Queue OCR & ASR work

src/vision.ts

@@ -2,8 +2,26 @@ import {createWorker} from 'tesseract.js';
 import {AbortablePromise, Ai} from './ai.ts';
 
 export class Vision {
+	private worker: any = null;
+	private queue: Array<{ path: string, resolve: any, reject: any }> = [];
+	private busy = false;
 
-	constructor(private ai: Ai) { }
+	constructor(private ai: Ai) {}
+
+	private async processQueue() {
+		if(this.busy || !this.queue.length) return;
+		this.busy = true;
+		const job = this.queue.shift()!;
+		if(!this.worker) this.worker = await createWorker(this.ai.options.ocr || 'eng', 2, {cachePath: this.ai.options.path});
+		try {
+			const {data} = await this.worker.recognize(job.path);
+			job.resolve(data.text.trim() || null);
+		} catch(err) {
+			job.reject(err);
+		}
+		this.busy = false;
+		this.processQueue();
+	}
 
 	/**
 	 * Convert image to text using Optical Character Recognition
@@ -11,13 +29,16 @@ export class Vision {
 	 * @returns {AbortablePromise<string | null>} Promise of extracted text with abort method
 	 */
 	ocr(path: string): AbortablePromise<string | null> {
-		let worker: any;
-		const p = new Promise<string | null>(async res => {
-			worker = await createWorker(this.ai.options.ocr || 'eng', 2, {cachePath: this.ai.options.path});
-			const {data} = await worker.recognize(path);
-			await worker.terminate();
-			res(data.text.trim() || null);
+		let aborted = false;
+		const abort = () => { aborted = true; };
+		const p = new Promise<string | null>((resolve, reject) => {
+			this.queue.push({
+				path,
+				resolve: (text: string | null) => !aborted && resolve(text),
+				reject: (err: Error) => !aborted && reject(err)
+			});
+			this.processQueue();
 		});
-		return Object.assign(p, {abort: () => worker?.terminate()});
+		return Object.assign(p, {abort});
 	}
 }