Trait bp_messages::target_chain::MessageDispatch

pub trait MessageDispatch {
    type DispatchPayload: Decode;
    type DispatchLevelResult: Clone + Debug + Eq;
    type LaneId: Encode;

    // Required methods
    fn is_active(lane: Self::LaneId) -> bool;
    fn dispatch_weight(
        message: &mut DispatchMessage<Self::DispatchPayload, Self::LaneId>,
    ) -> Weight;
    fn dispatch(
        message: DispatchMessage<Self::DispatchPayload, Self::LaneId>,
    ) -> MessageDispatchResult<Self::DispatchLevelResult>;
}

Called when inbound message is received.

Required Associated Types

type DispatchPayload: Decode

Decoded message payload type. Valid message may contain invalid payload. In this case message is delivered, but dispatch fails. Therefore, two separate types of payload (opaque MessagePayload used in delivery and this DispatchPayload used in dispatch).

type DispatchLevelResult: Clone + Debug + Eq

Fine-grained result of single message dispatch (for better diagnostic purposes)

type LaneId: Encode

Lane identifier type.

Required Methods

fn is_active(lane: Self::LaneId) -> bool

Returns true if dispatcher is ready to accept additional messages. The false should be treated as a hint by both dispatcher and its consumers - i.e. dispatcher shall not simply drop messages if it returns false. The consumer may still call the dispatch if dispatcher has returned false.

We check it in the messages delivery transaction prologue. So if it becomes false after some portion of messages is already dispatched, it doesn’t fail the whole transaction.

fn dispatch_weight( message: &mut DispatchMessage<Self::DispatchPayload, Self::LaneId>, ) -> Weight

Estimate dispatch weight.

This function must return correct upper bound of dispatch weight. The return value of this function is expected to match return value of the corresponding From<Chain>InboundLaneApi::message_details().dispatch_weight call.

fn dispatch( message: DispatchMessage<Self::DispatchPayload, Self::LaneId>, ) -> MessageDispatchResult<Self::DispatchLevelResult>

Called when inbound message is received.

It is up to the implementers of this trait to determine whether the message is invalid (i.e. improperly encoded, has too large weight, …) or not.

Object Safety

This trait is not object safe.

Implementors

impl<DispatchPayload: Decode, LaneId: Encode> MessageDispatch for ForbidInboundMessages<DispatchPayload, LaneId>

type DispatchPayload = DispatchPayload

type DispatchLevelResult = ()

type LaneId = LaneId