feat(statement-distribution): Implement requestManager

dot/parachain/network-bridge/messages/attested_candidate.go

@@ -0,0 +1,91 @@
+// Copyright 2025 ChainSafe Systems (ON)
+// SPDX-License-Identifier: LGPL-3.0-only
+
+package messages
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/ChainSafe/gossamer/dot/network"
+	parachaintypes "github.com/ChainSafe/gossamer/dot/parachain/types"
+	"github.com/ChainSafe/gossamer/pkg/scale"
+)
+
+const (
+	// AttestedCandidateTimeout We want attested candidate requests to time out relatively fast,
+	// because slow requests will bottleneck the backing system. Ideally, we'd have
+	// an adaptive timeout based on the candidate size, because there will be a lot of variance
+	// in candidate sizes: candidates with no code and no messages vs candidates with code
+	// and messages.
+	//
+	// We supply leniency because there are often large candidates and asynchronous
+	// backing allows them to be included over a longer window of time. Exponential back-off
+	// up to a maximum of 10 seconds would be ideal, but isn't supported by the
+	// infrastructure here yet: see https://github.com/paritytech/polkadot/issues/6009
+	AttestedCandidateTimeout = time.Millisecond * 2500
+
+	// MaxParallelAttestedCandidateRequests We don't want a slow peer to slow down all the others,
+	// at the same time we want to get out the data quickly in full to at least some peers
+	// (as this will reduce load on us as they then can start serving the data). So this value is a tradeoff.
+	// 5 seems to be sensible. So we would need to have 5 slow nodes connected, to delay transfer for others
+	// by [AttestedCandidateTimeout].
+	MaxParallelAttestedCandidateRequests = 5
+)
+
+// AttestedCandidateRequest is a request for a candidate with statements.
+type AttestedCandidateRequest struct {
+	// Hash of the candidate we want to request.
+	CandidateHash parachaintypes.CandidateHash
+	// Statement filter with 'OR' semantics, indicating which validators
+	// not to send statements for.
+	//
+	// The filter must have exactly the minimum size required to
+	// fit all validators from the backing group.
+	//
+	// The response may not contain any statements masked out by this mask.
+	Mask parachaintypes.StatementFilter
+}
+
+// Encode returns the SCALE encoding of the AttestedCandidateRequest
+func (r *AttestedCandidateRequest) Encode() ([]byte, error) {
+	return scale.Marshal(*r)
+}
+
+// Decode returns the SCALE decoding of the AttestedCandidateRequest
+func (r *AttestedCandidateRequest) Decode(in []byte) (err error) {
+	return scale.Unmarshal(in, r)
+}
+
+func (r *AttestedCandidateRequest) Response() network.ResponseMessage {
+	return &AttestedCandidateResponse{}
+}
+
+func (r *AttestedCandidateRequest) Protocol() ReqProtocolName {
+	return AttestedCandidateV2
+}
+
+// AttestedCandidateResponse is the response to an [AttestedCandidateRequest].
+type AttestedCandidateResponse struct {
+	CandidateReceipt        parachaintypes.CommittedCandidateReceiptV2
+	PersistedValidationData parachaintypes.PersistedValidationData
+	Statements              []any // TODO: implement parachaintypes.UncheckedSignedStatement
+}
+
+// Encode returns the SCALE encoding of the AttestedCandidateResponse
+func (r *AttestedCandidateResponse) Encode() ([]byte, error) {
+	return scale.Marshal(*r)
+}
+
+// Decode returns the SCALE decoding of the AttestedCandidateResponse
+func (r *AttestedCandidateResponse) Decode(in []byte) (err error) {
+	return scale.Unmarshal(in, r)
+}
+
+// String returns a human-readable representation of the AttestedCandidateResponse
+func (r *AttestedCandidateResponse) String() string {
+	return fmt.Sprintf(
+		"AttestedCandidateResponse CandidateReceipt=%v",
+		r.CandidateReceipt,
+	)
+}

dot/parachain/network-bridge/messages/request_response_protocols.go

@@ -21,6 +21,7 @@ const (
 	AvailableDataFetchingV1
 	StatementFetchingV1
 	DisputeSendingV1
+	AttestedCandidateV2
 )
 
 func (n ReqProtocolName) String() string {
@@ -39,6 +40,8 @@ func (n ReqProtocolName) String() string {
 		return "req_statement/1"
 	case DisputeSendingV1:
 		return "send_dispute/1"
+	case AttestedCandidateV2:
+		return "/req_attested_candidate/2"
 	default:
 		panic("unknown protocol")
 	}