| 1 | package hub |
| 2 | |
| 3 | import "context" |
| 4 | |
| 5 | func admittedCountLocked(r *room) int { |
| 6 | n := 0 |
| 7 | for _, p := range r.peers { |
| 8 | if p.Admitted { |
| 9 | n++ |
| 10 | } |
| 11 | } |
| 12 | return n |
| 13 | } |
| 14 | |
| 15 | func waitingCountLocked(r *room) int { |
| 16 | n := 0 |
| 17 | for _, p := range r.peers { |
| 18 | if p.Joined && !p.Admitted { |
| 19 | n++ |
| 20 | } |
| 21 | } |
| 22 | return n |
| 23 | } |
| 24 | |
| 25 | // rosterFor is the authoritative snapshot for one viewer: admitted peers |
| 26 | // with the viewer's pair generation, and the waiting queue only when the |
| 27 | // viewer is a member (spec §4.3). |
| 28 | func (h *Hub) rosterFor(r *room, viewer *Participation) *Roster { |
| 29 | ro := &Roster{} |
| 30 | for _, p := range r.peers { |
| 31 | if !p.Admitted { |
| 32 | continue |
| 33 | } |
| 34 | rp := RosterPeer{Peer: p.Peer, Name: p.Name, Kind: p.Kind.String(), Media: p.Media} |
| 35 | if p.Peer != viewer.Peer { |
| 36 | rp.Gen = h.genLocked(r, viewer.Peer, p.Peer) |
| 37 | } |
| 38 | ro.Peers = append(ro.Peers, rp) |
| 39 | } |
| 40 | if viewer.Kind == KindMember { |
| 41 | for _, p := range r.peers { |
| 42 | if p.Joined && !p.Admitted { |
| 43 | // Usually a guest, but a peer the tick promoted while the |
| 44 | // room was full waits on as a member (spec §2.4). |
| 45 | ro.Waiting = append(ro.Waiting, RosterPeer{Peer: p.Peer, Name: p.Name, Kind: p.Kind.String()}) |
| 46 | } |
| 47 | } |
| 48 | } |
| 49 | return ro |
| 50 | } |
| 51 | |
| 52 | // genLocked returns the pair's generation, starting it at one on first |
| 53 | // sight (spec §4.6). |
| 54 | func (h *Hub) genLocked(r *room, a, b PeerID) uint64 { |
| 55 | k := keyFor(a, b) |
| 56 | if r.gens[k] == 0 { |
| 57 | r.gens[k] = 1 |
| 58 | } |
| 59 | return r.gens[k] |
| 60 | } |
| 61 | |
| 62 | // admitLocked is the one transition into the admitted state: the cap |
| 63 | // under the lock, roster to the newcomer, peer to the others, knock-gone |
| 64 | // to members if they were waiting. Returns false when the room is full. |
| 65 | func (h *Hub) admitLocked(r *room, p *Participation) bool { |
| 66 | if admittedCountLocked(r) >= MaxAdmitted { |
| 67 | return false |
| 68 | } |
| 69 | wasWaiting := p.Joined && !p.Admitted |
| 70 | p.Admitted = true |
| 71 | p.Joined = true |
| 72 | p.JoinedAt = h.cfg.Now() |
| 73 | h.sendLocked(p, Message{Type: TypeRoster, Roster: h.rosterFor(r, p)}) |
| 74 | for _, q := range r.peers { |
| 75 | if q.Admitted && q.Peer != p.Peer && q.sub != nil { |
| 76 | // The one-entry roster carries this recipient's own pair |
| 77 | // generation with the newcomer; browsers read it from |
| 78 | // roster.peers[0]. |
| 79 | q.sub.send(Message{Type: TypePeer, Peer: p.Peer, Name: p.Name, |
| 80 | Roster: &Roster{Peers: []RosterPeer{{Peer: p.Peer, Name: p.Name, Kind: p.Kind.String(), Gen: h.genLocked(r, q.Peer, p.Peer), Media: p.Media}}}}) |
| 81 | } |
| 82 | } |
| 83 | if wasWaiting { |
| 84 | // Not to the newcomer: a peer the tick promoted to member is |
| 85 | // admitted as one, and would otherwise be told its own knock had |
| 86 | // gone, a moment after the roster that already said so. |
| 87 | h.broadcastLocked(r, Message{Type: TypeKnockGone, From: p.Peer}, func(q *Participation) bool { |
| 88 | return q.Peer != p.Peer && admittedMembers(q) |
| 89 | }) |
| 90 | } |
| 91 | return true |
| 92 | } |
| 93 | |
| 94 | // refreshRostersLocked sends the authoritative snapshot to every |
| 95 | // admitted peer, which is what a kind change owes them (spec §2.4). |
| 96 | func (h *Hub) refreshRostersLocked(r *room) { |
| 97 | for _, q := range r.peers { |
| 98 | if q.Admitted && q.sub != nil { |
| 99 | q.sub.send(Message{Type: TypeRoster, Roster: h.rosterFor(r, q)}) |
| 100 | } |
| 101 | } |
| 102 | } |
| 103 | |
| 104 | // setKindLocked records a re-derived kind. A kind that actually changed |
| 105 | // on an admitted peer owes every admitted peer a fresh roster, whether |
| 106 | // the change was seen on the tick or on a request (spec §2.4), so every |
| 107 | // re-derivation writes Kind through here and nowhere else. |
| 108 | func (h *Hub) setKindLocked(r *room, p *Participation, kind Kind) { |
| 109 | if p.Kind == kind { |
| 110 | return |
| 111 | } |
| 112 | p.Kind = kind |
| 113 | if p.Admitted { |
| 114 | h.refreshRostersLocked(r) |
| 115 | } |
| 116 | } |
| 117 | |
| 118 | // standingLostLocked applies a loss of standing the way spec §2.4 asks. |
| 119 | // A member loses the room; so does anyone not yet admitted, a guest with |
| 120 | // the reason their grant earns. An **admitted** guest is untouched: a |
| 121 | // participation is never ended by a grant expiring, because the |
| 122 | // participation is the authority now (ruling 14). It reports whether the |
| 123 | // participation ended, and announces the departure when it did. |
| 124 | func (h *Hub) standingLostLocked(r *room, p *Participation) bool { |
| 125 | if p.Kind != KindMember && p.Admitted { |
| 126 | return false |
| 127 | } |
| 128 | reason := ReasonExpired |
| 129 | if p.Kind == KindMember { |
| 130 | reason = ReasonStanding |
| 131 | } |
| 132 | wasAdmitted, wasWaiting := h.endLocked(r, p, reason) |
| 133 | h.announceDepartureLocked(r, p, wasAdmitted, wasWaiting) |
| 134 | return true |
| 135 | } |
| 136 | |
| 137 | // memberStandingGone re-derives standing for a participation whose kind |
| 138 | // is `member`, which spec §2.5's paragraph — and §15.12, which corrects |
| 139 | // the table row above it — require on **every** request that |
| 140 | // participation makes, not only on the tick: "a member who has just been |
| 141 | // removed is dropped by the next thing they do, not the next tick." |
| 142 | // Relay, Reset, Resume and CanResume all go through here first. |
| 143 | // |
| 144 | // A guest is never touched and never costs a standing read: ruling 14 |
| 145 | // makes the participation the authority once someone is admitted, and a |
| 146 | // waiting guest is the tick's to expire. |
| 147 | // |
| 148 | // end says whether this call may write **at all**. The mutating callers |
| 149 | // (Relay, Reset, Resume) end a member who has lost standing here and |
| 150 | // now, with lost{standing} and the departure the room is owed, and |
| 151 | // record a kind that has changed; the probe (CanResume) passes false and |
| 152 | // writes nothing whatever the answer was — not the ending, and not the |
| 153 | // kind either, because recording a member's demotion to guest would |
| 154 | // broadcast a fresh roster to every admitted peer, which is a room-wide |
| 155 | // event caused by a request that is defined as changing nothing (§15.3, |
| 156 | // Codex S2-10). The next mutating request, or the tick, applies it. |
| 157 | // |
| 158 | // The standing read happens with the lock down, like every other one |
| 159 | // (StandingFor is a database read), so the participation is re-found |
| 160 | // under the lock afterwards: it may have ended while the read was in |
| 161 | // flight. |
| 162 | func (h *Hub) memberStandingGone(ctx context.Context, sqid, session string, peer PeerID, end bool) (bool, error) { |
| 163 | h.mu.Lock() |
| 164 | p, found := h.findLocked(sqid, session, peer) |
| 165 | if !found || p.Kind != KindMember { |
| 166 | // Not found is the caller's own lookup to answer, in its own |
| 167 | // words; a guest is not this function's business at all. |
| 168 | h.mu.Unlock() |
| 169 | return false, nil |
| 170 | } |
| 171 | personID := p.PersonID |
| 172 | h.mu.Unlock() |
| 173 | |
| 174 | kind, ok, err := h.cfg.StandingFor(ctx, sqid, personID) |
| 175 | if err != nil { |
| 176 | return false, err |
| 177 | } |
| 178 | |
| 179 | h.mu.Lock() |
| 180 | defer h.mu.Unlock() |
| 181 | p, found = h.findLocked(sqid, session, peer) |
| 182 | if !found { |
| 183 | return false, nil |
| 184 | } |
| 185 | r := h.rooms[sqid] |
| 186 | if !ok { |
| 187 | if !end { |
| 188 | // The kind is read again rather than remembered: the tick may |
| 189 | // have made this an admitted guest while the read was out, and |
| 190 | // that one keeps everything (ruling 14). |
| 191 | return p.Kind == KindMember, nil |
| 192 | } |
| 193 | return h.standingLostLocked(r, p), nil |
| 194 | } |
| 195 | if !end { |
| 196 | return false, nil |
| 197 | } |
| 198 | h.setKindLocked(r, p, kind) |
| 199 | return false, nil |
| 200 | } |
| 201 | |
| 202 | // Join is the entry, so standing is re-derived now (spec §2.5). |
| 203 | func (h *Hub) Join(ctx context.Context, sqid, session string, peer PeerID) error { |
| 204 | kind, ok, err := h.standing(ctx, sqid, session, peer) |
| 205 | if err != nil { |
| 206 | return err |
| 207 | } |
| 208 | waiting := true |
| 209 | if h.cfg.WaitingRoom != nil { |
| 210 | waiting, err = h.cfg.WaitingRoom(ctx, sqid) |
| 211 | if err != nil { |
| 212 | return err |
| 213 | } |
| 214 | } |
| 215 | h.mu.Lock() |
| 216 | defer h.mu.Unlock() |
| 217 | p, found := h.findLocked(sqid, session, peer) |
| 218 | if !found { |
| 219 | return ErrUnknownPeer // it ended while standing was being read |
| 220 | } |
| 221 | r := h.rooms[sqid] |
| 222 | if !ok { |
| 223 | // Standing is checked before the kind is written, because what a |
| 224 | // loss costs depends on the kind the peer held. A member is |
| 225 | // dropped by the next thing they do, not the next tick (§2.5); |
| 226 | // an admitted guest whose grant lapsed keeps everything. |
| 227 | if h.standingLostLocked(r, p) { |
| 228 | return ErrNotYours |
| 229 | } |
| 230 | return nil |
| 231 | } |
| 232 | h.setKindLocked(r, p, kind) |
| 233 | if p.Joined && p.Admitted { |
| 234 | return nil // idempotent |
| 235 | } |
| 236 | if p.Joined { |
| 237 | // Waiting. A guest waits on; a peer the tick promoted to member |
| 238 | // while the room was full may retry here, which is the retry |
| 239 | // §2.4 promises them. |
| 240 | if kind != KindMember && waiting { |
| 241 | return nil |
| 242 | } |
| 243 | if !h.admitLocked(r, p) { |
| 244 | h.sendLocked(p, Message{Type: TypeFull}) |
| 245 | return ErrMeshFull |
| 246 | } |
| 247 | return nil |
| 248 | } |
| 249 | if kind == KindMember || !waiting { |
| 250 | if !h.admitLocked(r, p) { |
| 251 | h.sendLocked(p, Message{Type: TypeFull}) |
| 252 | return ErrMeshFull |
| 253 | } |
| 254 | return nil |
| 255 | } |
| 256 | if waitingCountLocked(r) >= MaxWaiting { |
| 257 | h.sendLocked(p, Message{Type: TypeFull}) |
| 258 | return ErrTooManyWaiting |
| 259 | } |
| 260 | p.Joined = true |
| 261 | p.JoinedAt = h.cfg.Now() |
| 262 | h.broadcastLocked(r, Message{Type: TypeKnock, From: p.Peer, Name: p.Name}, admittedMembers) |
| 263 | // Who is already looking, gathered here because it needs the lock and |
| 264 | // must not be re-read later: by the time the notification is sent the |
| 265 | // room may have changed, and telling someone who *was* present is a |
| 266 | // smaller fault than holding the mutex across a network call. |
| 267 | if h.cfg.Knocked != nil { |
| 268 | watching := make([]int64, 0, len(r.peers)) |
| 269 | for _, other := range r.peers { |
| 270 | if other.Admitted && other.Kind == KindMember { |
| 271 | watching = append(watching, other.PersonID) |
| 272 | } |
| 273 | } |
| 274 | go h.cfg.Knocked(r.sqid, watching, p.Name) |
| 275 | } |
| 276 | return nil |
| 277 | } |
| 278 | |
| 279 | // standing looks the peer up to find its person, then asks the app |
| 280 | // without holding the lock, because it is a database read. |
| 281 | func (h *Hub) standing(ctx context.Context, sqid, session string, peer PeerID) (Kind, bool, error) { |
| 282 | h.mu.Lock() |
| 283 | p, found := h.findLocked(sqid, session, peer) |
| 284 | var personID int64 |
| 285 | if found { |
| 286 | personID = p.PersonID |
| 287 | } |
| 288 | h.mu.Unlock() |
| 289 | if !found { |
| 290 | return 0, false, ErrUnknownPeer |
| 291 | } |
| 292 | return h.cfg.StandingFor(ctx, sqid, personID) |
| 293 | } |
| 294 | |
| 295 | // Admit: the actor must be admitted with current member kind; the target |
| 296 | // waiting with entry authority now; the cap under the lock (spec §4.3). |
| 297 | // |
| 298 | // The actor's own authority is settled completely — found, current |
| 299 | // standing applied, admitted, member — before the target is looked at |
| 300 | // at all. The other order (found first in an earlier revision) let any |
| 301 | // joined participation, admitted or not, learn from the shape of the |
| 302 | // refusal alone whether a candidate peer id existed in the room, and |
| 303 | // spent a StandingFor call on the target even when the actor had no |
| 304 | // business asking (review Important 3). |
| 305 | func (h *Hub) Admit(ctx context.Context, sqid, session string, actor, target PeerID) error { |
| 306 | actorKind, actorOK, err := h.standing(ctx, sqid, session, actor) |
| 307 | if err != nil { |
| 308 | return err |
| 309 | } |
| 310 | |
| 311 | h.mu.Lock() |
| 312 | a, ok := h.findLocked(sqid, session, actor) |
| 313 | if !ok { |
| 314 | h.mu.Unlock() |
| 315 | return ErrUnknownPeer |
| 316 | } |
| 317 | r := h.rooms[sqid] |
| 318 | if !actorOK { |
| 319 | lost := h.standingLostLocked(r, a) |
| 320 | h.mu.Unlock() |
| 321 | if lost { |
| 322 | return ErrNotYours |
| 323 | } |
| 324 | // An admitted guest whose grant lapsed keeps the room but never |
| 325 | // gains the authority to let anyone else in. |
| 326 | return ErrNotMember |
| 327 | } |
| 328 | h.setKindLocked(r, a, actorKind) |
| 329 | if !a.Admitted { |
| 330 | h.mu.Unlock() |
| 331 | return ErrNotAdmitted |
| 332 | } |
| 333 | if a.Kind != KindMember { |
| 334 | h.mu.Unlock() |
| 335 | return ErrNotMember |
| 336 | } |
| 337 | // Only now, with the actor's authority settled, is the target looked |
| 338 | // at — first for its bare existence in this room, still under this |
| 339 | // same lock, before it costs a StandingFor call at all. |
| 340 | tp, found := r.peers[target] |
| 341 | if !found || !tp.Joined || tp.Admitted { |
| 342 | h.mu.Unlock() |
| 343 | return ErrNotWaiting |
| 344 | } |
| 345 | targetPerson := tp.PersonID |
| 346 | h.mu.Unlock() |
| 347 | |
| 348 | targetKind, targetOK, err := h.cfg.StandingFor(ctx, sqid, targetPerson) |
| 349 | if err != nil { |
| 350 | return err |
| 351 | } |
| 352 | |
| 353 | h.mu.Lock() |
| 354 | defer h.mu.Unlock() |
| 355 | // Both participations are re-found: either may have ended while the |
| 356 | // target's standing read was in flight. |
| 357 | a, ok = h.findLocked(sqid, session, actor) |
| 358 | if !ok { |
| 359 | return ErrUnknownPeer |
| 360 | } |
| 361 | r = h.rooms[sqid] |
| 362 | if !a.Admitted { |
| 363 | return ErrNotAdmitted |
| 364 | } |
| 365 | if a.Kind != KindMember { |
| 366 | return ErrNotMember |
| 367 | } |
| 368 | tp, ok = r.peers[target] |
| 369 | if !ok || !tp.Joined || tp.Admitted { |
| 370 | return ErrNotWaiting |
| 371 | } |
| 372 | if !targetOK { |
| 373 | // Through standingLostLocked, not endLocked: a loss of standing |
| 374 | // costs what the kind held earns, and there is exactly one place |
| 375 | // that decides which (spec §2.4). The target is always waiting |
| 376 | // here — the guard above refuses an admitted one — but it is not |
| 377 | // always a guest: the tick promotes a waiting guest to member |
| 378 | // and leaves it waiting when the mesh is full, and that one is |
| 379 | // owed reason "standing", not "expired". |
| 380 | h.standingLostLocked(r, tp) |
| 381 | return nil |
| 382 | } |
| 383 | h.setKindLocked(r, tp, targetKind) |
| 384 | if !h.admitLocked(r, tp) { |
| 385 | h.sendLocked(a, Message{Type: TypeFull}) |
| 386 | } |
| 387 | return nil |
| 388 | } |
| 389 | |
| 390 | // Leave ends a participation in any state at its own request. It is not |
| 391 | // a tombstoned ending: a leave is not something to resume from. |
| 392 | func (h *Hub) Leave(sqid, session string, peer PeerID) error { |
| 393 | h.mu.Lock() |
| 394 | defer h.mu.Unlock() |
| 395 | r, ok := h.rooms[sqid] |
| 396 | if !ok { |
| 397 | return ErrUnknownPeer |
| 398 | } |
| 399 | p, found := h.findLocked(sqid, session, peer) |
| 400 | if !found { |
| 401 | return ErrUnknownPeer |
| 402 | } |
| 403 | wasAdmitted, wasWaiting := h.endLocked(r, p, ReasonBuffer) |
| 404 | delete(h.tombstones, p.Peer) |
| 405 | h.announceDepartureLocked(r, p, wasAdmitted, wasWaiting) |
| 406 | return nil |
| 407 | } |
| 408 | |
| 409 | // Remove is spec §3.5: the actor holds an admitted member participation |
| 410 | // in this room (kind re-derived), the target is any other participation. |
| 411 | func (h *Hub) Remove(ctx context.Context, sqid, session string, actor, target PeerID) error { |
| 412 | kind, ok, err := h.standing(ctx, sqid, session, actor) |
| 413 | if err != nil { |
| 414 | return err |
| 415 | } |
| 416 | h.mu.Lock() |
| 417 | defer h.mu.Unlock() |
| 418 | a, found := h.findLocked(sqid, session, actor) |
| 419 | if !found { |
| 420 | return ErrUnknownPeer |
| 421 | } |
| 422 | r := h.rooms[sqid] |
| 423 | if !ok { |
| 424 | if h.standingLostLocked(r, a) { |
| 425 | return ErrNotYours |
| 426 | } |
| 427 | return ErrNotMember // an admitted guest, grant lapsed: still not a member |
| 428 | } |
| 429 | h.setKindLocked(r, a, kind) |
| 430 | if !a.Admitted { |
| 431 | return ErrNotAdmitted |
| 432 | } |
| 433 | if a.Kind != KindMember { |
| 434 | return ErrNotMember |
| 435 | } |
| 436 | tp, found := r.peers[target] |
| 437 | if !found || tp.Peer == a.Peer { |
| 438 | return ErrUnknownPeer |
| 439 | } |
| 440 | wasAdmitted, wasWaiting := h.endLocked(r, tp, ReasonRemoved) |
| 441 | h.announceDepartureLocked(r, tp, wasAdmitted, wasWaiting) |
| 442 | return nil |
| 443 | } |
| 444 | |
| 445 | // Takeover ends the session's live participation in the room with the |
| 446 | // state-dependent departure (spec §4.2), leaving a replaced tombstone so |
| 447 | // the displaced stream can be told why. |
| 448 | func (h *Hub) Takeover(sqid, session string) (PeerID, error) { |
| 449 | h.mu.Lock() |
| 450 | defer h.mu.Unlock() |
| 451 | r, ok := h.rooms[sqid] |
| 452 | if !ok { |
| 453 | return "", ErrUnknownPeer |
| 454 | } |
| 455 | id, ok := h.bySession[sqid][session] |
| 456 | if !ok { |
| 457 | return "", ErrUnknownPeer |
| 458 | } |
| 459 | p, ok := r.peers[id] |
| 460 | if !ok { |
| 461 | delete(h.bySession[sqid], session) |
| 462 | return "", ErrUnknownPeer |
| 463 | } |
| 464 | wasAdmitted, wasWaiting := h.endLocked(r, p, ReasonReplaced) |
| 465 | h.announceDepartureLocked(r, p, wasAdmitted, wasWaiting) |
| 466 | return id, nil |
| 467 | } |
| 468 | |
| 469 | // End is the meeting ending: lost{ended} to every stream, every |
| 470 | // participation ended, and the room kept only as a headstone so a stream |
| 471 | // racing the ending is refused (spec §2.4). A room nobody opened needs |
| 472 | // no headstone: the handler has already read ended_at, and every later |
| 473 | // entry reads it too. |
| 474 | func (h *Hub) End(sqid string) { |
| 475 | h.mu.Lock() |
| 476 | defer h.mu.Unlock() |
| 477 | r, ok := h.rooms[sqid] |
| 478 | if !ok { |
| 479 | return |
| 480 | } |
| 481 | for _, p := range r.peers { |
| 482 | h.endLocked(r, p, ReasonEnded) |
| 483 | } |
| 484 | r.ended = true |
| 485 | delete(h.bySession, sqid) |
| 486 | // Nothing reaps rooms today, so a headstone lives as long as the |
| 487 | // process. If a future round ever does reap them, it must leave an |
| 488 | // ended room in place for at least TombstoneLife: the tombstones |
| 489 | // written just above are answered only through their own room |
| 490 | // (resumeRefusalLocked), and a room reaped ahead of them turns spec |
| 491 | // §4.5's terminal 410 "ended" into a 404, which sends a browser off |
| 492 | // to open a fresh stream on a meeting that is over. |
| 493 | } |
| 494 | |
| 495 | // RefreshWaiting rechecks queued guests through the normal entry gate after |
| 496 | // meeting settings change. Database callbacks must run outside the hub lock. |
| 497 | func (h *Hub) RefreshWaiting(ctx context.Context, sqid string) error { |
| 498 | type waitingPeer struct { |
| 499 | session string |
| 500 | peer PeerID |
| 501 | } |
| 502 | h.mu.Lock() |
| 503 | var peers []waitingPeer |
| 504 | if room := h.rooms[sqid]; room != nil { |
| 505 | for _, p := range room.peers { |
| 506 | if p.Joined && !p.Admitted { |
| 507 | peers = append(peers, waitingPeer{p.Session, p.Peer}) |
| 508 | } |
| 509 | } |
| 510 | } |
| 511 | h.mu.Unlock() |
| 512 | for _, p := range peers { |
| 513 | err := h.Join(ctx, sqid, p.session, p.peer) |
| 514 | if err != nil && err != ErrMeshFull && err != ErrUnknownPeer && err != ErrNotYours { |
| 515 | return err |
| 516 | } |
| 517 | } |
| 518 | return nil |
| 519 | } |
| 520 | |
amadan