Maxim Dolgolyov
fd29acbbdd
Classroom performance: - WebSocket server (ws-server.js) for low-latency cursor & stroke preview Replaces HTTP POST per event → eliminates per-message auth overhead Session member cache (30s TTL) avoids SQLite query per WS message Fallback to HTTP POST when WS not connected - Cursor throttle reduced 100ms → 33ms (~30fps) - Stroke preview throttle reduced 50ms → 20ms - whiteboard.js: render() is now rAF-gated (_doRender/_rafPending) Multiple render() calls within one frame collapse into one repaint document.hidden check — zero CPU when tab is in background visibilitychange listener restores canvas on tab focus Guest board: - guestClassroom.js route: public token-based read-only access - guest-board.html: name entry + read-only whiteboard + SSE - SSE: addGuestClient/removeGuestClient/emitToGuests Screen share picker: - Discord-style modal with tab switching (screen/window/tab) - Live video preview before confirming share - useExistingScreenStream() in ClassroomRTC Fullscreen exit overlay: - #cr-fs-exit-overlay button inside cr-board-wrap - Visible only via CSS :fullscreen selector (touchpad users) File sharing from library: - Teacher picks file from library, sends as styled card in chat - crDownloadLibraryFile() fetches with Bearer auth Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
86 lines
2.6 KiB
JavaScript
86 lines
2.6 KiB
JavaScript
/* ── SSE registry — shared between controllers ─────────────────────────── */
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const clients = new Map(); // userId -> Set<res>
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const guestClients = new Map(); // sessionId -> Set<res>
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const db = require('./db/db');
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function addClient(userId, res) {
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if (!clients.has(userId)) clients.set(userId, new Set());
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clients.get(userId).add(res);
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}
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function removeClient(userId, res) {
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const set = clients.get(userId);
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if (!set) return;
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set.delete(res);
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if (set.size === 0) clients.delete(userId);
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}
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function emit(userId, data) {
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const conns = clients.get(userId);
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if (!conns?.size) return;
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const payload = `data: ${JSON.stringify(data)}\n\n`;
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for (const res of conns) {
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try { res.write(payload); } catch {}
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}
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}
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// Heartbeat: detect and remove dead connections every 30s
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setInterval(() => {
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for (const [userId, conns] of clients) {
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for (const res of conns) {
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try {
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if (res.writableEnded || res.destroyed) { conns.delete(res); continue; }
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res.write(': heartbeat\n\n');
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} catch { conns.delete(res); }
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}
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if (conns.size === 0) clients.delete(userId);
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}
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for (const [sessionId, conns] of guestClients) {
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for (const res of conns) {
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try {
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if (res.writableEnded || res.destroyed) { conns.delete(res); continue; }
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res.write(': heartbeat\n\n');
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} catch { conns.delete(res); }
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}
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if (conns.size === 0) guestClients.delete(sessionId);
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}
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}, 30_000).unref();
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/* Broadcast to all members of a class */
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function emitToClass(classId, data) {
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const members = db.prepare('SELECT user_id FROM class_members WHERE class_id=?').all(classId);
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for (const { user_id } of members) emit(user_id, data);
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}
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/* ── Guest SSE (session-scoped, no userId) ── */
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function addGuestClient(sessionId, res) {
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if (!guestClients.has(sessionId)) guestClients.set(sessionId, new Set());
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guestClients.get(sessionId).add(res);
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}
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function removeGuestClient(sessionId, res) {
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const set = guestClients.get(sessionId);
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if (!set) return;
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set.delete(res);
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if (set.size === 0) guestClients.delete(sessionId);
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}
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function emitToGuests(sessionId, data) {
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const set = guestClients.get(sessionId);
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if (!set?.size) return;
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const payload = `data: ${JSON.stringify(data)}\n\n`;
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for (const res of set) {
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try { res.write(payload); } catch {}
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}
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}
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/* Returns array of user IDs currently connected via SSE */
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function getOnlineUserIds() {
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return [...clients.keys()];
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}
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module.exports = {
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addClient, removeClient, emit, emitToClass, getOnlineUserIds,
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addGuestClient, removeGuestClient, emitToGuests,
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};
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