chore: Request txs in prover-node after each block finishes (#11749)

To prevent a burst of requests from the prover node at the epoch end.

Note that this may trigger the requests for the last block in the epoch
twice, but given we're moving away from this model soon, I think it's
acceptable.

yarn-project/prover-node/src/prover-node.ts

@@ -20,6 +20,7 @@ import { type ContractDataSource } from '@aztec/circuits.js';
 import { compact } from '@aztec/foundation/collection';
 import { memoize } from '@aztec/foundation/decorators';
 import { createLogger } from '@aztec/foundation/log';
+import { RunningPromise } from '@aztec/foundation/running-promise';
 import { DateProvider } from '@aztec/foundation/timer';
 import { type Maybe } from '@aztec/foundation/types';
 import { type P2P } from '@aztec/p2p';
@@ -67,6 +68,9 @@ export class ProverNode implements ClaimsMonitorHandler, EpochMonitorHandler, Pr
   private options: ProverNodeOptions;
   private metrics: ProverNodeMetrics;
 
+  private txFetcher: RunningPromise;
+  private lastBlockNumber: number | undefined;
+
   public readonly tracer: Tracer;
 
   constructor(
@@ -97,6 +101,7 @@ export class ProverNode implements ClaimsMonitorHandler, EpochMonitorHandler, Pr
 
     this.metrics = new ProverNodeMetrics(telemetryClient, 'ProverNode');
     this.tracer = telemetryClient.getTracer('ProverNode');
+    this.txFetcher = new RunningPromise(() => this.checkForTxs(), this.log, this.options.txGatheringIntervalMs);
   }
 
   public getP2P() {
@@ -202,6 +207,7 @@ export class ProverNode implements ClaimsMonitorHandler, EpochMonitorHandler, Pr
    * This method returns once the prover node has deposited an initial bond into the escrow contract.
    */
   async start() {
+    this.txFetcher.start();
     await this.bondManager.ensureBond();
     this.epochsMonitor.start(this);
     this.claimsMonitor.start(this);
@@ -213,6 +219,7 @@ export class ProverNode implements ClaimsMonitorHandler, EpochMonitorHandler, Pr
    */
   async stop() {
     this.log.info('Stopping ProverNode');
+    await this.txFetcher.stop();
     await this.epochsMonitor.stop();
     await this.claimsMonitor.stop();
     await this.prover.stop();
@@ -312,6 +319,22 @@ export class ProverNode implements ClaimsMonitorHandler, EpochMonitorHandler, Pr
     return this.l2BlockSource.getL1Constants();
   }
 
+  /** Monitors for new blocks and requests their txs from the p2p layer to ensure they are available for proving. */
+  @trackSpan('ProverNode.checkForTxs')
+  private async checkForTxs() {
+    const blockNumber = await this.l2BlockSource.getBlockNumber();
+    if (this.lastBlockNumber === undefined || blockNumber > this.lastBlockNumber) {
+      const block = await this.l2BlockSource.getBlock(blockNumber);
+      if (!block) {
+        return;
+      }
+      const txHashes = block.body.txEffects.map(tx => tx.txHash);
+      this.log.verbose(`Fetching ${txHashes.length} for block number ${blockNumber} from coordination`);
+      await this.coordination.getTxsByHash(txHashes); // This stores the txs in the tx pool, no need to persist them here
+      this.lastBlockNumber = blockNumber;
+    }
+  }
+
   @trackSpan('ProverNode.gatherEpochData', epochNumber => ({ [Attributes.EPOCH_NUMBER]: Number(epochNumber) }))
   private async gatherEpochData(epochNumber: bigint) {
     // Gather blocks for this epoch and their txs