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async_client::helpers::process_subscription_close_response, BatchMessage, ClientT, RegisterNotificationMessage,
RequestMessage, Subscription, SubscriptionClientT, SubscriptionKind, SubscriptionMessage, TransportReceiverT,
TransportSenderT,
build_unsubscribe_message, call_with_timeout, process_batch_response, process_error_response, process_notification,
process_single_response, process_subscription_response, stop_subscription,
};
use manager::RequestManager;
use crate::error::Error;
use async_trait::async_trait;
use futures_channel::{mpsc, oneshot};
use futures_util::future::Either;
use futures_util::sink::SinkExt;
use futures_util::stream::StreamExt;
use jsonrpsee_types::{
response::SubscriptionError, ErrorResponse, Id, Notification, NotificationSer, ParamsSer, RequestSer, Response,
SubscriptionResponse,
use serde::de::DeserializeOwned;
use super::{FrontToBack, IdKind, RequestIdManager};
/// Wrapper over a [`oneshot::Receiver`](futures_channel::oneshot::Receiver) that reads
/// the underlying channel once and then stores the result in String.
/// It is possible that the error is read more than once if several calls are made
/// when the background thread has been terminated.
#[derive(Debug)]
enum ErrorFromBack {
/// Error message is already read.
Read(String),
/// Error message is unread.
Unread(oneshot::Receiver<Error>),
}
impl ErrorFromBack {
async fn read_error(self) -> (Self, Error) {
match self {
Self::Unread(rx) => {
let msg = match rx.await {
Ok(msg) => msg.to_string(),
// This should never happen because the receiving end is still alive.
// Would be a bug in the logic of the background task.
Err(_) => "Error reason could not be found. This is a bug. Please open an issue.".to_string(),
};
let err = Error::RestartNeeded(msg.clone());
(Self::Read(msg), err)
}
Self::Read(msg) => (Self::Read(msg.clone()), Error::RestartNeeded(msg)),
}
}
}
#[derive(Clone, Debug)]
max_concurrent_requests: usize,
max_notifs_per_subscription: usize,
impl Default for ClientBuilder {
fn default() -> Self {
max_concurrent_requests: 256,
max_notifs_per_subscription: 1024,
id_kind: IdKind::Number,
/// Set request timeout (default is 60 seconds).
pub fn request_timeout(mut self, timeout: Duration) -> Self {
self
}
/// Set max concurrent requests (default is 256).
pub fn max_concurrent_requests(mut self, max: usize) -> Self {
self.max_concurrent_requests = max;
self
}
/// Set max concurrent notification capacity for each subscription; when the capacity is exceeded the subscription
/// will be dropped (default is 1024).
///
/// You may prevent the subscription from being dropped by polling often enough
/// [`Subscription::next()`](../../jsonrpsee_core/client/struct.Subscription.html#method.next) such that
/// it can keep with the rate as server produces new items on the subscription.
///
/// **Note**: The actual capacity is `num_senders + max_subscription_capacity`
/// because it is passed to [`futures_channel::mpsc::channel`].
pub fn max_notifs_per_subscription(mut self, max: usize) -> Self {
self.max_notifs_per_subscription = max;
self
}
/// Configure the data type of the request object ID (default is number).
pub fn id_format(mut self, id_kind: IdKind) -> Self {
self.id_kind = id_kind;
self
}
/// Build the client with given transport.
///
/// ## Panics
///
/// Panics if being called outside of `tokio` runtime context.
pub fn build<S: TransportSenderT, R: TransportReceiverT>(self, sender: S, receiver: R) -> Client {
let (to_back, from_front) = mpsc::channel(self.max_concurrent_requests);
let (err_tx, err_rx) = oneshot::channel();
let max_notifs_per_subscription = self.max_notifs_per_subscription;
tokio::spawn(async move {
background_task(sender, receiver, from_front, err_tx, max_notifs_per_subscription).await;
request_timeout: self.request_timeout,
error: Mutex::new(ErrorFromBack::Unread(err_rx)),
id_manager: RequestIdManager::new(self.max_concurrent_requests, self.id_kind),
}
/// Generic asyncronous client.
#[derive(Debug)]
pub struct Client {
/// Channel to send requests to the background task.
to_back: mpsc::Sender<FrontToBack>,
/// If the background thread terminates the error is sent to this channel.
// NOTE(niklasad1): This is a Mutex to circumvent that the async fns takes immutable references.
error: Mutex<ErrorFromBack>,
/// Request timeout. Defaults to 60sec.
request_timeout: Duration,
/// Request ID manager.
id_manager: RequestIdManager,
}
impl Client {
/// Checks if the client is connected to the target.
pub fn is_connected(&self) -> bool {
!self.to_back.is_closed()
}
// Reads the error message from the backend thread.
async fn read_error_from_backend(&self) -> Error {
let mut err_lock = self.error.lock().await;
let from_back = std::mem::replace(&mut *err_lock, ErrorFromBack::Read(String::new()));
let (next_state, err) = from_back.read_error().await;
*err_lock = next_state;
err
impl<S: TransportSenderT, R: TransportReceiverT> From<(S, R)> for Client {
fn from(transport: (S, R)) -> Client {
ClientBuilder::default().build(transport.0, transport.1)
}
}
impl Drop for Client {
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fn drop(&mut self) {
self.to_back.close_channel();
}
}
#[async_trait]
async fn notification<'a>(&self, method: &'a str, params: Option<ParamsSer<'a>>) -> Result<(), Error> {
// NOTE: we use this to guard against max number of concurrent requests.
let _req_id = self.id_manager.next_request_id()?;
let raw = serde_json::to_string(¬if).map_err(Error::ParseError)?;
tracing::trace!("[frontend]: send notification: {:?}", raw);
let mut sender = self.to_back.clone();
let fut = sender.send(FrontToBack::Notification(raw));
let timeout = tokio::time::sleep(self.request_timeout);
let res = tokio::select! {
x = fut => x,
_ = timeout => return Err(Error::RequestTimeout)
};
Ok(()) => Ok(()),
Err(_) => Err(self.read_error_from_backend().await),
}
async fn request<'a, R>(&self, method: &'a str, params: Option<ParamsSer<'a>>) -> Result<R, Error>
{
let (send_back_tx, send_back_rx) = oneshot::channel();
let guard = self.id_manager.next_request_id()?;
let id = guard.inner();
let raw = serde_json::to_string(&RequestSer::new(&id, method, params)).map_err(Error::ParseError)?;
tracing::trace!("[frontend]: send request: {:?}", raw);
if self
.to_back
.send(FrontToBack::Request(RequestMessage { raw, id, send_back: Some(send_back_tx) }))
.is_err()
{
return Err(self.read_error_from_backend().await);
}
let res = call_with_timeout(self.request_timeout, send_back_rx).await;
let json_value = match res {
Ok(Ok(v)) => v,
Ok(Err(err)) => return Err(err),
Err(_) => return Err(self.read_error_from_backend().await),
serde_json::from_value(json_value).map_err(Error::ParseError)
async fn batch_request<'a, R>(&self, batch: Vec<(&'a str, Option<ParamsSer<'a>>)>) -> Result<Vec<R>, Error>
R: DeserializeOwned + Default + Clone,
let guard = self.id_manager.next_request_ids(batch.len())?;
let batch_ids: Vec<Id> = guard.inner();
let mut batches = Vec::with_capacity(batch.len());
for (idx, (method, params)) in batch.into_iter().enumerate() {
batches.push(RequestSer::new(&batch_ids[idx], method, params));
let (send_back_tx, send_back_rx) = oneshot::channel();
let raw = serde_json::to_string(&batches).map_err(Error::ParseError)?;
tracing::trace!("[frontend]: send batch request: {:?}", raw);
.send(FrontToBack::Batch(BatchMessage { raw, ids: batch_ids, send_back: send_back_tx }))
.await
.is_err()
{
return Err(self.read_error_from_backend().await);
}
let res = call_with_timeout(self.request_timeout, send_back_rx).await;
let json_values = match res {
Ok(Ok(v)) => v,
Ok(Err(err)) => return Err(err),
Err(_) => return Err(self.read_error_from_backend().await),
};
let values: Result<_, _> =
json_values.into_iter().map(|val| serde_json::from_value(val).map_err(Error::ParseError)).collect();
#[async_trait]
impl SubscriptionClientT for Client {
/// Send a subscription request to the server.
///
/// The `subscribe_method` and `params` are used to ask for the subscription towards the
/// server. The `unsubscribe_method` is used to close the subscription.
unsubscribe_method: &'a str,
) -> Result<Subscription<N>, Error>
where
N: DeserializeOwned,
{
tracing::trace!("[frontend]: subscribe: {:?}, unsubscribe: {:?}", subscribe_method, unsubscribe_method);
if subscribe_method == unsubscribe_method {
return Err(Error::SubscriptionNameConflict(unsubscribe_method.to_owned()));
let guard = self.id_manager.next_request_ids(2)?;
let mut ids: Vec<Id> = guard.inner();
let raw =
serde_json::to_string(&RequestSer::new(&ids[0], subscribe_method, params)).map_err(Error::ParseError)?;
let (send_back_tx, send_back_rx) = oneshot::channel();
if self
.to_back
.send(FrontToBack::Subscribe(SubscriptionMessage {
subscribe_id: ids.swap_remove(0),
unsubscribe_id: ids.swap_remove(0),
unsubscribe_method: unsubscribe_method.to_owned(),
send_back: send_back_tx,
}))
.is_err()
{
return Err(self.read_error_from_backend().await);
}
let res = call_with_timeout(self.request_timeout, send_back_rx).await;
let (notifs_rx, id) = match res {
Ok(Ok(val)) => val,
Ok(Err(err)) => return Err(err),
Err(_) => return Err(self.read_error_from_backend().await),
Ok(Subscription::new(self.to_back.clone(), notifs_rx, SubscriptionKind::Subscription(id)))
/// Subscribe to a specific method.
async fn subscribe_to_method<'a, N>(&self, method: &'a str) -> Result<Subscription<N>, Error>
where
N: DeserializeOwned,
{
tracing::trace!("[frontend]: register_notification: {:?}", method);
let (send_back_tx, send_back_rx) = oneshot::channel();
if self
.to_back
.clone()
.send(FrontToBack::RegisterNotification(RegisterNotificationMessage {
send_back: send_back_tx,
method: method.to_owned(),
}))
.await
.is_err()
{
return Err(self.read_error_from_backend().await);
}
let res = call_with_timeout(self.request_timeout, send_back_rx).await;
let (notifs_rx, method) = match res {
Ok(Ok(val)) => val,
Ok(Err(err)) => return Err(err),
Err(_) => return Err(self.read_error_from_backend().await),
};
Ok(Subscription::new(self.to_back.clone(), notifs_rx, SubscriptionKind::Method(method)))
}
/// Function being run in the background that processes messages from the frontend.
async fn background_task<S: TransportSenderT, R: TransportReceiverT>(
mut sender: S,
receiver: R,
front_error: oneshot::Sender<Error>,
max_notifs_per_subscription: usize,
let mut manager = RequestManager::new();
let backend_event = futures_util::stream::unfold(receiver, |mut receiver| async {
let res = receiver.receive().await;
futures_util::pin_mut!(backend_event);
loop {
let next_frontend = frontend.next();
let next_backend = backend_event.next();
futures_util::pin_mut!(next_frontend, next_backend);
match futures_util::future::select(next_frontend, next_backend).await {
// User dropped the sender side of the channel.
// There is nothing to do just terminate.
Either::Left((None, _)) => {
tracing::trace!("[backend]: frontend dropped; terminate client");
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break;
}
Either::Left((Some(FrontToBack::Batch(batch)), _)) => {
tracing::trace!("[backend]: client prepares to send batch request: {:?}", batch.raw);
// NOTE(niklasad1): annoying allocation.
if let Err(send_back) = manager.insert_pending_batch(batch.ids.clone(), batch.send_back) {
tracing::warn!("[backend]: batch request: {:?} already pending", batch.ids);
let _ = send_back.send(Err(Error::InvalidRequestId));
continue;
}
if let Err(e) = sender.send(batch.raw).await {
tracing::warn!("[backend]: client batch request failed: {:?}", e);
manager.complete_pending_batch(batch.ids);
// User called `notification` on the front-end
Either::Left((Some(FrontToBack::Notification(notif)), _)) => {
tracing::trace!("[backend]: client prepares to send notification: {:?}", notif);
if let Err(e) = sender.send(notif).await {
tracing::warn!("[backend]: client notif failed: {:?}", e);
}
// User called `request` on the front-end
Either::Left((Some(FrontToBack::Request(request)), _)) => {
tracing::trace!("[backend]: client prepares to send request={:?}", request);
match sender.send(request.raw).await {
Ok(_) => manager
.insert_pending_call(request.id, request.send_back)
.expect("ID unused checked above; qed"),
Err(e) => {
tracing::warn!("[backend]: client request failed: {:?}", e);
let _ = request.send_back.map(|s| s.send(Err(Error::Transport(e.into()))));
// User called `subscribe` on the front-end.
Either::Left((Some(FrontToBack::Subscribe(sub)), _)) => match sender.send(sub.raw).await {
Ok(_) => manager
.insert_pending_subscription(
sub.subscribe_id,
sub.unsubscribe_id,
sub.send_back,
sub.unsubscribe_method,
)
.expect("Request ID unused checked above; qed"),
Err(e) => {
tracing::warn!("[backend]: client subscription failed: {:?}", e);
let _ = sub.send_back.send(Err(Error::Transport(e.into())));
// User dropped a subscription.
Either::Left((Some(FrontToBack::SubscriptionClosed(sub_id)), _)) => {
tracing::trace!("Closing subscription: {:?}", sub_id);
// NOTE: The subscription may have been closed earlier if
// the channel was full or disconnected.
if let Some(unsub) = manager
.get_request_id_by_subscription_id(&sub_id)
.and_then(|req_id| build_unsubscribe_message(&mut manager, req_id, sub_id))
stop_subscription(&mut sender, &mut manager, unsub).await;
// User called `register_notification` on the front-end.
Either::Left((Some(FrontToBack::RegisterNotification(reg)), _)) => {
tracing::trace!("[backend] registering notification handler: {:?}", reg.method);
let (subscribe_tx, subscribe_rx) = mpsc::channel(max_notifs_per_subscription);
if manager.insert_notification_handler(®.method, subscribe_tx).is_ok() {
let _ = reg.send_back.send(Ok((subscribe_rx, reg.method)));
} else {
let _ = reg.send_back.send(Err(Error::MethodAlreadyRegistered(reg.method)));
}
}
// User dropped the notificationHandler for this method
Either::Left((Some(FrontToBack::UnregisterNotification(method)), _)) => {
tracing::trace!("[backend] unregistering notification handler: {:?}", method);
let _ = manager.remove_notification_handler(method);
}
Either::Right((Some(Ok(raw)), _)) => {
// Single response to a request.
if let Ok(single) = serde_json::from_str::<Response<_>>(&raw) {
tracing::debug!("[backend]: recv method_call {:?}", single);
match process_single_response(&mut manager, single, max_notifs_per_subscription) {
Ok(Some(unsub)) => {
stop_subscription(&mut sender, &mut manager, unsub).await;
Err(err) => {
let _ = front_error.send(err);
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break;
else if let Ok(response) = serde_json::from_str::<SubscriptionResponse<_>>(&raw) {
tracing::debug!("[backend]: recv subscription {:?}", response);
if let Err(Some(unsub)) = process_subscription_response(&mut manager, response) {
let _ = stop_subscription(&mut sender, &mut manager, unsub).await;
// Subscription error response.
else if let Ok(response) = serde_json::from_str::<SubscriptionError<_>>(&raw) {
tracing::debug!("[backend]: recv subscription closed {:?}", response);
let _ = process_subscription_close_response(&mut manager, response);
}
// Incoming Notification
else if let Ok(notif) = serde_json::from_str::<Notification<_>>(&raw) {
tracing::debug!("[backend]: recv notification {:?}", notif);
let _ = process_notification(&mut manager, notif);
}
else if let Ok(batch) = serde_json::from_str::<Vec<Response<_>>>(&raw) {
tracing::debug!("[backend]: recv batch {:?}", batch);
if let Err(e) = process_batch_response(&mut manager, batch) {
let _ = front_error.send(e);
break;
else if let Ok(err) = serde_json::from_str::<ErrorResponse>(&raw) {
tracing::debug!("[backend]: recv error response {:?}", err);
if let Err(e) = process_error_response(&mut manager, err) {
let _ = front_error.send(e);
break;
// Unparsable response
else {
"[backend]: recv unparseable message: {:?}",
serde_json::from_str::<serde_json::Value>(&raw)
);
let _ = front_error.send(Error::Custom("Unparsable response".into()));
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break;
}
Either::Right((Some(Err(e)), _)) => {
tracing::error!("Error: {:?} terminating client", e);
let _ = front_error.send(Error::Transport(e.into()));
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break;
}
Either::Right((None, _)) => {
tracing::error!("[backend]: WebSocket receiver dropped; terminate client");
let _ = front_error.send(Error::Custom("WebSocket receiver dropped".into()));
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break;
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// Send close message to the server.
let _ = sender.close().await;