@@ -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
@@ -59,19 +76,24 @@ 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
83+#if mingw32_HOST_OS
84+import Katip.Compat
85+#else
6686import System.Posix
87+#endif
88+
6789-------------------------------------------------------------------------------
6890
6991
7092readMay :: Read a => String -> Maybe a
7193readMay s = case [x | (x,t) <- reads s, ("","") <- lex t] of
7294 [x] -> Just x
73− [] -> Nothing -- no parse
74− _ -> Nothing -- Ambiguous parse
95+ [] -> Nothing -- no parse
96+ _ -> Nothing -- Ambiguous parse
7597
7698
7799-------------------------------------------------------------------------------
@@ -81,7 +103,7 @@ readMay s = case [x | (x,t) <- reads s, ("","") <- lex t] of
81103-- IsString/OverloadedStrings, so "foo" will result in Namespace
82104-- ["foo"].
83105newtype Namespace = Namespace { unNamespace :: [Text] }
84− deriving (Eq,Show,Read,Ord,Generic,ToJSON,FromJSON,Semigroup,Monoid)
106+ deriving (Eq,Show,Read,Ord,Generic,ToJSON,FromJSON,SG.Semigroup,Monoid)
85107
86108instance IsString Namespace where
87109 fromString s = Namespace [fromString s]
@@ -121,33 +143,35 @@ data Severity
121143-- - 'V3' implies the maximum amount of payload information.
122144-- - Anything in between is left to the discretion of the developer.
123145data Verbosity = V0 | V1 | V2 | V3
124− deriving (Eq, Ord, Show, Read, Generic, Enum)
146+ deriving (Eq, Ord, Show, Read, Generic, Enum, Bounded)
125147
126148
127149-------------------------------------------------------------------------------
128150renderSeverity :: Severity -> Text
129151renderSeverity s = case s of
130− DebugS -> "Debug"
131− InfoS -> "Info"
132− NoticeS -> "Notice"
133− WarningS -> "Warning"
134− ErrorS -> "Error"
135− CriticalS -> "Critical"
136− AlertS -> "Alert"
152+ DebugS -> "Debug"
153+ InfoS -> "Info"
154+ NoticeS -> "Notice"
155+ WarningS -> "Warning"
156+ ErrorS -> "Error"
157+ CriticalS -> "Critical"
158+ AlertS -> "Alert"
137159 EmergencyS -> "Emergency"
138160
139161
140162-------------------------------------------------------------------------------
141163textToSeverity :: Text -> Maybe Severity
142−textToSeverity "Debug" = Just DebugS
143−textToSeverity "Info" = Just InfoS
144−textToSeverity "Notice" = Just NoticeS
145−textToSeverity "Warning" = Just WarningS
146−textToSeverity "Error" = Just ErrorS
147−textToSeverity "Critical" = Just CriticalS
148−textToSeverity "Alert" = Just AlertS
149−textToSeverity "Emergency" = Just EmergencyS
150−textToSeverity _ = Nothing
164+textToSeverity = go . T.toLower
165+ where
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
174+ go _ = Nothing
151175
152176
153177instance ToJSON Severity where
@@ -157,14 +181,29 @@ instance FromJSON Severity where
157181 parseJSON = A.withText "Severity" parseSeverity
158182 where
159183 parseSeverity t = case textToSeverity t of
160− Just x -> return x
184+ Just x -> return x
161185 Nothing -> fail $ "Invalid Severity " ++ toS t
162186
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+
163202
164203-------------------------------------------------------------------------------
165−-- | Log message with Builder unerneath; use '<>' to concat in O(1).
204+-- | Log message with Builder underneath; use '<>' to concat in O(1).
166205newtype LogStr = LogStr { unLogStr :: B.Builder }
167− deriving (Generic, Show)
206+ deriving (Generic, Show, Eq)
168207
169208instance IsString LogStr where
170209 fromString = LogStr . B.fromString
@@ -186,7 +225,7 @@ instance FromJSON LogStr where
186225
187226-------------------------------------------------------------------------------
188227-- | Pack any string-like thing into a 'LogStr'. This will
189−-- automatically work on 'String', 'ByteString, 'Text' and any of the
228+-- automatically work on 'String', 'ByteString', 'Text' and any of the
190229-- lazy variants.
191230logStr :: StringConv a Text => a -> LogStr
192231logStr t = LogStr (B.fromText $ toS t)
@@ -199,7 +238,7 @@ ls = logStr
199238
200239
201240-------------------------------------------------------------------------------
202−-- | Convert any showable type into a LogStr.
241+-- | Convert any showable type into a 'LogStr'.
203242showLS :: Show a => a -> LogStr
204243showLS = ls . show
205244
@@ -211,7 +250,9 @@ newtype ThreadIdText = ThreadIdText {
211250
212251
213252mkThreadIdText :: ThreadId -> ThreadIdText
214−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)
215256
216257
217258-------------------------------------------------------------------------------
@@ -231,31 +272,62 @@ data Item a = Item {
231272 } deriving (Generic, Functor)
232273makeLenses ''Item
233274
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+ ]
234298
235299instance Show a => Show (Item a) where
236− show Item{..} = "Item {_itemApp = " ++ show _itemApp ++ ", " ++
237− "_itemEnv = " ++ show _itemEnv ++ ", " ++
238− "_itemSeverity = " ++ show _itemSeverity ++ ", " ++
239− "_itemThread = " ++ show _itemThread ++ ", " ++
240− "_itemHost = " ++ show _itemHost ++ ", " ++
241− "_itemProcess = " ++ show _itemProcess ++ ", " ++
242− "_itemPayload = " ++ show _itemPayload ++ ", " ++
243− "_itemMessage = " ++ show _itemMessage ++ ", " ++
244− "_itemTime = " ++ show _itemTime ++ ", " ++
245− "_itemNamespace = " ++ show _itemNamespace ++ ", " ++
246− "_itemLoc = " ++ show (LocShow <$> _itemLoc) ++ "}"
247−
300+ showsPrec d Item{..} = showParen (d >= 11) ( showString "Item {"
301+ . field "_itemApp" _itemApp
302+ . field "_itemEnv" _itemEnv
303+ . field "_itemSeverity" _itemSeverity
304+ . field "_itemThread" _itemThread
305+ . field "_itemHost" _itemHost
306+ . field "_itemProcess" _itemProcess
307+ . field "_itemPayload" _itemPayload
308+ . field "_itemMessage" _itemMessage
309+ . field "_itemTime" _itemTime
310+ . field "_itemNamespace" _itemNamespace
311+ . showString "_itemLoc = " . shows (LocShow <$> _itemLoc)
312+ . showChar '}'
313+ )
314+ where
315+ field n v = showString n . showString " = " . shows v . showString ", "
248316
249317newtype LocShow = LocShow Loc
250318
251319
252320instance Show LocShow where
253− show (LocShow Loc{..}) =
254− "Loc {loc_filename = " ++ show loc_filename ++ ", " ++
255− "loc_package = " ++ show loc_package ++ ", " ++
256− "loc_module = " ++ show loc_module ++ ", " ++
257− "loc_start = " ++ show loc_start ++ ", " ++
258− "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 ", "
259331
260332
261333instance ToJSON a => ToJSON (Item a) where
@@ -336,7 +408,7 @@ instance FromJSON ProcessIDJs where
336408 parseJSON = A.withText "ProcessID" parseProcessID
337409 where
338410 parseProcessID t = case textToProcessID t of
339− Just p -> return $ ProcessIDJs p
411+ Just p -> return $ ProcessIDJs p
340412 Nothing -> fail $ "Invalid ProcessIDJs " ++ toS t
341413
342414
@@ -373,7 +445,7 @@ class ToObject a where
373445 default toObject :: ToJSON a => a -> A.Object
374446 toObject v = case toJSON v of
375447 A.Object o -> o
376− _ -> mempty
448+ _ -> mempty
377449
378450instance ToObject ()
379451instance ToObject A.Object
@@ -425,7 +497,7 @@ instance ToObject SimpleLogPayload
425497
426498instance LogItem SimpleLogPayload where
427499 payloadKeys V0 _ = SomeKeys []
428− payloadKeys _ _ = AllKeys
500+ payloadKeys _ _ = AllKeys
429501
430502
431503instance Semigroup SimpleLogPayload where
@@ -448,7 +520,7 @@ sl a b = SimpleLogPayload [(a, AnyLogPayload b)]
448520-- automatically bubble higher verbosity levels to lower ones.
449521payloadObject :: LogItem a => Verbosity -> a -> A.Object
450522payloadObject verb a = case FT.foldMap (flip payloadKeys a) [(V0)..verb] of
451− AllKeys -> toObject a
523+ AllKeys -> toObject a
452524 SomeKeys ks -> HM.filterWithKey (\ k _ -> k `FT.elem` ks) $ toObject a
453525
454526
@@ -468,49 +540,107 @@ itemJson verb a = toJSON $ a & itemPayload %~ payloadObject verb
468540--
469541-- Scribes should always take a 'Severity' and 'Verbosity'.
470542--
471−-- Severity is used to *exclude log messages* that are < the provided
472−-- Severity. For instance, if the user passes InfoS, DebugS items
473−-- 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.
474549--
475550-- Verbosity is used to select keys from the log item's payload. Each
476551-- 'LogItem' instance describes what keys should be retained for each
477552-- Verbosity level. Use the 'payloadObject' utility for extracting the keys
478−-- that should be permitted.
479−--
480−-- There is no built-in mechanism in katip for telling a scribe that
481−-- its time to shut down. 'unregisterScribe' merely drops it from the
482−-- 'LogEnv'. This means there are 2 ways to handle resources as a scribe:
553+-- that should be written.
483554--
484−-- 1. Pass in the resource when the scribe is created. Handle
485−-- allocation and release of the resource elsewhere. This is what the
486−-- 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.
487564--
488−-- 2. Return a finalizing function that tells the scribe to shut
489−-- down. @katip-elasticsearch@'s @mkEsScribe@ returns a @IO (Scribe,
490−-- IO ())@. The finalizer will flush any queued log messages and shut
491−-- down gracefully before returning. This can be hooked into your
492−-- application's shutdown routine to ensure you never miss any log
493−-- messages on shutdown.
494−data Scribe = Scribe {
495− liPush :: forall a. LogItem a => Item a -> IO ()
496− }
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
497577
498578
579+-- | AND together 2 permit functions
580+permitAND :: PermitFunc -> PermitFunc -> PermitFunc
581+permitAND f1 f2 = \a -> liftA2 (&&) (f1 a) (f2 a)
582+
583+-- | OR together 2 permit functions
584+permitOR :: PermitFunc -> PermitFunc -> PermitFunc
585+permitOR f1 f2 = \a -> liftA2 (||) (f1 a) (f2 a)
586+
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.
499612instance Semigroup Scribe where
500− (Scribe a) <> (Scribe b) = Scribe $ \ item -> do
501− a item
502− 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)
503619
504620
505621instance Monoid Scribe where
506− mempty = Scribe $ const $ return ()
622+ mempty = Scribe (const (return ())) (return ()) (permitItem DebugS)
507623 mappend = (<>)
508624
509625
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+
510639-------------------------------------------------------------------------------
511640-- | Should this item be logged given the user's maximum severity?
512−permitItem :: Severity -> Item a -> Bool
513−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)
514644
515645
516646-------------------------------------------------------------------------------
@@ -529,16 +659,16 @@ data LogEnv = LogEnv {
529659 -- 'AutoUpdate' for high volume logs but note that this may cause
530660 -- some output forms to display logs out of order. Alternatively,
531661 -- you could just use 'getCurrentTime'.
532− , _logEnvScribes :: M.Map Text Scribe
662+ , _logEnvScribes :: M.Map Text ScribeHandle
533663 }
534664makeLenses ''LogEnv
535665
536666
537667-------------------------------------------------------------------------------
538−-- | Create a reasonable default InitLogEnv. Uses an 'AutoUdate' with
539−-- the default settings as the timer. If you are concerned about
540−-- timestamp precision or event ordering in log outputs like
541−-- 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'.
542672initLogEnv
543673 :: Namespace
544674 -- ^ A base namespace for this application
@@ -550,45 +680,123 @@ initLogEnv an env = LogEnv
550680 <*> getProcessID
551681 <*> pure an
552682 <*> pure env
553− <*> mkAutoUpdate defaultUpdateSettings { updateAction = getCurrentTime }
683+ <*> mkAutoUpdate defaultUpdateSettings { updateAction = getCurrentTime, updateFreq = 1000 }
554684 <*> pure mempty
555685
556686
557687-------------------------------------------------------------------------------
558688-- | Add a scribe to the list. All future log calls will go to this
559−-- 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.
560692registerScribe
561693 :: Text
562694 -- ^ Name the scribe
563695 -> Scribe
696+ -> ScribeSettings
564697 -> LogEnv
565− -> LogEnv
566−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 ()
567726
568727
569728-------------------------------------------------------------------------------
570−-- | Remove a scribe from the list. All future log calls will no
571−-- longer use this scribe. If the given scribe doesn't exist, its a no-op.
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
741+
742+
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.
572748unregisterScribe
573749 :: Text
574750 -- ^ Name of the scribe
575751 -> LogEnv
576752 -> LogEnv
577−unregisterScribe nm = logEnvScribes %~ M.delete nm
753+unregisterScribe nm = logEnvScribes %~ M.delete nm
578754
579755
580756-------------------------------------------------------------------------------
581−-- | Unregister *all* scribes. Logs will go off into space from this
582−-- point onward until new scribes are added. Note that you could use
583−-- this with `local` if you're using a Reader based stack to
584−-- temporarily disable log output. See `katipNoLogging` for an
585−-- 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.
586761clearScribes
587762 :: LogEnv
588763 -> LogEnv
589764clearScribes = logEnvScribes .~ mempty
590765
591766
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+
592800-------------------------------------------------------------------------------
593801-- | Monads where katip logging actions can be performed. Katip is the
594802-- most basic logging monad. You will typically use this directly if
@@ -599,44 +807,86 @@ clearScribes = logEnvScribes .~ mempty
599807-- which keeps a namespace and merged context. You can write simple
600808-- functions that add additional namespacing and merges additional
601809-- 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.
602815class MonadIO m => Katip m where
603816 getLogEnv :: m LogEnv
817+ localLogEnv :: (LogEnv -> LogEnv) -> m a -> m a
604818
605819
606820instance Katip m => Katip (ReaderT s m) where
607821 getLogEnv = lift getLogEnv
822+ localLogEnv = mapReaderT . localLogEnv
608823
609824
825+#if !MIN_VERSION_either(4, 5, 0)
610826instance Katip m => Katip (EitherT s m) where
611827 getLogEnv = lift getLogEnv
828+ localLogEnv = mapEitherT . localLogEnv
829+#endif
830+
612831
613832instance Katip m => Katip (ExceptT s m) where
614833 getLogEnv = lift getLogEnv
834+ localLogEnv = mapExceptT . localLogEnv
835+
615836
616837instance Katip m => Katip (MaybeT m) where
617838 getLogEnv = lift getLogEnv
839+ localLogEnv = mapMaybeT . localLogEnv
618840
619841
620842instance Katip m => Katip (StateT s m) where
621843 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
622860
623861
624862instance (Katip m, Monoid s) => Katip (WriterT s m) where
625863 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+
626871
627872instance (Katip m) => Katip (ResourceT m) where
628873 getLogEnv = lift getLogEnv
874+ localLogEnv = transResourceT . localLogEnv
629875
630876
631877-------------------------------------------------------------------------------
632−-- | 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.
633881newtype KatipT m a = KatipT { unKatipT :: ReaderT LogEnv m a }
634882 deriving ( Functor, Applicative, Monad, MonadIO
635− , MonadMask, MonadCatch, MonadThrow, MonadTrans, MonadBase b)
883+ , MonadMask, MonadCatch, MonadThrow, MonadResource, MonadTrans
884+ , MonadBase b)
636885
637886
638887instance MonadIO m => Katip (KatipT m) where
639888 getLogEnv = KatipT ask
889+ localLogEnv f (KatipT m) = KatipT $ local f m
640890
641891
642892instance MonadTransControl KatipT where
@@ -652,6 +902,21 @@ instance (MonadBaseControl b m) => MonadBaseControl b (KatipT m) where
652902 liftBaseWith = defaultLiftBaseWith
653903 restoreM = defaultRestoreM
654904
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
655920
656921-------------------------------------------------------------------------------
657922-- | Execute 'KatipT' on a log env.
@@ -659,6 +924,17 @@ runKatipT :: LogEnv -> KatipT m a -> m a
659924runKatipT le (KatipT f) = runReaderT f le
660925
661926
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+
662938-------------------------------------------------------------------------------
663939-- | Log with everything, including a source code location. This is
664940-- very low level and you typically can use 'logT' in its place.
@@ -672,20 +948,43 @@ logItem
672948 -> m ()
673949logItem a ns loc sev msg = do
674950 LogEnv{..} <- getLogEnv
675− liftIO $ do
676− item <- Item
677− <$> pure _logEnvApp
678− <*> pure _logEnvEnv
679− <*> pure sev
680− <*> (mkThreadIdText <$> myThreadId)
681− <*> pure _logEnvHost
682− <*> pure _logEnvPid
683− <*> pure a
684− <*> pure msg
685− <*> _logEnvTimer
686− <*> pure (_logEnvApp <> ns)
687− <*> pure loc
688− 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)
689988
690989
691990-------------------------------------------------------------------------------
@@ -717,10 +1016,10 @@ logException
7171016 -> Severity -- ^ Severity
7181017 -> m b -- ^ Main action being run
7191018 -> m b
720−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
7211020 where
7221021 f e = logF a ns sev (msg e)
723− msg e = ls (T.pack "An exception has occured: ") <> showLS e
1022+ msg e = ls (T.pack "An exception has occurred: ") <> showLS e
7241023
7251024
7261025-------------------------------------------------------------------------------
@@ -748,14 +1047,14 @@ instance TH.Lift Verbosity where
7481047
7491048
7501049instance TH.Lift Severity where
751− lift DebugS = [| DebugS |]
752− lift InfoS = [| InfoS |]
753− lift NoticeS = [| NoticeS |]
754− lift WarningS = [| WarningS |]
755− lift ErrorS = [| ErrorS |]
1050+ lift DebugS = [| DebugS |]
1051+ lift InfoS = [| InfoS |]
1052+ lift NoticeS = [| NoticeS |]
1053+ lift WarningS = [| WarningS |]
1054+ lift ErrorS = [| ErrorS |]
7561055 lift CriticalS = [| CriticalS |]
757− lift AlertS = [| AlertS |]
758− lift EmergencyS = [| EmergencyS |]
1056+ lift AlertS = [| AlertS |]
1057+ lift EmergencyS = [| EmergencyS |]
7591058
7601059
7611060-- | Lift a location into an Exp.
@@ -774,11 +1073,15 @@ liftLoc (Loc a b c (d1, d2) (e1, e2)) = [|Loc
7741073-- fill the 'Maybe Loc' gap in 'logF' of this module, and relies on implicit
7751074-- callstacks when available (GHC > 7.8).
7761075#if MIN_VERSION_base(4, 8, 0)
777−getLoc :: (?loc :: CallStack) => Maybe Loc
778−getLoc = case getCallStack ?loc of
1076+getLoc :: HasCallStack => Maybe Loc
1077+getLoc = case getCallStack callStack of
7791078 [] -> Nothing
780− xs -> Just . toLoc . last $ xs
1079+ xs -> Just . toLoc . head $ filter filterKatip xs
7811080 where
1081+ filterKatip :: (String, SrcLoc) -> Bool
1082+ filterKatip (_, srcloc) = not $
1083+ "katip-" `isPrefixOf` srcLocPackage srcloc
1084+
7821085 toLoc :: (String, SrcLoc) -> Loc
7831086 toLoc (_, l) = Loc {
7841087 loc_filename = srcLocFile l
@@ -809,7 +1112,7 @@ logT = [| \ a ns sev msg -> logItem a ns (Just $(getLocTH)) sev msg |]
8091112
8101113
8111114-------------------------------------------------------------------------------
812−-- | 'Loc'-tagged logging using implicit-callstacks when available.
1115+-- | 'Loc'-tagged logging using 'GHC.Stack' when available.
8131116--
8141117-- This function does not require template-haskell as it
8151118-- automatically uses <https://hackage.haskell.org/package/base-4.8.2.0/docs/GHC-Stack.html#v:getCallStack implicit-callstacks>
@@ -819,7 +1122,11 @@ logT = [| \ a ns sev msg -> logItem a ns (Just $(getLocTH)) sev msg |]
8191122-- `logT` for maximum compatibility.
8201123--
8211124-- @logLoc obj mempty InfoS "Hello world"@
1125+#if MIN_VERSION_base(4, 8, 0)
1126+logLoc :: (Applicative m, LogItem a, Katip m, HasCallStack)
1127+#else
8221128logLoc :: (Applicative m, LogItem a, Katip m)
1129+#endif
8231130 => a
8241131 -> Namespace
8251132 -> Severity