feat(api): 新增 /ws/collab 通道与课堂求助控制面
学生发起/撤销求助，在线教师收到全量列表。求助只在内存，不落库。 二进制帧的限流单独一档，避免协作输入把连接踢掉。 Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01K1d8B3f4SXJwDvUY625eQd
This commit is contained in:
165
apps/api/src/collab/handler.ts
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165
apps/api/src/collab/handler.ts
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@@ -0,0 +1,165 @@
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import { and, eq, isNull } from "drizzle-orm"
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import { touchSession } from "../auth/session"
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import { db, schema } from "../db"
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import {
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addRequest,
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addTeacher,
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getRequest,
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hasTeacherOnline,
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listRequests,
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queueAheadOf,
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removeRequest,
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removeTeacher,
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teacherSockets,
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type CollabSocket,
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type HelpRequest,
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} from "./state"
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const TEACHER_ROLES = ["Teacher Admin", "Super Admin"]
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function isTeacher(ws: CollabSocket) {
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return TEACHER_ROLES.includes(ws.data.adminType ?? "")
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}
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/** 推给老师的列表条目。不含 socket，也不含任何代码内容 */
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function serializeRequest(request: HelpRequest) {
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return {
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studentId: request.studentId,
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studentName: request.studentName,
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className: request.className,
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problemId: request.problemId,
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problemTitle: request.problemTitle,
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createdAt: request.createdAt,
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status: request.status,
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teacherName: request.teacherName ?? null,
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}
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}
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export function broadcastRequests() {
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const payload = JSON.stringify({
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type: "requests",
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list: listRequests().map(serializeRequest),
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})
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for (const ws of teacherSockets()) ws.send(payload)
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}
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function sendHelpStatus(
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ws: CollabSocket,
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status: "pending" | "active" | "cancelled" | "no_teacher",
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extra: Record<string, unknown> = {},
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) {
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ws.send(JSON.stringify({ type: "help_status", status, ...extra }))
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}
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export function handleCollabOpen(ws: CollabSocket) {
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if (isTeacher(ws)) {
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addTeacher(ws)
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// 新上线的老师要立刻看到当前队列，不能等下一次变更
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ws.send(
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JSON.stringify({ type: "requests", list: listRequests().map(serializeRequest) }),
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)
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}
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}
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export function handleCollabClose(ws: CollabSocket) {
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if (isTeacher(ws)) removeTeacher(ws)
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// 房间与请求的清理在 Task 3 补
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}
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export async function handleCollabMessage(ws: CollabSocket, raw: string) {
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let message: { type?: unknown; problemId?: unknown; studentId?: unknown }
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try {
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message = JSON.parse(raw) as typeof message
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} catch {
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ws.send(JSON.stringify({ type: "error", message: "Invalid JSON" }))
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return
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}
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// 心跳不查库，和 /ws/submissions 的处理一致
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if (message.type === "ping") {
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ws.send(JSON.stringify({ type: "pong", timestamp: (message as any).timestamp }))
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return
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}
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// 握手时校验过一次不算数 —— 这条连接能挂几个小时
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if (!(await touchSession(ws.data.token))) {
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ws.close(1008, "Session expired")
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return
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}
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switch (message.type) {
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case "help_request":
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await handleHelpRequest(ws, message.problemId)
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return
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case "help_cancel":
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handleHelpCancel(ws)
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return
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default:
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ws.send(JSON.stringify({ type: "error", message: "Invalid message" }))
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}
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}
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async function handleHelpRequest(ws: CollabSocket, problemId: unknown) {
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if (typeof problemId !== "string" || !problemId) {
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ws.send(JSON.stringify({ type: "error", message: "Invalid problemId" }))
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return
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}
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if (isTeacher(ws)) {
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ws.send(JSON.stringify({ type: "error", message: "教师不能发起求助" }))
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return
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}
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if (!hasTeacherOnline()) {
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sendHelpStatus(ws, "no_teacher")
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return
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}
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// 只认非比赛题：contest_id 为空的那条。比赛题不提供求助
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const [problem] = await db
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.select({ title: schema.problem.title })
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.from(schema.problem)
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.where(
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and(
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eq(schema.problem.displayId, problemId),
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isNull(schema.problem.contestId),
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),
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)
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.limit(1)
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if (!problem) {
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ws.send(JSON.stringify({ type: "error", message: "题目不存在或不支持求助" }))
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return
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}
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const existing = getRequest(ws.data.userId)
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// 已经在协作中就不重复登记，否则会把正在进行的房间挤掉
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if (existing?.status === "active") return
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const [student] = await db
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.select({ className: schema.user.className })
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.from(schema.user)
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.where(eq(schema.user.id, ws.data.userId))
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.limit(1)
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addRequest({
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studentId: ws.data.userId,
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studentName: ws.data.username ?? "",
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className: student?.className ?? null,
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problemId,
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problemTitle: problem.title,
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createdAt: Date.now(),
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status: "pending",
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socket: ws,
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})
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sendHelpStatus(ws, "pending", { queueAhead: queueAheadOf(ws.data.userId) })
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broadcastRequests()
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}
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function handleHelpCancel(ws: CollabSocket) {
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const request = getRequest(ws.data.userId)
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if (!request || request.status === "active") return
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removeRequest(ws.data.userId)
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broadcastRequests()
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}
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/** Task 3 会把它换成真正的按房间转发。此刻房间还不存在，先收下不处理 */
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export function handleCollabBinary(_ws: CollabSocket, _data: Buffer | Uint8Array) {}
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83
apps/api/src/collab/state.ts
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83
apps/api/src/collab/state.ts
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@@ -0,0 +1,83 @@
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/**
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* 课堂求助的内存状态。
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*
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* 不落库是有意的：求助是课堂上的即时行为，学生关掉页面这条请求就该消失。
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* 服务端只有一个 serve 进程（main.ts 单二进制 + 子命令，compose 里 oj-api 一个容器），
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* 所以内存态够用，不需要 Redis 同步。进程重启丢掉全部状态，两端重连后回到干净状态。
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*/
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export type CollabSocket = Bun.ServerWebSocket<import("../websocket").SubmissionSocketData>
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export interface HelpRequest {
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studentId: number
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studentName: string
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className: string | null
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/** 题目的展示号（problem._id 列，前端一路用的都是它），不是自增主键 */
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problemId: string
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problemTitle: string
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createdAt: number
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status: "pending" | "active"
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teacherId?: number
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teacherName?: string
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socket: CollabSocket
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}
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/** 求助表，以学生为键 —— 一个学生同时只有一个求助 */
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const requests = new Map<number, HelpRequest>()
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/** 在线老师的连接。用于推列表，也用于判断 no_teacher */
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const teachers = new Set<CollabSocket>()
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export function addRequest(request: HelpRequest) {
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requests.set(request.studentId, request)
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}
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export function getRequest(studentId: number) {
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return requests.get(studentId)
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}
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export function removeRequest(studentId: number) {
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return requests.delete(studentId)
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}
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export function hasRequest(studentId: number) {
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return requests.has(studentId)
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}
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/** 按发起时间正序。老师端按等待时长排序展示，不强制先来先到 */
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export function listRequests() {
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return Array.from(requests.values()).sort((a, b) => a.createdAt - b.createdAt)
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}
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/** 比自己早创建、且仍在排队的请求数 */
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export function queueAheadOf(studentId: number) {
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const self = requests.get(studentId)
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if (!self) return 0
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let ahead = 0
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for (const request of requests.values()) {
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if (request.status === "pending" && request.createdAt < self.createdAt) ahead += 1
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}
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return ahead
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}
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export function addTeacher(ws: CollabSocket) {
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teachers.add(ws)
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}
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export function removeTeacher(ws: CollabSocket) {
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teachers.delete(ws)
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}
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export function hasTeacherOnline() {
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return teachers.size > 0
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}
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export function teacherSockets() {
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return teachers
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}
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/** 仅供进程退出或测试用，正常路径不该调 */
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export function resetCollabState() {
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requests.clear()
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teachers.clear()
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}
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@@ -100,19 +100,30 @@ const server = Bun.serve<SubmissionSocketData>({
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new Response("Not found", { status: 404 })
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)
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}
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if (url.pathname === "/ws/submissions" || url.pathname === "/ws/config") {
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if (
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url.pathname === "/ws/submissions" ||
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url.pathname === "/ws/config" ||
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url.pathname === "/ws/collab"
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) {
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if (!isAllowedWebSocketOrigin(request.headers.get("origin"), url)) {
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return new Response("Forbidden", { status: 403 })
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}
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const user = await getRequestSessionUser(request)
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if (!user) return new Response("Unauthorized", { status: 401 })
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const kind = url.pathname === "/ws/config" ? "config" : "submissions"
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const kind =
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url.pathname === "/ws/config"
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? "config"
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: url.pathname === "/ws/collab"
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? "collab"
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: "submissions"
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if (
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bunServer.upgrade(request, {
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data: {
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userId: user.id,
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kind,
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token: readRequestSessionToken(request),
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username: user.username,
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adminType: user.adminType,
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},
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})
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) {
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@@ -2,6 +2,12 @@ import { flowchartUpdateSchema, submissionUpdateSchema } from "@oj2/contract"
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import { and, eq } from "drizzle-orm"
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import { touchSession } from "./auth/session"
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import {
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handleCollabBinary,
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handleCollabClose,
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handleCollabMessage,
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handleCollabOpen,
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} from "./collab/handler"
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import { config } from "./config"
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import { db, schema } from "./db"
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import {
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@@ -51,12 +57,17 @@ export function isAllowedWebSocketOrigin(origin: string | null, url: URL) {
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export interface SubmissionSocketData {
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userId: number
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/** 同一个 Bun.serve 只能挂一个 websocket handler，用它区分两条通道 */
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kind: "submissions" | "config"
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/** 同一个 Bun.serve 只能挂一个 websocket handler，用它区分通道 */
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kind: "submissions" | "config" | "collab"
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/** 握手时那张会话的 token，留着定期确认它还没被登出 / 过期，见 sweepSessions */
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token: string
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/** 令牌桶，open 时初始化，见 allowMessage */
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rate?: { tokens: number; updatedAt: number }
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/** 以下两项只有 kind === "collab" 时才填，握手时从会话里读 */
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username?: string
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adminType?: string
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/** 当前所在协作房间的房主（学生）id，见 collab/handler.ts */
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roomOwnerId?: number
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}
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/**
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@@ -69,11 +80,24 @@ export interface SubmissionSocketData {
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const RATE_BURST = 20
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const RATE_REFILL_PER_SECOND = 2
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function allowMessage(ws: Bun.ServerWebSocket<SubmissionSocketData>) {
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/**
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* collab 通道的二进制帧（Yjs update / awareness）单独一档。
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*
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* 它不查库、不解析，纯内存按房间转发，成本和文本控制帧完全不是一个量级；
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* 而连续快速输入大约 5-10 帧/秒，用严格档几秒钟就会把正在协作的人踢下线。
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*/
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const COLLAB_BINARY_BURST = 200
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const COLLAB_BINARY_REFILL_PER_SECOND = 100
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function allowMessage(
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ws: Bun.ServerWebSocket<SubmissionSocketData>,
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burst = RATE_BURST,
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refillPerSecond = RATE_REFILL_PER_SECOND,
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) {
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const now = Date.now()
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const rate = (ws.data.rate ??= { tokens: RATE_BURST, updatedAt: now })
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const refill = ((now - rate.updatedAt) / 1000) * RATE_REFILL_PER_SECOND
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rate.tokens = Math.min(RATE_BURST, rate.tokens + refill)
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const rate = (ws.data.rate ??= { tokens: burst, updatedAt: now })
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const refill = ((now - rate.updatedAt) / 1000) * refillPerSecond
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rate.tokens = Math.min(burst, rate.tokens + refill)
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rate.updatedAt = now
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if (rate.tokens < 1) return false
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rate.tokens -= 1
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@@ -165,6 +189,10 @@ export function submissionWebSocketHandler(): Bun.WebSocketHandler<SubmissionSoc
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open(ws) {
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liveSockets.add(ws)
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ws.data.rate = { tokens: RATE_BURST, updatedAt: Date.now() }
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if (ws.data.kind === "collab") {
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handleCollabOpen(ws)
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return
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}
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if (ws.data.kind === "config") {
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ws.subscribe(configTopic)
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return
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@@ -173,6 +201,25 @@ export function submissionWebSocketHandler(): Bun.WebSocketHandler<SubmissionSoc
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ws.subscribe(userEventTopic(ws.data.userId))
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},
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message(ws, message) {
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if (ws.data.kind === "collab") {
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if (typeof message !== "string") {
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if (!allowMessage(ws, COLLAB_BINARY_BURST, COLLAB_BINARY_REFILL_PER_SECOND)) {
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ws.close(1008, "Too many messages")
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return
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}
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handleCollabBinary(ws, message)
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return
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}
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if (!allowMessage(ws)) {
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ws.close(1008, "Too many messages")
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return
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}
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handleCollabMessage(ws, message).catch((error) => {
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console.error("Failed to handle collab message", error)
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ws.send(JSON.stringify({ type: "error", message: "Internal error" }))
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})
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return
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}
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if (!allowMessage(ws)) {
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ws.close(1008, "Too many messages")
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return
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@@ -187,6 +234,10 @@ export function submissionWebSocketHandler(): Bun.WebSocketHandler<SubmissionSoc
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},
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close(ws) {
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liveSockets.delete(ws)
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if (ws.data.kind === "collab") {
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handleCollabClose(ws)
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return
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}
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if (ws.data.kind === "config") {
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ws.unsubscribe(configTopic)
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return
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Reference in New Issue
Block a user