rentgendroid/http_server/code/screenshot.mjs

import fs from "fs";
import { sleep } from "./utils.mjs";
import { WebSocket } from "ws";

export const android_websocket = new WebSocket("ws://android:3000");

let doneWrite = 0;
let screenshotPromise = null;

async function screenshot() {
	const time_start = Date.now();
	let retries = 0;
	while (android_websocket.readyState != WebSocket.OPEN) {
		await sleep(15);
		retries++;
		if (retries > 50)
		{
			console.error("Screenshot ws timeout");
			doneWrite = 0;
			screenshotPromise = null;
			return ;
		}
	}
	android_websocket.send("screenshot");
	while (!doneWrite) {
		await sleep(15);
		if (Date.now() - time_start > 2000) {
			console.error("Screenshot timed out after 2s");
			break; // timeout
		}
	}
	doneWrite = 0;
	screenshotPromise = null;
}

export async function guardedScreenshot() {
	if (!screenshotPromise) {
		screenshotPromise = screenshot();
	} else {
		console.log("ongoing screenshot promise not taking a new one");
	}
	return screenshotPromise;
}

export async function waitFullBoot() {
	var start = performance.now();
	var counter = 0;

	//will timeout after 10 min
	while (performance.now() - start < 600 * 1000) {
		var before = performance.now();
		await screenshot();
		var after = performance.now();
		if (after - before < process.env.screenshotDelayMs) counter++;
		else counter = 0;

		if (counter === 10) return;
	}

	throw new Error("wait for screenshot time to be less than 0.5s timed out");
}

android_websocket.on("message", (dataBuf) => {
	let fd;
	fd = fs.openSync("/code/screenshot.png", "w");
	fs.writeSync(fd, dataBuf);
	fs.close(fd);
	doneWrite = 1;
});