Implemented mempool events

Author: rpanic

packages/common/src/events/EventEmitter.ts

@@ -17,9 +17,9 @@ export class EventEmitter<Events extends EventsRecord> {
     }
   }
 
-  public on(
-    event: keyof Events,
-    listener: (...args: Events[typeof event]) => void
+  public on<Key extends keyof Events>(
+    event: Key,
+    listener: (...args: Events[Key]) => void
   ) {
     (this.listeners[event] ??= []).push(listener);
   }

packages/sequencer/src/mempool/Mempool.ts

@@ -1,12 +1,18 @@
 import type { Field } from "o1js";
+import { EventEmittingComponent, EventsRecord } from "@proto-kit/common";
 
 import type { PendingTransaction } from "./PendingTransaction.js";
 
 export interface MempoolCommitment {
   transactionsHash: Field;
 }
 
-export interface Mempool {
+export interface MempoolEvents extends EventsRecord {
+  transactionAdded: [PendingTransaction, MempoolCommitment];
+  transactionsRemoved: [PendingTransaction[]]
+}
+
+export interface Mempool extends EventEmittingComponent<MempoolEvents> {
   /**
    * Add a transaction to the mempool
    * @returns The new commitment to the mempool

packages/sequencer/src/mempool/private/PrivateMempool.ts

@@ -1,7 +1,7 @@
 import { Field, Poseidon } from "o1js";
-import { noop } from "@proto-kit/common";
+import { EventEmitter, noop } from "@proto-kit/common";
 
-import type { Mempool, MempoolCommitment } from "../Mempool.js";
+import type { Mempool, MempoolCommitment, MempoolEvents } from "../Mempool.js";
 import type { PendingTransaction } from "../PendingTransaction.js";
 import { sequencerModule, SequencerModule } from "../../sequencer/builder/SequencerModule";
 import { TransactionValidator } from "../verification/TransactionValidator";
@@ -12,6 +12,8 @@ export class PrivateMempool extends SequencerModule<object> implements Mempool {
 
   private queue: PendingTransaction[] = [];
 
+  public events = new EventEmitter<MempoolEvents>();
+
   public constructor(
     private readonly transactionValidator: TransactionValidator
   ) {
@@ -27,6 +29,8 @@ export class PrivateMempool extends SequencerModule<object> implements Mempool {
       // Figure out how to generalize this
       this.commitment = Poseidon.hash([this.commitment, tx.hash()]);
 
+      this.events.emit("transactionAdded", [tx, this.commitment]);
+
       return { transactionsHash: this.commitment };
     }
     throw new Error(`Valdiation of tx failed: ${error ?? "unknown error"}`);
@@ -45,7 +49,12 @@ export class PrivateMempool extends SequencerModule<object> implements Mempool {
   public removeTxs(txs: PendingTransaction[]): boolean {
     const { length } = this.queue;
     this.queue = this.queue.filter((tx) => !txs.includes(tx));
+
+    this.events.emit("transactionsRemoved", [txs]);
+
     // Check that all elements have been removed and were in the mempool prior
+    // eslint-disable-next-line no-warning-comments,max-len
+    // TODO Make sure that in case of return value false, it gets rolled back somehow
     // eslint-disable-next-line unicorn/consistent-destructuring
     return length === this.queue.length + txs.length;
   }