Safe Haskell	None
Language	Haskell2010

Control.Monad.Trace.Class

Description

The MonadTrace class

Synopsis

class Monad m => MonadTrace m where
- trace :: Builder -> m a -> m a
- activeSpan :: m (Maybe Span)
- addSpanEntry :: Key -> Value -> m ()
data Builder = Builder {
- builderName :: !Name
- builderTraceID :: !(Maybe TraceID)
- builderSpanID :: !(Maybe SpanID)
- builderReferences :: !(Set Reference)
- builderTags :: !(Map Key Value)
- builderBaggages :: !(Map Key ByteString)
}
type Name = Text
data SpanID
data TraceID
data Reference
- = ChildOf !SpanID
- | FollowsFrom !Context
builder :: Name -> Builder
data Span = Span {
- spanName :: !Name
- spanContext :: !Context
- spanReferences :: !(Set Reference)
}
data Context = Context {
- contextTraceID :: !TraceID
- contextSpanID :: !SpanID
- contextBaggages :: !(Map Key ByteString)
}
type Key = Text
data Value
tagDoubleValue :: Double -> Value
tagInt64Value :: Integral a => a -> Value
tagTextValue :: Text -> Value
logValue :: ToJSON a => a -> Value
logValueAt :: ToJSON a => POSIXTime -> a -> Value

Documentation

class Monad m => MonadTrace m where Source #

A monad capable of generating traces.

There are currently two instances of this monad:

TraceT, which emits spans for each trace in IO and is meant to be used in production.
Identity, where tracing is a no-op and allows testing traced functions without any overhead or complex setup.

Minimal complete definition

trace

Methods

trace :: Builder -> m a -> m a Source #

Trace an action, wrapping it inside a new span.

activeSpan :: m (Maybe Span) Source #

Extracts the currently active span, or Nothing if the action is not being traced.

activeSpan :: (MonadTrace n, MonadTrans t, m ~ t n) => m (Maybe Span) Source #

Extracts the currently active span, or Nothing if the action is not being traced.

addSpanEntry :: Key -> Value -> m () Source #

Adds information to the active span, if present.

addSpanEntry :: (MonadTrace n, MonadTrans t, m ~ t n) => Key -> Value -> m () Source #

Adds information to the active span, if present.

Instances

MonadTrace Identity Source #
Instance details Defined in Control.Monad.Trace.Class Methods trace :: Builder -> Identity a -> Identity a Source # activeSpan :: Identity (Maybe Span) Source # addSpanEntry :: Key -> Value -> Identity () Source #
MonadUnliftIO m => MonadTrace (TraceT m) Source #
Instance details Defined in Control.Monad.Trace Methods trace :: Builder -> TraceT m a -> TraceT m a Source # activeSpan :: TraceT m (Maybe Span) Source # addSpanEntry :: Key -> Value -> TraceT m () Source #
(Monad m, MonadTrace m) => MonadTrace (ExceptT e m) Source #
Instance details Defined in Control.Monad.Trace.Class Methods trace :: Builder -> ExceptT e m a -> ExceptT e m a Source # activeSpan :: ExceptT e m (Maybe Span) Source # addSpanEntry :: Key -> Value -> ExceptT e m () Source #
(Monad m, MonadTrace m) => MonadTrace (StateT s m) Source #
Instance details Defined in Control.Monad.Trace.Class Methods trace :: Builder -> StateT s m a -> StateT s m a Source # activeSpan :: StateT s m (Maybe Span) Source # addSpanEntry :: Key -> Value -> StateT s m () Source #
(Monad m, MonadTrace m) => MonadTrace (StateT s m) Source #
Instance details Defined in Control.Monad.Trace.Class Methods trace :: Builder -> StateT s m a -> StateT s m a Source # activeSpan :: StateT s m (Maybe Span) Source # addSpanEntry :: Key -> Value -> StateT s m () Source #
(Monad m, MonadTrace m, Monoid w) => MonadTrace (WriterT w m) Source #
Instance details Defined in Control.Monad.Trace.Class Methods trace :: Builder -> WriterT w m a -> WriterT w m a Source # activeSpan :: WriterT w m (Maybe Span) Source # addSpanEntry :: Key -> Value -> WriterT w m () Source #
(Monad m, MonadTrace m, Monoid w) => MonadTrace (WriterT w m) Source #
Instance details Defined in Control.Monad.Trace.Class Methods trace :: Builder -> WriterT w m a -> WriterT w m a Source # activeSpan :: WriterT w m (Maybe Span) Source # addSpanEntry :: Key -> Value -> WriterT w m () Source #
(Monad m, MonadTrace m) => MonadTrace (ReaderT r m) Source #
Instance details Defined in Control.Monad.Trace.Class Methods trace :: Builder -> ReaderT r m a -> ReaderT r m a Source # activeSpan :: ReaderT r m (Maybe Span) Source # addSpanEntry :: Key -> Value -> ReaderT r m () Source #
(Monad m, MonadTrace m, Monoid w) => MonadTrace (RWST r w s m) Source #
Instance details Defined in Control.Monad.Trace.Class Methods trace :: Builder -> RWST r w s m a -> RWST r w s m a Source # activeSpan :: RWST r w s m (Maybe Span) Source # addSpanEntry :: Key -> Value -> RWST r w s m () Source #
(Monad m, MonadTrace m, Monoid w) => MonadTrace (RWST r w s m) Source #
Instance details Defined in Control.Monad.Trace.Class Methods trace :: Builder -> RWST r w s m a -> RWST r w s m a Source # activeSpan :: RWST r w s m (Maybe Span) Source # addSpanEntry :: Key -> Value -> RWST r w s m () Source #

data Builder Source #

A trace builder.

Note that Builder has an IsString instance, producing a span with the given string as name, no additional references, tags, or baggages. This allows convenient creation of spans via the OverloadedStrings pragma.

Constructors

Builder

Fields

builderName :: !Name
Name of the generated span.
builderTraceID :: !(Maybe TraceID)
The trace ID of the generated span. If unset, the active span's trace ID will be used if present, otherwise a new ID will be generated.
builderSpanID :: !(Maybe SpanID)
The ID of the generated span, otherwise the ID will be auto-generated.
builderReferences :: !(Set Reference)
Span references.
builderTags :: !(Map Key Value)
Initial set of tags.
builderBaggages :: !(Map Key ByteString)
Span context baggages.

Instances

Show Builder Source #
Instance details Defined in Control.Monad.Trace.Class Methods showsPrec :: Int -> Builder -> ShowS # show :: Builder -> String # showList :: [Builder] -> ShowS #
IsString Builder Source #
Instance details Defined in Control.Monad.Trace.Class Methods fromString :: String -> Builder #

type Name = Text Source #

The name of a span.

data SpanID Source #

A 64-bit span identifier.

Instances

Eq SpanID Source #
Instance details Defined in Control.Monad.Trace.Internal Methods (==) :: SpanID -> SpanID -> Bool # (/=) :: SpanID -> SpanID -> Bool #
Ord SpanID Source #
Instance details Defined in Control.Monad.Trace.Internal Methods compare :: SpanID -> SpanID -> Ordering # (<) :: SpanID -> SpanID -> Bool # (<=) :: SpanID -> SpanID -> Bool # (>) :: SpanID -> SpanID -> Bool # (>=) :: SpanID -> SpanID -> Bool # max :: SpanID -> SpanID -> SpanID # min :: SpanID -> SpanID -> SpanID #
Show SpanID Source #
Instance details Defined in Control.Monad.Trace.Internal Methods showsPrec :: Int -> SpanID -> ShowS # show :: SpanID -> String # showList :: [SpanID] -> ShowS #
ToJSON SpanID Source #
Instance details Defined in Control.Monad.Trace.Internal Methods toJSON :: SpanID -> Value # toEncoding :: SpanID -> Encoding # toJSONList :: [SpanID] -> Value # toEncodingList :: [SpanID] -> Encoding #
FromJSON SpanID Source #
Instance details Defined in Control.Monad.Trace.Internal Methods parseJSON :: Value -> Parser SpanID # parseJSONList :: Value -> Parser [SpanID] #

data TraceID Source #

A 128-bit trace identifier.

Instances

Eq TraceID Source #
Instance details Defined in Control.Monad.Trace.Internal Methods (==) :: TraceID -> TraceID -> Bool # (/=) :: TraceID -> TraceID -> Bool #
Ord TraceID Source #
Instance details Defined in Control.Monad.Trace.Internal Methods compare :: TraceID -> TraceID -> Ordering # (<) :: TraceID -> TraceID -> Bool # (<=) :: TraceID -> TraceID -> Bool # (>) :: TraceID -> TraceID -> Bool # (>=) :: TraceID -> TraceID -> Bool # max :: TraceID -> TraceID -> TraceID # min :: TraceID -> TraceID -> TraceID #
Show TraceID Source #
Instance details Defined in Control.Monad.Trace.Internal Methods showsPrec :: Int -> TraceID -> ShowS # show :: TraceID -> String # showList :: [TraceID] -> ShowS #
ToJSON TraceID Source #
Instance details Defined in Control.Monad.Trace.Internal Methods toJSON :: TraceID -> Value # toEncoding :: TraceID -> Encoding # toJSONList :: [TraceID] -> Value # toEncodingList :: [TraceID] -> Encoding #
FromJSON TraceID Source #
Instance details Defined in Control.Monad.Trace.Internal Methods parseJSON :: Value -> Parser TraceID # parseJSONList :: Value -> Parser [TraceID] #

data Reference Source #

A relationship between spans.

There are currently two types of references, both of which model direct causal relationships between a child and a parent. More background on references is available in the opentracing specification: https://github.com/opentracing/specification/blob/master/specification.md.

Constructors

ChildOf !SpanID	`ChildOf` references imply that the parent span depends on the child span in some capacity. Note that this reference type is only valid within a single trace.
FollowsFrom !Context	If the parent does not depend on the child, we use a `FollowsFrom` reference.

Instances

Eq Reference Source #
Instance details Defined in Control.Monad.Trace.Internal Methods (==) :: Reference -> Reference -> Bool # (/=) :: Reference -> Reference -> Bool #
Ord Reference Source #
Instance details Defined in Control.Monad.Trace.Internal Methods compare :: Reference -> Reference -> Ordering # (<) :: Reference -> Reference -> Bool # (<=) :: Reference -> Reference -> Bool # (>) :: Reference -> Reference -> Bool # (>=) :: Reference -> Reference -> Bool # max :: Reference -> Reference -> Reference # min :: Reference -> Reference -> Reference #
Show Reference Source #
Instance details Defined in Control.Monad.Trace.Internal Methods showsPrec :: Int -> Reference -> ShowS # show :: Reference -> String # showList :: [Reference] -> ShowS #

builder :: Name -> Builder Source #

Returns a Builder with the given input as name and all other fields empty.

data Span Source #

A part of a trace.

Constructors

Span
Fields spanName :: !Name spanContext :: !Context spanReferences :: !(Set Reference)

data Context Source #

A fully qualified span identifier, containing both the ID of the trace the span belongs to and the span's ID. Span contexts can be exported (resp. imported) via their toJSON (resp. fromJSON) instance.

Constructors

Context
Fields contextTraceID :: !TraceID contextSpanID :: !SpanID contextBaggages :: !(Map Key ByteString)

Instances

Eq Context Source #
Instance details Defined in Control.Monad.Trace.Internal Methods (==) :: Context -> Context -> Bool # (/=) :: Context -> Context -> Bool #
Ord Context Source #
Instance details Defined in Control.Monad.Trace.Internal Methods compare :: Context -> Context -> Ordering # (<) :: Context -> Context -> Bool # (<=) :: Context -> Context -> Bool # (>) :: Context -> Context -> Bool # (>=) :: Context -> Context -> Bool # max :: Context -> Context -> Context # min :: Context -> Context -> Context #
Show Context Source #
Instance details Defined in Control.Monad.Trace.Internal Methods showsPrec :: Int -> Context -> ShowS # show :: Context -> String # showList :: [Context] -> ShowS #

type Key = Text Source #

The type of annotations' keys.

Keys starting with double underscores are reserved and should not be used.

data Value Source #

Metadata attached to a span.

tagDoubleValue :: Double -> Value Source #

Generates a tag value from a double.

tagInt64Value :: Integral a => a -> Value Source #

Generates a 64-bit integer tag value from any integer.

tagTextValue :: Text -> Value Source #

Generates a Unicode text tag value.

logValue :: ToJSON a => a -> Value Source #

Generates a log value with the time of writing as timestamp. Note that the value may be written later than it is created. For more control on the timestamp, use logValueAt.

logValueAt :: ToJSON a => POSIXTime -> a -> Value Source #

Generates a log value with a custom time.