Refactor Selenium to make it more robust.

It should stop runaway Firefox processes.

lib/www/server/lib/selenium/index.js

@@ -1,52 +1,110 @@
-// TODO Append location to PATH
-
 const path = require('path');
 const fs = require('fs');
-const {Builder, By, Key, until} = require('selenium-webdriver');
-const firefox   = require('selenium-webdriver/firefox');
+const { Builder, By, Key, until } = require('selenium-webdriver');
+const firefox = require('selenium-webdriver/firefox');
+const { execSync } = require('child_process');
 
 const geckodriverPath = path.resolve(__dirname, "geckodriver");
 
-// We launch a browser instance and then start an activity timer.
-// We shut down the browser after a period of inactivity, to
-// save memory.
+// State to prevent race conditions
 let driver = null;
 let timer = null;
+let isShuttingDown = false;
 
-function resetTimer () {
-	clearTimeout(timer);
-	timer = setTimeout(shutdown, 120000); // Yup, hardcoded to two minutes. For now anyway
+// Verify GeckoDriver exists
+if (!fs.existsSync(geckodriverPath)) {
+	throw new Error(`GeckoDriver not found at ${geckodriverPath}`);
 }
 
-async function launch () {
+function resetTimer() {
+	clearTimeout(timer);
+	timer = setTimeout(shutdown, 120000); // 2 minutes inactivity timeout
+}
+
+async function launch() {
+	if (isShuttingDown) {
+		console.log("Shutdown in progress, waiting...");
+		await new Promise(resolve => setTimeout(resolve, 1000));
+		return launch(); // Retry after delay
+	}
 	resetTimer();
 	if (!driver) {
 		console.log("Launching Firefox");
 		const options = new firefox.Options();
+		// Explicitly set headless mode and optimize for server
+		options.addArguments('--headless', '--no-sandbox', '--disable-gpu');
+		// Limit content processes to reduce resource usage
+		options.setPreference('dom.ipc.processCount', 1);
+
+		const service = new firefox.ServiceBuilder(geckodriverPath);
 		driver = await new Builder()
 			.forBrowser('firefox')
-			.setFirefoxService(new firefox.ServiceBuilder(geckodriverPath))
-			.setFirefoxOptions(options.headless())
+			.setFirefoxService(service)
+			.setFirefoxOptions(options)
 			.build();
 	}
 }
 
-async function shutdown () {
-	if (driver) {
+async function shutdown() {
+	if (driver && !isShuttingDown) {
+		isShuttingDown = true;
 		console.log("Shutting down Firefox");
-		// This is an attempt at avoiding a race condition if someone
-		// makes a call and resets the timer while the shutdown is in
-		// progress.
-		const d = driver;
-		driver = null;
-		await d.quit();
+		try {
+			const d = driver;
+			driver = null;
+			await d.quit();
+			// Explicitly stop the service
+			const service = d.service;
+			if (service) {
+				service.stop();
+			}
+			console.log("Firefox shutdown complete");
+		} catch (error) {
+			console.error("Error during shutdown:", error);
+			// Forcefully kill lingering processes (Linux/Unix)
+			try {
+				execSync('pkill -u $USER firefox || true');
+				execSync('pkill -u $USER geckodriver || true');
+				console.log("Terminated lingering Firefox/GeckoDriver processes");
+			} catch (killError) {
+				console.error("Error killing processes:", killError);
+			}
+		} finally {
+			isShuttingDown = false;
+		}
 	}
 }
 
-async function url2pdf (url) {
+async function url2pdf(url) {
 	await launch();
-	await driver.get(url);
-	return await driver.printPage({width: 21.0, height: 29.7});
+	try {
+		console.log(`Navigating to ${url}`);
+		await driver.get(url);
+		// Add delay to stabilize Marionette communication
+		await driver.sleep(3000);
+		const pdf = await driver.printPage({ width: 21.0, height: 29.7 });
+		resetTimer(); // Reset timer after successful operation
+		return pdf;
+	} catch (error) {
+		console.error("Error in url2pdf:", error);
+		await shutdown(); // Force shutdown on error
+		throw error;
+	}
 }
 
+// Periodically clean up orphaned processes (every 5 minutes)
+setInterval(() => {
+	try {
+		const firefoxCount = execSync('pgrep -c firefox || echo 0').toString().trim();
+		if (parseInt(firefoxCount) > 0 && !driver) {
+			console.log(`Found ${firefoxCount} orphaned Firefox processes, cleaning up...`);
+			execSync('pkill -u $USER firefox || true');
+			execSync('pkill -u $USER geckodriver || true');
+			console.log("Cleaned up orphaned processes");
+		}
+	} catch (error) {
+		console.error("Error checking orphaned processes:", error);
+	}
+}, 300000);
+
 module.exports = { url2pdf };