| 1 | use std::{ |
| 2 | collections::HashMap, |
| 3 | fmt, |
| 4 | pin::Pin, |
| 5 | sync::{Arc, Mutex, MutexGuard, PoisonError}, |
| 6 | task::{Context, Poll}, |
| 7 | time::Duration, |
| 8 | }; |
| 9 | |
| 10 | use futures_util::{Stream, StreamExt}; |
| 11 | use imbl::Vector; |
| 12 | use matrix_sdk::{ |
| 13 | SendOutsideWasm, |
| 14 | executor::{AbortHandle, spawn}, |
| 15 | }; |
| 16 | use ruma::{OwnedDeviceId, OwnedRoomId, OwnedTransactionId, OwnedUserId}; |
| 17 | #[cfg(feature = "serde")] |
| 18 | use serde::{Deserialize, Serialize}; |
| 19 | use tokio::sync::broadcast; |
| 20 | |
| 21 | use crate::{ |
| 22 | ClientHandle, Command, ConnectionState, EncryptionState, EngineFailure, ErrorKind, Event, |
| 23 | HistoryState, ImagePacks, RoomSummary, TimelineCommand, TimelineDiff, TimelineId, TimelineItem, |
| 24 | TypingState, UploadOutcome, VerificationState, VerificationTarget, |
| 25 | engine::executor::EngineBoxFuture, |
| 26 | }; |
| 27 | |
| 28 | #[cfg(not(target_family = "wasm"))] |
| 29 | type EngineBoxStream<T> = futures_util::stream::BoxStream<'static, T>; |
| 30 | #[cfg(target_family = "wasm")] |
| 31 | type EngineBoxStream<T> = futures_util::stream::LocalBoxStream<'static, T>; |
| 32 | |
| 33 | const DEFAULT_CAPACITY: usize = 256; |
| 34 | const RESYNC_BACKOFF: Duration = Duration::from_millis(100); |
| 35 | const RESYNC_BACKOFF_CAP: Duration = Duration::from_secs(10); |
| 36 | |
| 37 | /// everything the engine has said so far, folded together |
| 38 | #[derive(Clone, Debug, PartialEq)] |
| 39 | #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))] |
| 40 | #[non_exhaustive] |
| 41 | pub struct State { |
| 42 | pub user_id: Option<OwnedUserId>, |
| 43 | pub session: SessionStatus, |
| 44 | pub connection: ConnectionState, |
| 45 | pub encryption: Option<EncryptionState>, |
| 46 | pub verification: Option<VerificationState>, |
| 47 | pub verification_target: Option<VerificationTarget>, |
| 48 | pub rooms: Vector<RoomSummary>, |
| 49 | pub image_packs: ImagePacks, |
| 50 | pub timelines: imbl::HashMap<TimelineId, TimelineState>, |
| 51 | pub typing: imbl::HashMap<OwnedRoomId, Vec<OwnedUserId>>, |
| 52 | pub uploads: imbl::HashMap<OwnedTransactionId, UploadState>, |
| 53 | /// what stopped the engine, if something went wrong |
| 54 | pub engine_failure: Option<EngineFailure>, |
| 55 | /// the last save of the session record that failed, until one succeeds |
| 56 | pub session_save_failure: Option<String>, |
| 57 | } |
| 58 | |
| 59 | #[derive(Clone, Debug, PartialEq)] |
| 60 | #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))] |
| 61 | #[non_exhaustive] |
| 62 | pub struct TimelineState { |
| 63 | pub items: Vector<TimelineItem>, |
| 64 | pub history: HistoryState, |
| 65 | /// a batch didn't fit, so `items` is the last good copy until the next reset |
| 66 | pub diverged: bool, |
| 67 | } |
| 68 | |
| 69 | #[derive(Clone, Debug, Eq, PartialEq)] |
| 70 | #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))] |
| 71 | #[non_exhaustive] |
| 72 | pub struct UploadState { |
| 73 | pub room_id: OwnedRoomId, |
| 74 | pub uploaded_bytes: u64, |
| 75 | pub total_bytes: u64, |
| 76 | pub complete: bool, |
| 77 | pub failure: Option<UploadFailure>, |
| 78 | } |
| 79 | |
| 80 | #[derive(Clone, Copy, Debug, Eq, PartialEq)] |
| 81 | #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))] |
| 82 | #[non_exhaustive] |
| 83 | pub struct UploadFailure { |
| 84 | pub kind: ErrorKind, |
| 85 | pub will_retry: bool, |
| 86 | } |
| 87 | |
| 88 | /// the `Termination` it'll end in, as far as the events tell |
| 89 | #[derive(Clone, Debug, Eq, PartialEq)] |
| 90 | #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))] |
| 91 | pub enum SessionStatus { |
| 92 | Active, |
| 93 | SoftLoggedOut { |
| 94 | device_id: OwnedDeviceId, |
| 95 | }, |
| 96 | AccessRevoked, |
| 97 | LoggedOut, |
| 98 | /// stopped with the session still good |
| 99 | Stopped, |
| 100 | } |
| 101 | |
| 102 | #[derive(Clone, Debug)] |
| 103 | #[non_exhaustive] |
| 104 | pub struct Update { |
| 105 | /// one more than the update before it, and a `State` carries the one it's current as of |
| 106 | pub sequence: u64, |
| 107 | pub change: StateChange, |
| 108 | } |
| 109 | |
| 110 | #[derive(Clone, Debug)] |
| 111 | pub enum StateChange { |
| 112 | /// start over from this. a subscription opens with one and gets another after lagging |
| 113 | State(Arc<State>), |
| 114 | Authenticated(OwnedUserId), |
| 115 | Session(SessionStatus), |
| 116 | /// the record on disk may now hold a spent refresh token |
| 117 | SessionSaveFailed(String), |
| 118 | /// saved again after `SessionSaveFailed` |
| 119 | SessionSaved, |
| 120 | Connection(ConnectionState), |
| 121 | Encryption(EncryptionState), |
| 122 | Verification(VerificationState), |
| 123 | VerificationTarget(VerificationTarget), |
| 124 | /// room modes arrive with the `Rooms` that follows |
| 125 | NotificationSettings, |
| 126 | Rooms(Vector<RoomSummary>), |
| 127 | ImagePacks(ImagePacks), |
| 128 | Timeline { |
| 129 | timeline_id: TimelineId, |
| 130 | change: TimelineChange, |
| 131 | }, |
| 132 | History { |
| 133 | timeline_id: TimelineId, |
| 134 | state: HistoryState, |
| 135 | }, |
| 136 | Typing(TypingState), |
| 137 | Upload { |
| 138 | transaction_id: OwnedTransactionId, |
| 139 | upload: UploadState, |
| 140 | }, |
| 141 | UploadFinished { |
| 142 | room_id: OwnedRoomId, |
| 143 | transaction_id: OwnedTransactionId, |
| 144 | outcome: UploadOutcome, |
| 145 | }, |
| 146 | Failed(EngineFailure), |
| 147 | } |
| 148 | |
| 149 | #[derive(Clone, Debug)] |
| 150 | pub enum TimelineChange { |
| 151 | Reset { |
| 152 | items: Vector<TimelineItem>, |
| 153 | }, |
| 154 | /// `items` is what applying `diffs` left |
| 155 | Changed { |
| 156 | diffs: Arc<[TimelineDiff]>, |
| 157 | items: Vector<TimelineItem>, |
| 158 | }, |
| 159 | /// a batch didn't fit. a resync is on its way and nothing changes until its reset |
| 160 | Diverged, |
| 161 | Closed, |
| 162 | } |
| 163 | |
| 164 | /// drains the event stream into a `State` that any number of `MirrorHandle`s watch |
| 165 | pub struct Mirror { |
| 166 | handle: ClientHandle, |
| 167 | events: EngineBoxStream<Event>, |
| 168 | shared: Arc<Shared>, |
| 169 | resyncs: HashMap<TimelineId, AbortHandle>, |
| 170 | rooms_fetch: Option<AbortHandle>, |
| 171 | packs_fetch: Option<AbortHandle>, |
| 172 | } |
| 173 | |
| 174 | impl fmt::Debug for Mirror { |
| 175 | fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result { |
| 176 | formatter.debug_struct("Mirror").finish_non_exhaustive() |
| 177 | } |
| 178 | } |
| 179 | |
| 180 | impl Mirror { |
| 181 | /// takes any stream of the engine's events, so a host can still look at them on the way past |
| 182 | pub fn new( |
| 183 | handle: ClientHandle, |
| 184 | events: impl Stream<Item = Event> + SendOutsideWasm + 'static, |
| 185 | ) -> (Self, MirrorHandle) { |
| 186 | Self::with_capacity(handle, events, DEFAULT_CAPACITY) |
| 187 | } |
| 188 | |
| 189 | /// `capacity` updates can queue for a subscriber before it lags and starts over. a zero |
| 190 | /// capacity counts as one |
| 191 | pub fn with_capacity( |
| 192 | handle: ClientHandle, |
| 193 | events: impl Stream<Item = Event> + SendOutsideWasm + 'static, |
| 194 | capacity: usize, |
| 195 | ) -> (Self, MirrorHandle) { |
| 196 | let state = State { |
| 197 | user_id: None, |
| 198 | session: SessionStatus::Active, |
| 199 | connection: *handle.connection_state().borrow(), |
| 200 | encryption: handle.encryption_state(), |
| 201 | verification: None, |
| 202 | verification_target: None, |
| 203 | rooms: Vector::new(), |
| 204 | image_packs: ImagePacks::default(), |
| 205 | timelines: imbl::HashMap::new(), |
| 206 | typing: imbl::HashMap::new(), |
| 207 | uploads: imbl::HashMap::new(), |
| 208 | engine_failure: None, |
| 209 | session_save_failure: None, |
| 210 | }; |
| 211 | let shared = Arc::new(Shared { |
| 212 | published: Mutex::new(Published { |
| 213 | state: Arc::new(state), |
| 214 | sequence: 0, |
| 215 | updates: Some(broadcast::channel(capacity.max(1)).0), |
| 216 | rooms_fetch: Fetch::Idle, |
| 217 | packs_fetch: Fetch::Idle, |
| 218 | }), |
| 219 | }); |
| 220 | #[cfg(not(target_family = "wasm"))] |
| 221 | let events = events.boxed(); |
| 222 | #[cfg(target_family = "wasm")] |
| 223 | let events = events.boxed_local(); |
| 224 | let mirror = Self { |
| 225 | handle, |
| 226 | events, |
| 227 | shared: shared.clone(), |
| 228 | resyncs: HashMap::new(), |
| 229 | rooms_fetch: None, |
| 230 | packs_fetch: None, |
| 231 | }; |
| 232 | (mirror, MirrorHandle { shared }) |
| 233 | } |
| 234 | |
| 235 | /// resolves once the event stream ends, which is just after `Stopped` |
| 236 | pub fn run(mut self) -> EngineBoxFuture<'static, ()> { |
| 237 | Box::pin(async move { |
| 238 | self.refetch_rooms(); |
| 239 | self.refetch_image_packs(); |
| 240 | while let Some(event) = self.events.next().await { |
| 241 | self.apply(event); |
| 242 | } |
| 243 | }) |
| 244 | } |
| 245 | |
| 246 | fn apply(&mut self, event: Event) { |
| 247 | match event { |
| 248 | Event::ConnectionChanged(connection) => self.publish(|state| { |
| 249 | state.connection = connection; |
| 250 | Some(StateChange::Connection(connection)) |
| 251 | }), |
| 252 | Event::Authenticated { user_id } => self.publish(|state| { |
| 253 | state.user_id = Some(user_id.clone()); |
| 254 | Some(StateChange::Authenticated(user_id)) |
| 255 | }), |
| 256 | Event::SessionSaveFailed { message } => self.publish(|state| { |
| 257 | state.session_save_failure = Some(message.clone()); |
| 258 | Some(StateChange::SessionSaveFailed(message)) |
| 259 | }), |
| 260 | Event::SessionTokensChanged => self.publish(|state| { |
| 261 | state.session_save_failure.take()?; |
| 262 | Some(StateChange::SessionSaved) |
| 263 | }), |
| 264 | Event::SessionAccessRejected { soft_logout } => self.publish(|state| { |
| 265 | state.session = match soft_logout { |
| 266 | Some(device_id) => SessionStatus::SoftLoggedOut { device_id }, |
| 267 | None => SessionStatus::AccessRevoked, |
| 268 | }; |
| 269 | Some(StateChange::Session(state.session.clone())) |
| 270 | }), |
| 271 | Event::LoggedOut => self.publish(|state| { |
| 272 | state.session = SessionStatus::LoggedOut; |
| 273 | Some(StateChange::Session(SessionStatus::LoggedOut)) |
| 274 | }), |
| 275 | Event::Stopped => { |
| 276 | self.cancel_resyncs(); |
| 277 | self.publish(|state| { |
| 278 | if state.session != SessionStatus::Active { |
| 279 | return None; |
| 280 | } |
| 281 | state.session = SessionStatus::Stopped; |
| 282 | Some(StateChange::Session(SessionStatus::Stopped)) |
| 283 | }); |
| 284 | } |
| 285 | Event::Failed(failure) => self.publish(|state| { |
| 286 | state.engine_failure = Some(failure.clone()); |
| 287 | Some(StateChange::Failed(failure)) |
| 288 | }), |
| 289 | Event::NotificationSettingsChanged => { |
| 290 | self.publish(|_| Some(StateChange::NotificationSettings)); |
| 291 | } |
| 292 | Event::RoomsChanged => self.refetch_rooms(), |
| 293 | Event::ImagePacksChanged => self.refetch_image_packs(), |
| 294 | Event::EncryptionChanged(encryption) => self.publish(|state| { |
| 295 | state.encryption = Some(encryption.clone()); |
| 296 | Some(StateChange::Encryption(encryption)) |
| 297 | }), |
| 298 | Event::VerificationChanged(verification) => self.publish(|state| { |
| 299 | state.verification = Some(verification.clone()); |
| 300 | Some(StateChange::Verification(verification)) |
| 301 | }), |
| 302 | Event::VerificationTargetChanged(target) => self.publish(|state| { |
| 303 | state.verification_target = Some(target.clone()); |
| 304 | Some(StateChange::VerificationTarget(target)) |
| 305 | }), |
| 306 | Event::TimelineReset { timeline_id, items } => { |
| 307 | self.cancel_resync(&timeline_id); |
| 308 | self.publish(|state| { |
| 309 | let history = state |
| 310 | .timelines |
| 311 | .get(&timeline_id) |
| 312 | .map_or(HistoryState::Idle, |timeline| timeline.history.clone()); |
| 313 | let timeline = TimelineState { |
| 314 | items: items.clone(), |
| 315 | history, |
| 316 | diverged: false, |
| 317 | }; |
| 318 | state.timelines.insert(timeline_id.clone(), timeline); |
| 319 | Some(StateChange::Timeline { |
| 320 | timeline_id, |
| 321 | change: TimelineChange::Reset { items }, |
| 322 | }) |
| 323 | }); |
| 324 | } |
| 325 | Event::TimelineChanged { timeline_id, diffs } => self.apply_diffs(timeline_id, diffs), |
| 326 | Event::HistoryChanged { |
| 327 | timeline_id, |
| 328 | state: history, |
| 329 | } => self.publish(|state| { |
| 330 | state.timelines.get_mut(&timeline_id)?.history = history.clone(); |
| 331 | Some(StateChange::History { |
| 332 | timeline_id, |
| 333 | state: history, |
| 334 | }) |
| 335 | }), |
| 336 | Event::TimelineClosed { timeline_id } => { |
| 337 | self.cancel_resync(&timeline_id); |
| 338 | self.publish(|state| { |
| 339 | state.timelines.remove(&timeline_id)?; |
| 340 | Some(StateChange::Timeline { |
| 341 | timeline_id, |
| 342 | change: TimelineChange::Closed, |
| 343 | }) |
| 344 | }); |
| 345 | } |
| 346 | Event::TypingChanged(typing) => self.publish(|state| { |
| 347 | if typing.users.is_empty() { |
| 348 | state.typing.remove(&typing.room_id); |
| 349 | } else { |
| 350 | state |
| 351 | .typing |
| 352 | .insert(typing.room_id.clone(), typing.users.clone()); |
| 353 | } |
| 354 | Some(StateChange::Typing(typing)) |
| 355 | }), |
| 356 | Event::MediaUploadProgress { |
| 357 | room_id, |
| 358 | transaction_id, |
| 359 | uploaded_bytes, |
| 360 | total_bytes, |
| 361 | complete, |
| 362 | } => self.publish(|state| { |
| 363 | let upload = UploadState { |
| 364 | room_id, |
| 365 | uploaded_bytes, |
| 366 | total_bytes, |
| 367 | complete, |
| 368 | failure: None, |
| 369 | }; |
| 370 | state.uploads.insert(transaction_id.clone(), upload.clone()); |
| 371 | Some(StateChange::Upload { |
| 372 | transaction_id, |
| 373 | upload, |
| 374 | }) |
| 375 | }), |
| 376 | Event::MediaUploadFailed { |
| 377 | room_id, |
| 378 | transaction_id, |
| 379 | kind, |
| 380 | will_retry, |
| 381 | } => self.publish(|state| { |
| 382 | let upload = state |
| 383 | .uploads |
| 384 | .entry(transaction_id.clone()) |
| 385 | .or_insert_with(|| UploadState { |
| 386 | room_id, |
| 387 | uploaded_bytes: 0, |
| 388 | total_bytes: 0, |
| 389 | complete: false, |
| 390 | failure: None, |
| 391 | }); |
| 392 | upload.failure = Some(UploadFailure { kind, will_retry }); |
| 393 | Some(StateChange::Upload { |
| 394 | transaction_id, |
| 395 | upload: upload.clone(), |
| 396 | }) |
| 397 | }), |
| 398 | Event::MediaUploadFinished { |
| 399 | room_id, |
| 400 | transaction_id, |
| 401 | outcome, |
| 402 | } => self.publish(|state| { |
| 403 | state.uploads.remove(&transaction_id); |
| 404 | Some(StateChange::UploadFinished { |
| 405 | room_id, |
| 406 | transaction_id, |
| 407 | outcome, |
| 408 | }) |
| 409 | }), |
| 410 | } |
| 411 | } |
| 412 | |
| 413 | fn apply_diffs(&mut self, timeline_id: TimelineId, diffs: Vec<TimelineDiff>) { |
| 414 | let mut diverged = false; |
| 415 | self.publish(|state| { |
| 416 | let Some(timeline) = state.timelines.get_mut(&timeline_id) else { |
| 417 | diverged = true; |
| 418 | state.timelines.insert( |
| 419 | timeline_id.clone(), |
| 420 | TimelineState { |
| 421 | items: Vector::new(), |
| 422 | history: HistoryState::Idle, |
| 423 | diverged: true, |
| 424 | }, |
| 425 | ); |
| 426 | return Some(StateChange::Timeline { |
| 427 | timeline_id: timeline_id.clone(), |
| 428 | change: TimelineChange::Diverged, |
| 429 | }); |
| 430 | }; |
| 431 | if timeline.diverged { |
| 432 | return None; |
| 433 | } |
| 434 | let diffs: Arc<[TimelineDiff]> = diffs.into(); |
| 435 | let change = match TimelineDiff::try_apply_all(diffs.to_vec(), &mut timeline.items) { |
| 436 | Ok(()) => TimelineChange::Changed { |
| 437 | diffs, |
| 438 | items: timeline.items.clone(), |
| 439 | }, |
| 440 | Err(error) => { |
| 441 | tracing::debug!(?timeline_id, length = error.length, "timeline diverged"); |
| 442 | timeline.diverged = true; |
| 443 | diverged = true; |
| 444 | TimelineChange::Diverged |
| 445 | } |
| 446 | }; |
| 447 | Some(StateChange::Timeline { |
| 448 | timeline_id: timeline_id.clone(), |
| 449 | change, |
| 450 | }) |
| 451 | }); |
| 452 | if diverged { |
| 453 | let task = spawn(resync(self.handle.clone(), timeline_id.clone())); |
| 454 | self.resyncs.insert(timeline_id, task.abort_handle()); |
| 455 | } |
| 456 | } |
| 457 | |
| 458 | fn refetch_rooms(&mut self) { |
| 459 | let fetch = fetch_rooms(self.handle.clone(), self.shared.clone()); |
| 460 | if let Some(task) = self |
| 461 | .shared |
| 462 | .start(|published| &mut published.rooms_fetch, fetch) |
| 463 | { |
| 464 | self.rooms_fetch = Some(task); |
| 465 | } |
| 466 | } |
| 467 | |
| 468 | fn refetch_image_packs(&mut self) { |
| 469 | let fetch = fetch_image_packs(self.handle.clone(), self.shared.clone()); |
| 470 | if let Some(task) = self |
| 471 | .shared |
| 472 | .start(|published| &mut published.packs_fetch, fetch) |
| 473 | { |
| 474 | self.packs_fetch = Some(task); |
| 475 | } |
| 476 | } |
| 477 | |
| 478 | fn cancel_resync(&mut self, timeline_id: &TimelineId) { |
| 479 | if let Some(task) = self.resyncs.remove(timeline_id) { |
| 480 | task.abort(); |
| 481 | } |
| 482 | } |
| 483 | |
| 484 | fn cancel_resyncs(&mut self) { |
| 485 | for (_, task) in self.resyncs.drain() { |
| 486 | task.abort(); |
| 487 | } |
| 488 | } |
| 489 | |
| 490 | fn publish(&self, change: impl FnOnce(&mut State) -> Option<StateChange>) { |
| 491 | self.shared.publish(change); |
| 492 | } |
| 493 | } |
| 494 | |
| 495 | impl Drop for Mirror { |
| 496 | fn drop(&mut self) { |
| 497 | self.cancel_resyncs(); |
| 498 | for task in [self.rooms_fetch.take(), self.packs_fetch.take()] |
| 499 | .into_iter() |
| 500 | .flatten() |
| 501 | { |
| 502 | task.abort(); |
| 503 | } |
| 504 | self.shared.lock().updates = None; |
| 505 | } |
| 506 | } |
| 507 | |
| 508 | /// asks until the engine answers, since a busy room or a full queue is only ever for now. |
| 509 | /// a reset or a close for the timeline aborts it, and the engine sends a reset before it answers |
| 510 | async fn resync(handle: ClientHandle, timeline_id: TimelineId) { |
| 511 | let mut backoff = RESYNC_BACKOFF; |
| 512 | loop { |
| 513 | let command = Command::Timeline(TimelineCommand::Resync { |
| 514 | timeline_id: timeline_id.clone(), |
| 515 | }); |
| 516 | match handle.execute(command).await { |
| 517 | Ok(_) => return, |
| 518 | Err(error) if error.kind == ErrorKind::Interrupted => return, |
| 519 | Err(error) => { |
| 520 | tracing::debug!(%error, ?timeline_id, "resync refused, trying again"); |
| 521 | matrix_sdk::sleep::sleep(backoff).await; |
| 522 | backoff = (backoff * 2).min(RESYNC_BACKOFF_CAP); |
| 523 | } |
| 524 | } |
| 525 | } |
| 526 | } |
| 527 | |
| 528 | async fn fetch_rooms(handle: ClientHandle, shared: Arc<Shared>) { |
| 529 | loop { |
| 530 | let rooms: Vector<RoomSummary> = handle.rooms().await.into(); |
| 531 | shared.publish(|state| { |
| 532 | state.rooms = rooms.clone(); |
| 533 | Some(StateChange::Rooms(rooms)) |
| 534 | }); |
| 535 | if !shared.fetched(|published| &mut published.rooms_fetch) { |
| 536 | return; |
| 537 | } |
| 538 | } |
| 539 | } |
| 540 | |
| 541 | /// a failed read keeps the packs from before, the next change asks again |
| 542 | async fn fetch_image_packs(handle: ClientHandle, shared: Arc<Shared>) { |
| 543 | loop { |
| 544 | match handle.image_packs().await { |
| 545 | Ok(packs) => shared.publish(|state| { |
| 546 | if state.image_packs == packs { |
| 547 | return None; |
| 548 | } |
| 549 | state.image_packs = packs.clone(); |
| 550 | Some(StateChange::ImagePacks(packs)) |
| 551 | }), |
| 552 | Err(error) => tracing::warn!(%error, "reading image packs failed"), |
| 553 | } |
| 554 | if !shared.fetched(|published| &mut published.packs_fetch) { |
| 555 | return; |
| 556 | } |
| 557 | } |
| 558 | } |
| 559 | |
| 560 | /// cheap to clone, one per frontend |
| 561 | #[derive(Clone, Debug)] |
| 562 | pub struct MirrorHandle { |
| 563 | shared: Arc<Shared>, |
| 564 | } |
| 565 | |
| 566 | impl MirrorHandle { |
| 567 | #[must_use] |
| 568 | pub fn snapshot(&self) -> Arc<State> { |
| 569 | self.shared.lock().state.clone() |
| 570 | } |
| 571 | |
| 572 | /// opens with the current state, then every update after it. ends once the mirror stops |
| 573 | #[must_use] |
| 574 | pub fn subscribe(&self) -> Subscription { |
| 575 | let (first, receiving) = self.shared.clone().subscribe(); |
| 576 | let rest = futures_util::stream::unfold(receiving, |(shared, receiver)| async move { |
| 577 | let mut receiver = receiver?; |
| 578 | match receiver.recv().await { |
| 579 | Ok(update) => Some((update, (shared, Some(receiver)))), |
| 580 | Err(broadcast::error::RecvError::Lagged(missed)) => { |
| 581 | tracing::debug!(missed, "mirror subscriber lagged, starting it over"); |
| 582 | Some(shared.subscribe()) |
| 583 | } |
| 584 | Err(broadcast::error::RecvError::Closed) => None, |
| 585 | } |
| 586 | }); |
| 587 | let updates = futures_util::stream::once(std::future::ready(first)).chain(rest); |
| 588 | #[cfg(not(target_family = "wasm"))] |
| 589 | let updates = updates.boxed(); |
| 590 | #[cfg(target_family = "wasm")] |
| 591 | let updates = updates.boxed_local(); |
| 592 | Subscription(updates) |
| 593 | } |
| 594 | } |
| 595 | |
| 596 | pub struct Subscription(EngineBoxStream<Update>); |
| 597 | |
| 598 | impl fmt::Debug for Subscription { |
| 599 | fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result { |
| 600 | formatter |
| 601 | .debug_struct("Subscription") |
| 602 | .finish_non_exhaustive() |
| 603 | } |
| 604 | } |
| 605 | |
| 606 | impl Stream for Subscription { |
| 607 | type Item = Update; |
| 608 | |
| 609 | fn poll_next(mut self: Pin<&mut Self>, context: &mut Context<'_>) -> Poll<Option<Update>> { |
| 610 | self.0.poll_next_unpin(context) |
| 611 | } |
| 612 | } |
| 613 | |
| 614 | #[derive(Debug)] |
| 615 | struct Shared { |
| 616 | published: Mutex<Published>, |
| 617 | } |
| 618 | |
| 619 | #[derive(Debug)] |
| 620 | struct Published { |
| 621 | state: Arc<State>, |
| 622 | sequence: u64, |
| 623 | /// gone once the mirror stops, which ends every subscription |
| 624 | updates: Option<broadcast::Sender<Update>>, |
| 625 | rooms_fetch: Fetch, |
| 626 | packs_fetch: Fetch, |
| 627 | } |
| 628 | |
| 629 | #[derive(Clone, Copy, Debug, Eq, PartialEq)] |
| 630 | enum Fetch { |
| 631 | Idle, |
| 632 | Running, |
| 633 | Again, |
| 634 | } |
| 635 | |
| 636 | impl Shared { |
| 637 | fn lock(&self) -> MutexGuard<'_, Published> { |
| 638 | self.published |
| 639 | .lock() |
| 640 | .unwrap_or_else(PoisonError::into_inner) |
| 641 | } |
| 642 | |
| 643 | /// one fetch at a time, with at most one more owed |
| 644 | fn start( |
| 645 | &self, |
| 646 | fetch: impl FnOnce(&mut Published) -> &mut Fetch, |
| 647 | task: impl Future<Output = ()> + SendOutsideWasm + 'static, |
| 648 | ) -> Option<AbortHandle> { |
| 649 | let mut published = self.lock(); |
| 650 | let fetch = fetch(&mut published); |
| 651 | match *fetch { |
| 652 | Fetch::Idle => { |
| 653 | *fetch = Fetch::Running; |
| 654 | drop(published); |
| 655 | Some(spawn(task).abort_handle()) |
| 656 | } |
| 657 | Fetch::Running => { |
| 658 | *fetch = Fetch::Again; |
| 659 | None |
| 660 | } |
| 661 | Fetch::Again => None, |
| 662 | } |
| 663 | } |
| 664 | |
| 665 | /// whether another fetch was asked for while this one ran |
| 666 | fn fetched(&self, fetch: impl FnOnce(&mut Published) -> &mut Fetch) -> bool { |
| 667 | let mut published = self.lock(); |
| 668 | let fetch = fetch(&mut published); |
| 669 | if *fetch == Fetch::Again { |
| 670 | *fetch = Fetch::Running; |
| 671 | return true; |
| 672 | } |
| 673 | *fetch = Fetch::Idle; |
| 674 | false |
| 675 | } |
| 676 | |
| 677 | /// state, sequence and send move together under the one lock, which is what lets |
| 678 | /// `subscribe` take a snapshot and a receiver with nothing between them |
| 679 | fn publish(&self, change: impl FnOnce(&mut State) -> Option<StateChange>) { |
| 680 | let mut published = self.lock(); |
| 681 | let Some(change) = change(Arc::make_mut(&mut published.state)) else { |
| 682 | return; |
| 683 | }; |
| 684 | published.sequence += 1; |
| 685 | let update = Update { |
| 686 | sequence: published.sequence, |
| 687 | change, |
| 688 | }; |
| 689 | if let Some(updates) = &published.updates { |
| 690 | let _ = updates.send(update); |
| 691 | } |
| 692 | } |
| 693 | |
| 694 | fn subscribe(self: Arc<Self>) -> (Update, (Arc<Self>, Option<broadcast::Receiver<Update>>)) { |
| 695 | let published = self.lock(); |
| 696 | let update = Update { |
| 697 | sequence: published.sequence, |
| 698 | change: StateChange::State(published.state.clone()), |
| 699 | }; |
| 700 | let receiver = published.updates.as_ref().map(broadcast::Sender::subscribe); |
| 701 | drop(published); |
| 702 | (update, (self, receiver)) |
| 703 | } |
| 704 | } |