Added failsafe in case producer is busy

Author: rpanic

packages/common/src/events/EventEmitter.ts

@@ -1,26 +1,68 @@
 import { EventsRecord } from "./EventEmittingComponent";
 
 type ListenersHolder<Events extends EventsRecord> = {
-  // eslint-disable-next-line putout/putout
-  [key in keyof Events]?: ((...args: Events[key]) => void)[];
+  [key in keyof Events]?: {
+    id: number;
+    listener: (...args: Events[key]) => void;
+  }[];
 };
 
 export class EventEmitter<Events extends EventsRecord> {
   private readonly listeners: ListenersHolder<Events> = {};
 
+  private counter = 0;
+
+  // Fields used for offSelf()
+  private currentListenerId: number | undefined = undefined;
+
+  private currentListenerEventName: keyof Events | undefined = undefined;
+
   public emit(event: keyof Events, ...parameters: Events[typeof event]) {
     const listeners = this.listeners[event];
-    if(listeners !== undefined) {
+    if (listeners !== undefined) {
+      this.currentListenerEventName = event;
+
       listeners.forEach((listener) => {
-        listener(...parameters);
+        this.currentListenerId = listener.id;
+
+        listener.listener(...parameters);
+
+        this.currentListenerId = undefined;
       });
+      this.currentListenerEventName = undefined;
     }
   }
 
   public on<Key extends keyof Events>(
     event: Key,
     listener: (...args: Events[Key]) => void
-  ) {
-    (this.listeners[event] ??= []).push(listener);
+  ): number {
+    // eslint-disable-next-line no-multi-assign
+    const id = (this.counter += 1);
+    (this.listeners[event] ??= []).push({
+      id,
+      listener,
+    });
+    return id;
+  }
+
+  // eslint-disable-next-line no-warning-comments
+  // TODO Improve to be thread-safe
+  public offSelf() {
+    if (
+      this.currentListenerEventName !== undefined &&
+      this.currentListenerId !== undefined
+    ) {
+      this.off(this.currentListenerEventName, this.currentListenerId);
+    }
+  }
+
+  public off<Key extends keyof Events>(event: Key, id: number) {
+    const listeners = this.listeners[event];
+    if (listeners !== undefined) {
+      this.listeners[event] = listeners.filter(
+        (listener) => listener.id !== id
+      );
+    }
   }
 }

packages/sequencer/src/protocol/production/trigger/AutomaticBlockTrigger.ts

@@ -28,7 +28,21 @@ export class AutomaticBlockTrigger
     // eslint-disable-next-line @typescript-eslint/no-misused-promises
     this.mempool.events.on("transactionAdded", async () => {
       log.info("Transaction received, creating block...");
-      await this.unprovenProducerModule.tryProduceUnprovenBlock();
+      const block = await this.unprovenProducerModule.tryProduceUnprovenBlock();
+
+      // In case the block producer was busy, we need to re-trigger production
+      // as soon as the previous production was finished
+      if (block === undefined) {
+        this.unprovenProducerModule.events.on(
+          "unprovenBlockProduced",
+          async () => {
+            // eslint-disable-next-line max-len
+            // Make sure this comes before await, because otherwise we have a race condition
+            this.unprovenProducerModule.events.offSelf();
+            await this.unprovenProducerModule.tryProduceUnprovenBlock();
+          }
+        );
+      }
     });
   }
 }