SSE emit payload attributes before each slot

packages/api/src/beacon/routes/events.ts

@@ -1,8 +1,9 @@
 import {Epoch, phase0, capella, Slot, ssz, StringType, RootHex, altair, UintNum64, allForks} from "@lodestar/types";
 import {ContainerType} from "@chainsafe/ssz";
 import {ChainForkConfig} from "@lodestar/config";
+import {isForkExecution, ForkName} from "@lodestar/params";
 
-import {RouteDef, TypeJson} from "../../utils/index.js";
+import {RouteDef, TypeJson, WithVersion} from "../../utils/index.js";
 import {HttpStatusCode} from "../../utils/client/httpStatusCode.js";
 import {ApiClientResponse} from "../../interfaces.js";
 
@@ -36,6 +37,8 @@ export enum EventType {
   lightClientFinalityUpdate = "light_client_finality_update",
   /** New or better light client update available */
   lightClientUpdate = "light_client_update",
+  /** Payload attributes for block proposal */
+  payloadAttributes = "payload_attributes",
 }
 
 export const eventTypes: {[K in EventType]: K} = {
@@ -50,6 +53,7 @@ export const eventTypes: {[K in EventType]: K} = {
   [EventType.lightClientOptimisticUpdate]: EventType.lightClientOptimisticUpdate,
   [EventType.lightClientFinalityUpdate]: EventType.lightClientFinalityUpdate,
   [EventType.lightClientUpdate]: EventType.lightClientUpdate,
+  [EventType.payloadAttributes]: EventType.payloadAttributes,
 };
 
 export type EventData = {
@@ -90,6 +94,7 @@ export type EventData = {
   [EventType.lightClientOptimisticUpdate]: allForks.LightClientOptimisticUpdate;
   [EventType.lightClientFinalityUpdate]: allForks.LightClientFinalityUpdate;
   [EventType.lightClientUpdate]: allForks.LightClientUpdate;
+  [EventType.payloadAttributes]: {version: ForkName; data: allForks.SSEPayloadAttributes};
 };
 
 export type BeaconEvent = {[K in EventType]: {type: K; message: EventData[K]}}[EventType];
@@ -182,6 +187,9 @@ export function getTypeByEvent(config: ChainForkConfig): {[K in EventType]: Type
     ),
 
     [EventType.contributionAndProof]: ssz.altair.SignedContributionAndProof,
+    [EventType.payloadAttributes]: WithVersion((fork) =>
+      isForkExecution(fork) ? ssz.allForksExecution[fork].SSEPayloadAttributes : ssz.bellatrix.SSEPayloadAttributes
+    ),
 
     [EventType.lightClientOptimisticUpdate]: {
       toJson: (data) =>

packages/api/test/unit/beacon/testData/events.ts

@@ -1,4 +1,5 @@
 import {ssz} from "@lodestar/types";
+import {ForkName} from "@lodestar/params";
 import {Api, EventData, EventType} from "../../../../src/beacon/routes/events.js";
 import {GenericServerTestCases} from "../../../utils/genericServerTest.js";
 
@@ -104,4 +105,8 @@ export const eventTestData: EventData = {
     signatureSlot: ssz.Slot.defaultValue(),
   },
   [EventType.lightClientUpdate]: ssz.altair.LightClientUpdate.defaultValue(),
+  [EventType.payloadAttributes]: {
+    version: ForkName.bellatrix,
+    data: ssz.bellatrix.SSEPayloadAttributes.defaultValue(),
+  },
 };

packages/beacon-node/src/chain/options.ts

@@ -44,6 +44,7 @@ export type BlockProcessOpts = {
    * will still issue fcU for block proposal
    */
   disableImportExecutionFcU?: boolean;
+  emitPayloadAttributes?: boolean;
 };
 
 export const defaultChainOptions: IChainOptions = {
@@ -57,4 +58,5 @@ export const defaultChainOptions: IChainOptions = {
   suggestedFeeRecipient: defaultValidatorOptions.suggestedFeeRecipient,
   assertCorrectProgressiveBalances: false,
   archiveStateEpochFrequency: 1024,
+  emitPayloadAttributes: false,
 };

packages/beacon-node/src/chain/prepareNextSlot.ts

@@ -2,12 +2,13 @@ import {computeEpochAtSlot, isExecutionStateType, computeTimeAtSlot} from "@lode
 import {ChainForkConfig} from "@lodestar/config";
 import {ForkSeq, SLOTS_PER_EPOCH, ForkExecution} from "@lodestar/params";
 import {Slot} from "@lodestar/types";
-import {Logger, sleep} from "@lodestar/utils";
+import {Logger, sleep, fromHex} from "@lodestar/utils";
+import {routes} from "@lodestar/api";
 import {GENESIS_SLOT, ZERO_HASH_HEX} from "../constants/constants.js";
 import {Metrics} from "../metrics/index.js";
 import {TransitionConfigurationV1} from "../execution/engine/interface.js";
 import {ChainEvent} from "./emitter.js";
-import {prepareExecutionPayload} from "./produceBlock/produceBlockBody.js";
+import {prepareExecutionPayload, getPayloadAttributesForSSE} from "./produceBlock/produceBlockBody.js";
 import {IBeaconChain} from "./interface.js";
 import {RegenCaller} from "./regen/index.js";
 
@@ -156,6 +157,19 @@ export class PrepareNextSlotScheduler {
             feeRecipient,
           });
         }
+
+        // If emitPayloadAttributes is true emit a SSE payloadAttributes event
+        if (this.chain.opts.emitPayloadAttributes === true) {
+          const data = await getPayloadAttributesForSSE(fork as ForkExecution, this.chain, {
+            prepareState,
+            prepareSlot,
+            parentBlockRoot: fromHex(headRoot),
+            // The likely consumers of this API are builders and will anyway ignore the
+            // feeRecipient, so just pass zero hash for now till a real use case arises
+            feeRecipient: "0x0000000000000000000000000000000000000000000000000000000000000000",
+          });
+          this.chain.emitter.emit(routes.events.EventType.payloadAttributes, {data, version: fork});
+        }
       }
     } catch (e) {
       this.metrics?.precomputeNextEpochTransition.count.inc({result: "error"}, 1);

packages/beacon-node/src/chain/produceBlock/produceBlockBody.ts

@@ -28,7 +28,7 @@ import {
 } from "@lodestar/state-transition";
 import {ChainForkConfig} from "@lodestar/config";
 import {ForkSeq, ForkExecution, isForkExecution} from "@lodestar/params";
-import {toHex, sleep, Logger} from "@lodestar/utils";
+import {toHex, sleep, Logger, fromHex} from "@lodestar/utils";
 
 import type {BeaconChain} from "../chain.js";
 import {PayloadId, IExecutionEngine, IExecutionBuilder, PayloadAttributes} from "../../execution/index.js";
@@ -418,7 +418,7 @@ async function prepareExecutionPayloadHeader(
   return chain.executionBuilder.getHeader(state.slot, parentHash, proposerPubKey);
 }
 
-async function getExecutionPayloadParentHash(
+export async function getExecutionPayloadParentHash(
   chain: {
     eth1: IEth1ForBlockProduction;
     config: ChainForkConfig;
@@ -452,4 +452,49 @@ async function getExecutionPayloadParentHash(
   }
 }
 
+export async function getPayloadAttributesForSSE(
+  fork: ForkExecution,
+  chain: {
+    eth1: IEth1ForBlockProduction;
+    config: ChainForkConfig;
+  },
+  {
+    prepareState,
+    prepareSlot,
+    parentBlockRoot,
+    feeRecipient,
+  }: {prepareState: CachedBeaconStateExecutions; prepareSlot: Slot; parentBlockRoot: Root; feeRecipient: string}
+): Promise<allForks.SSEPayloadAttributes> {
+  const parentHashRes = await getExecutionPayloadParentHash(chain, prepareState);
+
+  if (!parentHashRes.isPremerge) {
+    const {parentHash} = parentHashRes;
+    const timestamp = computeTimeAtSlot(chain.config, prepareSlot, prepareState.genesisTime);
+    const prevRandao = getRandaoMix(prepareState, prepareState.epochCtx.epoch);
+    const payloadAttributes = {
+      timestamp,
+      prevRandao,
+      suggestedFeeRecipient: fromHex(feeRecipient),
+    };
+
+    if (ForkSeq[fork] >= ForkSeq.capella) {
+      (payloadAttributes as capella.SSEPayloadAttributes["payloadAttributes"]).withdrawals = getExpectedWithdrawals(
+        prepareState as CachedBeaconStateCapella
+      ).withdrawals;
+    }
+
+    const ssePayloadAttributes: allForks.SSEPayloadAttributes = {
+      proposerIndex: prepareState.epochCtx.getBeaconProposer(prepareSlot),
+      proposalSlot: prepareSlot,
+      proposalBlockNumber: prepareState.latestExecutionPayloadHeader.blockNumber + 1,
+      parentBlockRoot,
+      parentBlockHash: parentHash,
+      payloadAttributes,
+    };
+    return ssePayloadAttributes;
+  } else {
+    throw Error("The execution is still pre-merge");
+  }
+}
+
 /** process_sync_committee_contributions is implemented in syncCommitteeContribution.getSyncAggregate */

packages/beacon-node/test/unit/chain/prepareNextSlot.test.ts

@@ -5,8 +5,10 @@ import {ForkChoice, ProtoBlock} from "@lodestar/fork-choice";
 import {WinstonLogger} from "@lodestar/utils";
 import {ForkName, SLOTS_PER_EPOCH} from "@lodestar/params";
 import {ChainForkConfig} from "@lodestar/config";
+import {routes} from "@lodestar/api";
 import {BeaconChain, ChainEventEmitter} from "../../../src/chain/index.js";
 import {IBeaconChain} from "../../../src/chain/interface.js";
+import {IChainOptions} from "../../../src/chain/options.js";
 import {LocalClock} from "../../../src/chain/clock/index.js";
 import {PrepareNextSlotScheduler} from "../../../src/chain/prepareNextSlot.js";
 import {StateRegenerator} from "../../../src/chain/regen/index.js";
@@ -17,8 +19,9 @@ import {PayloadIdCache} from "../../../src/execution/engine/payloadIdCache.js";
 import {ExecutionEngineHttp} from "../../../src/execution/engine/http.js";
 import {IExecutionEngine} from "../../../src/execution/engine/interface.js";
 import {StubbedChainMutable} from "../../utils/stub/index.js";
+import {zeroProtoBlock} from "../../utils/mocks/chain/chain.js";
 
-type StubbedChain = StubbedChainMutable<"clock" | "forkChoice" | "emitter" | "regen">;
+type StubbedChain = StubbedChainMutable<"clock" | "forkChoice" | "emitter" | "regen" | "opts">;
 
 describe("PrepareNextSlot scheduler", () => {
   const sandbox = sinon.createSandbox();
@@ -33,7 +36,8 @@ describe("PrepareNextSlot scheduler", () => {
   let getForkStub: SinonStubFn<typeof config["getForkName"]>;
   let updateBuilderStatus: SinonStubFn<IBeaconChain["updateBuilderStatus"]>;
   let executionEngineStub: SinonStubbedInstance<ExecutionEngineHttp> & ExecutionEngineHttp;
-
+  const emitPayloadAttributes = true;
+  const proposerIndex = 0;
   beforeEach(() => {
     sandbox.useFakeTimers();
     chainStub = sandbox.createStubInstance(BeaconChain) as StubbedChain;
@@ -42,9 +46,8 @@ describe("PrepareNextSlot scheduler", () => {
     chainStub.clock = clockStub;
     forkChoiceStub = sandbox.createStubInstance(ForkChoice) as SinonStubbedInstance<ForkChoice> & ForkChoice;
     chainStub.forkChoice = forkChoiceStub;
-    const emitterStub = sandbox.createStubInstance(ChainEventEmitter) as SinonStubbedInstance<ChainEventEmitter> &
-      ChainEventEmitter;
-    chainStub.emitter = emitterStub;
+    const emitter = new ChainEventEmitter();
+    chainStub.emitter = emitter;
     regenStub = sandbox.createStubInstance(StateRegenerator) as SinonStubbedInstance<StateRegenerator> &
       StateRegenerator;
     chainStub.regen = regenStub;
@@ -60,6 +63,8 @@ describe("PrepareNextSlot scheduler", () => {
       ExecutionEngineHttp;
     ((chainStub as unknown) as {executionEngine: IExecutionEngine}).executionEngine = executionEngineStub;
     ((chainStub as unknown) as {config: ChainForkConfig}).config = (config as unknown) as ChainForkConfig;
+    chainStub.opts = {emitPayloadAttributes} as IChainOptions;
+
     scheduler = new PrepareNextSlotScheduler(chainStub, config, null, loggerStub, abortController.signal);
   });
 
@@ -135,12 +140,15 @@ describe("PrepareNextSlot scheduler", () => {
   });
 
   it("bellatrix - should prepare payload", async () => {
+    const spy = sinon.spy();
+    chainStub.emitter.on(routes.events.EventType.payloadAttributes, spy);
     getForkStub.returns(ForkName.bellatrix);
-    chainStub.recomputeForkChoiceHead.returns({slot: SLOTS_PER_EPOCH - 3} as ProtoBlock);
+    chainStub.recomputeForkChoiceHead.returns({...zeroProtoBlock, slot: SLOTS_PER_EPOCH - 3} as ProtoBlock);
     forkChoiceStub.getJustifiedBlock.returns({} as ProtoBlock);
     forkChoiceStub.getFinalizedBlock.returns({} as ProtoBlock);
     updateBuilderStatus.returns(void 0);
     const state = generateCachedBellatrixState();
+    sinon.stub(state.epochCtx, "getBeaconProposer").returns(proposerIndex);
     regenStub.getBlockSlotState.resolves(state);
     beaconProposerCacheStub.get.returns("0x fee recipient address");
     ((executionEngineStub as unknown) as {payloadIdCache: PayloadIdCache}).payloadIdCache = new PayloadIdCache();
@@ -157,5 +165,6 @@ describe("PrepareNextSlot scheduler", () => {
     expect(forkChoiceStub.getFinalizedBlock, "expect forkChoice.getFinalizedBlock to be called").to.be.called;
     expect(executionEngineStub.notifyForkchoiceUpdate, "expect executionEngine.notifyForkchoiceUpdate to be called").to
       .be.calledOnce;
+    expect(spy).to.be.calledOnce;
   });
 });

packages/cli/src/options/beaconNodeOptions/chain.ts

@@ -18,6 +18,7 @@ export type ChainArgs = {
   "chain.maxSkipSlots": number;
   "safe-slots-to-import-optimistically": number;
   "chain.archiveStateEpochFrequency": number;
+  emitPayloadAttributes: boolean;
 };
 
 export function parseArgs(args: ChainArgs): IBeaconNodeOptions["chain"] {
@@ -37,6 +38,7 @@ export function parseArgs(args: ChainArgs): IBeaconNodeOptions["chain"] {
     maxSkipSlots: args["chain.maxSkipSlots"],
     safeSlotsToImportOptimistically: args["safe-slots-to-import-optimistically"],
     archiveStateEpochFrequency: args["chain.archiveStateEpochFrequency"],
+    emitPayloadAttributes: args["emitPayloadAttributes"],
   };
 }
 
@@ -49,6 +51,13 @@ export const options: CliCommandOptions<ChainArgs> = {
     group: "chain",
   },
 
+  emitPayloadAttributes: {
+    type: "boolean",
+    defaultDescription: String(defaultOptions.chain.emitPayloadAttributes),
+    description: "Flag to SSE emit execution payloadAttributes before every slot",
+    group: "chain",
+  },
+
   "chain.blsVerifyAllMultiThread": {
     hidden: true,
     type: "boolean",

packages/cli/test/unit/options/beaconNodeOptions.test.ts

@@ -30,6 +30,7 @@ describe("options / beaconNodeOptions", () => {
       "chain.maxSkipSlots": 100,
       "safe-slots-to-import-optimistically": 256,
       "chain.archiveStateEpochFrequency": 1024,
+      emitPayloadAttributes: false,
 
       eth1: true,
       "eth1.providerUrl": "http://my.node:8545",
@@ -117,6 +118,7 @@ describe("options / beaconNodeOptions", () => {
         assertCorrectProgressiveBalances: true,
         maxSkipSlots: 100,
         archiveStateEpochFrequency: 1024,
+        emitPayloadAttributes: false,
       },
       eth1: {
         enabled: true,

packages/types/src/allForks/sszTypes.ts

@@ -60,6 +60,7 @@ export const allForksExecution = {
     ExecutionPayloadHeader: bellatrix.ExecutionPayloadHeader,
     BuilderBid: bellatrix.BuilderBid,
     SignedBuilderBid: bellatrix.SignedBuilderBid,
+    SSEPayloadAttributes: bellatrix.SSEPayloadAttributes,
   },
   capella: {
     BeaconBlockBody: capella.BeaconBlockBody,
@@ -71,6 +72,7 @@ export const allForksExecution = {
     ExecutionPayloadHeader: capella.ExecutionPayloadHeader,
     BuilderBid: capella.BuilderBid,
     SignedBuilderBid: capella.SignedBuilderBid,
+    SSEPayloadAttributes: capella.SSEPayloadAttributes,
   },
   deneb: {
     BeaconBlockBody: deneb.BeaconBlockBody,
@@ -81,6 +83,7 @@ export const allForksExecution = {
     ExecutionPayloadHeader: deneb.ExecutionPayloadHeader,
     BuilderBid: deneb.BuilderBid,
     SignedBuilderBid: deneb.SignedBuilderBid,
+    SSEPayloadAttributes: capella.SSEPayloadAttributes,
   },
 };
 

packages/types/src/allForks/types.ts

@@ -88,6 +88,8 @@ export type LightClientOptimisticUpdate =
 export type LightClientStore = altair.LightClientStore | capella.LightClientStore | deneb.LightClientStore;
 
 export type SignedBeaconBlockAndBlobsSidecar = deneb.SignedBeaconBlockAndBlobsSidecar;
+
+export type SSEPayloadAttributes = bellatrix.SSEPayloadAttributes | capella.SSEPayloadAttributes;
 /**
  * Types known to change between forks
  */
@@ -214,6 +216,9 @@ export type AllForksExecutionSSZTypes = {
   SignedBuilderBid: AllForksTypeOf<
     typeof bellatrixSsz.SignedBuilderBid | typeof capellaSsz.SignedBuilderBid | typeof denebSsz.SignedBuilderBid
   >;
+  SSEPayloadAttributes: AllForksTypeOf<
+    typeof bellatrixSsz.SSEPayloadAttributes | typeof capellaSsz.SSEPayloadAttributes
+  >;
 };
 
 export type AllForksBlindedSSZTypes = {

packages/types/src/bellatrix/sszTypes.ts

@@ -215,3 +215,28 @@ export const SignedBuilderBid = new ContainerType(
   },
   {typeName: "SignedBuilderBid", jsonCase: "eth2"}
 );
+
+// PayloadAttributes primarily for SSE event
+export const PayloadAttributes = new ContainerType(
+  {timestamp: UintNum64, prevRandao: Bytes32, suggestedFeeRecipient: ExecutionAddress},
+  {typeName: "PayloadAttributes", jsonCase: "eth2"}
+);
+
+export const SSEPayloadAttributesCommon = new ContainerType(
+  {
+    proposerIndex: UintNum64,
+    proposalSlot: Slot,
+    proposalBlockNumber: UintNum64,
+    parentBlockRoot: Root,
+    parentBlockHash: Root,
+  },
+  {typeName: "SSEPayloadAttributesCommon", jsonCase: "eth2"}
+);
+
+export const SSEPayloadAttributes = new ContainerType(
+  {
+    ...SSEPayloadAttributesCommon.fields,
+    payloadAttributes: PayloadAttributes,
+  },
+  {typeName: "SSEPayloadAttributes", jsonCase: "eth2"}
+);

packages/types/src/bellatrix/types.ts

@@ -18,5 +18,6 @@ export type ValidatorRegistrationV1 = ValueOf<typeof ssz.ValidatorRegistrationV1
 export type SignedValidatorRegistrationV1 = ValueOf<typeof ssz.SignedValidatorRegistrationV1>;
 export type BuilderBid = ValueOf<typeof ssz.BuilderBid>;
 export type SignedBuilderBid = ValueOf<typeof ssz.SignedBuilderBid>;
+export type SSEPayloadAttributes = ValueOf<typeof ssz.SSEPayloadAttributes>;
 
 export type FullOrBlindedExecutionPayload = ExecutionPayload | ExecutionPayloadHeader;