[import-netapp] import Netapp code into Garage codebase

src/net/endpoint.rs

@@ -0,0 +1,201 @@
+use std::marker::PhantomData;
+use std::sync::Arc;
+
+use arc_swap::ArcSwapOption;
+use async_trait::async_trait;
+
+use crate::error::Error;
+use crate::message::*;
+use crate::netapp::*;
+
+/// This trait should be implemented by an object of your application
+/// that can handle a message of type `M`, if it wishes to handle
+/// streams attached to the request and/or to send back streams
+/// attached to the response..
+///
+/// The handler object should be in an Arc, see `Endpoint::set_handler`
+#[async_trait]
+pub trait StreamingEndpointHandler<M>: Send + Sync
+where
+	M: Message,
+{
+	async fn handle(self: &Arc<Self>, m: Req<M>, from: NodeID) -> Resp<M>;
+}
+
+/// 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<M: Message> EndpointHandler<M> for () {
+	async fn handle(self: &Arc<()>, _m: &M, _from: NodeID) -> M::Response {
+		panic!("This endpoint should not have a local handler.");
+	}
+}
+
+// ----
+
+/// This trait should be implemented by an object of your application
+/// that can handle a message of type `M`, in the cases where it doesn't
+/// care about attached stream in the request nor in the response.
+#[async_trait]
+pub trait EndpointHandler<M>: Send + Sync
+where
+	M: Message,
+{
+	async fn handle(self: &Arc<Self>, m: &M, from: NodeID) -> M::Response;
+}
+
+#[async_trait]
+impl<T, M> StreamingEndpointHandler<M> for T
+where
+	T: EndpointHandler<M>,
+	M: Message,
+{
+	async fn handle(self: &Arc<Self>, mut m: Req<M>, from: NodeID) -> Resp<M> {
+		// Immediately drop stream to ignore all data that comes in,
+		// instead of buffering it indefinitely
+		drop(m.take_stream());
+		Resp::new(EndpointHandler::handle(self, m.msg(), from).await)
+	}
+}
+
+// ----
+
+/// 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 `StreamingEndpointHandler`).
+pub struct Endpoint<M, H>
+where
+	M: Message,
+	H: StreamingEndpointHandler<M>,
+{
+	_phantom: PhantomData<M>,
+	netapp: Arc<NetApp>,
+	path: String,
+	handler: ArcSwapOption<H>,
+}
+
+impl<M, H> Endpoint<M, H>
+where
+	M: Message,
+	H: StreamingEndpointHandler<M>,
+{
+	pub(crate) fn new(netapp: Arc<NetApp>, 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<H>) {
+		self.handler.swap(Some(h));
+	}
+
+	/// Call this endpoint on a remote node (or on the local node,
+	/// for that matter). This function invokes the full version that
+	/// allows to attach a stream to the request and to
+	/// receive such a stream attached to the response.
+	pub async fn call_streaming<T>(
+		&self,
+		target: &NodeID,
+		req: T,
+		prio: RequestPriority,
+	) -> Result<Resp<M>, Error>
+	where
+		T: IntoReq<M>,
+	{
+		if *target == self.netapp.id {
+			match self.handler.load_full() {
+				None => Err(Error::NoHandler),
+				Some(h) => Ok(h.handle(req.into_req_local(), 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.into_req()?, self.path.as_str(), prio).await,
+			}
+		}
+	}
+
+	/// Call this endpoint on a remote node. This function is the simplified
+	/// version that doesn't allow to have streams attached to the request
+	/// or the response; see `call_streaming` for the full version.
+	pub async fn call(
+		&self,
+		target: &NodeID,
+		req: M,
+		prio: RequestPriority,
+	) -> Result<<M as Message>::Response, Error> {
+		Ok(self.call_streaming(target, req, prio).await?.into_msg())
+	}
+}
+
+// ---- Internal stuff ----
+
+pub(crate) type DynEndpoint = Box<dyn GenericEndpoint + Send + Sync>;
+
+#[async_trait]
+pub(crate) trait GenericEndpoint {
+	async fn handle(&self, req_enc: ReqEnc, from: NodeID) -> Result<RespEnc, Error>;
+	fn drop_handler(&self);
+	fn clone_endpoint(&self) -> DynEndpoint;
+}
+
+#[derive(Clone)]
+pub(crate) struct EndpointArc<M, H>(pub(crate) Arc<Endpoint<M, H>>)
+where
+	M: Message,
+	H: StreamingEndpointHandler<M>;
+
+#[async_trait]
+impl<M, H> GenericEndpoint for EndpointArc<M, H>
+where
+	M: Message,
+	H: StreamingEndpointHandler<M> + 'static,
+{
+	async fn handle(&self, req_enc: ReqEnc, from: NodeID) -> Result<RespEnc, Error> {
+		match self.0.handler.load_full() {
+			None => Err(Error::NoHandler),
+			Some(h) => {
+				let req = Req::from_enc(req_enc)?;
+				let res = h.handle(req, from).await;
+				Ok(res.into_enc()?)
+			}
+		}
+	}
+
+	fn drop_handler(&self) {
+		self.0.handler.swap(None);
+	}
+
+	fn clone_endpoint(&self) -> DynEndpoint {
+		Box::new(Self(self.0.clone()))
+	}
+}