@@ -5,8 +5,8 @@
55{-# LANGUAGE ExistentialQuantification #-}
66{-# LANGUAGE FlexibleContexts #-}
77{-# LANGUAGE FlexibleInstances #-}
8+{-# LANGUAGE GADTs #-}
89{-# LANGUAGE GeneralizedNewtypeDeriving #-}
9−{-# LANGUAGE ImplicitParams #-}
1010{-# LANGUAGE MultiParamTypeClasses #-}
1111{-# LANGUAGE OverloadedStrings #-}
1212{-# LANGUAGE RankNTypes #-}
@@ -22,36 +22,53 @@
2222module Katip.Core where
2323
2424-------------------------------------------------------------------------------
25−import Control.Applicative as A
25+import Control.Applicative as A
2626import Control.AutoUpdate
2727import 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)
2833import Control.Monad.Base
29−import Control.Monad.Catch
34+#if MIN_VERSION_base(4, 9, 0)
35+import qualified Control.Monad.Fail as MF
36+#endif
3037import Control.Monad.IO.Class
38+import Control.Monad.IO.Unlift
3139import Control.Monad.Trans.Class
3240import Control.Monad.Trans.Control
41+#if !MIN_VERSION_either(4, 5, 0)
3342import Control.Monad.Trans.Either
43+#endif
3444import Control.Monad.Trans.Except
3545import Control.Monad.Trans.Maybe
3646import Control.Monad.Trans.Reader
37−import Control.Monad.Trans.Resource
38−import Control.Monad.Trans.State
39−import Control.Monad.Trans.Writer
40−import Data.Aeson (FromJSON (..), ToJSON (..),
41− object)
42−import qualified Data.Aeson as A
43−import Data.Foldable as FT
44−import qualified Data.HashMap.Strict as HM
47+import Control.Monad.Trans.Resource (MonadResource, ResourceT,
48+ transResourceT)
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,
55+ mapWriterT)
56+import Data.Aeson (FromJSON (..), ToJSON (..),
57+ object)
58+import qualified Data.Aeson as A
59+import Data.Foldable as FT
60+import qualified Data.HashMap.Strict as HM
4561import Data.List
46−import qualified Data.Map.Strict as M
47−import Data.Semigroup
62+import qualified Data.Map.Strict as M
63+import Data.Maybe (fromMaybe)
64+import Data.Semigroup as SG
4865import Data.String
4966import Data.String.Conv
50−import Data.Text (Text)
51−import qualified Data.Text as T
52−import qualified Data.Text.Lazy.Builder as B
67+import Data.Text (Text)
68+import qualified Data.Text as T
69+import qualified Data.Text.Lazy.Builder as B
5370import Data.Time
54−import GHC.Generics hiding (to)
71+import GHC.Generics hiding (to)
5572#if MIN_VERSION_base(4, 8, 0)
5673#if !MIN_VERSION_base(4, 9, 0)
5774import GHC.SrcLoc
@@ -59,7 +76,7 @@ import GHC.SrcLoc
5976import GHC.Stack
6077#endif
6178import Language.Haskell.TH
62−import qualified Language.Haskell.TH.Syntax as TH
79+import qualified Language.Haskell.TH.Syntax as TH
6380import Lens.Micro
6481import Lens.Micro.TH
6582import Network.HostName
@@ -75,8 +92,8 @@ import System.Posix
7592readMay :: Read a => String -> Maybe a
7693readMay s = case [x | (x,t) <- reads s, ("","") <- lex t] of
7794 [x] -> Just x
78− [] -> Nothing -- no parse
79− _ -> Nothing -- Ambiguous parse
95+ [] -> Nothing -- no parse
96+ _ -> Nothing -- Ambiguous parse
8097
8198
8299-------------------------------------------------------------------------------
@@ -86,7 +103,7 @@ readMay s = case [x | (x,t) <- reads s, ("","") <- lex t] of
86103-- IsString/OverloadedStrings, so "foo" will result in Namespace
87104-- ["foo"].
88105newtype Namespace = Namespace { unNamespace :: [Text] }
89− deriving (Eq,Show,Read,Ord,Generic,ToJSON,FromJSON,Semigroup,Monoid)
106+ deriving (Eq,Show,Read,Ord,Generic,ToJSON,FromJSON,SG.Semigroup,Monoid)
90107
91108instance IsString Namespace where
92109 fromString s = Namespace [fromString s]
@@ -126,19 +143,19 @@ data Severity
126143-- - 'V3' implies the maximum amount of payload information.
127144-- - Anything in between is left to the discretion of the developer.
128145data Verbosity = V0 | V1 | V2 | V3
129− deriving (Eq, Ord, Show, Read, Generic, Enum)
146+ deriving (Eq, Ord, Show, Read, Generic, Enum, Bounded)
130147
131148
132149-------------------------------------------------------------------------------
133150renderSeverity :: Severity -> Text
134151renderSeverity s = case s of
135− DebugS -> "Debug"
136− InfoS -> "Info"
137− NoticeS -> "Notice"
138− WarningS -> "Warning"
139− ErrorS -> "Error"
140− CriticalS -> "Critical"
141− AlertS -> "Alert"
152+ DebugS -> "Debug"
153+ InfoS -> "Info"
154+ NoticeS -> "Notice"
155+ WarningS -> "Warning"
156+ ErrorS -> "Error"
157+ CriticalS -> "Critical"
158+ AlertS -> "Alert"
142159 EmergencyS -> "Emergency"
143160
144161
@@ -164,14 +181,29 @@ instance FromJSON Severity where
164181 parseJSON = A.withText "Severity" parseSeverity
165182 where
166183 parseSeverity t = case textToSeverity t of
167− Just x -> return x
184+ Just x -> return x
168185 Nothing -> fail $ "Invalid Severity " ++ toS t
169186
187+instance ToJSON Verbosity where
188+ toJSON s = A.String $ case s of
189+ V0 -> "V0"
190+ V1 -> "V1"
191+ V2 -> "V2"
192+ V3 -> "V3"
193+
194+instance FromJSON Verbosity where
195+ parseJSON = A.withText "Verbosity" $ \s -> case s of
196+ "V0" -> return V0
197+ "V1" -> return V1
198+ "V2" -> return V2
199+ "V3" -> return V3
200+ _ -> fail $ "Invalid Verbosity " ++ toS s
201+
170202
171203-------------------------------------------------------------------------------
172204-- | Log message with Builder underneath; use '<>' to concat in O(1).
173205newtype LogStr = LogStr { unLogStr :: B.Builder }
174− deriving (Generic, Show)
206+ deriving (Generic, Show, Eq)
175207
176208instance IsString LogStr where
177209 fromString = LogStr . B.fromString
@@ -218,7 +250,9 @@ newtype ThreadIdText = ThreadIdText {
218250
219251
220252mkThreadIdText :: ThreadId -> ThreadIdText
221−mkThreadIdText = ThreadIdText . T.pack . show
253+mkThreadIdText = ThreadIdText . stripPrefix' "ThreadId " . T.pack . show
254+ where
255+ stripPrefix' pfx t = fromMaybe t (T.stripPrefix pfx t)
222256
223257
224258-------------------------------------------------------------------------------
@@ -238,31 +272,62 @@ data Item a = Item {
238272 } deriving (Generic, Functor)
239273makeLenses ''Item
240274
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
295+ ]
296+ _ -> False
297+ ]
241298
242299instance Show a => Show (Item a) where
243− show Item{..} = "Item {_itemApp = " ++ show _itemApp ++ ", " ++
244− "_itemEnv = " ++ show _itemEnv ++ ", " ++
245− "_itemSeverity = " ++ show _itemSeverity ++ ", " ++
246− "_itemThread = " ++ show _itemThread ++ ", " ++
247− "_itemHost = " ++ show _itemHost ++ ", " ++
248− "_itemProcess = " ++ show _itemProcess ++ ", " ++
249− "_itemPayload = " ++ show _itemPayload ++ ", " ++
250− "_itemMessage = " ++ show _itemMessage ++ ", " ++
251− "_itemTime = " ++ show _itemTime ++ ", " ++
252− "_itemNamespace = " ++ show _itemNamespace ++ ", " ++
253− "_itemLoc = " ++ show (LocShow <$> _itemLoc) ++ "}"
254−
300+ showsPrec d Item{..} = showParen (d >= 11) ( showString "Item {"
301+ . field "_itemApp" _itemApp
302+ . field "_itemEnv" _itemEnv
303+ . field "_itemSeverity" _itemSeverity
304+ . field "_itemThread" _itemThread
305+ . field "_itemHost" _itemHost
306+ . field "_itemProcess" _itemProcess
307+ . field "_itemPayload" _itemPayload
308+ . field "_itemMessage" _itemMessage
309+ . field "_itemTime" _itemTime
310+ . field "_itemNamespace" _itemNamespace
311+ . showString "_itemLoc = " . shows (LocShow <$> _itemLoc)
312+ . showChar '}'
313+ )
314+ where
315+ field n v = showString n . showString " = " . shows v . showString ", "
255316
256317newtype LocShow = LocShow Loc
257318
258319
259320instance Show LocShow where
260− show (LocShow Loc{..}) =
261− "Loc {loc_filename = " ++ show loc_filename ++ ", " ++
262− "loc_package = " ++ show loc_package ++ ", " ++
263− "loc_module = " ++ show loc_module ++ ", " ++
264− "loc_start = " ++ show loc_start ++ ", " ++
265− "loc_end = " ++ show loc_end ++ "}"
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
327+ . showChar '}'
328+ )
329+ where
330+ field n v = showString n . showString " = " . shows v . showString ", "
266331
267332
268333instance ToJSON a => ToJSON (Item a) where
@@ -343,7 +408,7 @@ instance FromJSON ProcessIDJs where
343408 parseJSON = A.withText "ProcessID" parseProcessID
344409 where
345410 parseProcessID t = case textToProcessID t of
346− Just p -> return $ ProcessIDJs p
411+ Just p -> return $ ProcessIDJs p
347412 Nothing -> fail $ "Invalid ProcessIDJs " ++ toS t
348413
349414
@@ -380,7 +445,7 @@ class ToObject a where
380445 default toObject :: ToJSON a => a -> A.Object
381446 toObject v = case toJSON v of
382447 A.Object o -> o
383− _ -> mempty
448+ _ -> mempty
384449
385450instance ToObject ()
386451instance ToObject A.Object
@@ -432,7 +497,7 @@ instance ToObject SimpleLogPayload
432497
433498instance LogItem SimpleLogPayload where
434499 payloadKeys V0 _ = SomeKeys []
435− payloadKeys _ _ = AllKeys
500+ payloadKeys _ _ = AllKeys
436501
437502
438503instance Semigroup SimpleLogPayload where
@@ -455,7 +520,7 @@ sl a b = SimpleLogPayload [(a, AnyLogPayload b)]
455520-- automatically bubble higher verbosity levels to lower ones.
456521payloadObject :: LogItem a => Verbosity -> a -> A.Object
457522payloadObject verb a = case FT.foldMap (flip payloadKeys a) [(V0)..verb] of
458− AllKeys -> toObject a
523+ AllKeys -> toObject a
459524 SomeKeys ks -> HM.filterWithKey (\ k _ -> k `FT.elem` ks) $ toObject a
460525
461526
@@ -475,49 +540,107 @@ itemJson verb a = toJSON $ a & itemPayload %~ payloadObject verb
475540--
476541-- Scribes should always take a 'Severity' and 'Verbosity'.
477542--
478−-- Severity is used to *exclude log messages* that are < the provided
479−-- Severity. For instance, if the user passes InfoS, DebugS items
480−-- should be ignored. Katip provides the 'permitItem' utility for this.
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
548+-- they wish to.
481549--
482550-- Verbosity is used to select keys from the log item's payload. Each
483551-- 'LogItem' instance describes what keys should be retained for each
484552-- Verbosity level. Use the 'payloadObject' utility for extracting the keys
485−-- that should be permitted.
486−--
487−-- There is no built-in mechanism in katip for telling a scribe that
488−-- its time to shut down. 'unregisterScribe' merely drops it from the
489−-- 'LogEnv'. This means there are 2 ways to handle resources as a scribe:
553+-- that should be written.
490554--
491−-- 1. Pass in the resource when the scribe is created. Handle
492−-- allocation and release of the resource elsewhere. This is what the
493−-- Handle scribe does.
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
563+-- durably written.
494564--
495−-- 2. Return a finalizing function that tells the scribe to shut
496−-- down. @katip-elasticsearch@'s @mkEsScribe@ returns an @IO (Scribe,
497−-- IO ())@. The finalizer will flush any queued log messages and shut
498−-- down gracefully before returning. This can be hooked into your
499−-- application's shutdown routine to ensure you never miss any log
500−-- messages on shutdown.
501−data Scribe = Scribe {
502− liPush :: forall a. LogItem a => Item a -> IO ()
503− }
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.
571+
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
577+
578+
579+-- | AND together 2 permit functions
580+permitAND :: PermitFunc -> PermitFunc -> PermitFunc
581+permitAND f1 f2 = \a -> liftA2 (&&) (f1 a) (f2 a)
504582
583+-- | OR together 2 permit functions
584+permitOR :: PermitFunc -> PermitFunc -> PermitFunc
585+permitOR f1 f2 = \a -> liftA2 (||) (f1 a) (f2 a)
505586
587+
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'
601+ }
602+
603+
604+whenM :: Monad m => m Bool -> m () -> m ()
605+whenM mbool = (>>=) mbool . flip when
606+
607+
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
611+-- right.
506612instance Semigroup Scribe where
507− (Scribe a) <> (Scribe b) = Scribe $ \ item -> do
508− a item
509− b item
613+ (Scribe pushA finA permitA) <> (Scribe pushB finB permitB) =
614+ Scribe (\item -> whenM (permitA item) (pushA item)
615+ >> whenM (permitB item) (pushB item)
616+ )
617+ (finA `finally` finB)
618+ (permitOR permitA permitB)
510619
511620
512621instance Monoid Scribe where
513− mempty = Scribe $ const $ return ()
622+ mempty = Scribe (const (return ())) (return ()) (permitItem DebugS)
514623 mappend = (<>)
515624
516625
626+-------------------------------------------------------------------------------
627+data ScribeHandle = ScribeHandle {
628+ shScribe :: Scribe
629+ , shChan :: BQ.TBQueue WorkerMessage
630+ }
631+
632+
633+-------------------------------------------------------------------------------
634+data WorkerMessage where
635+ NewItem :: LogItem a => Item a -> WorkerMessage
636+ PoisonPill :: WorkerMessage
637+
638+
517639-------------------------------------------------------------------------------
518640-- | Should this item be logged given the user's maximum severity?
519−permitItem :: Severity -> Item a -> Bool
520−permitItem sev i = _itemSeverity i >= sev
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)
521644
522645
523646-------------------------------------------------------------------------------
@@ -536,16 +659,16 @@ data LogEnv = LogEnv {
536659 -- 'AutoUpdate' for high volume logs but note that this may cause
537660 -- some output forms to display logs out of order. Alternatively,
538661 -- you could just use 'getCurrentTime'.
539− , _logEnvScribes :: M.Map Text Scribe
662+ , _logEnvScribes :: M.Map Text ScribeHandle
540663 }
541664makeLenses ''LogEnv
542665
543666
544667-------------------------------------------------------------------------------
545−-- | Create a reasonable default InitLogEnv. Uses an 'AutoUdate' with
546−-- the default settings as the timer. If you are concerned about
547−-- timestamp precision or event ordering in log outputs like
548−-- ElasticSearch, you should replace the timer with 'getCurrentTime'
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'.
549672initLogEnv
550673 :: Namespace
551674 -- ^ A base namespace for this application
@@ -557,45 +680,123 @@ initLogEnv an env = LogEnv
557680 <*> getProcessID
558681 <*> pure an
559682 <*> pure env
560− <*> mkAutoUpdate defaultUpdateSettings { updateAction = getCurrentTime }
683+ <*> mkAutoUpdate defaultUpdateSettings { updateAction = getCurrentTime, updateFreq = 1000 }
561684 <*> pure mempty
562685
563686
564687-------------------------------------------------------------------------------
565688-- | Add a scribe to the list. All future log calls will go to this
566−-- scribe in addition to the others.
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.
567692registerScribe
568693 :: Text
569694 -- ^ Name the scribe
570695 -> Scribe
696+ -> ScribeSettings
571697 -> LogEnv
572− -> LogEnv
573−registerScribe nm h = logEnvScribes %~ M.insert nm h
698+ -> IO LogEnv
699+registerScribe nm scribe ScribeSettings {..} le = do
700+ queue <- atomically (BQ.newTBQueue (fromIntegral _scribeBufferSize))
701+ worker <- spawnScribeWorker scribe queue
702+ let fin = do
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)
708+
709+ let sh = ScribeHandle (scribe { scribeFinalizer = fin }) queue
710+ return (le & logEnvScribes %~ M.insert nm sh)
711+
712+
713+-------------------------------------------------------------------------------
714+spawnScribeWorker :: Scribe -> BQ.TBQueue WorkerMessage -> IO (Async.Async ())
715+spawnScribeWorker (Scribe write _ _) queue = Async.async go
716+ where
717+ go = do
718+ newCmd <- atomically (BQ.readTBQueue queue)
719+ case newCmd of
720+ NewItem a -> do
721+ -- Swallow any direct exceptions from the
722+ -- scribe. safe-exceptions won't catch async exceptions.
723+ void (tryAny (write a))
724+ go
725+ PoisonPill -> return ()
726+
727+
728+-------------------------------------------------------------------------------
729+data ScribeSettings = ScribeSettings {
730+ _scribeBufferSize :: Int
731+ }
732+ deriving (Show, Eq)
733+
734+makeLenses ''ScribeSettings
735+
736+
737+-- | Reasonable defaults for a scribe. Buffer
738+-- size of 4096.
739+defaultScribeSettings :: ScribeSettings
740+defaultScribeSettings = ScribeSettings 4096
574741
575742
576743-------------------------------------------------------------------------------
577−-- | Remove a scribe from the list. All future log calls will no
578−-- longer use this scribe. If the given scribe doesn't exist, its a no-op.
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.
579748unregisterScribe
580749 :: Text
581750 -- ^ Name of the scribe
582751 -> LogEnv
583752 -> LogEnv
584−unregisterScribe nm = logEnvScribes %~ M.delete nm
753+unregisterScribe nm = logEnvScribes %~ M.delete nm
585754
586755
587756-------------------------------------------------------------------------------
588−-- | Unregister *all* scribes. Logs will go off into space from this
589−-- point onward until new scribes are added. Note that you could use
590−-- this with `local` if you're using a Reader based stack to
591−-- temporarily disable log output. See `katipNoLogging` for an
592−-- example.
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.
593761clearScribes
594762 :: LogEnv
595763 -> LogEnv
596764clearScribes = logEnvScribes .~ mempty
597765
598766
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.
773+closeScribe
774+ :: Text
775+ -- ^ Name of the scribe
776+ -> LogEnv
777+ -> IO LogEnv
778+closeScribe nm le = do
779+ maybe (return ()) (scribeFinalizer . shScribe) (M.lookup nm (_logEnvScribes le))
780+ return (le & logEnvScribes %~ M.delete nm)
781+
782+
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.
789+closeScribes
790+ :: LogEnv
791+ -> IO LogEnv
792+closeScribes le = do
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)
798+
799+
599800-------------------------------------------------------------------------------
600801-- | Monads where katip logging actions can be performed. Katip is the
601802-- most basic logging monad. You will typically use this directly if
@@ -606,44 +807,86 @@ clearScribes = logEnvScribes .~ mempty
606807-- which keeps a namespace and merged context. You can write simple
607808-- functions that add additional namespacing and merges additional
608809-- context on the fly.
810+--
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.
609815class MonadIO m => Katip m where
610816 getLogEnv :: m LogEnv
817+ localLogEnv :: (LogEnv -> LogEnv) -> m a -> m a
611818
612819
613820instance Katip m => Katip (ReaderT s m) where
614821 getLogEnv = lift getLogEnv
822+ localLogEnv = mapReaderT . localLogEnv
615823
616824
825+#if !MIN_VERSION_either(4, 5, 0)
617826instance Katip m => Katip (EitherT s m) where
618827 getLogEnv = lift getLogEnv
828+ localLogEnv = mapEitherT . localLogEnv
829+#endif
830+
619831
620832instance Katip m => Katip (ExceptT s m) where
621833 getLogEnv = lift getLogEnv
834+ localLogEnv = mapExceptT . localLogEnv
835+
622836
623837instance Katip m => Katip (MaybeT m) where
624838 getLogEnv = lift getLogEnv
839+ localLogEnv = mapMaybeT . localLogEnv
625840
626841
627842instance Katip m => Katip (StateT s m) where
628843 getLogEnv = lift getLogEnv
844+ localLogEnv = mapStateT . localLogEnv
845+
846+
847+instance (Katip m, Monoid w) => Katip (RWST r w s m) where
848+ getLogEnv = lift getLogEnv
849+ localLogEnv = mapRWST . localLogEnv
850+
851+
852+instance (Katip m, Monoid w) => Katip (Strict.RWST r w s m) where
853+ getLogEnv = lift getLogEnv
854+ localLogEnv = Strict.mapRWST . localLogEnv
855+
856+
857+instance Katip m => Katip (Strict.StateT s m) where
858+ getLogEnv = lift getLogEnv
859+ localLogEnv = Strict.mapStateT . localLogEnv
629860
630861
631862instance (Katip m, Monoid s) => Katip (WriterT s m) where
632863 getLogEnv = lift getLogEnv
864+ localLogEnv = mapWriterT . localLogEnv
865+
866+
867+instance (Katip m, Monoid s) => Katip (Strict.WriterT s m) where
868+ getLogEnv = lift getLogEnv
869+ localLogEnv = Strict.mapWriterT . localLogEnv
870+
633871
634872instance (Katip m) => Katip (ResourceT m) where
635873 getLogEnv = lift getLogEnv
874+ localLogEnv = transResourceT . localLogEnv
636875
637876
638877-------------------------------------------------------------------------------
639−-- | A concrete monad you can use to run logging actions.
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.
640881newtype KatipT m a = KatipT { unKatipT :: ReaderT LogEnv m a }
641882 deriving ( Functor, Applicative, Monad, MonadIO
642− , MonadMask, MonadCatch, MonadThrow, MonadTrans, MonadBase b)
883+ , MonadMask, MonadCatch, MonadThrow, MonadResource, MonadTrans
884+ , MonadBase b)
643885
644886
645887instance MonadIO m => Katip (KatipT m) where
646888 getLogEnv = KatipT ask
889+ localLogEnv f (KatipT m) = KatipT $ local f m
647890
648891
649892instance MonadTransControl KatipT where
@@ -659,6 +902,21 @@ instance (MonadBaseControl b m) => MonadBaseControl b (KatipT m) where
659902 liftBaseWith = defaultLiftBaseWith
660903 restoreM = defaultRestoreM
661904
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)
909+#else
910+ askUnliftIO = KatipT $
911+ withUnliftIO $ \u ->
912+ pure (UnliftIO (unliftIO u . unKatipT))
913+#endif
914+
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)
918+ {-# INLINE fail #-}
919+#endif
662920
663921-------------------------------------------------------------------------------
664922-- | Execute 'KatipT' on a log env.
@@ -666,6 +924,17 @@ runKatipT :: LogEnv -> KatipT m a -> m a
666924runKatipT le (KatipT f) = runReaderT f le
667925
668926
927+-------------------------------------------------------------------------------
928+-- | Disable all scribes for the given monadic action, then restore
929+-- them afterwards. Works in any Katip monad.
930+katipNoLogging
931+ :: ( Katip m
932+ )
933+ => m a
934+ -> m a
935+katipNoLogging = localLogEnv (\le -> set logEnvScribes mempty le)
936+
937+
669938-------------------------------------------------------------------------------
670939-- | Log with everything, including a source code location. This is
671940-- very low level and you typically can use 'logT' in its place.
@@ -679,20 +948,43 @@ logItem
679948 -> m ()
680949logItem a ns loc sev msg = do
681950 LogEnv{..} <- getLogEnv
682− liftIO $ do
683− item <- Item
684− <$> pure _logEnvApp
685− <*> pure _logEnvEnv
686− <*> pure sev
687− <*> (mkThreadIdText <$> myThreadId)
688− <*> pure _logEnvHost
689− <*> pure _logEnvPid
690− <*> pure a
691− <*> pure msg
692− <*> _logEnvTimer
693− <*> pure (_logEnvApp <> ns)
694− <*> pure loc
695− FT.forM_ (M.elems _logEnvScribes) $ \ (Scribe h) -> h item
951+ logKatipItem =<< liftIO
952+ (Item <$> pure _logEnvApp
953+ <*> pure _logEnvEnv
954+ <*> pure sev
955+ <*> (mkThreadIdText <$> myThreadId)
956+ <*> pure _logEnvHost
957+ <*> pure _logEnvPid
958+ <*> pure a
959+ <*> pure msg
960+ <*> _logEnvTimer
961+ <*> pure (_logEnvApp <> ns)
962+ <*> pure loc)
963+
964+-- | Log already constructed 'Item'. This is the lowest level function that other log*
965+-- functions use.
966+-- It can be useful when implementing centralised logging services.
967+logKatipItem
968+ :: (A.Applicative m, LogItem a, Katip m)
969+ => Item a
970+ -> m ()
971+logKatipItem item = do
972+ LogEnv{..} <- getLogEnv
973+ liftIO $
974+ FT.forM_ (M.elems _logEnvScribes) $ \ ScribeHandle {..} -> do
975+ whenM (scribePermitItem shScribe item) $
976+ void $ atomically (tryWriteTBQueue shChan (NewItem item))
977+
978+-------------------------------------------------------------------------------
979+tryWriteTBQueue
980+ :: TBQueue a
981+ -> a
982+ -> STM Bool
983+ -- ^ Did we write?
984+tryWriteTBQueue q a = do
985+ full <- isFullTBQueue q
986+ unless full (writeTBQueue q a)
987+ return (not full)
696988
697989
698990-------------------------------------------------------------------------------
@@ -724,10 +1016,10 @@ logException
7241016 -> Severity -- ^ Severity
7251017 -> m b -- ^ Main action being run
7261018 -> m b
727−logException a ns sev action = action `catchAll` \e -> f e >> throwM e
1019+logException a ns sev action = action `catchAny` \e -> f e >> throwM e
7281020 where
7291021 f e = logF a ns sev (msg e)
730− msg e = ls (T.pack "An exception has occured: ") <> showLS e
1022+ msg e = ls (T.pack "An exception has occurred: ") <> showLS e
7311023
7321024
7331025-------------------------------------------------------------------------------
@@ -755,14 +1047,14 @@ instance TH.Lift Verbosity where
7551047
7561048
7571049instance TH.Lift Severity where
758− lift DebugS = [| DebugS |]
759− lift InfoS = [| InfoS |]
760− lift NoticeS = [| NoticeS |]
761− lift WarningS = [| WarningS |]
762− lift ErrorS = [| ErrorS |]
1050+ lift DebugS = [| DebugS |]
1051+ lift InfoS = [| InfoS |]
1052+ lift NoticeS = [| NoticeS |]
1053+ lift WarningS = [| WarningS |]
1054+ lift ErrorS = [| ErrorS |]
7631055 lift CriticalS = [| CriticalS |]
764− lift AlertS = [| AlertS |]
765− lift EmergencyS = [| EmergencyS |]
1056+ lift AlertS = [| AlertS |]
1057+ lift EmergencyS = [| EmergencyS |]
7661058
7671059
7681060-- | Lift a location into an Exp.
@@ -781,11 +1073,15 @@ liftLoc (Loc a b c (d1, d2) (e1, e2)) = [|Loc
7811073-- fill the 'Maybe Loc' gap in 'logF' of this module, and relies on implicit
7821074-- callstacks when available (GHC > 7.8).
7831075#if MIN_VERSION_base(4, 8, 0)
784−getLoc :: (?loc :: CallStack) => Maybe Loc
785−getLoc = case getCallStack ?loc of
1076+getLoc :: HasCallStack => Maybe Loc
1077+getLoc = case getCallStack callStack of
7861078 [] -> Nothing
787− xs -> Just . toLoc . last $ xs
1079+ xs -> Just . toLoc . head $ filter filterKatip xs
7881080 where
1081+ filterKatip :: (String, SrcLoc) -> Bool
1082+ filterKatip (_, srcloc) = not $
1083+ "katip-" `isPrefixOf` srcLocPackage srcloc
1084+
7891085 toLoc :: (String, SrcLoc) -> Loc
7901086 toLoc (_, l) = Loc {
7911087 loc_filename = srcLocFile l
@@ -816,7 +1112,7 @@ logT = [| \ a ns sev msg -> logItem a ns (Just $(getLocTH)) sev msg |]
8161112
8171113
8181114-------------------------------------------------------------------------------
819−-- | 'Loc'-tagged logging using implicit-callstacks when available.
1115+-- | 'Loc'-tagged logging using 'GHC.Stack' when available.
8201116--
8211117-- This function does not require template-haskell as it
8221118-- automatically uses <https://hackage.haskell.org/package/base-4.8.2.0/docs/GHC-Stack.html#v:getCallStack implicit-callstacks>
@@ -827,7 +1123,7 @@ logT = [| \ a ns sev msg -> logItem a ns (Just $(getLocTH)) sev msg |]
8271123--
8281124-- @logLoc obj mempty InfoS "Hello world"@
8291125#if MIN_VERSION_base(4, 8, 0)
830−logLoc :: (Applicative m, LogItem a, Katip m, ?loc :: CallStack)
1126+logLoc :: (Applicative m, LogItem a, Katip m, HasCallStack)
8311127#else
8321128logLoc :: (Applicative m, LogItem a, Katip m)
8331129#endif