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use std::{collections::HashMap, sync::Arc};
use futures::{SinkExt, StreamExt};
use tokio::task::{AbortHandle, JoinSet};
use crate::{
Channel, Listener, Service,
protocol::{RpcCall, RpcCancel, RpcMessage, RpcResponse},
};
#[derive(Clone)]
struct Services(Arc<HashMap<String, Arc<dyn Service>>>);
impl Services {
fn new(services: HashMap<String, Arc<dyn Service>>) -> Self {
Self(Arc::new(services))
}
fn get_service(&self, name: &str) -> std::io::Result<Arc<dyn Service>> {
match self.0.get(name) {
Some(service) => Ok(service.clone()),
None => Err(std::io::Error::new(
std::io::ErrorKind::NotFound,
"service not found",
)),
}
}
}
type ListenerSpawner =
Box<dyn FnOnce(&mut JoinSet<std::io::Result<()>>, Services) -> AbortHandle + Send + 'static>;
#[derive(Debug, Default)]
struct AbortHandles(Vec<AbortHandle>);
impl Drop for AbortHandles {
fn drop(&mut self) {
for handle in &self.0 {
handle.abort();
}
}
}
impl AbortHandles {
pub fn push(&mut self, handle: AbortHandle) {
self.0.push(handle);
}
}
#[derive(Default)]
pub struct Server {
services: HashMap<String, Arc<dyn Service>>,
listener_spawners: Vec<ListenerSpawner>,
}
impl Server {
pub fn with_service<T>(mut self, service: T) -> Self
where
T: Service,
{
let name = T::name();
let service = Arc::new(service);
self.services.insert(name.to_string(), service);
self
}
pub fn with_listener<L, C>(mut self, listener: L) -> Self
where
C: Channel,
L: Listener<C>,
{
self.listener_spawners
.push(Box::new(move |join_set, services| {
join_set.spawn(listener_loop(listener, services))
}));
self
}
pub async fn serve(self) -> std::io::Result<()> {
let services = Services::new(self.services);
let mut join_set = JoinSet::default();
let mut abort_handles = AbortHandles::default();
for spawner in self.listener_spawners {
let abort_handle = (spawner)(&mut join_set, services.clone());
abort_handles.push(abort_handle);
}
match join_set.join_next().await {
Some(Ok(Ok(()))) => Ok(()),
Some(Ok(Err(err))) => Err(err),
Some(Err(err)) => Err(std::io::Error::other(err)),
None => Ok(()),
}
}
}
async fn listener_loop<L, C>(mut listener: L, services: Services) -> std::io::Result<()>
where
C: Channel,
L: Listener<C>,
{
while let Some(result) = listener.next().await {
let channel = result?;
let services = services.clone();
tokio::spawn(channel_handler(channel, services));
}
Ok(())
}
async fn channel_handler<C: Channel>(mut channel: C, services: Services) -> std::io::Result<()> {
enum Select {
Empty,
Message(RpcMessage),
}
let (response_tx, mut response_rx) =
tokio::sync::mpsc::unbounded_channel::<std::io::Result<RpcResponse>>();
let mut requests: HashMap<u64, AbortHandle> = Default::default();
loop {
let select = tokio::select! {
reqopt = channel.next() => match reqopt {
Some(Ok(message)) => Select::Message(message),
Some(Err(err)) => return Err(err),
None => Select::Empty,
},
Some(response) = response_rx.recv() => match response {
Ok(response) => Select::Message(RpcMessage::Response(response)),
Err(err) => return Err(err),
}
};
match select {
Select::Empty => break,
Select::Message(message) => match message {
RpcMessage::Call(RpcCall {
id,
service,
method,
arguments,
}) => {
let response_tx = response_tx.clone();
let service = services.get_service(&service)?;
let handle = tokio::spawn(async move {
let response = match service.call(method, arguments).await {
Ok(value) => Ok(RpcResponse { id, value }),
Err(err) => Err(err),
};
let _ = response_tx.send(response);
})
.abort_handle();
requests.insert(id, handle);
}
RpcMessage::Cancel(RpcCancel { id }) => {
if let Some(handle) = requests.remove(&id) {
handle.abort();
}
}
RpcMessage::Response(response) => {
requests.remove(&response.id);
channel.send(RpcMessage::Response(response)).await?;
}
},
}
}
Ok(())
}
|
