@@ -1,54 +1,109 @@
1+{-# LANGUAGE CPP #-}
2+{-# LANGUAGE DefaultSignatures #-}
3+{-# LANGUAGE DeriveFunctor #-}
14{-# LANGUAGE DeriveGeneric #-}
5+{-# LANGUAGE ExistentialQuantification #-}
26{-# LANGUAGE FlexibleContexts #-}
37{-# LANGUAGE FlexibleInstances #-}
8+{-# LANGUAGE GADTs #-}
49{-# LANGUAGE GeneralizedNewtypeDeriving #-}
510{-# LANGUAGE MultiParamTypeClasses #-}
611{-# LANGUAGE OverloadedStrings #-}
712{-# LANGUAGE RankNTypes #-}
813{-# LANGUAGE RecordWildCards #-}
914{-# LANGUAGE TemplateHaskell #-}
10−
15+{-# LANGUAGE TypeFamilies #-}
16+{-# 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.
1122module Katip.Core where
1223
1324-------------------------------------------------------------------------------
14−import Control.Applicative
25+import Control.Applicative as A
1526import Control.AutoUpdate
1627import Control.Concurrent
17−import Control.Lens
18−import Control.Monad
19−import Control.Monad.Catch
28+import qualified Control.Concurrent.Async as Async
29+import Control.Concurrent.STM
30+import qualified Control.Concurrent.STM.TBQueue as BQ
31+import Control.Exception.Safe
32+import Control.Monad (unless, void, when)
33+import Control.Monad.Base
34+#if MIN_VERSION_base(4, 9, 0)
35+import qualified Control.Monad.Fail as MF
36+#endif
2037import Control.Monad.IO.Class
38+import Control.Monad.IO.Unlift
2139import Control.Monad.Trans.Class
40+import Control.Monad.Trans.Control
41+#if !MIN_VERSION_either(4, 5, 0)
2242import Control.Monad.Trans.Either
43+#endif
44+import Control.Monad.Trans.Except
2345import Control.Monad.Trans.Maybe
2446import Control.Monad.Trans.Reader
25−import Control.Monad.Trans.Resource
26−import Control.Monad.Trans.State
27−import Control.Monad.Trans.Writer
28−import Data.Aeson (ToJSON (..))
29−import qualified Data.Aeson as A
30−import Data.Foldable (foldMap)
31−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
3261import Data.List
33−import qualified Data.Map.Strict as M
34−import Data.Monoid
62+import qualified Data.Map.Strict as M
63+import Data.Maybe (fromMaybe)
64+import Data.Semigroup as SG
3565import Data.String
3666import Data.String.Conv
37−import Data.Text (Text)
38−import qualified Data.Text as T
39−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
4070import Data.Time
41−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
4278import Language.Haskell.TH
43−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
4482import Network.HostName
83+#if mingw32_HOST_OS
84+import Katip.Compat
85+#else
4586import System.Posix
87+#endif
88+
4689-------------------------------------------------------------------------------
4790
4891
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+
4999-------------------------------------------------------------------------------
100+-- | Represents a heirarchy of namespaces going from general to
101+-- specific. For instance: ["processname", "subsystem"]. Note that
102+-- single-segment namespaces can be created using
103+-- IsString/OverloadedStrings, so "foo" will result in Namespace
104+-- ["foo"].
50105newtype Namespace = Namespace { unNamespace :: [Text] }
51− deriving (Eq,Show,Read,Ord,Generic,ToJSON,Monoid)
106+ deriving (Eq,Show,Read,Ord,Generic,ToJSON,FromJSON,SG.Semigroup,Monoid)
52107
53108instance IsString Namespace where
54109 fromString s = Namespace [fromString s]
@@ -63,7 +118,7 @@ intercalateNs (Namespace xs) = intersperse "." xs
63118-------------------------------------------------------------------------------
64119-- | Application environment, like @prod@, @devel@, @testing@.
65120newtype Environment = Environment { getEnvironment :: Text }
66− deriving (Eq,Show,Read,Ord,Generic,ToJSON,IsString)
121+ deriving (Eq,Show,Read,Ord,Generic,ToJSON,FromJSON,IsString)
67122
68123
69124-------------------------------------------------------------------------------
@@ -88,65 +143,125 @@ data Severity
88143-- - 'V3' implies the maximum amount of payload information.
89144-- - Anything in between is left to the discretion of the developer.
90145data Verbosity = V0 | V1 | V2 | V3
91− deriving (Eq, Ord, Show, Read, Generic, Enum)
146+ deriving (Eq, Ord, Show, Read, Generic, Enum, Bounded)
92147
93148
94149-------------------------------------------------------------------------------
95150renderSeverity :: Severity -> Text
96151renderSeverity s = case s of
97− DebugS -> "Debug"
98− InfoS -> "Info"
99− NoticeS -> "Notice"
100− WarningS -> "Warning"
101− ErrorS -> "Error"
102− CriticalS -> "Critical"
103− AlertS -> "Alert"
152+ DebugS -> "Debug"
153+ InfoS -> "Info"
154+ NoticeS -> "Notice"
155+ WarningS -> "Warning"
156+ ErrorS -> "Error"
157+ CriticalS -> "Critical"
158+ AlertS -> "Alert"
104159 EmergencyS -> "Emergency"
105160
106161
107162-------------------------------------------------------------------------------
163+textToSeverity :: Text -> Maybe Severity
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
175+
176+
108177instance ToJSON Severity where
109178 toJSON s = A.String (renderSeverity s)
110179
180+instance FromJSON Severity where
181+ parseJSON = A.withText "Severity" parseSeverity
182+ where
183+ parseSeverity t = case textToSeverity t of
184+ Just x -> return x
185+ Nothing -> fail $ "Invalid Severity " ++ toS t
186+
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+
111202
112203-------------------------------------------------------------------------------
113−-- | Log message with Builder unerneath; use '<>' to concat in O(1).
204+-- | Log message with Builder underneath; use '<>' to concat in O(1).
114205newtype LogStr = LogStr { unLogStr :: B.Builder }
115− deriving (Generic)
206+ deriving (Generic, Show, Eq)
116207
117208instance IsString LogStr where
118209 fromString = LogStr . B.fromString
119210
211+
212+instance Semigroup LogStr where
213+ (LogStr a) <> (LogStr b) = LogStr (a <> b)
214+
215+
120216instance Monoid LogStr where
121− mappend (LogStr a) (LogStr b) = LogStr (a `mappend` b)
217+ mappend = (<>)
122218 mempty = LogStr mempty
123219
220+
221+instance FromJSON LogStr where
222+ parseJSON = A.withText "LogStr" parseLogStr
223+ where
224+ parseLogStr = return . LogStr . B.fromText
225+
124226-------------------------------------------------------------------------------
125227-- | Pack any string-like thing into a 'LogStr'. This will
126−-- automatically work on 'String', 'ByteString, 'Text' and any of the
228+-- automatically work on 'String', 'ByteString', 'Text' and any of the
127229-- lazy variants.
128230logStr :: StringConv a Text => a -> LogStr
129231logStr t = LogStr (B.fromText $ toS t)
130232
131233
132234-------------------------------------------------------------------------------
133−-- | Shorthand for 'logMsg'
235+-- | Shorthand for 'logStr'
134236ls :: StringConv a Text => a -> LogStr
135237ls = logStr
136238
137239
138240-------------------------------------------------------------------------------
241+-- | Convert any showable type into a 'LogStr'.
139242showLS :: Show a => a -> LogStr
140243showLS = ls . show
141244
142245
246+-------------------------------------------------------------------------------
247+newtype ThreadIdText = ThreadIdText {
248+ getThreadIdText :: Text
249+ } deriving (ToJSON, FromJSON, Show, Eq, Ord)
250+
251+
252+mkThreadIdText :: ThreadId -> ThreadIdText
253+mkThreadIdText = ThreadIdText . stripPrefix' "ThreadId " . T.pack . show
254+ where
255+ stripPrefix' pfx t = fromMaybe t (T.stripPrefix pfx t)
256+
257+
143258-------------------------------------------------------------------------------
144259-- | This has everything each log message will contain.
145260data Item a = Item {
146261 _itemApp :: Namespace
147262 , _itemEnv :: Environment
148263 , _itemSeverity :: Severity
149− , _itemThread :: ThreadId
264+ , _itemThread :: ThreadIdText
150265 , _itemHost :: HostName
151266 , _itemProcess :: ProcessID
152267 , _itemPayload :: a
@@ -154,18 +269,75 @@ data Item a = Item {
154269 , _itemTime :: UTCTime
155270 , _itemNamespace :: Namespace
156271 , _itemLoc :: Maybe Loc
157− } deriving (Generic)
272+ } deriving (Generic, Functor)
158273makeLenses ''Item
159274
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+ ]
298+
299+instance Show a => Show (Item a) where
300+ showsPrec d Item{..} = showParen (d >= 11) ( showString "Item {"
301+ . field "_itemApp" _itemApp
302+ . field "_itemEnv" _itemEnv
303+ . field "_itemSeverity" _itemSeverity
304+ . field "_itemThread" _itemThread
305+ . field "_itemHost" _itemHost
306+ . field "_itemProcess" _itemProcess
307+ . field "_itemPayload" _itemPayload
308+ . field "_itemMessage" _itemMessage
309+ . field "_itemTime" _itemTime
310+ . field "_itemNamespace" _itemNamespace
311+ . showString "_itemLoc = " . shows (LocShow <$> _itemLoc)
312+ . showChar '}'
313+ )
314+ where
315+ field n v = showString n . showString " = " . shows v . showString ", "
316+
317+newtype LocShow = LocShow Loc
318+
319+
320+instance Show LocShow where
321+ showsPrec d (LocShow Loc{..}) = showParen (d >= 11) ( showString "Loc {"
322+ . field "loc_filename" loc_filename
323+ . field "loc_package" loc_package
324+ . field "loc_module" loc_module
325+ . field "loc_start" loc_start
326+ . showString "loc_end = " . shows loc_end
327+ . showChar '}'
328+ )
329+ where
330+ field n v = showString n . showString " = " . shows v . showString ", "
331+
160332
161333instance ToJSON a => ToJSON (Item a) where
162334 toJSON Item{..} = A.object
163335 [ "app" A..= _itemApp
164336 , "env" A..= _itemEnv
165337 , "sev" A..= _itemSeverity
166− , "thread" A..= show _itemThread
338+ , "thread" A..= getThreadIdText _itemThread
167339 , "host" A..= _itemHost
168− , "pid" A..= A.String (toS (show _itemProcess))
340+ , "pid" A..= ProcessIDJs _itemProcess
169341 , "data" A..= _itemPayload
170342 , "msg" A..= (B.toLazyText $ unLogStr _itemMessage)
171343 , "at" A..= _itemTime
@@ -186,17 +358,76 @@ instance ToJSON LocJs where
186358 ]
187359
188360
361+instance FromJSON LocJs where
362+ parseJSON = A.withObject "LocJs" parseLocJs
363+ where
364+ parseLocJs o = do
365+ fn <- o A..: "loc_fn"
366+ p <- o A..: "loc_pkg"
367+ m <- o A..: "loc_mod"
368+ l <- o A..: "loc_ln"
369+ c <- o A..: "loc_col"
370+ return $ LocJs $ Loc fn p m (l, c) (l, c)
371+
372+
373+instance FromJSON a => FromJSON (Item a) where
374+ parseJSON = A.withObject "Item" parseItem
375+ where
376+ parseItem o = Item
377+ <$> o A..: "app"
378+ <*> o A..: "env"
379+ <*> o A..: "sev"
380+ <*> o A..: "thread"
381+ <*> o A..: "host"
382+ <*> (getProcessIDJs <$> o A..: "pid")
383+ <*> o A..: "data"
384+ <*> o A..: "msg"
385+ <*> o A..: "at"
386+ <*> o A..: "ns"
387+ <*> (fmap getLocJs <$> o A..: "loc")
388+
389+
390+processIDToText :: ProcessID -> Text
391+processIDToText = toS . show
392+
393+
394+textToProcessID :: Text -> Maybe ProcessID
395+textToProcessID = readMay . toS
396+
397+
398+newtype ProcessIDJs = ProcessIDJs {
399+ getProcessIDJs :: ProcessID
400+ }
401+
402+
403+instance ToJSON ProcessIDJs where
404+ toJSON (ProcessIDJs p) = A.String (processIDToText p)
405+
406+
407+instance FromJSON ProcessIDJs where
408+ parseJSON = A.withText "ProcessID" parseProcessID
409+ where
410+ parseProcessID t = case textToProcessID t of
411+ Just p -> return $ ProcessIDJs p
412+ Nothing -> fail $ "Invalid ProcessIDJs " ++ toS t
413+
414+
189415-------------------------------------------------------------------------------
190416-- | Field selector by verbosity within JSON payload.
191417data PayloadSelection
192418 = AllKeys
193419 | 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+
194427
195428instance Monoid PayloadSelection where
196429 mempty = SomeKeys []
197− mappend AllKeys _ = AllKeys
198− mappend _ AllKeys = AllKeys
199− mappend (SomeKeys as) (SomeKeys bs) = SomeKeys (as++bs)
430+ mappend = (<>)
200431
201432
202433-------------------------------------------------------------------------------
@@ -209,17 +440,26 @@ instance Monoid PayloadSelection where
209440-- a ToJSON instance like:
210441--
211442-- > instance ToObject Foo
212−class ToJSON a => ToObject a where
443+class ToObject a where
213444 toObject :: a -> A.Object
445+ default toObject :: ToJSON a => a -> A.Object
214446 toObject v = case toJSON v of
215447 A.Object o -> o
216− _ -> mempty
448+ _ -> mempty
217449
218450instance ToObject ()
219451instance ToObject A.Object
220452
221453-------------------------------------------------------------------------------
222−-- | Payload objects need instances of this class.
454+-- | Payload objects need instances of this class. LogItem makes it so
455+-- that you can have very verbose items getting logged with lots of
456+-- extra fields but under normal circumstances, if your scribe is
457+-- configured for a lower verbosity level, it will only log a
458+-- selection of those keys. Furthermore, each 'Scribe' can be
459+-- configured with a different 'Verbosity' level. You could even use
460+-- 'registerScribe', 'unregisterScribe', and 'clearScribes' to at
461+-- runtime swap out your existing scribes for more verbose debugging
462+-- scribes if you wanted to.
223463--
224464-- When defining 'payloadKeys', don't redundantly declare the same
225465-- keys for higher levels of verbosity. Each level of verbosity
@@ -234,13 +474,54 @@ class ToObject a => LogItem a where
234474instance LogItem () where payloadKeys _ _ = SomeKeys []
235475
236476
477+data AnyLogPayload = forall a. ToJSON a => AnyLogPayload a
478+
479+newtype SimpleLogPayload = SimpleLogPayload {
480+ unSimpleLogPayload :: [(Text, AnyLogPayload)]
481+ }
482+
483+-------------------------------------------------------------------------------
484+-- | A built-in convenience log payload that won't log anything on 'V0',
485+-- but will log everything in any other level of verbosity. Intended
486+-- for easy in-line usage without having to define new log types.
487+--
488+-- Construct using 'sl' and combine multiple tuples using '<>' from
489+-- 'Monoid'.
490+instance ToJSON SimpleLogPayload where
491+ toJSON (SimpleLogPayload as) = object $ map go as
492+ where go (k, AnyLogPayload v) = k A..= v
493+
494+
495+instance ToObject SimpleLogPayload
496+
497+
498+instance LogItem SimpleLogPayload where
499+ payloadKeys V0 _ = SomeKeys []
500+ payloadKeys _ _ = AllKeys
501+
502+
503+instance Semigroup SimpleLogPayload where
504+ SimpleLogPayload a <> SimpleLogPayload b = SimpleLogPayload (a <> b)
505+
506+
507+instance Monoid SimpleLogPayload where
508+ mempty = SimpleLogPayload []
509+ mappend = (<>)
510+
511+
512+-------------------------------------------------------------------------------
513+-- | Construct a simple log from any JSON item.
514+sl :: ToJSON a => Text -> a -> SimpleLogPayload
515+sl a b = SimpleLogPayload [(a, AnyLogPayload b)]
516+
517+
237518-------------------------------------------------------------------------------
238519-- | Constrain payload based on verbosity. Backends should use this to
239520-- automatically bubble higher verbosity levels to lower ones.
240521payloadObject :: LogItem a => Verbosity -> a -> A.Object
241−payloadObject verb a = case foldMap (flip payloadKeys a) [(V0)..verb] of
242− AllKeys -> toObject a
243− SomeKeys ks -> HM.filterWithKey (\ k _ -> k `elem` ks) $ toObject a
522+payloadObject verb a = case FT.foldMap (flip payloadKeys a) [(V0)..verb] of
523+ AllKeys -> toObject a
524+ SomeKeys ks -> HM.filterWithKey (\ k _ -> k `FT.elem` ks) $ toObject a
244525
245526
246527-------------------------------------------------------------------------------
@@ -254,30 +535,140 @@ itemJson verb a = toJSON $ a & itemPayload %~ payloadObject verb
254535-------------------------------------------------------------------------------
255536-- | Scribes are handlers of incoming items. Each registered scribe
256537-- knows how to push a log item somewhere.
538+--
539+-- = Guidelines for writing your own 'Scribe'
540+--
541+-- Scribes should always take a 'Severity' and 'Verbosity'.
542+--
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.
549+--
550+-- Verbosity is used to select keys from the log item's payload. Each
551+-- 'LogItem' instance describes what keys should be retained for each
552+-- Verbosity level. Use the 'payloadObject' utility for extracting the keys
553+-- that should be written.
554+--
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.
564+--
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+
257588data Scribe = Scribe {
258− lhPush :: forall a. LogItem a => Item a -> IO ()
259− }
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)
260619
261620
262621instance Monoid Scribe where
263− mempty = Scribe $ const $ return ()
264− mappend (Scribe a) (Scribe b) = Scribe $ \ item -> do
265− a item
266− 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
637+
638+
639+-------------------------------------------------------------------------------
640+-- | Should this item be logged given the user's maximum severity?
641+-- Most new scribes will use this as a base for their 'PermitFunc'
642+permitItem :: Monad m => Severity -> Item a -> m Bool
643+permitItem sev item = return (_itemSeverity item >= sev)
644+
267645
268646-------------------------------------------------------------------------------
269647data LogEnv = LogEnv {
270648 _logEnvHost :: HostName
271649 , _logEnvPid :: ProcessID
272− , _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"
273656 , _logEnvEnv :: Environment
274657 , _logEnvTimer :: IO UTCTime
275− , _logEnvScribes :: M.Map Text Scribe
658+ -- ^ Action to fetch the timestamp. You can use something like
659+ -- 'AutoUpdate' for high volume logs but note that this may cause
660+ -- some output forms to display logs out of order. Alternatively,
661+ -- you could just use 'getCurrentTime'.
662+ , _logEnvScribes :: M.Map Text ScribeHandle
276663 }
277664makeLenses ''LogEnv
278665
279666
280667-------------------------------------------------------------------------------
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'.
281672initLogEnv
282673 :: Namespace
283674 -- ^ A base namespace for this application
@@ -289,69 +680,243 @@ initLogEnv an env = LogEnv
289680 <*> getProcessID
290681 <*> pure an
291682 <*> pure env
292− <*> mkAutoUpdate defaultUpdateSettings { updateAction = getCurrentTime }
683+ <*> mkAutoUpdate defaultUpdateSettings { updateAction = getCurrentTime, updateFreq = 1000 }
293684 <*> pure mempty
294685
295686
296687-------------------------------------------------------------------------------
688+-- | Add a scribe to the list. All future log calls will go to this
689+-- scribe in addition to the others. Writes will be buffered per the
690+-- ScribeSettings to prevent slow scribes from slowing down
691+-- logging. Writes will be dropped if the buffer fills.
297692registerScribe
298693 :: Text
299694 -- ^ Name the scribe
300695 -> Scribe
696+ -> ScribeSettings
301697 -> LogEnv
302− -> LogEnv
303−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 ()
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
304741
305742
306743-------------------------------------------------------------------------------
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.
307748unregisterScribe
308749 :: Text
309750 -- ^ Name of the scribe
310751 -> LogEnv
311752 -> LogEnv
312−unregisterScribe nm = logEnvScribes . at nm .~ Nothing
753+unregisterScribe nm = logEnvScribes %~ M.delete nm
313754
314755
756+-------------------------------------------------------------------------------
757+-- | Unregister __all__ scribes. Note that this is __not__ for closing or
758+-- finalizing scribes, use 'closeScribes' for that. This mainly only
759+-- makes sense to use with something like MonadReader's @local@
760+-- function to temporarily disavow any loggers for a block of code.
761+clearScribes
762+ :: LogEnv
763+ -> LogEnv
764+clearScribes = logEnvScribes .~ mempty
765+
766+
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+
315799
316800-------------------------------------------------------------------------------
317−-- | Monads where katip logging actions can be performed
318−class MonadIO m => Katip m where
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
319816 getLogEnv :: m LogEnv
817+ localLogEnv :: (LogEnv -> LogEnv) -> m a -> m a
320818
321819
322820instance Katip m => Katip (ReaderT s m) where
323821 getLogEnv = lift getLogEnv
822+ localLogEnv = mapReaderT . localLogEnv
324823
325824
825+#if !MIN_VERSION_either(4, 5, 0)
326826instance Katip m => Katip (EitherT s m) where
327827 getLogEnv = lift getLogEnv
828+ localLogEnv = mapEitherT . localLogEnv
829+#endif
830+
831+
832+instance Katip m => Katip (ExceptT s m) where
833+ getLogEnv = lift getLogEnv
834+ localLogEnv = mapExceptT . localLogEnv
328835
329836
330837instance Katip m => Katip (MaybeT m) where
331838 getLogEnv = lift getLogEnv
839+ localLogEnv = mapMaybeT . localLogEnv
332840
333841
334842instance Katip m => Katip (StateT s m) where
335843 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
336860
337861
338862instance (Katip m, Monoid s) => Katip (WriterT s m) where
339863 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+
340871
341872instance (Katip m) => Katip (ResourceT m) where
342873 getLogEnv = lift getLogEnv
874+ localLogEnv = transResourceT . localLogEnv
343875
344876
345877-------------------------------------------------------------------------------
346−-- | 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.
347881newtype KatipT m a = KatipT { unKatipT :: ReaderT LogEnv m a }
348882 deriving ( Functor, Applicative, Monad, MonadIO
349− , MonadMask, MonadCatch, MonadThrow, MonadTrans )
883+ , MonadMask, MonadCatch, MonadThrow, MonadResource, MonadTrans
884+ , MonadBase b)
350885
351886
352887instance MonadIO m => Katip (KatipT m) where
353888 getLogEnv = KatipT ask
354−
889+ localLogEnv f (KatipT m) = KatipT $ local f m
890+
891+
892+instance MonadTransControl KatipT where
893+ type StT (KatipT) a = a
894+ liftWith f = KatipT $ ReaderT $ \le -> f $ \t -> runKatipT le t
895+ restoreT = KatipT . ReaderT . const
896+ {-# INLINABLE liftWith #-}
897+ {-# INLINABLE restoreT #-}
898+
899+
900+instance (MonadBaseControl b m) => MonadBaseControl b (KatipT m) where
901+ type StM ((KatipT) m) a = ComposeSt (KatipT) m a
902+ liftBaseWith = defaultLiftBaseWith
903+ restoreM = defaultRestoreM
904+
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
355920
356921-------------------------------------------------------------------------------
357922-- | Execute 'KatipT' on a log env.
@@ -359,11 +924,22 @@ runKatipT :: LogEnv -> KatipT m a -> m a
359924runKatipT le (KatipT f) = runReaderT f le
360925
361926
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+
362938-------------------------------------------------------------------------------
363939-- | Log with everything, including a source code location. This is
364940-- very low level and you typically can use 'logT' in its place.
365941logItem
366− :: (Applicative m, LogItem a, Katip m)
942+ :: (A.Applicative m, LogItem a, Katip m)
367943 => a
368944 -> Namespace
369945 -> Maybe Loc
@@ -372,19 +948,43 @@ logItem
372948 -> m ()
373949logItem a ns loc sev msg = do
374950 LogEnv{..} <- getLogEnv
375− item <- Item
376− <$> pure _logEnvNs
377− <*> pure _logEnvEnv
378− <*> pure sev
379− <*> liftIO myThreadId
380− <*> pure _logEnvHost
381− <*> pure _logEnvPid
382− <*> pure a
383− <*> pure msg
384− <*> liftIO _logEnvTimer
385− <*> pure (_logEnvNs <> ns)
386− <*> pure loc
387− liftIO $ 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)
388988
389989
390990-------------------------------------------------------------------------------
@@ -403,6 +1003,25 @@ logF
4031003logF a ns sev msg = logItem a ns Nothing sev msg
4041004
4051005
1006+
1007+-------------------------------------------------------------------------------
1008+-- | Perform an action while logging any exceptions that may occur.
1009+-- Inspired by 'onException`.
1010+--
1011+-- >>>> logException () mempty ErrorS (error "foo")
1012+logException
1013+ :: (Katip m, LogItem a, MonadCatch m, Applicative m)
1014+ => a -- ^ Log context
1015+ -> Namespace -- ^ Namespace
1016+ -> Severity -- ^ Severity
1017+ -> m b -- ^ Main action being run
1018+ -> m b
1019+logException a ns sev action = action `catchAny` \e -> f e >> throwM e
1020+ where
1021+ f e = logF a ns sev (msg e)
1022+ msg e = ls (T.pack "An exception has occurred: ") <> showLS e
1023+
1024+
4061025-------------------------------------------------------------------------------
4071026-- | Log a message without any payload/context or code location.
4081027logMsg
@@ -428,14 +1047,14 @@ instance TH.Lift Verbosity where
4281047
4291048
4301049instance TH.Lift Severity where
431− lift DebugS = [| DebugS |]
432− lift InfoS = [| InfoS |]
433− lift NoticeS = [| NoticeS |]
434− lift WarningS = [| WarningS |]
435− lift ErrorS = [| ErrorS |]
1050+ lift DebugS = [| DebugS |]
1051+ lift InfoS = [| InfoS |]
1052+ lift NoticeS = [| NoticeS |]
1053+ lift WarningS = [| WarningS |]
1054+ lift ErrorS = [| ErrorS |]
4361055 lift CriticalS = [| CriticalS |]
437− lift AlertS = [| AlertS |]
438− lift EmergencyS = [| EmergencyS |]
1056+ lift AlertS = [| AlertS |]
1057+ lift EmergencyS = [| EmergencyS |]
4391058
4401059
4411060-- | Lift a location into an Exp.
@@ -451,17 +1070,69 @@ liftLoc (Loc a b c (d1, d2) (e1, e2)) = [|Loc
4511070
4521071-------------------------------------------------------------------------------
4531072-- | For use when you want to include location in your logs. This will
454−-- fill the 'Maybe Loc' gap in 'logF' of this module.
455−getLoc :: Q Exp
456−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
4571097
4581098
4591099-------------------------------------------------------------------------------
460−-- | 'Loc'-tagged logging when using template-haskell is OK.
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 = [| $(location >>= liftLoc) |]
1104+
1105+
1106+-------------------------------------------------------------------------------
1107+-- | 'Loc'-tagged logging when using template-haskell.
4611108--
4621109-- @$(logT) obj mempty InfoS "Hello world"@
4631110logT :: ExpQ
464−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
4651136
4661137
4671138-- taken from the file-location package