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//! [WebSocket] client.
//!
//! [WebSocket]: https://developer.mozilla.org/ru/docs/WebSockets
use std::{cell::RefCell, fmt, rc::Rc, time::Duration};
use derive_more::Display;
use futures::{
channel::{mpsc, oneshot},
future::LocalBoxFuture,
stream::{LocalBoxStream, StreamExt as _},
};
use medea_client_api_proto::{
ClientMsg, CloseReason as CloseByServerReason, Command, Credential, Event,
MemberId, RoomId, RpcSettings, ServerMsg,
};
use medea_macro::dispatchable;
use medea_reactive::ObservableCell;
use serde::Serialize;
use tracerr::Traced;
use crate::{
platform,
rpc::{
ApiUrl, CloseMsg, CloseReason, ClosedStateReason, ConnectionLostReason,
Heartbeat, IdleTimeout, PingInterval, RpcClientError,
},
};
/// Reasons of closing WebSocket RPC connection by a client side.
#[derive(Copy, Clone, Display, Debug, Eq, PartialEq, Serialize)]
pub enum ClientDisconnect {
/// [`Room`] was dropped without any [`CloseReason`].
///
/// [`Room`]: crate::room::Room
RoomUnexpectedlyDropped,
/// [`Room`] was normally closed bu client.
///
/// [`Room`]: crate::room::Room
RoomClosed,
/// [`WebSocketRpcClient`] was unexpectedly dropped.
RpcClientUnexpectedlyDropped,
/// [`platform::RpcTransport`] was unexpectedly dropped.
RpcTransportUnexpectedlyDropped,
/// [`WebSocketRpcSession`] was unexpectedly dropped.
///
/// [`WebSocketRpcSession`]: crate::rpc::WebSocketRpcSession
SessionUnexpectedlyDropped,
}
impl ClientDisconnect {
/// Indicates whether this [`ClientDisconnect`] is considered as error.
#[must_use]
pub const fn is_err(self) -> bool {
match self {
Self::RoomUnexpectedlyDropped
| Self::RpcClientUnexpectedlyDropped
| Self::RpcTransportUnexpectedlyDropped
| Self::SessionUnexpectedlyDropped => true,
Self::RoomClosed => false,
}
}
}
impl From<ClientDisconnect> for CloseReason {
fn from(v: ClientDisconnect) -> Self {
Self::ByClient {
is_err: v.is_err(),
reason: v,
}
}
}
/// State of a [`WebSocketRpcClient`] and a [`platform::RpcTransport`].
#[derive(Clone, Debug, PartialEq)]
pub enum ClientState {
/// [`WebSocketRpcClient`] is currently establishing a connection to RPC
/// server.
Connecting,
/// Connection with RPC Server is active.
Open,
/// Connection with RPC server is currently closed.
Closed(ClosedStateReason),
}
/// Inner state of [`WebSocketRpcClient`].
struct Inner {
/// Transport connection with remote media server.
sock: Option<Rc<dyn platform::RpcTransport>>,
/// Connection loss detector via ping/pong mechanism.
heartbeat: Option<Heartbeat>,
/// Event's subscribers list.
subs: Vec<mpsc::UnboundedSender<RpcEvent>>,
/// Subscribers that will be notified with [`CloseReason`] when underlying
/// transport is gracefully closed.
on_close_subscribers: Vec<oneshot::Sender<CloseReason>>,
/// Reason of [`WebSocketRpcClient`] closing.
///
/// This reason will be provided to the underlying
/// [`platform::RpcTransport`].
close_reason: ClientDisconnect,
/// Subscribers that will be notified when underlying transport connection
/// is lost.
on_connection_loss_subs: Vec<mpsc::UnboundedSender<ConnectionLostReason>>,
/// Closure which will create new [`platform::RpcTransport`]s for this
/// [`WebSocketRpcClient`] on each
/// [`WebSocketRpcClient:: establish_connection`] call.
rpc_transport_factory: RpcTransportFactory,
/// URL that [`platform::RpcTransport`] will connect to.
///
/// [`None`] if this [`WebSocketRpcClient`] has never been connected to
/// a sever.
url: Option<ApiUrl>,
/// Current [`ClientState`] of this [`WebSocketRpcClient`].
state: ObservableCell<ClientState>,
}
impl fmt::Debug for Inner {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Inner")
.field("heartbeat", &self.heartbeat)
.field("subs", &self.subs)
.field("on_close_subscribers", &self.on_close_subscribers)
.field("close_reason", &self.close_reason)
.field("on_connection_loss_subs", &self.on_connection_loss_subs)
.field("url", &self.url)
.field("state", &self.state)
.finish_non_exhaustive()
}
}
/// Factory closure producing a [`platform::RpcTransport`].
pub type RpcTransportFactory = Box<dyn Fn() -> Rc<dyn platform::RpcTransport>>;
impl Inner {
/// Instantiates new [`Inner`] state of [`WebSocketRpcClient`].
fn new(rpc_transport_factory: RpcTransportFactory) -> RefCell<Self> {
RefCell::new(Self {
sock: None,
on_close_subscribers: Vec::new(),
subs: Vec::new(),
heartbeat: None,
close_reason: ClientDisconnect::RpcClientUnexpectedlyDropped,
on_connection_loss_subs: Vec::new(),
rpc_transport_factory,
url: None,
state: ObservableCell::new(ClientState::Closed(
ClosedStateReason::NeverConnected,
)),
})
}
}
/// Events which can be thrown by [`WebSocketRpcClient`].
#[dispatchable(self: &Self)]
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum RpcEvent {
/// Notification of the subscribers that [`WebSocketRpcClient`] is joined
/// [`Room`] on Media Server.
///
/// [`Room`]: crate::room::Room
JoinedRoom {
/// ID of the joined [`Room`].
///
/// [`Room`]: crate::room::Room
room_id: RoomId,
/// ID of the joined `Member`.
member_id: MemberId,
},
/// Notification of the subscribers that [`WebSocketRpcClient`] left
/// [`Room`] on Media Server.
///
/// [`Room`]: crate::room::Room
LeftRoom {
/// ID of the [`Room`] being left.
///
/// [`Room`]: crate::room::Room
room_id: RoomId,
/// Reason of why the [`Room`] has been left.
///
/// [`Room`]: crate::room::Room
close_reason: CloseReason,
},
/// [`WebSocketRpcClient`] received [`Event`] from Media Server.
Event {
/// ID of the [`Room`] for that this [`Event`] has been received for.
///
/// [`Room`]: crate::room::Room
room_id: RoomId,
/// Received [`Event`].
event: Event,
},
}
/// Client API RPC client to talk with server via [WebSocket].
///
/// [WebSocket]: https://developer.mozilla.org/ru/docs/WebSockets
#[derive(Debug)]
pub struct WebSocketRpcClient(RefCell<Inner>);
impl WebSocketRpcClient {
/// Creates new [`WebSocketRpcClient`] with provided [`RpcTransportFactory`]
/// closure.
#[must_use]
pub fn new(rpc_transport_factory: RpcTransportFactory) -> Self {
Self(Inner::new(rpc_transport_factory))
}
/// Authorizes [`WebSocketRpcClient`] on the Media Server.
pub fn authorize(
&self,
room_id: RoomId,
member_id: MemberId,
credential: Credential,
) {
self.send_command(
room_id,
Command::JoinRoom {
member_id,
credential,
},
);
}
/// Leaves `Room` with a provided [`RoomId`].
pub fn leave_room(&self, room_id: RoomId, member_id: MemberId) {
self.send_command(room_id, Command::LeaveRoom { member_id });
}
/// Stops [`Heartbeat`] and notifies all
/// [`WebSocketRpcClient::on_connection_loss`] subs about connection
/// loss.
fn handle_connection_loss(&self, close_msg: ConnectionLostReason) {
self.0.borrow().state.set(ClientState::Closed(
ClosedStateReason::ConnectionLost(close_msg),
));
drop(self.0.borrow_mut().heartbeat.take());
self.0
.borrow_mut()
.on_connection_loss_subs
.retain(|sub| sub.unbounded_send(close_msg).is_ok());
}
/// Handles [`CloseMsg`] from a remote server.
///
/// This function will be called on every WebSocket close (normal and
/// abnormal) regardless of the [`CloseReason`].
fn handle_close_message(&self, close_msg: CloseMsg) {
drop(self.0.borrow_mut().heartbeat.take());
match close_msg {
CloseMsg::Normal(_, reason) => match reason {
CloseByServerReason::Reconnected => (),
CloseByServerReason::Idle => {
self.handle_connection_loss(ConnectionLostReason::Idle);
}
CloseByServerReason::Finished
| CloseByServerReason::Rejected
| CloseByServerReason::InternalError
| CloseByServerReason::Evicted => {
self.0.borrow().state.set(ClientState::Closed(
ClosedStateReason::ConnectionLost(
ConnectionLostReason::WithMessage(close_msg),
),
));
drop(self.0.borrow_mut().sock.take());
self.0
.borrow_mut()
.on_close_subscribers
.drain(..)
.for_each(|sub| {
_ = sub.send(CloseReason::ByServer(reason));
});
}
},
CloseMsg::Abnormal(_) => {
self.handle_connection_loss(ConnectionLostReason::WithMessage(
close_msg,
));
}
}
}
/// Handles [`ServerMsg`]s from a remote server.
fn on_transport_message(&self, msg: ServerMsg) {
let msg = match msg {
ServerMsg::Event { room_id, event } => match event {
Event::RoomJoined { member_id } => {
Some(RpcEvent::JoinedRoom { room_id, member_id })
}
Event::RoomLeft { close_reason } => Some(RpcEvent::LeftRoom {
room_id,
close_reason: CloseReason::ByServer(close_reason),
}),
Event::PeerCreated { .. }
| Event::SdpAnswerMade { .. }
| Event::LocalDescriptionApplied { .. }
| Event::IceCandidateDiscovered { .. }
| Event::PeersRemoved { .. }
| Event::PeerUpdated { .. }
| Event::ConnectionQualityUpdated { .. }
| Event::StateSynchronized { .. } => {
Some(RpcEvent::Event { room_id, event })
}
},
ServerMsg::RpcSettings(settings) => {
self.0.borrow_mut().heartbeat.as_ref().map_or_else(
|| {
log::error!(
"Failed to update socket settings because \
Heartbeat is None",
);
},
|heartbeat| {
heartbeat.update_settings(
IdleTimeout(Duration::from_millis(
settings.idle_timeout_ms.into(),
)),
PingInterval(Duration::from_millis(
settings.ping_interval_ms.into(),
)),
);
},
);
None
}
ServerMsg::Ping(_) => None,
};
if let Some(m) = msg {
self.0
.borrow_mut()
.subs
.retain(|sub| sub.unbounded_send(m.clone()).is_ok());
}
}
/// Starts [`Heartbeat`] with provided [`RpcSettings`] for provided
/// [`platform::RpcTransport`].
async fn start_heartbeat(
self: Rc<Self>,
transport: Rc<dyn platform::RpcTransport>,
rpc_settings: RpcSettings,
) -> Result<(), Traced<RpcClientError>> {
let idle_timeout = IdleTimeout(Duration::from_millis(
rpc_settings.idle_timeout_ms.into(),
));
let ping_interval = PingInterval(Duration::from_millis(
rpc_settings.ping_interval_ms.into(),
));
let heartbeat =
Heartbeat::start(transport, ping_interval, idle_timeout);
let mut on_idle = heartbeat.on_idle();
let weak_this = Rc::downgrade(&self);
platform::spawn(async move {
while on_idle.next().await.is_some() {
if let Some(this) = weak_this.upgrade() {
this.handle_connection_loss(ConnectionLostReason::Idle);
}
}
});
self.0.borrow_mut().heartbeat = Some(heartbeat);
Ok(())
}
/// Tries to establish [`WebSocketRpcClient`] connection.
async fn establish_connection(
self: Rc<Self>,
url: ApiUrl,
) -> Result<(), Traced<RpcClientError>> {
self.0.borrow_mut().url = Some(url.clone());
self.0.borrow().state.set(ClientState::Connecting);
// wait for transport open
let transport = (self.0.borrow().rpc_transport_factory)();
let mut on_message = transport.on_message();
transport.connect(url).await.map_err(|e| {
let transport_err = e.into_inner();
self.0.borrow().state.set(ClientState::Closed(
ClosedStateReason::CouldNotEstablish(transport_err.clone()),
));
tracerr::new!(RpcClientError::from(
ClosedStateReason::CouldNotEstablish(transport_err)
))
})?;
// wait for ServerMsg::RpcSettings
if let Some(msg) = on_message.next().await {
if let ServerMsg::RpcSettings(rpc_settings) = msg {
Rc::clone(&self)
.start_heartbeat(Rc::clone(&transport), rpc_settings)
.await?;
} else {
let close_reason =
ClosedStateReason::FirstServerMsgIsNotRpcSettings;
self.0
.borrow()
.state
.set(ClientState::Closed(close_reason.clone()));
return Err(tracerr::new!(RpcClientError::ConnectionFailed(
close_reason
)));
}
} else {
self.0.borrow().state.set(ClientState::Closed(
ClosedStateReason::FirstServerMsgIsNotRpcSettings,
));
return Err(tracerr::new!(RpcClientError::ConnectionFailed(
ClosedStateReason::FirstServerMsgIsNotRpcSettings
)));
}
// subscribe to transport close
{
let mut transport_state_changes = transport.on_state_change();
let weak_this = Rc::downgrade(&self);
platform::spawn(async move {
while let Some(state) = transport_state_changes.next().await {
if let Some(this) = weak_this.upgrade() {
if let platform::TransportState::Closed(msg) = state {
this.handle_close_message(msg);
}
}
}
});
}
// subscribe to transport message received
{
let weak_this = Rc::downgrade(&self);
let mut on_socket_message = transport.on_message();
platform::spawn(async move {
while let Some(msg) = on_socket_message.next().await {
if let Some(this) = weak_this.upgrade() {
this.on_transport_message(msg);
}
}
});
}
drop(self.0.borrow_mut().sock.replace(transport));
self.0.borrow().state.set(ClientState::Open);
Ok(())
}
/// Subscribes to [`WebSocketRpcClient`]'s [`ClientState`] changes and when
/// [`ClientState::Connecting`] will be changed to something else, then this
/// [`Future`] will be resolved and based on new [`ClientState`] [`Result`]
/// will be returned.
///
/// [`Future`]: std::future::Future
async fn connecting_result(&self) -> Result<(), Traced<RpcClientError>> {
let mut state_changes = self.0.borrow().state.subscribe();
while let Some(state) = state_changes.next().await {
match state {
ClientState::Open => {
return Ok(());
}
ClientState::Closed(reason) => {
return Err(tracerr::new!(
RpcClientError::ConnectionFailed(reason)
));
}
ClientState::Connecting => (),
}
}
Err(tracerr::new!(RpcClientError::RpcClientGone))
}
/// Tries to upgrade [`ClientState`] of this [`WebSocketRpcClient`] to
/// [`ClientState::Open`].
///
/// This function is also used for reconnecting this [`WebSocketRpcClient`].
///
/// If [`WebSocketRpcClient`] is closed than this function will try to
/// establish new RPC connection.
///
/// If [`WebSocketRpcClient`] already in [`ClientState::Connecting`] then
/// this function will not perform one more connection try. It will
/// subscribe to [`ClientState`] changes and wait for first connection
/// result, and, based on this result, this function will be resolved.
///
/// If [`WebSocketRpcClient`] already in [`ClientState::Open`] then this
/// function will be instantly resolved.
///
/// # Errors
///
/// Errors if [`WebSocketRpcClient`] fails to establish connection with a
/// server.
pub async fn connect(
self: Rc<Self>,
url: ApiUrl,
) -> Result<(), Traced<RpcClientError>> {
let current_url = self.0.borrow().url.clone();
if current_url.as_ref() == Some(&url) {
let state = self.0.borrow().state.borrow().clone();
match state {
ClientState::Open => Ok(()),
ClientState::Connecting => self.connecting_result().await,
ClientState::Closed(_) => self.establish_connection(url).await,
}
} else {
self.establish_connection(url).await
}
}
/// Subscribes on this [`WebSocketRpcClient`]'s [`RpcEvent`]s.
pub fn subscribe(&self) -> LocalBoxStream<'static, RpcEvent> {
let (tx, rx) = mpsc::unbounded();
self.0.borrow_mut().subs.push(tx);
Box::pin(rx)
}
/// Sends [`Command`] for the provided [`RoomId`] to server.
pub fn send_command(&self, room_id: RoomId, command: Command) {
let socket_borrow = &self.0.borrow().sock;
if let Some(socket) = socket_borrow.as_ref() {
if let Err(e) = socket
.send(&ClientMsg::Command { room_id, command })
.map_err(tracerr::map_from_and_wrap!(=> RpcClientError))
{
log::error!("{e}");
}
}
}
/// [`Future`] resolving on normal [`WebSocketRpcClient`] connection
/// closing.
///
/// This [`Future`] wouldn't be resolved on abnormal closes.
/// An [`WebSocketRpcClient::on_connection_loss`] will be thrown instead.
///
/// [`Future`]: std::future::Future
pub fn on_normal_close(
&self,
) -> LocalBoxFuture<'static, Result<CloseReason, oneshot::Canceled>> {
let (tx, rx) = oneshot::channel();
self.0.borrow_mut().on_close_subscribers.push(tx);
Box::pin(rx)
}
/// Subscribe to connection loss events.
///
/// Connection loss is any unexpected [`platform::RpcTransport`] close. In
/// case of connection loss, client side user should select reconnection
/// strategy with [`ReconnectHandle`] (or simply close [`Room`]).
///
/// [`ReconnectHandle`]: crate::rpc::ReconnectHandle
/// [`Room`]: crate::room::Room
/// [`Stream`]: futures::Stream
pub fn on_connection_loss(
&self,
) -> LocalBoxStream<'static, ConnectionLostReason> {
let (tx, rx) = mpsc::unbounded();
self.0.borrow_mut().on_connection_loss_subs.push(tx);
Box::pin(rx)
}
/// Sets reason being passed to the underlying transport when this client is
/// dropped.
pub fn set_close_reason(&self, close_reason: ClientDisconnect) {
self.0.borrow_mut().close_reason = close_reason;
}
}
impl Drop for Inner {
/// Drops the related connection and its [`Heartbeat`].
fn drop(&mut self) {
if let Some(socket) = self.sock.take() {
socket.set_close_reason(self.close_reason);
}
}
}