Control.Monad.Trace

This module is useful for tracing backend implementors. If you are only interested in adding tracing to an application, start at Monitor.Tracing.

Documentation

data TraceT m a

Asynchronous trace collection monad.

Instances

MonadTrans TraceT

Defined in Control.Monad.Trace

Methods

lift :: Monad m => m a -> TraceT m a

MonadReader r m => MonadReader r (TraceT m)

Defined in Control.Monad.Trace

Methods

ask :: TraceT m r

local :: (r -> r) -> TraceT m a -> TraceT m a

reader :: (r -> a) -> TraceT m a

Monad m => Monad (TraceT m)

Defined in Control.Monad.Trace

Methods

(>>=) :: TraceT m a -> (a -> TraceT m b) -> TraceT m b

(>>) :: TraceT m a -> TraceT m b -> TraceT m b

return :: a -> TraceT m a

fail :: String -> TraceT m a

Functor m => Functor (TraceT m)

Defined in Control.Monad.Trace

Methods

fmap :: (a -> b) -> TraceT m a -> TraceT m b

(<$) :: a -> TraceT m b -> TraceT m a

Applicative m => Applicative (TraceT m)

Defined in Control.Monad.Trace

Methods

pure :: a -> TraceT m a

(<*>) :: TraceT m (a -> b) -> TraceT m a -> TraceT m b

liftA2 :: (a -> b -> c) -> TraceT m a -> TraceT m b -> TraceT m c

(*>) :: TraceT m a -> TraceT m b -> TraceT m b

(<*) :: TraceT m a -> TraceT m b -> TraceT m a

MonadIO m => MonadIO (TraceT m)

Defined in Control.Monad.Trace

Methods

liftIO :: IO a -> TraceT m a

MonadUnliftIO m => MonadUnliftIO (TraceT m)

Defined in Control.Monad.Trace

Methods

askUnliftIO :: TraceT m (UnliftIO (TraceT m))

withRunInIO :: ((forall a. TraceT m a -> IO a) -> IO b) -> TraceT m b

MonadUnliftIO m => MonadTrace (TraceT m)

Defined in Control.Monad.Trace

Methods

trace :: Builder -> TraceT m a -> TraceT m a

activeSpan :: TraceT m (Maybe Span)

addSpanEntry :: Key -> Value -> TraceT m ()

runTraceT :: TraceT m a -> Tracer -> m a

Trace an action.

data Tracer

A tracer collects spans emitted inside TraceT.

Constructors

Tracer

Fields

• tracerChannel :: TChan (Span, Tags, Logs, Interval)

  Channel spans get written to when they complete.

• tracerPendingCount :: TVar Int

  The number of spans currently in flight (started but not yet completed).

type Tags = Map Key Value

A collection of span tags.

type Logs = [(POSIXTime, Key, Value)]

A collection of span logs, sorted in chronological order.

data Interval

Timing information about a span.

Constructors

Interval

Fields

• intervalStart :: !POSIXTime
• intervalDuration :: !NominalDiffTime

newTracer :: MonadIO m => m Tracer

Creates a new Tracer.