chore: jump to next slop on local network if there are pending txs (#20654)

Warp to the next slot when there are pending txs so the sequencer can
start building blocks with those txs.
This speeds up the starting time of the sandbox, which deploys some
testing accounts by default. It used to take ~50s to deploy an account,
and is reduced to ~5s with this change. Users' txs will also be mined
faster.

Author: LeilaWang

yarn-project/aztec/src/cli/aztec_start_action.ts

@@ -37,11 +37,11 @@ export async function aztecStart(options: any, userLog: LogFn, debugLogger: Logg
         l1RpcUrls: options.l1RpcUrls,
         testAccounts: localNetwork.testAccounts,
         realProofs: false,
-        // Setting the epoch duration to 4 by default for local network. This allows the epoch to be "proven" faster, so
+        // Setting the epoch duration to 2 by default for local network. This allows the epoch to be "proven" faster, so
         // the users can consume out hash without having to wait for a long time.
         // Note: We are not proving anything in the local network (realProofs == false). But in `createLocalNetwork`,
         // the EpochTestSettler will set the out hash to the outbox when an epoch is complete.
-        aztecEpochDuration: 4,
+        aztecEpochDuration: 2,
       },
       userLog,
     );

yarn-project/aztec/src/local-network/local-network.ts

@@ -18,6 +18,7 @@ import type { LogFn } from '@aztec/foundation/log';
 import { DateProvider, TestDateProvider } from '@aztec/foundation/timer';
 import { getVKTreeRoot } from '@aztec/noir-protocol-circuits-types/vk-tree';
 import { protocolContractsHash } from '@aztec/protocol-contracts';
+import { SequencerState } from '@aztec/sequencer-client';
 import type { ProvingJobBroker } from '@aztec/stdlib/interfaces/server';
 import type { PublicDataTreeLeaf } from '@aztec/stdlib/trees';
 import {
@@ -181,6 +182,21 @@ export async function createLocalNetwork(config: Partial<LocalNetworkConfig> = {
   const blobClient = createBlobClient();
   const node = await createAztecNode(aztecNodeConfig, { telemetry, blobClient, dateProvider }, { prefilledPublicData });
 
+  // Now that the node is up, let the watcher check for pending txs so it can skip unfilled slots faster when
+  // transactions are waiting in the mempool. Also let it check if the sequencer is actively building, to avoid
+  // warping time out from under an in-progress block.
+  watcher?.setGetPendingTxCount(() => node.getPendingTxCount());
+  const sequencer = node.getSequencer()?.getSequencer();
+  if (sequencer) {
+    const idleStates: Set<string> = new Set([
+      SequencerState.STOPPED,
+      SequencerState.STOPPING,
+      SequencerState.IDLE,
+      SequencerState.SYNCHRONIZING,
+    ]);
+    watcher?.setIsSequencerBuilding(() => !idleStates.has(sequencer.getState()));
+  }
+
   let epochTestSettler: EpochTestSettler | undefined;
   if (!aztecNodeConfig.p2pEnabled) {
     epochTestSettler = new EpochTestSettler(

yarn-project/aztec/src/testing/anvil_test_watcher.ts

@@ -31,6 +31,15 @@ export class AnvilTestWatcher {
 
   private isMarkingAsProven = true;
 
+  // Optional callback to check if there are pending txs in the mempool.
+  private getPendingTxCount?: () => Promise<number>;
+
+  // Optional callback to check if the sequencer is actively building a block.
+  private isSequencerBuilding?: () => boolean;
+
+  // Tracks when we first observed the current unfilled slot with pending txs (real wall time).
+  private unfilledSlotFirstSeen?: { slot: number; realTime: number };
+
   constructor(
     private cheatcodes: EthCheatCodes,
     rollupAddress: EthAddress,
@@ -59,6 +68,16 @@ export class AnvilTestWatcher {
     this.isLocalNetwork = isLocalNetwork;
   }
 
+  /** Sets a callback to check for pending txs, used to skip unfilled slots faster when txs are waiting. */
+  setGetPendingTxCount(fn: () => Promise<number>) {
+    this.getPendingTxCount = fn;
+  }
+
+  /** Sets a callback to check if the sequencer is actively building, to avoid warping while it works. */
+  setIsSequencerBuilding(fn: () => boolean) {
+    this.isSequencerBuilding = fn;
+  }
+
   async start() {
     if (this.filledRunningPromise) {
       throw new Error('Watcher already watching for filled slot');
@@ -131,15 +150,8 @@ export class AnvilTestWatcher {
       const nextSlotTimestamp = Number(await this.rollup.read.getTimestampForSlot([BigInt(nextSlot)]));
 
       if (BigInt(currentSlot) === checkpointLog.slotNumber) {
-        // We should jump to the next slot
-        try {
-          await this.cheatcodes.warp(nextSlotTimestamp, {
-            resetBlockInterval: true,
-          });
-        } catch (e) {
-          this.logger.error(`Failed to warp to timestamp ${nextSlotTimestamp}: ${e}`);
-        }
-
+        // The current slot has been filled, we should jump to the next slot.
+        await this.warpToTimestamp(nextSlotTimestamp);
         this.logger.info(`Slot ${currentSlot} was filled, jumped to next slot`);
         return;
       }
@@ -149,18 +161,50 @@ export class AnvilTestWatcher {
         return;
       }
 
-      const currentTimestamp = this.dateProvider?.now() ?? Date.now();
-      if (currentTimestamp > nextSlotTimestamp * 1000) {
-        try {
-          await this.cheatcodes.warp(nextSlotTimestamp, { resetBlockInterval: true });
-        } catch (e) {
-          this.logger.error(`Failed to warp to timestamp ${nextSlotTimestamp}: ${e}`);
+      // If there are pending txs and the sequencer missed them, warp quickly (after a 2s real-time debounce) so the
+      // sequencer can retry in the next slot. Without this, we'd have to wait a full real-time slot duration (~36s) for
+      // the dateProvider to catch up to the next slot timestamp. We skip the warp if the sequencer is actively building
+      // to avoid invalidating its in-progress work.
+      if (this.getPendingTxCount) {
+        const pendingTxs = await this.getPendingTxCount();
+        if (pendingTxs > 0) {
+          if (this.isSequencerBuilding?.()) {
+            this.unfilledSlotFirstSeen = undefined;
+            return;
+          }
+
+          const realNow = Date.now();
+          if (!this.unfilledSlotFirstSeen || this.unfilledSlotFirstSeen.slot !== currentSlot) {
+            this.unfilledSlotFirstSeen = { slot: currentSlot, realTime: realNow };
+            return;
+          }
+
+          if (realNow - this.unfilledSlotFirstSeen.realTime > 2000) {
+            await this.warpToTimestamp(nextSlotTimestamp);
+            this.unfilledSlotFirstSeen = undefined;
+            this.logger.info(`Slot ${currentSlot} was missed with pending txs, jumped to next slot`);
+          }
+
+          return;
         }
+      }
 
+      // Fallback: warp when the dateProvider time has passed the next slot timestamp.
+      const currentTimestamp = this.dateProvider?.now() ?? Date.now();
+      if (currentTimestamp > nextSlotTimestamp * 1000) {
+        await this.warpToTimestamp(nextSlotTimestamp);
         this.logger.info(`Slot ${currentSlot} was missed, jumped to next slot`);
       }
     } catch {
       this.logger.error('mineIfSlotFilled failed');
     }
   }
+
+  private async warpToTimestamp(timestamp: number) {
+    try {
+      await this.cheatcodes.warp(timestamp, { resetBlockInterval: true });
+    } catch (e) {
+      this.logger.error(`Failed to warp to timestamp ${timestamp}: ${e}`);
+    }
+  }
 }

yarn-project/sequencer-client/src/sequencer/sequencer.ts

@@ -422,6 +422,13 @@ export class Sequencer extends (EventEmitter as new () => TypedEventEmitter<Sequ
     );
   }
 
+  /**
+   * Returns the current sequencer state.
+   */
+  public getState(): SequencerState {
+    return this.state;
+  }
+
   /**
    * Internal helper for setting the sequencer state and checks if we have enough time left in the slot to transition to the new state.
    * @param proposedState - The new state to transition to.