use std::borrow::Borrow; use std::marker::PhantomData; use std::sync::Arc; use arc_swap::ArcSwapOption; use async_trait::async_trait; use serde::{Deserialize, Serialize}; use crate::error::Error; use crate::netapp::*; use crate::proto::*; use crate::util::*; /// This trait should be implemented by all messages your application /// wants to handle pub trait Message: Serialize + for<'de> Deserialize<'de> + Send + Sync { type Response: Serialize + for<'de> Deserialize<'de> + Send + Sync; } /// This trait should be implemented by an object of your application /// that can handle a message of type `M`. /// /// The handler object should be in an Arc, see `Endpoint::set_handler` #[async_trait] pub trait EndpointHandler: Send + Sync where M: Message, { async fn handle(self: &Arc, m: &M, from: NodeID) -> M::Response; } /// If one simply wants to use an endpoint in a client fashion, /// without locally serving requests to that endpoint, /// use the unit type `()` as the handler type: /// it will panic if it is ever made to handle request. #[async_trait] impl EndpointHandler for () { async fn handle(self: &Arc<()>, _m: &M, _from: NodeID) -> M::Response { panic!("This endpoint should not have a local handler."); } } /// This struct represents an endpoint for message of type `M`. /// /// Creating a new endpoint is done by calling `NetApp::endpoint`. /// An endpoint is identified primarily by its path, which is specified /// at creation time. /// /// An `Endpoint` is used both to send requests to remote nodes, /// and to specify the handler for such requests on the local node. /// The type `H` represents the type of the handler object for /// endpoint messages (see `EndpointHandler`). pub struct Endpoint where M: Message, H: EndpointHandler, { phantom: PhantomData, netapp: Arc, path: String, handler: ArcSwapOption, } impl Endpoint where M: Message, H: EndpointHandler, { pub(crate) fn new(netapp: Arc, path: String) -> Self { Self { phantom: PhantomData::default(), netapp, path, handler: ArcSwapOption::from(None), } } /// Get the path of this endpoint pub fn path(&self) -> &str { &self.path } /// Set the object that is responsible of handling requests to /// this endpoint on the local node. pub fn set_handler(&self, h: Arc) { self.handler.swap(Some(h)); } /// Call this endpoint on a remote node (or on the local node, /// for that matter) pub async fn call( &self, target: &NodeID, req: B, prio: RequestPriority, ) -> Result<::Response, Error> where B: Borrow, { if *target == self.netapp.id { match self.handler.load_full() { None => Err(Error::NoHandler), Some(h) => Ok(h.handle(req.borrow(), self.netapp.id).await), } } else { let conn = self .netapp .client_conns .read() .unwrap() .get(target) .cloned(); match conn { None => Err(Error::Message(format!( "Not connected: {}", hex::encode(&target[..8]) ))), Some(c) => c.call(req, self.path.as_str(), prio).await, } } } } // ---- Internal stuff ---- pub(crate) type DynEndpoint = Box; #[async_trait] pub(crate) trait GenericEndpoint { async fn handle(&self, buf: &[u8], from: NodeID) -> Result, Error>; fn drop_handler(&self); fn clone_endpoint(&self) -> DynEndpoint; } #[derive(Clone)] pub(crate) struct EndpointArc(pub(crate) Arc>) where M: Message, H: EndpointHandler; #[async_trait] impl GenericEndpoint for EndpointArc where M: Message + 'static, H: EndpointHandler + 'static, { async fn handle(&self, buf: &[u8], from: NodeID) -> Result, Error> { match self.0.handler.load_full() { None => Err(Error::NoHandler), Some(h) => { let req = rmp_serde::decode::from_read_ref::<_, M>(buf)?; let res = h.handle(&req, from).await; let res_bytes = rmp_to_vec_all_named(&res)?; Ok(res_bytes) } } } fn drop_handler(&self) { self.0.handler.swap(None); } fn clone_endpoint(&self) -> DynEndpoint { Box::new(Self(self.0.clone())) } }