Trait Config 

pub trait Config: Config<OnSetCode = ParachainSetCode<Self>> + Config<RuntimeEvent: From<Event<Self>>> {
    type RuntimeEvent: From<Event<Self>> + IsType<<Self as Config>::RuntimeEvent>;
    type OnSystemEvent: OnSystemEvent;
    type SelfParaId: Get<ParaId>;
    type OutboundXcmpMessageSource: XcmpMessageSource;
    type DmpQueue: HandleMessage;
    type ReservedDmpWeight: Get<Weight>;
    type XcmpMessageHandler: XcmpMessageHandler;
    type ReservedXcmpWeight: Get<Weight>;
    type CheckAssociatedRelayNumber: CheckAssociatedRelayNumber;
    type WeightInfo: WeightInfo;
    type ConsensusHook: ConsensusHook;
    type RelayParentOffset: Get<u32>;
    type SchedulingSignatureVerifier: VerifySchedulingSignature;
}

Configuration trait of this pallet.

The main purpose of this trait is to act as an interface between this pallet and the runtime in which it is embedded in. A type, function, or constant in this trait is essentially left to be configured by the runtime that includes this pallet.

Consequently, a runtime that wants to include this pallet must implement this trait.

Required Associated Types

type RuntimeEvent: From<Event<Self>> + IsType<<Self as Config>::RuntimeEvent>

The overarching event type.

type OnSystemEvent: OnSystemEvent

Something which can be notified when the validation data is set.

type SelfParaId: Get<ParaId>

Returns the parachain ID we are running with.

type OutboundXcmpMessageSource: XcmpMessageSource

The place where outbound XCMP messages come from. This is queried in finalize_block.

type DmpQueue: HandleMessage

Queues inbound downward messages for delayed processing.

All inbound DMP messages from the relay are pushed into this. The handler is expected to eventually process all the messages that are pushed to it.

type ReservedDmpWeight: Get<Weight>

The weight we reserve at the beginning of the block for processing DMP messages.

type XcmpMessageHandler: XcmpMessageHandler

The message handler that will be invoked when messages are received via XCMP.

This should normally link to the XCMP Queue pallet.

type ReservedXcmpWeight: Get<Weight>

The weight we reserve at the beginning of the block for processing XCMP messages.

type CheckAssociatedRelayNumber: CheckAssociatedRelayNumber

Something that can check the associated relay parent block number.

type WeightInfo: WeightInfo

Weight info for functions and calls.

type ConsensusHook: ConsensusHook

An entry-point for higher-level logic to manage the backlog of unincluded parachain blocks and authorship rights for those blocks.

Typically, this should be a hook tailored to the collator-selection/consensus mechanism that is used for this chain.

However, to maintain the same behavior as prior to asynchronous backing, provide the consensus_hook::ExpectParentIncluded here. This is only necessary in the case that collators aren’t expected to have node versions that supply the included block in the relay-chain state proof.

type RelayParentOffset: Get<u32>

The offset between the tip of the relay chain and the parent relay block used as parent when authoring a parachain block.

This setting directly impacts the number of descendant headers that are expected in the set_validation_data inherent.

For any setting N larger than zero, the inherent expects that the inherent includes the relay parent plus N descendants. These headers are required to validate that new parachain blocks are authored at the correct offset.

While this helps to reduce forks on the parachain side, it increases the delay for processing XCM messages. So, the value should be chosen wisely.

If set to 0, this config has no impact.

type SchedulingSignatureVerifier: VerifySchedulingSignature

Verifier for V3 scheduling proofs.

Reports whether V3 scheduling validation is enabled and supplies the verification logic for the proof itself. Use () to keep V3 scheduling disabled.

When enabled, this changes how building on older relay parents is enforced:

• The old relay_parent_descendants validation in the inherent is disabled
• V3 scheduling validation is used instead, with the header chain provided via PVF parameters

Migration Guide

v3 scheduling is work in progress, and for the moment this should be left as (). If V3 is wrongfully enabled, the parachain will stall.

Before enabling this:

1. Ensure all collators are updated to a version that supports V3 candidates
2. Ensure the relay chain has CandidateReceiptV3 node feature enabled
3. Swap the verifier for one whose V3_SCHEDULING_ENABLED const is true, via a runtime upgrade.

Once enabled, collators will:

• Stop providing relay_parent_descendants in the inherent (empty vec)
• Provide the header chain via V3 extension in PVF parameters

The RelayParentOffset config continues to define the header chain length.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors