ Provide a __blocking__ finalizer to call when your scribe is
593+ -- removed. All pending writes should be flushed synchronously. If
594+ -- this is not relevant to your scribe, return () is fine.
595+ , scribePermitItem :: PermitFunc
596+ -- ^ Provide a filtering function to allow the item to be logged,
597+ -- or not. It can check Severity or some string in item's
598+ -- body. The initial value of this is usually created from
599+ -- 'permitItem'. Scribes and users can customize this by ANDing
600+ -- or ORing onto the default with 'permitAND' or 'permitOR'
604+whenM :: Monad m => m Bool -> m () -> m ()
605+whenM mbool = (>>=) mbool . flip when
608+-- | Combine two scribes. Publishes to the left scribe if the left
609+-- would permit the item and to the right scribe if the right would
610+-- permit the item. Finalizers are called in sequence from left to
612+instance Semigroup Scribe where
613+ (Scribe pushA finA permitA) <> (Scribe pushB finB permitB) =
614+ Scribe (\item -> whenM (permitA item) (pushA item)
615+ >> whenM (permitB item) (pushB item)
617+ (finA `finally` finB)
618+ (permitOR permitA permitB)
621+instance Monoid Scribe where
622+ mempty = Scribe (const (return ())) (return ()) (permitItem DebugS)
626+-------------------------------------------------------------------------------
627+data ScribeHandle = ScribeHandle {
629+ , shChan :: BQ.TBQueue WorkerMessage
633+-------------------------------------------------------------------------------
634+data WorkerMessage where
635+ NewItem :: LogItem a => Item a -> WorkerMessage
636+ PoisonPill :: WorkerMessage
639+-------------------------------------------------------------------------------
640+-- | Should this item be logged given the user's maximum severity?
641+-- Most new scribes will use this as a base for their 'PermitFunc'
642+permitItem :: Monad m => Severity -> Item a -> m Bool
643+permitItem sev item = return (_itemSeverity item >= sev)
646+-------------------------------------------------------------------------------
647+data LogEnv = LogEnv {
648+ _logEnvHost :: HostName
649+ , _logEnvPid :: ProcessID
650+ , _logEnvApp :: Namespace
651+ -- ^ Name of application. This will typically never change. This
652+ -- field gets prepended to the namespace of your individual log
653+ -- messages. For example, if your app is MyApp and you write a log
654+ -- using "logItem" and the namespace "WebServer", the final
655+ -- namespace will be "MyApp.WebServer"
656+ , _logEnvEnv :: Environment
657+ , _logEnvTimer :: IO UTCTime
658+ -- ^ Action to fetch the timestamp. You can use something like
659+ -- 'AutoUpdate' for high volume logs but note that this may cause
660+ -- some output forms to display logs out of order. Alternatively,
661+ -- you could just use 'getCurrentTime'.
662+ , _logEnvScribes :: M.Map Text ScribeHandle
667+-------------------------------------------------------------------------------
668+-- | Create a reasonable default InitLogEnv. Uses an 'AutoUpdate' which
669+-- updates the timer every 1ms. If you need even more timestamp
670+-- precision at the cost of performance, consider setting
671+-- '_logEnvTimer' with 'getCurrentTime'.
674+ -- ^ A base namespace for this application
676+ -- ^ Current run environment (e.g. @prod@ vs. @devel@)
678+initLogEnv an env = LogEnv
683+ <*> mkAutoUpdate defaultUpdateSettings { updateAction = getCurrentTime, updateFreq = 1000 }
687+-------------------------------------------------------------------------------
688+-- | Add a scribe to the list. All future log calls will go to this
689+-- scribe in addition to the others. Writes will be buffered per the
690+-- ScribeSettings to prevent slow scribes from slowing down
691+-- logging. Writes will be dropped if the buffer fills.
694+ -- ^ Name the scribe
699+registerScribe nm scribe ScribeSettings {..} le = do
700+ queue <- atomically (BQ.newTBQueue (fromIntegral _scribeBufferSize))
701+ worker <- spawnScribeWorker scribe queue
703+ atomically (BQ.writeTBQueue queue PoisonPill)
704+ -- wait for our worker to finish final write
705+ void (Async.waitCatch worker)
706+ -- wait for scribe to finish final write
707+ void (scribeFinalizer scribe)
709+ let sh = ScribeHandle (scribe { scribeFinalizer = fin }) queue
710+ return (le & logEnvScribes %~ M.insert nm sh)
713+-------------------------------------------------------------------------------
714+spawnScribeWorker :: Scribe -> BQ.TBQueue WorkerMessage -> IO (Async.Async ())
715+spawnScribeWorker (Scribe write _ _) queue = Async.async go
718+ newCmd <- atomically (BQ.readTBQueue queue)
721+ -- Swallow any direct exceptions from the
722+ -- scribe. safe-exceptions won't catch async exceptions.
723+ void (tryAny (write a))
725+ PoisonPill -> return ()
728+-------------------------------------------------------------------------------
729+data ScribeSettings = ScribeSettings {
730+ _scribeBufferSize :: Int
734+makeLenses ''ScribeSettings
737+-- | Reasonable defaults for a scribe. Buffer
739+defaultScribeSettings :: ScribeSettings
740+defaultScribeSettings = ScribeSettings 4096
743+-------------------------------------------------------------------------------
744+-- | Remove a scribe from the environment. This does __not__ finalize
745+-- the scribe. This mainly only makes sense to use with something like
746+-- MonadReader's @local@ function to temporarily disavow a single
747+-- logger for a block of code.
750+ -- ^ Name of the scribe
753+unregisterScribe nm = logEnvScribes %~ M.delete nm
756+-------------------------------------------------------------------------------
757+-- | Unregister __all__ scribes. Note that this is __not__ for closing or
758+-- finalizing scribes, use 'closeScribes' for that. This mainly only
759+-- makes sense to use with something like MonadReader's @local@
760+-- function to temporarily disavow any loggers for a block of code.
764+clearScribes = logEnvScribes .~ mempty
767+-------------------------------------------------------------------------------
768+-- | Finalize a scribe. The scribe is removed from the environment,
769+-- its finalizer is called so that it can never be written to again
770+-- and all pending writes are flushed. Note that this will throw any
771+-- exceptions yoru finalizer will throw, and that LogEnv is immutable,
772+-- so it will not be removed in that case.
775+ -- ^ Name of the scribe
778+closeScribe nm le = do
779+ maybe (return ()) (scribeFinalizer . shScribe) (M.lookup nm (_logEnvScribes le))
780+ return (le & logEnvScribes %~ M.delete nm)
783+-------------------------------------------------------------------------------
784+-- | Call this at the end of your program. This is a blocking call
785+-- that stop writing to a scribe's queue, waits for the queue to
786+-- empty, finalizes each scribe in the log environment and then
787+-- removes it. Finalizers are all run even if one of them throws, but
788+-- the exception will be re-thrown at the end.
793+ -- We want to run every finalizer here so we'll not save
794+ -- intermediate logenvs and just clear scribes at the end.
795+ let actions = [void (closeScribe k le) | k <- M.keys (_logEnvScribes le)]
796+ FT.foldr finally (return ()) actions
797+ return (le & logEnvScribes .~ mempty)
800+-------------------------------------------------------------------------------
801+-- | Monads where katip logging actions can be performed. Katip is the
802+-- most basic logging monad. You will typically use this directly if
803+-- you either don't want to use namespaces/contexts heavily or if you
804+-- want to pass in specific contexts and/or namespaces at each log site.
806+-- For something more powerful, look at the docs for 'KatipContext',
807+-- which keeps a namespace and merged context. You can write simple
808+-- functions that add additional namespacing and merges additional
809+-- context on the fly.
811+-- 'localLogEnv' was added to allow for lexically-scoped modifications
812+-- of the log env that are reverted when the supplied monad
813+-- completes. 'katipNoLogging', for example, uses this to temporarily
814+-- pause log outputs.
815+class MonadIO m => Katip m where
816+ getLogEnv :: m LogEnv
817+ localLogEnv :: (LogEnv -> LogEnv) -> m a -> m a
820+instance Katip m => Katip (ReaderT s m) where
821+ getLogEnv = lift getLogEnv
822+ localLogEnv = mapReaderT . localLogEnv
825+#if !MIN_VERSION_either(4, 5, 0)
826+instance Katip m => Katip (EitherT s m) where
827+ getLogEnv = lift getLogEnv
828+ localLogEnv = mapEitherT . localLogEnv
832+instance Katip m => Katip (ExceptT s m) where
833+ getLogEnv = lift getLogEnv
834+ localLogEnv = mapExceptT . localLogEnv
837+instance Katip m => Katip (MaybeT m) where
838+ getLogEnv = lift getLogEnv
839+ localLogEnv = mapMaybeT . localLogEnv
842+instance Katip m => Katip (StateT s m) where
843+ getLogEnv = lift getLogEnv
844+ localLogEnv = mapStateT . localLogEnv
847+instance (Katip m, Monoid w) => Katip (RWST r w s m) where
848+ getLogEnv = lift getLogEnv
849+ localLogEnv = mapRWST . localLogEnv
852+instance (Katip m, Monoid w) => Katip (Strict.RWST r w s m) where
853+ getLogEnv = lift getLogEnv
854+ localLogEnv = Strict.mapRWST . localLogEnv
857+instance Katip m => Katip (Strict.StateT s m) where
858+ getLogEnv = lift getLogEnv
859+ localLogEnv = Strict.mapStateT . localLogEnv
862+instance (Katip m, Monoid s) => Katip (WriterT s m) where
863+ getLogEnv = lift getLogEnv
864+ localLogEnv = mapWriterT . localLogEnv
867+instance (Katip m, Monoid s) => Katip (Strict.WriterT s m) where
868+ getLogEnv = lift getLogEnv
869+ localLogEnv = Strict.mapWriterT . localLogEnv
872+instance (Katip m) => Katip (ResourceT m) where
873+ getLogEnv = lift getLogEnv
874+ localLogEnv = transResourceT . localLogEnv
877+-------------------------------------------------------------------------------
878+-- | A concrete monad you can use to run logging actions. Use this if
879+-- you prefer an explicit monad transformer stack and adding layers as
880+-- opposed to implementing 'Katip' for your monad.
881+newtype KatipT m a = KatipT { unKatipT :: ReaderT LogEnv m a }
882+ deriving ( Functor, Applicative, Monad, MonadIO
883+ , MonadMask, MonadCatch, MonadThrow, MonadResource, MonadTrans
887+instance MonadIO m => Katip (KatipT m) where
888+ getLogEnv = KatipT ask
889+ localLogEnv f (KatipT m) = KatipT $ local f m
892+instance MonadTransControl KatipT where
893+ type StT (KatipT) a = a
894+ liftWith f = KatipT $ ReaderT $ \le -> f $ \t -> runKatipT le t
895+ restoreT = KatipT . ReaderT . const
896+ {-# INLINABLE liftWith #-}
897+ {-# INLINABLE restoreT #-}
900+instance (MonadBaseControl b m) => MonadBaseControl b (KatipT m) where
901+ type StM ((KatipT) m) a = ComposeSt (KatipT) m a
902+ liftBaseWith = defaultLiftBaseWith
903+ restoreM = defaultRestoreM
905+instance MonadUnliftIO m => MonadUnliftIO (KatipT m) where
906+#if MIN_VERSION_unliftio_core(0, 2, 0)
907+ withRunInIO inner = KatipT $ ReaderT $ \le -> withRunInIO $ \run ->
908+ inner (run . runKatipT le)
910+ askUnliftIO = KatipT $
911+ withUnliftIO $ \u ->
912+ pure (UnliftIO (unliftIO u . unKatipT))
915+#if MIN_VERSION_base(4, 9, 0)
916+instance MF.MonadFail m => MF.MonadFail (KatipT m) where
917+ fail msg = lift (MF.fail msg)
921+-------------------------------------------------------------------------------
922+-- | Execute 'KatipT' on a log env.
923+runKatipT :: LogEnv -> KatipT m a -> m a
924+runKatipT le (KatipT f) = runReaderT f le
927+-------------------------------------------------------------------------------
928+-- | Disable all scribes for the given monadic action, then restore
929+-- them afterwards. Works in any Katip monad.
935+katipNoLogging = localLogEnv (\le -> set logEnvScribes mempty le)
938+-------------------------------------------------------------------------------
939+-- | Log with everything, including a source code location. This is
940+-- very low level and you typically can use 'logT' in its place.
942+ :: (A.Applicative m, LogItem a, Katip m)
949+logItem a ns loc sev msg = do
950+ LogEnv{..} <- getLogEnv
951+ logKatipItem =<< liftIO
952+ (Item <$> pure _logEnvApp
955+ <*> (mkThreadIdText <$> myThreadId)
956+ <*> pure _logEnvHost
961+ <*> pure (_logEnvApp <> ns)
964+-- | Log already constructed 'Item'. This is the lowest level function that other log*
966+-- It can be useful when implementing centralised logging services.
968+ :: (A.Applicative m, LogItem a, Katip m)
971+logKatipItem item = do
972+ LogEnv{..} <- getLogEnv
974+ FT.forM_ (M.elems _logEnvScribes) $ \ ScribeHandle {..} -> do
975+ whenM (scribePermitItem shScribe item) $
976+ void $ atomically (tryWriteTBQueue shChan (NewItem item))
978+-------------------------------------------------------------------------------
984+tryWriteTBQueue q a = do
985+ full <- isFullTBQueue q
986+ unless full (writeTBQueue q a)
990+-------------------------------------------------------------------------------
991+-- | Log with full context, but without any code location.
993+ :: (Applicative m, LogItem a, Katip m)
995+ -- ^ Contextual payload for the log
997+ -- ^ Specific namespace of the message.
999+ -- ^ Severity of the message
1001+ -- ^ The log message
1003+logF a ns sev msg = logItem a ns Nothing sev msg
1007+-------------------------------------------------------------------------------
1008+-- | Perform an action while logging any exceptions that may occur.
1009+-- Inspired by 'onException`.
1011+-- >>>> logException () mempty ErrorS (error "foo")
1013+ :: (Katip m, LogItem a, MonadCatch m, Applicative m)
1014+ => a -- ^ Log context
1015+ -> Namespace -- ^ Namespace
1016+ -> Severity -- ^ Severity
1017+ -> m b -- ^ Main action being run
1019+logException a ns sev action = action `catchAny` \e -> f e >> throwM e
1021+ f e = logF a ns sev (msg e)
1022+ msg e = ls (T.pack "An exception has occurred: ") <> showLS e
1025+-------------------------------------------------------------------------------
1026+-- | Log a message without any payload/context or code location.
1028+ :: (Applicative m, Katip m)
1033+logMsg ns sev msg = logF () ns sev msg
1036+instance TH.Lift Namespace where
1037+ lift (Namespace xs) =
1038+ let xs' = map T.unpack xs
1039+ in [| Namespace (map T.pack xs') |]
1042+instance TH.Lift Verbosity where
1049+instance TH.Lift Severity where
1050+ lift DebugS = [| DebugS |]
1051+ lift InfoS = [| InfoS |]
1052+ lift NoticeS = [| NoticeS |]
1053+ lift WarningS = [| WarningS |]
1054+ lift ErrorS = [| ErrorS |]
1055+ lift CriticalS = [| CriticalS |]
1056+ lift AlertS = [| AlertS |]
1057+ lift EmergencyS = [| EmergencyS |]
1060+-- | Lift a location into an Exp.
1061+liftLoc :: Loc -> Q Exp
1062+liftLoc (Loc a b c (d1, d2) (e1, e2)) = [|Loc
1066+ ($(TH.lift d1), $(TH.lift d2))
1067+ ($(TH.lift e1), $(TH.lift e2))
1071+-------------------------------------------------------------------------------
1072+-- | For use when you want to include location in your logs. This will
1073+-- fill the 'Maybe Loc' gap in 'logF' of this module, and relies on implicit
1074+-- callstacks when available (GHC > 7.8).
1075+#if MIN_VERSION_base(4, 8, 0)
1076+getLoc :: HasCallStack => Maybe Loc
1077+getLoc = case getCallStack callStack of
1079+ xs -> Just . toLoc . head $ filter filterKatip xs
1081+ filterKatip :: (String, SrcLoc) -> Bool
1082+ filterKatip (_, srcloc) = not $
1083+ "katip-" `isPrefixOf` srcLocPackage srcloc
1085+ toLoc :: (String, SrcLoc) -> Loc
1086+ toLoc (_, l) = Loc {
1087+ loc_filename = srcLocFile l
1088+ , loc_package = srcLocPackage l
1089+ , loc_module = srcLocModule l
1090+ , loc_start = (srcLocStartLine l, srcLocStartCol l)
1091+ , loc_end = (srcLocEndLine l, srcLocEndCol l)
1099+-------------------------------------------------------------------------------
1100+-- Like `getLoc`, but uses template-haskell and works with older versions of
1101+-- the compiler (GHC 7.8 or older).
1103+getLocTH = [| $(location >>= liftLoc) |]
1106+-------------------------------------------------------------------------------
1107+-- | 'Loc'-tagged logging when using template-haskell.
1109+-- @$(logT) obj mempty InfoS "Hello world"@
1111+logT = [| \ a ns sev msg -> logItem a ns (Just $(getLocTH)) sev msg |]
1114+-------------------------------------------------------------------------------
1115+-- | 'Loc'-tagged logging using 'GHC.Stack' when available.
1117+-- This function does not require template-haskell as it
1118+-- automatically uses <https://hackage.haskell.org/package/base-4.8.2.0/docs/GHC-Stack.html#v:getCallStack implicit-callstacks>
1119+-- when the code is compiled using GHC > 7.8. Using an older version of the
1120+-- compiler will result in the emission of a log line without any location information,
1121+-- so be aware of it. Users using GHC <= 7.8 may want to use the template-haskell function
1122+-- `logT` for maximum compatibility.
1124+-- @logLoc obj mempty InfoS "Hello world"@
1125+#if MIN_VERSION_base(4, 8, 0)
1126+logLoc :: (Applicative m, LogItem a, Katip m, HasCallStack)
1128+logLoc :: (Applicative m, LogItem a, Katip m)
1135+logLoc a ns = logItem a ns getLoc
1138+-- taken from the file-location package
1139+-- turn the TH Loc loaction information into a human readable string
1140+-- leaving out the loc_end parameter
1141+locationToString :: Loc -> String
1142+locationToString loc = (loc_package loc) ++ ':' : (loc_module loc) ++
1143+ ' ' : (loc_filename loc) ++ ':' : (line loc) ++ ':' : (char loc)
1145+ line = show . fst . loc_start
1146+ char = show . snd . loc_start