@@ -1,8 +1,11 @@
1+{-# LANGUAGE CPP #-}
2+{-# LANGUAGE DefaultSignatures #-}
13{-# LANGUAGE DeriveFunctor #-}
24{-# LANGUAGE DeriveGeneric #-}
35{-# LANGUAGE ExistentialQuantification #-}
46{-# LANGUAGE FlexibleContexts #-}
57{-# LANGUAGE FlexibleInstances #-}
8+{-# LANGUAGE GADTs #-}
69{-# LANGUAGE GeneralizedNewtypeDeriving #-}
710{-# LANGUAGE MultiParamTypeClasses #-}
811{-# LANGUAGE OverloadedStrings #-}
@@ -11,48 +14,88 @@
1114{-# LANGUAGE TemplateHaskell #-}
1215{-# LANGUAGE TypeFamilies #-}
1316{-# LANGUAGE UndecidableInstances #-}
17+#if MIN_VERSION_base(4, 9, 0)
18+{-# OPTIONS_GHC -fno-warn-redundant-constraints #-}
19+#endif
20+-- | This module is not meant to be imported directly and may contain
21+-- internal mechanisms that will change without notice.
1422module Katip.Core where
1523
1624-------------------------------------------------------------------------------
17−import Control.Applicative as A
25+import Control.Applicative as A
1826import Control.AutoUpdate
1927import Control.Concurrent
20−import Control.Lens
21−import Control.Monad
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)
2233import Control.Monad.Base
23−import Control.Monad.Catch
34+#if MIN_VERSION_base(4, 9, 0)
35+import qualified Control.Monad.Fail as MF
36+#endif
2437import Control.Monad.IO.Class
38+import Control.Monad.IO.Unlift
2539import Control.Monad.Trans.Class
2640import Control.Monad.Trans.Control
41+#if !MIN_VERSION_either(4, 5, 0)
2742import Control.Monad.Trans.Either
43+#endif
2844import Control.Monad.Trans.Except
2945import Control.Monad.Trans.Maybe
3046import Control.Monad.Trans.Reader
31−import Control.Monad.Trans.Resource
32−import Control.Monad.Trans.State
33−import Control.Monad.Trans.Writer
34−import Data.Aeson (FromJSON (..), ToJSON (..),
35− object)
36−import qualified Data.Aeson as A
37−import Data.Foldable as FT
38−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
3961import Data.List
40−import qualified Data.Map.Strict as M
41−import Data.Monoid
62+import qualified Data.Map.Strict as M
63+import Data.Maybe (fromMaybe)
64+import Data.Semigroup as SG
4265import Data.String
4366import Data.String.Conv
44−import Data.Text (Text)
45−import qualified Data.Text as T
46−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
4770import Data.Time
48−import GHC.Generics hiding (to)
71+import GHC.Generics hiding (to)
72+#if MIN_VERSION_base(4, 8, 0)
73+#if !MIN_VERSION_base(4, 9, 0)
74+import GHC.SrcLoc
75+#endif
76+import GHC.Stack
77+#endif
4978import Language.Haskell.TH
50−import qualified Language.Haskell.TH.Syntax as TH
79+import qualified Language.Haskell.TH.Syntax as TH
80+import Lens.Micro
81+import Lens.Micro.TH
5182import Network.HostName
83+#if mingw32_HOST_OS
84+import Katip.Compat
85+#else
5286import System.Posix
87+#endif
88+
5389-------------------------------------------------------------------------------
5490
5591
92+readMay :: Read a => String -> Maybe a
93+readMay s = case [x | (x,t) <- reads s, ("","") <- lex t] of
94+ [x] -> Just x
95+ [] -> Nothing -- no parse
96+ _ -> Nothing -- Ambiguous parse
97+
98+
5699-------------------------------------------------------------------------------
57100-- | Represents a heirarchy of namespaces going from general to
58101-- specific. For instance: ["processname", "subsystem"]. Note that
@@ -60,7 +103,7 @@ import System.Posix
60103-- IsString/OverloadedStrings, so "foo" will result in Namespace
61104-- ["foo"].
62105newtype Namespace = Namespace { unNamespace :: [Text] }
63− deriving (Eq,Show,Read,Ord,Generic,ToJSON,FromJSON,Monoid)
106+ deriving (Eq,Show,Read,Ord,Generic,ToJSON,FromJSON,SG.Semigroup,Monoid)
64107
65108instance IsString Namespace where
66109 fromString s = Namespace [fromString s]
@@ -100,60 +143,81 @@ data Severity
100143-- - 'V3' implies the maximum amount of payload information.
101144-- - Anything in between is left to the discretion of the developer.
102145data Verbosity = V0 | V1 | V2 | V3
103− deriving (Eq, Ord, Show, Read, Generic, Enum)
146+ deriving (Eq, Ord, Show, Read, Generic, Enum, Bounded)
104147
105148
106149-------------------------------------------------------------------------------
107150renderSeverity :: Severity -> Text
108151renderSeverity s = case s of
109− DebugS -> "Debug"
110− InfoS -> "Info"
111− NoticeS -> "Notice"
112− WarningS -> "Warning"
113− ErrorS -> "Error"
114− CriticalS -> "Critical"
115− AlertS -> "Alert"
152+ DebugS -> "Debug"
153+ InfoS -> "Info"
154+ NoticeS -> "Notice"
155+ WarningS -> "Warning"
156+ ErrorS -> "Error"
157+ CriticalS -> "Critical"
158+ AlertS -> "Alert"
116159 EmergencyS -> "Emergency"
117160
118161
119162-------------------------------------------------------------------------------
120−severityText :: Prism' Text Severity
121−severityText = prism renderSeverity toSev
163+textToSeverity :: Text -> Maybe Severity
164+textToSeverity = go . T.toLower
122165 where
123− toSev "Debug" = Right DebugS
124− toSev "Info" = Right InfoS
125− toSev "Notice" = Right NoticeS
126− toSev "Warning" = Right WarningS
127− toSev "Error" = Right ErrorS
128− toSev "Critical" = Right CriticalS
129− toSev "Alert" = Right AlertS
130− toSev "Emergency" = Right EmergencyS
131− toSev x = Left x
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
132175
133−instance ToJSON Severity where
134− toJSON s = A.String (s ^. re severityText)
135176
177+instance ToJSON Severity where
178+ toJSON s = A.String (renderSeverity s)
136179
137180instance FromJSON Severity where
138181 parseJSON = A.withText "Severity" parseSeverity
139182 where
140− parseSeverity t = case t ^? severityText of
141− Just x -> return x
183+ parseSeverity t = case textToSeverity t of
184+ Just x -> return x
142185 Nothing -> fail $ "Invalid Severity " ++ toS t
143186
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+
144202
145203-------------------------------------------------------------------------------
146−-- | Log message with Builder unerneath; use '<>' to concat in O(1).
204+-- | Log message with Builder underneath; use '<>' to concat in O(1).
147205newtype LogStr = LogStr { unLogStr :: B.Builder }
148− deriving (Generic, Show)
206+ deriving (Generic, Show, Eq)
149207
150208instance IsString LogStr where
151209 fromString = LogStr . B.fromString
152210
211+
212+instance Semigroup LogStr where
213+ (LogStr a) <> (LogStr b) = LogStr (a <> b)
214+
215+
153216instance Monoid LogStr where
154− mappend (LogStr a) (LogStr b) = LogStr (a `mappend` b)
217+ mappend = (<>)
155218 mempty = LogStr mempty
156219
220+
157221instance FromJSON LogStr where
158222 parseJSON = A.withText "LogStr" parseLogStr
159223 where
@@ -161,20 +225,20 @@ instance FromJSON LogStr where
161225
162226-------------------------------------------------------------------------------
163227-- | Pack any string-like thing into a 'LogStr'. This will
164−-- automatically work on 'String', 'ByteString, 'Text' and any of the
228+-- automatically work on 'String', 'ByteString', 'Text' and any of the
165229-- lazy variants.
166230logStr :: StringConv a Text => a -> LogStr
167231logStr t = LogStr (B.fromText $ toS t)
168232
169233
170234-------------------------------------------------------------------------------
171−-- | Shorthand for 'logMsg'
235+-- | Shorthand for 'logStr'
172236ls :: StringConv a Text => a -> LogStr
173237ls = logStr
174238
175239
176240-------------------------------------------------------------------------------
177−-- | Convert any showable type into a LogStr.
241+-- | Convert any showable type into a 'LogStr'.
178242showLS :: Show a => a -> LogStr
179243showLS = ls . show
180244
@@ -186,7 +250,9 @@ newtype ThreadIdText = ThreadIdText {
186250
187251
188252mkThreadIdText :: ThreadId -> ThreadIdText
189−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)
190256
191257
192258-------------------------------------------------------------------------------
@@ -206,31 +272,62 @@ data Item a = Item {
206272 } deriving (Generic, Functor)
207273makeLenses ''Item
208274
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+ ]
209298
210299instance Show a => Show (Item a) where
211− show Item{..} = "Item {_itemApp = " ++ show _itemApp ++ ", " ++
212− "_itemEnv = " ++ show _itemEnv ++ ", " ++
213− "_itemSeverity = " ++ show _itemSeverity ++ ", " ++
214− "_itemThread = " ++ show _itemThread ++ ", " ++
215− "_itemHost = " ++ show _itemHost ++ ", " ++
216− "_itemProcess = " ++ show _itemProcess ++ ", " ++
217− "_itemPayload = " ++ show _itemPayload ++ ", " ++
218− "_itemMessage = " ++ show _itemMessage ++ ", " ++
219− "_itemTime = " ++ show _itemTime ++ ", " ++
220− "_itemNamespace = " ++ show _itemNamespace ++ ", " ++
221− "_itemLoc = " ++ show (LocShow <$> _itemLoc) ++ "}"
222−
300+ showsPrec d Item{..} = showParen (d >= 11) ( showString "Item {"
301+ . field "_itemApp" _itemApp
302+ . field "_itemEnv" _itemEnv
303+ . field "_itemSeverity" _itemSeverity
304+ . field "_itemThread" _itemThread
305+ . field "_itemHost" _itemHost
306+ . field "_itemProcess" _itemProcess
307+ . field "_itemPayload" _itemPayload
308+ . field "_itemMessage" _itemMessage
309+ . field "_itemTime" _itemTime
310+ . field "_itemNamespace" _itemNamespace
311+ . showString "_itemLoc = " . shows (LocShow <$> _itemLoc)
312+ . showChar '}'
313+ )
314+ where
315+ field n v = showString n . showString " = " . shows v . showString ", "
223316
224317newtype LocShow = LocShow Loc
225318
226319
227320instance Show LocShow where
228− show (LocShow Loc{..}) =
229− "Loc {loc_filename = " ++ show loc_filename ++ ", " ++
230− "loc_package = " ++ show loc_package ++ ", " ++
231− "loc_module = " ++ show loc_module ++ ", " ++
232− "loc_start = " ++ show loc_start ++ ", " ++
233− "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 ", "
234331
235332
236333instance ToJSON a => ToJSON (Item a) where
@@ -290,13 +387,12 @@ instance FromJSON a => FromJSON (Item a) where
290387 <*> (fmap getLocJs <$> o A..: "loc")
291388
292389
293−processIDText :: Prism' Text ProcessID
294−processIDText = prism fromProcessID toProcessID
295− where
296− fromProcessID = toS . show
297− toProcessID t = case toS t ^? _Show of
298− Just i -> Right i
299− Nothing -> Left t
390+processIDToText :: ProcessID -> Text
391+processIDToText = toS . show
392+
393+
394+textToProcessID :: Text -> Maybe ProcessID
395+textToProcessID = readMay . toS
300396
301397
302398newtype ProcessIDJs = ProcessIDJs {
@@ -305,14 +401,14 @@ newtype ProcessIDJs = ProcessIDJs {
305401
306402
307403instance ToJSON ProcessIDJs where
308− toJSON (ProcessIDJs p) = A.String (p ^. re processIDText)
404+ toJSON (ProcessIDJs p) = A.String (processIDToText p)
309405
310406
311407instance FromJSON ProcessIDJs where
312408 parseJSON = A.withText "ProcessID" parseProcessID
313409 where
314− parseProcessID t = case t ^? processIDText of
315− Just p -> return $ ProcessIDJs p
410+ parseProcessID t = case textToProcessID t of
411+ Just p -> return $ ProcessIDJs p
316412 Nothing -> fail $ "Invalid ProcessIDJs " ++ toS t
317413
318414
@@ -321,12 +417,17 @@ instance FromJSON ProcessIDJs where
321417data PayloadSelection
322418 = AllKeys
323419 | SomeKeys [Text]
420+ deriving (Show, Eq)
421+
422+instance Semigroup PayloadSelection where
423+ AllKeys <> _ = AllKeys
424+ _ <> AllKeys = AllKeys
425+ SomeKeys as <> SomeKeys bs = SomeKeys (as <> bs)
426+
324427
325428instance Monoid PayloadSelection where
326429 mempty = SomeKeys []
327− mappend AllKeys _ = AllKeys
328− mappend _ AllKeys = AllKeys
329− mappend (SomeKeys as) (SomeKeys bs) = SomeKeys (as++bs)
430+ mappend = (<>)
330431
331432
332433-------------------------------------------------------------------------------
@@ -339,11 +440,12 @@ instance Monoid PayloadSelection where
339440-- a ToJSON instance like:
340441--
341442-- > instance ToObject Foo
342−class ToJSON a => ToObject a where
443+class ToObject a where
343444 toObject :: a -> A.Object
445+ default toObject :: ToJSON a => a -> A.Object
344446 toObject v = case toJSON v of
345447 A.Object o -> o
346− _ -> mempty
448+ _ -> mempty
347449
348450instance ToObject ()
349451instance ToObject A.Object
@@ -389,15 +491,22 @@ instance ToJSON SimpleLogPayload where
389491 toJSON (SimpleLogPayload as) = object $ map go as
390492 where go (k, AnyLogPayload v) = k A..= v
391493
494+
392495instance ToObject SimpleLogPayload
393496
497+
394498instance LogItem SimpleLogPayload where
395499 payloadKeys V0 _ = SomeKeys []
396− payloadKeys _ _ = AllKeys
500+ payloadKeys _ _ = AllKeys
501+
502+
503+instance Semigroup SimpleLogPayload where
504+ SimpleLogPayload a <> SimpleLogPayload b = SimpleLogPayload (a <> b)
505+
397506
398507instance Monoid SimpleLogPayload where
399508 mempty = SimpleLogPayload []
400− SimpleLogPayload a `mappend` SimpleLogPayload b = SimpleLogPayload (a `mappend` b)
509+ mappend = (<>)
401510
402511
403512-------------------------------------------------------------------------------
@@ -411,7 +520,7 @@ sl a b = SimpleLogPayload [(a, AnyLogPayload b)]
411520-- automatically bubble higher verbosity levels to lower ones.
412521payloadObject :: LogItem a => Verbosity -> a -> A.Object
413522payloadObject verb a = case FT.foldMap (flip payloadKeys a) [(V0)..verb] of
414− AllKeys -> toObject a
523+ AllKeys -> toObject a
415524 SomeKeys ks -> HM.filterWithKey (\ k _ -> k `FT.elem` ks) $ toObject a
416525
417526
@@ -431,67 +540,135 @@ itemJson verb a = toJSON $ a & itemPayload %~ payloadObject verb
431540--
432541-- Scribes should always take a 'Severity' and 'Verbosity'.
433542--
434−-- Severity is used to *exclude log messages* that are < the provided
435−-- Severity. For instance, if the user passes InfoS, DebugS items
436−-- 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.
437549--
438550-- Verbosity is used to select keys from the log item's payload. Each
439551-- 'LogItem' instance describes what keys should be retained for each
440552-- Verbosity level. Use the 'payloadObject' utility for extracting the keys
441−-- that should be permitted.
553+-- that should be written.
442554--
443−-- There is no built-in mechanism in katip for telling a scribe that
444−-- its time to shut down. 'unregisterScribe' merely drops it from the
445−-- 'LogEnv'. This means there are 2 ways to handle resources as a scribe:
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.
446564--
447−-- 1. Pass in the resource when the scribe is created. Handle
448−-- allocation and release of the resource elsewhere. This is what the
449−-- Handle scribe does.
450−--
451−-- 2. Return a finalizing function that tells the scribe to shut
452−-- down. @katip-elasticsearch@'s @mkEsScribe@ returns a @IO (Scribe,
453−-- IO ())@. The finalizer will flush any queued log messages and shut
454−-- down gracefully before returning. This can be hooked into your
455−-- application's shutdown routine to ensure you never miss any log
456−-- messages on shutdown.
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)
582+
583+-- | OR together 2 permit functions
584+permitOR :: PermitFunc -> PermitFunc -> PermitFunc
585+permitOR f1 f2 = \a -> liftA2 (||) (f1 a) (f2 a)
586+
587+
457588data Scribe = Scribe {
458− liPush :: forall a. LogItem a => Item a -> IO ()
459− }
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.
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)
616+ )
617+ (finA `finally` finB)
618+ (permitOR permitA permitB)
460619
461620
462621instance Monoid Scribe where
463− mempty = Scribe $ const $ return ()
464− mappend (Scribe a) (Scribe b) = Scribe $ \ item -> do
465− a item
466− b item
622+ mempty = Scribe (const (return ())) (return ()) (permitItem DebugS)
623+ mappend = (<>)
624+
625+
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
467637
468638
469639-------------------------------------------------------------------------------
470640-- | Should this item be logged given the user's maximum severity?
471−permitItem :: Severity -> Item a -> Bool
472−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)
473644
474645
475646-------------------------------------------------------------------------------
476647data LogEnv = LogEnv {
477648 _logEnvHost :: HostName
478649 , _logEnvPid :: ProcessID
479− , _logEnvNs :: Namespace
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"
480656 , _logEnvEnv :: Environment
481657 , _logEnvTimer :: IO UTCTime
482658 -- ^ Action to fetch the timestamp. You can use something like
483659 -- 'AutoUpdate' for high volume logs but note that this may cause
484− -- some output forms to display logs out of order.
485− , _logEnvScribes :: M.Map Text Scribe
660+ -- some output forms to display logs out of order. Alternatively,
661+ -- you could just use 'getCurrentTime'.
662+ , _logEnvScribes :: M.Map Text ScribeHandle
486663 }
487664makeLenses ''LogEnv
488665
489666
490667-------------------------------------------------------------------------------
491−-- | Create a reasonable default InitLogEnv. Uses an 'AutoUdate' with
492−-- the default settings as the timer. If you are concerned about
493−-- timestamp precision or event ordering in log outputs like
494−-- 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'.
495672initLogEnv
496673 :: Namespace
497674 -- ^ A base namespace for this application
@@ -503,36 +680,84 @@ initLogEnv an env = LogEnv
503680 <*> getProcessID
504681 <*> pure an
505682 <*> pure env
506− <*> mkAutoUpdate defaultUpdateSettings { updateAction = getCurrentTime }
683+ <*> mkAutoUpdate defaultUpdateSettings { updateAction = getCurrentTime, updateFreq = 1000 }
507684 <*> pure mempty
508685
509686
510687-------------------------------------------------------------------------------
511688-- | Add a scribe to the list. All future log calls will go to this
512−-- 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.
513692registerScribe
514693 :: Text
515694 -- ^ Name the scribe
516695 -> Scribe
696+ -> ScribeSettings
517697 -> LogEnv
518− -> LogEnv
519−registerScribe nm h = logEnvScribes . at nm .~ Just 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 ()
520726
521727
522728-------------------------------------------------------------------------------
523−-- | Remove a scribe from the list. All future log calls will no
524−-- 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.
525748unregisterScribe
526749 :: Text
527750 -- ^ Name of the scribe
528751 -> LogEnv
529752 -> LogEnv
530−unregisterScribe nm = logEnvScribes . at nm .~ Nothing
753+unregisterScribe nm = logEnvScribes %~ M.delete nm
531754
532755
533756-------------------------------------------------------------------------------
534−-- | Unregister *all* scribes. Logs will go off into space from this
535−-- point onward until new scribes are added.
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.
536761clearScribes
537762 :: LogEnv
538763 -> LogEnv
@@ -540,45 +765,128 @@ clearScribes = logEnvScribes .~ mempty
540765
541766
542767-------------------------------------------------------------------------------
543−-- | Monads where katip logging actions can be performed
544−class MonadIO m => Katip m where
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+
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.
805+--
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.
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.
815+class MonadIO m => Katip m where
545816 getLogEnv :: m LogEnv
817+ localLogEnv :: (LogEnv -> LogEnv) -> m a -> m a
546818
547819
548820instance Katip m => Katip (ReaderT s m) where
549821 getLogEnv = lift getLogEnv
822+ localLogEnv = mapReaderT . localLogEnv
550823
551824
825+#if !MIN_VERSION_either(4, 5, 0)
552826instance Katip m => Katip (EitherT s m) where
553827 getLogEnv = lift getLogEnv
828+ localLogEnv = mapEitherT . localLogEnv
829+#endif
830+
554831
555832instance Katip m => Katip (ExceptT s m) where
556833 getLogEnv = lift getLogEnv
834+ localLogEnv = mapExceptT . localLogEnv
835+
557836
558837instance Katip m => Katip (MaybeT m) where
559838 getLogEnv = lift getLogEnv
839+ localLogEnv = mapMaybeT . localLogEnv
560840
561841
562842instance Katip m => Katip (StateT s m) where
563843 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
564860
565861
566862instance (Katip m, Monoid s) => Katip (WriterT s m) where
567863 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+
568871
569872instance (Katip m) => Katip (ResourceT m) where
570873 getLogEnv = lift getLogEnv
874+ localLogEnv = transResourceT . localLogEnv
571875
572876
573877-------------------------------------------------------------------------------
574−-- | 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.
575881newtype KatipT m a = KatipT { unKatipT :: ReaderT LogEnv m a }
576882 deriving ( Functor, Applicative, Monad, MonadIO
577− , MonadMask, MonadCatch, MonadThrow, MonadTrans, MonadBase b)
883+ , MonadMask, MonadCatch, MonadThrow, MonadResource, MonadTrans
884+ , MonadBase b)
578885
579886
580887instance MonadIO m => Katip (KatipT m) where
581888 getLogEnv = KatipT ask
889+ localLogEnv f (KatipT m) = KatipT $ local f m
582890
583891
584892instance MonadTransControl KatipT where
@@ -594,6 +902,21 @@ instance (MonadBaseControl b m) => MonadBaseControl b (KatipT m) where
594902 liftBaseWith = defaultLiftBaseWith
595903 restoreM = defaultRestoreM
596904
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
597920
598921-------------------------------------------------------------------------------
599922-- | Execute 'KatipT' on a log env.
@@ -601,6 +924,17 @@ runKatipT :: LogEnv -> KatipT m a -> m a
601924runKatipT le (KatipT f) = runReaderT f le
602925
603926
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+
604938-------------------------------------------------------------------------------
605939-- | Log with everything, including a source code location. This is
606940-- very low level and you typically can use 'logT' in its place.
@@ -614,20 +948,43 @@ logItem
614948 -> m ()
615949logItem a ns loc sev msg = do
616950 LogEnv{..} <- getLogEnv
617− liftIO $ do
618− item <- Item
619− <$> pure _logEnvNs
620− <*> pure _logEnvEnv
621− <*> pure sev
622− <*> (mkThreadIdText <$> myThreadId)
623− <*> pure _logEnvHost
624− <*> pure _logEnvPid
625− <*> pure a
626− <*> pure msg
627− <*> _logEnvTimer
628− <*> pure (_logEnvNs <> ns)
629− <*> pure loc
630− 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)
631988
632989
633990-------------------------------------------------------------------------------
@@ -659,10 +1016,10 @@ logException
6591016 -> Severity -- ^ Severity
6601017 -> m b -- ^ Main action being run
6611018 -> m b
662−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
6631020 where
6641021 f e = logF a ns sev (msg e)
665− msg e = ls (T.pack "An exception has occured: ") <> showLS e
1022+ msg e = ls (T.pack "An exception has occurred: ") <> showLS e
6661023
6671024
6681025-------------------------------------------------------------------------------
@@ -690,14 +1047,14 @@ instance TH.Lift Verbosity where
6901047
6911048
6921049instance TH.Lift Severity where
693− lift DebugS = [| DebugS |]
694− lift InfoS = [| InfoS |]
695− lift NoticeS = [| NoticeS |]
696− lift WarningS = [| WarningS |]
697− lift ErrorS = [| ErrorS |]
1050+ lift DebugS = [| DebugS |]
1051+ lift InfoS = [| InfoS |]
1052+ lift NoticeS = [| NoticeS |]
1053+ lift WarningS = [| WarningS |]
1054+ lift ErrorS = [| ErrorS |]
6981055 lift CriticalS = [| CriticalS |]
699− lift AlertS = [| AlertS |]
700− lift EmergencyS = [| EmergencyS |]
1056+ lift AlertS = [| AlertS |]
1057+ lift EmergencyS = [| EmergencyS |]
7011058
7021059
7031060-- | Lift a location into an Exp.
@@ -713,9 +1070,37 @@ liftLoc (Loc a b c (d1, d2) (e1, e2)) = [|Loc
7131070
7141071-------------------------------------------------------------------------------
7151072-- | For use when you want to include location in your logs. This will
716−-- fill the 'Maybe Loc' gap in 'logF' of this module.
717−getLoc :: Q Exp
718−getLoc = [| $(location >>= liftLoc) |]
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
1078+ [] -> Nothing
1079+ xs -> Just . toLoc . head $ filter filterKatip xs
1080+ where
1081+ filterKatip :: (String, SrcLoc) -> Bool
1082+ filterKatip (_, srcloc) = not $
1083+ "katip-" `isPrefixOf` srcLocPackage srcloc
1084+
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)
1092+ }
1093+#else
1094+getLoc :: Maybe Loc
1095+getLoc = Nothing
1096+#endif
1097+
1098+
1099+-------------------------------------------------------------------------------
1100+-- Like `getLoc`, but uses template-haskell and works with older versions of
1101+-- the compiler (GHC 7.8 or older).
1102+getLocTH :: ExpQ
1103+getLocTH = [| $(location >>= liftLoc) |]
7191104
7201105
7211106-------------------------------------------------------------------------------
@@ -723,7 +1108,31 @@ getLoc = [| $(location >>= liftLoc) |]
7231108--
7241109-- @$(logT) obj mempty InfoS "Hello world"@
7251110logT :: ExpQ
726−logT = [| \ a ns sev msg -> logItem a ns (Just $(getLoc)) sev msg |]
1111+logT = [| \ a ns sev msg -> logItem a ns (Just $(getLocTH)) sev msg |]
1112+
1113+
1114+-------------------------------------------------------------------------------
1115+-- | 'Loc'-tagged logging using 'GHC.Stack' when available.
1116+--
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.
1123+--
1124+-- @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
1128+logLoc :: (Applicative m, LogItem a, Katip m)
1129+#endif
1130+ => a
1131+ -> Namespace
1132+ -> Severity
1133+ -> LogStr
1134+ -> m ()
1135+logLoc a ns = logItem a ns getLoc
7271136
7281137
7291138-- taken from the file-location package