Propose alternative API

1 files changed, 142 insertions, 63 deletions

diff --git a/src/message.rs b/src/message.rs
index 22cae6a..d918c29 100644
--- a/src/message.rs
+++ b/src/message.rs
@@ -1,3 +1,7 @@
+use std::fmt;
+use std::marker::PhantomData;
+use std::sync::Arc;
+
 use bytes::Bytes;
 use serde::{Deserialize, Serialize};
 
@@ -37,94 +41,169 @@ pub const PRIO_SECONDARY: RequestPriority = 0x01;
 
 /// This trait should be implemented by all messages your application
 /// wants to handle
-pub trait Message: SerializeMessage + Send + Sync {
-	type Response: SerializeMessage + Send + Sync;
+pub trait Message: Serialize + for<'de> Deserialize<'de> + Send + Sync {
+	type Response: Serialize + for<'de> Deserialize<'de> + Send + Sync;
+}
+
+pub struct Req<M: Message> {
+	pub(crate) _phantom: PhantomData<M>,
+	pub(crate) msg: Arc<M>,
+	pub(crate) msg_ser: Option<Bytes>,
+	pub(crate) body: BodyData,
 }
 
-/// A trait for de/serializing messages, with possible associated stream.
-/// This is default-implemented by anything that can already be serialized
-/// and deserialized. Adapters are provided that implement this for 
-/// adding a body, either from a fixed Bytes buffer (which allows the thing
-/// to be Clone), or from a streaming byte stream.
-pub trait SerializeMessage: Sized {
-	type SerializableSelf: Serialize + for<'de> Deserialize<'de> + Send;
+pub struct Resp<M: Message> {
+	pub(crate) _phantom: PhantomData<M>,
+	pub(crate) msg: M::Response,
+	pub(crate) body: BodyData,
+}
 
-	fn into_parts(self) -> (Self::SerializableSelf, Option<ByteStream>);
+pub(crate) enum BodyData {
+	None,
+	Fixed(Bytes),
+	Stream(ByteStream),
+}
 
-	fn from_parts(ser_self: Self::SerializableSelf, stream: ByteStream) -> Self;
+impl BodyData {
+	pub fn into_stream(self) -> Option<ByteStream> {
+		match self {
+			BodyData::None => None,
+			BodyData::Fixed(b) => Some(Box::pin(futures::stream::once(async move { Ok(b) }))),
+			BodyData::Stream(s) => Some(s),
+		}
+	}
 }
 
 // ----
 
-impl<T> SerializeMessage for T
-where
-	T: Serialize + for<'de> Deserialize<'de> + Send,
-{
-	type SerializableSelf = Self;
-	fn into_parts(self) -> (Self::SerializableSelf, Option<ByteStream>) {
-		(self, None)
+impl<M: Message> Req<M> {
+	pub fn msg(&self) -> &M {
+		&self.msg
 	}
 
-	fn from_parts(ser_self: Self::SerializableSelf, _stream: ByteStream) -> Self {
-		// TODO verify no stream
-		ser_self
+	pub fn with_fixed_body(self, b: Bytes) -> Self {
+		Self {
+			body: BodyData::Fixed(b),
+			..self
+		}
+	}
+
+	pub fn with_streaming_body(self, b: ByteStream) -> Self {
+		Self {
+			body: BodyData::Stream(b),
+			..self
+		}
 	}
 }
 
-// ----
+pub trait IntoReq<M: Message> {
+	fn into_req(self) -> Result<Req<M>, rmp_serde::encode::Error>;
+	fn into_req_local(self) -> Req<M>;
+}
 
-/// An adapter that adds a body from a fixed Bytes buffer to a serializable message,
-/// implementing the SerializeMessage trait. This allows for the SerializeMessage object
-/// to be cloned, which is usefull for requests that must be sent to multiple servers.
-/// Note that cloning the body is cheap thanks to Bytes; make sure that your serializable
-/// part is also easily clonable (e.g. by wrapping it in an Arc).
-/// Note that this CANNOT be used for a response type, as it cannot be reconstructed
-/// from a remote stream.
-#[derive(Clone)]
-pub struct WithFixedBody<T: Serialize + for<'de> Deserialize<'de> + Clone + Send + 'static>(
-	pub T,
-	pub Bytes,
-);
-
-impl<T> SerializeMessage for WithFixedBody<T>
-where
-	T: Serialize + for<'de> Deserialize<'de> + Clone + Send + 'static,
-{
-	type SerializableSelf = T;
-
-	fn into_parts(self) -> (Self::SerializableSelf, Option<ByteStream>) {
-		let body = self.1;
-		(
-			self.0,
-			Some(Box::pin(futures::stream::once(async move { Ok(body) }))),
-		)
+impl<M: Message> IntoReq<M> for M {
+	fn into_req(self) -> Result<Req<M>, rmp_serde::encode::Error> {
+		let msg_ser = rmp_to_vec_all_named(&self)?;
+		Ok(Req {
+			_phantom: Default::default(),
+			msg: Arc::new(self),
+			msg_ser: Some(Bytes::from(msg_ser)),
+			body: BodyData::None,
+		})
 	}
+	fn into_req_local(self) -> Req<M> {
+		Req {
+			_phantom: Default::default(),
+			msg: Arc::new(self),
+			msg_ser: None,
+			body: BodyData::None,
+		}
+	}
+}
 
-	fn from_parts(_ser_self: Self::SerializableSelf, _stream: ByteStream) -> Self {
-		panic!("Cannot use a WithFixedBody as a response type");
+impl<M: Message> IntoReq<M> for Req<M> {
+	fn into_req(self) -> Result<Req<M>, rmp_serde::encode::Error> {
+		Ok(self)
+	}
+	fn into_req_local(self) -> Req<M> {
+		self
 	}
 }
 
-/// An adapter that adds a body from a ByteStream. This is usefull for receiving
-/// responses to requests that contain attached byte streams. This type is
-/// not clonable.
-pub struct WithStreamingBody<T: Serialize + for<'de> Deserialize<'de> + Send>(
-	pub T,
-	pub ByteStream,
-);
+impl<M: Message> Clone for Req<M> {
+	fn clone(&self) -> Self {
+		let body = match &self.body {
+			BodyData::None => BodyData::None,
+			BodyData::Fixed(b) => BodyData::Fixed(b.clone()),
+			BodyData::Stream(_) => panic!("Cannot clone a Req<_> with a stream body"),
+		};
+		Self {
+			_phantom: Default::default(),
+			msg: self.msg.clone(),
+			msg_ser: self.msg_ser.clone(),
+			body,
+		}
+	}
+}
 
-impl<T> SerializeMessage for WithStreamingBody<T>
+impl<M> fmt::Debug for Req<M>
 where
-	T: Serialize + for<'de> Deserialize<'de> + Send,
+	M: Message + fmt::Debug,
 {
-	type SerializableSelf = T;
+	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+		write!(f, "Req[{:?}", self.msg)?;
+		match &self.body {
+			BodyData::None => write!(f, "]"),
+			BodyData::Fixed(b) => write!(f, "; body={}]", b.len()),
+			BodyData::Stream(_) => write!(f, "; body=stream]"),
+		}
+	}
+}
+
+impl<M> fmt::Debug for Resp<M>
+where
+	M: Message,
+	<M as Message>::Response: fmt::Debug,
+{
+	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+		write!(f, "Resp[{:?}", self.msg)?;
+		match &self.body {
+			BodyData::None => write!(f, "]"),
+			BodyData::Fixed(b) => write!(f, "; body={}]", b.len()),
+			BodyData::Stream(_) => write!(f, "; body=stream]"),
+		}
+	}
+}
+
+impl<M: Message> Resp<M> {
+	pub fn new(v: M::Response) -> Self {
+		Resp {
+			_phantom: Default::default(),
+			msg: v,
+			body: BodyData::None,
+		}
+	}
+
+	pub fn with_fixed_body(self, b: Bytes) -> Self {
+		Self {
+			body: BodyData::Fixed(b),
+			..self
+		}
+	}
+
+	pub fn with_streaming_body(self, b: ByteStream) -> Self {
+		Self {
+			body: BodyData::Stream(b),
+			..self
+		}
+	}
 
-	fn into_parts(self) -> (Self::SerializableSelf, Option<ByteStream>) {
-		(self.0, Some(self.1))
+	pub fn msg(&self) -> &M::Response {
+		&self.msg
 	}
 
-	fn from_parts(ser_self: Self::SerializableSelf, stream: ByteStream) -> Self {
-		WithStreamingBody(ser_self, stream)
+	pub fn into_msg(self) -> M::Response {
+		self.msg
 	}
 }