Safe Haskell	None
Language	Haskell2010

Ouroboros.Network.RethrowPolicy

Contents

Example policies

Description

Rethrow policy for MuxConnectionHandler .

Connection manager has a centralised way of handling exceptions. RethrowPolicy is a way to decided wheather it is enough to shutdown connection or the node should shut down itself. Theis mechanism is affected by the design choices in the mutliplexer.

Whenever a mini-protocol throws an exception, the bearer is closed. There is no way to recover a bidirectional connection if one side failed, in such way that the other end could still re-use it, e.g. if the initiator throws, we cannot just restart it on the same bearer, since there might be unconsumed bytes on the other end.

RethrowPolicy is supplied to makeMuxConnectionHandler which creates both the action that runs on each connection and error handler. Error handler is attached by the connection manager (see Core ). This error handler is using RethrowPolicy .

This mechanism is enough for both:

the server implemented in Server ,
PeerStateActions used by peer-to-peer governor.

Since both start mini-protocols with runMiniProtocol they can also have access to the result / exception thrown of a mini-protocol. PeerStateActions are only using this to inform the governor that the peer transitioned to PeerCold or to deactivate the peer.

Synopsis

newtype RethrowPolicy = RethrowPolicy {
- runRethrowPolicy :: RethrowPolicy_
}
mkRethrowPolicy :: forall e. Exception e => ( ErrorContext -> e -> ErrorCommand ) -> RethrowPolicy
data ErrorCommand
- = ShutdownNode
- | ShutdownPeer
data ErrorContext
- = OutboundError
- | InboundError
muxErrorRethrowPolicy :: RethrowPolicy
ioErrorRethrowPolicy :: RethrowPolicy

Documentation

newtype RethrowPolicy Source #

Constructors

RethrowPolicy
Fields runRethrowPolicy :: RethrowPolicy_

Instances

Instances details

Semigroup RethrowPolicy Source #
Instance details Defined in Ouroboros.Network.RethrowPolicy Methods (<>) :: RethrowPolicy -> RethrowPolicy -> RethrowPolicy Source # sconcat :: NonEmpty RethrowPolicy -> RethrowPolicy Source # stimes :: Integral b => b -> RethrowPolicy -> RethrowPolicy Source #
Monoid RethrowPolicy Source #
Instance details Defined in Ouroboros.Network.RethrowPolicy Methods mempty :: RethrowPolicy Source # mappend :: RethrowPolicy -> RethrowPolicy -> RethrowPolicy Source # mconcat :: [ RethrowPolicy ] -> RethrowPolicy Source #

mkRethrowPolicy :: forall e. Exception e => ( ErrorContext -> e -> ErrorCommand ) -> RethrowPolicy Source #

Smart constructor for RethrowPolicy .

data ErrorCommand Source #

Constructors

ShutdownNode	Shutdown node.
ShutdownPeer	Shutdown connection with the peer.

Instances

Instances details

Show ErrorCommand Source #
Instance details Defined in Ouroboros.Network.RethrowPolicy Methods showsPrec :: Int -> ErrorCommand -> ShowS Source # show :: ErrorCommand -> String Source # showList :: [ ErrorCommand ] -> ShowS Source #
Semigroup ErrorCommand Source #	`ErrorCommand` is a commutative semigroup with `ShutdownNode` being an absorbing element, and `ShutdownPeer` is the unit element.
Instance details Defined in Ouroboros.Network.RethrowPolicy Methods (<>) :: ErrorCommand -> ErrorCommand -> ErrorCommand Source # sconcat :: NonEmpty ErrorCommand -> ErrorCommand Source # stimes :: Integral b => b -> ErrorCommand -> ErrorCommand Source #
Monoid ErrorCommand Source #
Instance details Defined in Ouroboros.Network.RethrowPolicy Methods mempty :: ErrorCommand Source # mappend :: ErrorCommand -> ErrorCommand -> ErrorCommand Source # mconcat :: [ ErrorCommand ] -> ErrorCommand Source #

data ErrorContext Source #

Weather an exception happend on outbound or inbound connection.

TODO: It would be more useful to have access weather the exception happend on initiator or responder. The easiest way to fix this is make mux throw the exception together with context. This allows to keep error handling be done only by the connection manager (rather than by server and PeerStateActions ).

Constructors

OutboundError
InboundError

Instances

Instances details

Show ErrorContext Source #
Instance details Defined in Ouroboros.Network.RethrowPolicy Methods showsPrec :: Int -> ErrorContext -> ShowS Source # show :: ErrorContext -> String Source # showList :: [ ErrorContext ] -> ShowS Source #

Example policies

muxErrorRethrowPolicy :: RethrowPolicy Source #

ioErrorRethrowPolicy :: RethrowPolicy Source #