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|
use std::{collections::HashMap, sync::Arc};
use bytes::Bytes;
use futures::{SinkExt, StreamExt};
use tokio::{
sync::{mpsc, oneshot},
task::AbortHandle,
};
use crate::{
Channel,
protocol::{RpcCall, RpcMessage, RpcResponse},
};
const CLIENT_CHANNEL_BUFFER_SIZE: usize = 64;
struct ClientChannelMessage {
service: String,
method: String,
arguments: Bytes,
responder: oneshot::Sender<std::io::Result<Bytes>>,
}
struct ClientChannelInner {
sender: mpsc::Sender<ClientChannelMessage>,
abort_handle: AbortHandle,
}
impl Drop for ClientChannelInner {
fn drop(&mut self) {
self.abort_handle.abort();
}
}
#[derive(Clone)]
pub struct ClientChannel(Arc<ClientChannelInner>);
impl ClientChannel {
pub fn new<C: Channel>(channel: C) -> Self {
let (tx, rx) = mpsc::channel(CLIENT_CHANNEL_BUFFER_SIZE);
let abort_handle = tokio::spawn(client_channel_loop(channel, rx)).abort_handle();
Self(Arc::new(ClientChannelInner {
sender: tx,
abort_handle,
}))
}
pub async fn call(
&self,
service: String,
method: String,
arguments: Bytes,
) -> std::io::Result<Bytes> {
let (tx, rx) = oneshot::channel();
self.0
.sender
.send(ClientChannelMessage {
service,
method,
arguments,
responder: tx,
})
.await
.expect("client channel task should never shutdown while a client is alive");
rx.await
.expect("client channel task should never shutdown while a client is alive")
}
}
async fn client_channel_loop<C: Channel>(
mut channel: C,
mut rx: mpsc::Receiver<ClientChannelMessage>,
) {
enum Select {
RpcMessage(RpcMessage),
ClientChannelMessage(ClientChannelMessage),
}
let mut responders = HashMap::<u64, oneshot::Sender<std::io::Result<Bytes>>>::default();
let mut rpc_call_id = 0;
loop {
let select = tokio::select! {
Some(Ok(v)) = channel.next() => Select::RpcMessage(v),
Some(v) = rx.recv() => Select::ClientChannelMessage(v),
};
match select {
Select::RpcMessage(RpcMessage::Response(RpcResponse { id, value })) => {
if let Some(responder) = responders.remove(&id) {
let _ = responder.send(Ok(value));
}
}
Select::RpcMessage(_) => todo!(),
Select::ClientChannelMessage(ClientChannelMessage {
service,
method,
arguments,
responder,
}) => {
let id = rpc_call_id;
rpc_call_id += 1;
let result = channel
.send(RpcMessage::Call(RpcCall {
id,
service,
method,
arguments,
}))
.await;
match result {
Ok(()) => {
responders.insert(id, responder);
}
Err(err) => {
let _ = responder.send(Err(err));
}
}
}
}
}
}
|
