Add and heartbeat to engine exchangeTransitionConfigurationV1 method

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

@@ -5,6 +5,8 @@ import {Slot} from "@lodestar/types";
 import {ILogger, sleep} from "@lodestar/utils";
 import {GENESIS_SLOT, ZERO_HASH_HEX} from "../constants/constants.js";
 import {IMetrics} from "../metrics/index.js";
+import {bytesToData, numToQuantity} from "../eth1/provider/utils.js";
+import {TransitionConfigurationV1} from "../execution/engine/interface.js";
 import {ChainEvent} from "./emitter.js";
 import {prepareExecutionPayload} from "./factory/block/body.js";
 import {IBeaconChain} from "./interface.js";
@@ -28,6 +30,7 @@ const PREPARE_EPOCH_LIMIT = 1;
  *
  */
 export class PrepareNextSlotScheduler {
+  private transitionConfig: TransitionConfigurationV1 | null = null;
   constructor(
     private readonly chain: IBeaconChain,
     private readonly config: IChainForkConfig,
@@ -36,11 +39,24 @@ export class PrepareNextSlotScheduler {
     private readonly signal: AbortSignal
   ) {
     this.chain.emitter.on(ChainEvent.clockSlot, this.prepareForNextSlot);
+    // If the merge is configured
+    if (isFinite(this.config.BELLATRIX_FORK_EPOCH)) {
+      this.transitionConfig = {
+        terminalTotalDifficulty: numToQuantity(this.config.TERMINAL_TOTAL_DIFFICULTY),
+        terminalBlockHash: bytesToData(this.config.TERMINAL_BLOCK_HASH),
+        /** terminalBlockNumber has to be set to zero for now as per specs */
+        terminalBlockNumber: numToQuantity(0),
+      };
+      this.chain.emitter.on(ChainEvent.clockSlot, this.performExchangeTransitionHB);
+    }
 
     this.signal.addEventListener(
       "abort",
       () => {
         this.chain.emitter.off(ChainEvent.clockSlot, this.prepareForNextSlot);
+        if (this.transitionConfig) {
+          this.chain.emitter.off(ChainEvent.clockSlot, this.performExchangeTransitionHB);
+        }
       },
       {once: true}
     );
@@ -138,4 +154,24 @@ export class PrepareNextSlotScheduler {
       this.logger.error("Failed to run prepareForNextSlot", {nextEpoch, isEpochTransition, prepareSlot}, e as Error);
     }
   };
+
+  /**
+   * perform heart beat for EL lest it logs warning that CL is not connected
+   */
+  performExchangeTransitionHB = async (_clockSlot: Slot): Promise<void> => {
+    const transitionConfig = this.transitionConfig;
+    if (transitionConfig) {
+      const elTransitionConfig = await this.chain.executionEngine.exchangeTransitionConfigurationV1(transitionConfig);
+      if (
+        elTransitionConfig.terminalTotalDifficulty !== transitionConfig.terminalTotalDifficulty ||
+        elTransitionConfig.terminalBlockHash !== transitionConfig.terminalBlockHash
+      ) {
+        this.logger.error(
+          `Transition config mismatch, actual=${JSON.stringify(elTransitionConfig)}, expected=${JSON.stringify(
+            transitionConfig
+          )}`
+        );
+      }
+    }
+  };
 }

packages/beacon-node/src/execution/engine/disabled.ts

@@ -14,4 +14,7 @@ export class ExecutionEngineDisabled implements IExecutionEngine {
   async getPayload(): Promise<never> {
     throw Error("Execution engine disabled");
   }
+  async exchangeTransitionConfigurationV1(): Promise<never> {
+    throw Error("Execution engine disabled");
+  }
 }

packages/beacon-node/src/execution/engine/http.ts

@@ -22,6 +22,7 @@ import {
   PayloadId,
   PayloadAttributes,
   ApiPayloadAttributes,
+  TransitionConfigurationV1,
 } from "./interface.js";
 import {PayloadIdCache} from "./payloadIdCache.js";
 
@@ -60,6 +61,7 @@ export const defaultExecutionEngineHttpOpts: ExecutionEngineHttpOpts = {
 const notifyNewPayloadOpts: ReqOpts = {routeId: "notifyNewPayload"};
 const forkchoiceUpdatedV1Opts: ReqOpts = {routeId: "forkchoiceUpdated"};
 const getPayloadOpts: ReqOpts = {routeId: "getPayload"};
+const exchageTransitionConfigOpts: ReqOpts = {routeId: "exchangeTransitionConfiguration"};
 
 /**
  * based on Ethereum JSON-RPC API and inherits the following properties of this standard:
@@ -283,6 +285,29 @@ export class ExecutionEngineHttp implements IExecutionEngine {
     return parseExecutionPayload(executionPayloadRpc);
   }
 
+  /**
+   * `engine_exchangeTransitionConfigurationV1`
+   *
+   * An api method for EL<>CL transition config matching and heartbeat
+   */
+
+  async exchangeTransitionConfigurationV1(
+    transitionConfiguration: TransitionConfigurationV1
+  ): Promise<TransitionConfigurationV1> {
+    const method = "engine_exchangeTransitionConfigurationV1";
+    const exchangeTransitionConfigurationV1Res = await this.rpc.fetchWithRetries<
+      EngineApiRpcReturnTypes[typeof method],
+      EngineApiRpcParamTypes[typeof method]
+    >(
+      {
+        method,
+        params: [transitionConfiguration],
+      },
+      exchageTransitionConfigOpts
+    );
+    return exchangeTransitionConfigurationV1Res;
+  }
+
   async prunePayloadIdCache(): Promise<void> {
     this.payloadIdCache.prune();
   }
@@ -308,6 +333,10 @@ type EngineApiRpcParamTypes = {
    * 1. payloadId: QUANTITY, 64 Bits - Identifier of the payload building process
    */
   engine_getPayloadV1: [QUANTITY];
+  /**
+   * 1. Object - Instance of TransitionConfigurationV1
+   */
+  engine_exchangeTransitionConfigurationV1: [TransitionConfigurationV1];
 };
 
 type EngineApiRpcReturnTypes = {
@@ -328,6 +357,10 @@ type EngineApiRpcReturnTypes = {
    * payloadId | Error: QUANTITY, 64 Bits - Identifier of the payload building process
    */
   engine_getPayloadV1: ExecutionPayloadRpc;
+  /**
+   * Object - Instance of TransitionConfigurationV1
+   */
+  engine_exchangeTransitionConfigurationV1: TransitionConfigurationV1;
 };
 
 type ExecutionPayloadRpc = {

packages/beacon-node/src/execution/engine/interface.ts

@@ -1,4 +1,5 @@
 import {bellatrix, RootHex} from "@lodestar/types";
+import {DATA, QUANTITY} from "../../eth1/provider/utils.js";
 import {PayloadIdCache, PayloadId, ApiPayloadAttributes} from "./payloadIdCache.js";
 
 export {PayloadIdCache, PayloadId, ApiPayloadAttributes};
@@ -47,6 +48,12 @@ export type PayloadAttributes = {
   suggestedFeeRecipient: string;
 };
 
+export type TransitionConfigurationV1 = {
+  terminalTotalDifficulty: QUANTITY;
+  terminalBlockHash: DATA;
+  terminalBlockNumber: QUANTITY;
+};
+
 /**
  * Execution engine represents an abstract protocol to interact with execution clients. Potential transports include:
  * - JSON RPC over network
@@ -93,4 +100,8 @@ export interface IExecutionEngine {
    * https://github.com/ethereum/consensus-specs/blob/dev/specs/merge/validator.md#get_payload
    */
   getPayload(payloadId: PayloadId): Promise<bellatrix.ExecutionPayload>;
+
+  exchangeTransitionConfigurationV1(
+    transitionConfiguration: TransitionConfigurationV1
+  ): Promise<TransitionConfigurationV1>;
 }

packages/beacon-node/src/execution/engine/mock.ts

@@ -10,6 +10,7 @@ import {
   PayloadId,
   PayloadAttributes,
   PayloadIdCache,
+  TransitionConfigurationV1,
 } from "./interface.js";
 const INTEROP_GAS_LIMIT = 30e6;
 
@@ -228,6 +229,17 @@ export class ExecutionEngineMock implements IExecutionEngine {
     return payload;
   }
 
+  async exchangeTransitionConfigurationV1(
+    transitionConfiguration: TransitionConfigurationV1
+  ): Promise<TransitionConfigurationV1> {
+    const resTransitionConfig = {
+      terminalTotalDifficulty: transitionConfiguration.terminalTotalDifficulty,
+      terminalBlockHash: transitionConfiguration.terminalBlockHash,
+      terminalBlockNumber: transitionConfiguration.terminalBlockNumber,
+    };
+    return resTransitionConfig;
+  }
+
   /**
    * Non-spec method just to add more known blocks to this mock.
    */