Copyright	(c) 2020-2021 Sam May
License	GPL-3.0-or-later
Maintainer	ag@eitilt.life
Stability	stable
Portability	non-portable (requires libcdio)
Safe Haskell	None
Language	Haskell2010

Sound.Libcdio.Logging

Contents

Types
Utility

Description

The underlying library is rather loud in its error and warning messages, potentially emitting a lot of impure terminal clutter even on some otherwise-pure functions. Very helpfully, it also provides a mechanism for integrating the logs with whatever framework is in place for the larger project; that mechanism can be leveraged to cache the logs in memory until specifically asked for, at which point they can be packaged into Haskell types. Some of the immediacy—and therefore user ability to match note to source—is unfortunately lost, but the apparent purity is worth it.

Synopsis

class LibcdioLogger m where
- logCutoff :: m LogLevel
- setLogCutoff :: LogLevel -> m ()
- readLog :: m [LogEntry]
- clearLog :: m ()
- putLog :: LogEntry -> m ()
data LogEntry = LogEntry {
- logLevel :: LogLevel
- logMessage :: String
}
data LogLevel
- = LogDebug
- | LogInfo
- | LogWarn
- | LogError
- | LogAssert
isolateLogs :: (Monad m, LibcdioLogger m) => m a -> m a
setupLogger :: IO ()

Types

class LibcdioLogger m where #

An environment which integrates the libcdio logging interface; will almost always be a Monad, but as an Applicative might technically be able to implement these, that constraint isn't enforced.

Methods

logCutoff #

Arguments

:: m LogLevel

Check the current minimum severity which will be recorded in the logs.

setLogCutoff #

Arguments

:: LogLevel
-> m ()	Set the minimum severity required for a message to be recorded in the logs.

readLog #

Arguments

:: m [LogEntry]

Retrieve all messages currently in the log for further processing. Note that this retains the contents of the log for future calls; to remove them, a separate call to clearLog must be made.

>>> putLog $ LogEntry LogWarn "Testing log reading" >>= readLog
[LogEntry LogWarn "Testing log reading"]

>>> clearLog >>= readLog
[]

clearLog #

Arguments

:: m ()

Empty all messages currently in the log. There is no way to selectively remove only some messages; if that is desired, call readLog first:

>>> setupLogger
>>> msgs <- readLog
>>> clearLog
>>> mapM_ putLog $ filter p msgs

putLog #

Arguments

:: LogEntry
-> m ()	Append a message to the logs.

Instances

Instances details

LibcdioLogger IO #	The required initialization function `setupLogger` isn't called automatically; make sure to do so manually before using any of these.
Instance details Defined in Sound.Libcdio.Logging Methods logCutoff :: IO LogLevel # setLogCutoff :: LogLevel -> IO () # readLog :: IO [LogEntry] # clearLog :: IO () # putLog :: LogEntry -> IO () #
LibcdioLogger Cdio #
Instance details Defined in Sound.Libcdio.Types.Cdio Methods logCutoff :: Cdio LogLevel # setLogCutoff :: LogLevel -> Cdio () # readLog :: Cdio [LogEntry] # clearLog :: Cdio () # putLog :: LogEntry -> Cdio () #
LibcdioLogger CdText #
Instance details Defined in Sound.Libcdio.Read.CdText Methods logCutoff :: CdText LogLevel # setLogCutoff :: LogLevel -> CdText () # readLog :: CdText [LogEntry] # clearLog :: CdText () # putLog :: LogEntry -> CdText () #

data LogEntry #

An unstructured message emitted from the library to let the user know what's going on behind the scenes.

Constructors

LogEntry
Fields logLevel :: LogLevel How critical it is that the user receive this particular message. logMessage :: String The text of the message itself.

Instances

Instances details

Eq LogEntry #
Instance details Defined in Foreign.Libcdio.Logging Methods (==) :: LogEntry -> LogEntry -> Bool # (/=) :: LogEntry -> LogEntry -> Bool #
Read LogEntry #
Instance details Defined in Foreign.Libcdio.Logging Methods readsPrec :: Int -> ReadS LogEntry # readList :: ReadS [LogEntry] # readPrec :: ReadPrec LogEntry # readListPrec :: ReadPrec [LogEntry] #
Show LogEntry #
Instance details Defined in Foreign.Libcdio.Logging Methods showsPrec :: Int -> LogEntry -> ShowS # show :: LogEntry -> String # showList :: [LogEntry] -> ShowS #
Storable LogEntry #
Instance details Defined in Foreign.Libcdio.Logging Methods sizeOf :: LogEntry -> Int # alignment :: LogEntry -> Int # peekElemOff :: Ptr LogEntry -> Int -> IO LogEntry # pokeElemOff :: Ptr LogEntry -> Int -> LogEntry -> IO () # peekByteOff :: Ptr b -> Int -> IO LogEntry # pokeByteOff :: Ptr b -> Int -> LogEntry -> IO () # peek :: Ptr LogEntry -> IO LogEntry # poke :: Ptr LogEntry -> LogEntry -> IO () #

data LogLevel #

How much detail should be recorded in the logs.

Constructors

LogDebug
LogInfo
LogWarn
LogError
LogAssert

Instances

Instances details

Bounded LogLevel #
Instance details Defined in Foreign.Libcdio.Types.Enums Methods minBound :: LogLevel # maxBound :: LogLevel #
Enum LogLevel #
Instance details Defined in Foreign.Libcdio.Types.Enums Methods succ :: LogLevel -> LogLevel # pred :: LogLevel -> LogLevel # toEnum :: Int -> LogLevel # fromEnum :: LogLevel -> Int # enumFrom :: LogLevel -> [LogLevel] # enumFromThen :: LogLevel -> LogLevel -> [LogLevel] # enumFromTo :: LogLevel -> LogLevel -> [LogLevel] # enumFromThenTo :: LogLevel -> LogLevel -> LogLevel -> [LogLevel] #
Eq LogLevel #
Instance details Defined in Foreign.Libcdio.Types.Enums Methods (==) :: LogLevel -> LogLevel -> Bool # (/=) :: LogLevel -> LogLevel -> Bool #
Ord LogLevel #
Instance details Defined in Foreign.Libcdio.Types.Enums Methods compare :: LogLevel -> LogLevel -> Ordering # (<) :: LogLevel -> LogLevel -> Bool # (<=) :: LogLevel -> LogLevel -> Bool # (>) :: LogLevel -> LogLevel -> Bool # (>=) :: LogLevel -> LogLevel -> Bool # max :: LogLevel -> LogLevel -> LogLevel # min :: LogLevel -> LogLevel -> LogLevel #
Read LogLevel #
Instance details Defined in Foreign.Libcdio.Types.Enums Methods readsPrec :: Int -> ReadS LogLevel # readList :: ReadS [LogLevel] # readPrec :: ReadPrec LogLevel # readListPrec :: ReadPrec [LogLevel] #
Show LogLevel #
Instance details Defined in Foreign.Libcdio.Types.Enums Methods showsPrec :: Int -> LogLevel -> ShowS # show :: LogLevel -> String # showList :: [LogLevel] -> ShowS #

Utility

isolateLogs :: (Monad m, LibcdioLogger m) => m a -> m a #

Keep the monad pure by preventing it from reading stale logs, but since the outer IO might still care about them, restore the entire stack after.

Note that the logs are not thread-safe; messages from other threads may be interwoven with those from the passed computation even after this function is called.

setupLogger :: IO () #

Initialize the log-management backend to use the mechanisms provided by this library instead of just printing to standard output. While this will usually be taken care of automatically, it may still be necessary to call this explicitly if messages are being recorded before any disc session is opened.