Simple cross-process message protocol

3 files changed, 86 insertions, 225 deletions

diff --git a/crates/ra_proc_macro/src/msg.rs b/crates/ra_proc_macro/src/msg.rs
index 2fb065d32..aa95bcc8f 100644
--- a/crates/ra_proc_macro/src/msg.rs
+++ b/crates/ra_proc_macro/src/msg.rs
@@ -1,218 +1,93 @@
-//! A simplified version of lsp base protocol for rpc
+//! Defines messages for cross-process message based on `ndjson` wire protocol
 
 use std::{
-    fmt,
+    convert::TryFrom,
     io::{self, BufRead, Write},
 };
 
+use crate::{
+    rpc::{ListMacrosResult, ListMacrosTask},
+    ExpansionResult, ExpansionTask,
+};
 use serde::{de::DeserializeOwned, Deserialize, Serialize};
 
-#[derive(Serialize, Deserialize, Debug, Clone)]
-#[serde(untagged)]
-pub enum Message {
-    Request(Request),
-    Response(Response),
-}
-
-impl From<Request> for Message {
-    fn from(request: Request) -> Message {
-        Message::Request(request)
-    }
-}
-
-impl From<Response> for Message {
-    fn from(response: Response) -> Message {
-        Message::Response(response)
-    }
-}
-
-#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
-#[serde(transparent)]
-pub struct RequestId(IdRepr);
-
-#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
-#[serde(untagged)]
-enum IdRepr {
-    U64(u64),
-    String(String),
-}
-
-impl From<u64> for RequestId {
-    fn from(id: u64) -> RequestId {
-        RequestId(IdRepr::U64(id))
-    }
-}
-
-impl From<String> for RequestId {
-    fn from(id: String) -> RequestId {
-        RequestId(IdRepr::String(id))
-    }
-}
-
-impl fmt::Display for RequestId {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match &self.0 {
-            IdRepr::U64(it) => fmt::Display::fmt(it, f),
-            IdRepr::String(it) => fmt::Display::fmt(it, f),
-        }
-    }
-}
-
 #[derive(Debug, Serialize, Deserialize, Clone)]
-pub struct Request {
-    pub id: RequestId,
-    pub method: String,
-    pub params: serde_json::Value,
+pub enum Request {
+    ListMacro(ListMacrosTask),
+    ExpansionMacro(ExpansionTask),
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone)]
-pub struct Response {
-    // JSON RPC allows this to be null if it was impossible
-    // to decode the request's id. Ignore this special case
-    // and just die horribly.
-    pub id: RequestId,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub result: Option<serde_json::Value>,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub error: Option<ResponseError>,
+pub enum Response {
+    Error(ResponseError),
+    ListMacro(ListMacrosResult),
+    ExpansionMacro(ExpansionResult),
+}
+
+macro_rules! impl_try_from_response {
+    ($ty:ty, $tag:ident) => {
+        impl TryFrom<Response> for $ty {
+            type Error = &'static str;
+            fn try_from(value: Response) -> Result<Self, Self::Error> {
+                match value {
+                    Response::$tag(res) => Ok(res),
+                    _ => Err("Fail to convert from response"),
+                }
+            }
+        }
+    };
 }
 
+impl_try_from_response!(ListMacrosResult, ListMacro);
+impl_try_from_response!(ExpansionResult, ExpansionMacro);
+
 #[derive(Debug, Serialize, Deserialize, Clone)]
 pub struct ResponseError {
-    pub code: i32,
+    pub code: ErrorCode,
     pub message: String,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub data: Option<serde_json::Value>,
-}
-
-#[derive(Clone, Copy, Debug)]
-#[allow(unused)]
-pub enum ErrorCode {
-    // Defined by JSON RPC
-    ParseError = -32700,
-    InvalidRequest = -32600,
-    MethodNotFound = -32601,
-    InvalidParams = -32602,
-    InternalError = -32603,
-    ServerErrorStart = -32099,
-    ServerErrorEnd = -32000,
-    ServerNotInitialized = -32002,
-    UnknownErrorCode = -32001,
-
-    // Defined by protocol
-    ExpansionError = -32900,
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone)]
-pub struct Notification {
-    pub method: String,
-    pub params: serde_json::Value,
+pub enum ErrorCode {
+    ServerErrorEnd,
+    ExpansionError,
 }
 
-impl Message {
-    pub fn read(r: &mut impl BufRead) -> io::Result<Option<Message>> {
-        let text = match read_msg_text(r)? {
+pub trait Message: Sized + Serialize + DeserializeOwned {
+    fn read(r: &mut impl BufRead) -> io::Result<Option<Self>> {
+        let text = match read_json(r)? {
             None => return Ok(None),
             Some(text) => text,
         };
         let msg = serde_json::from_str(&text)?;
         Ok(Some(msg))
     }
-    pub fn write(self, w: &mut impl Write) -> io::Result<()> {
-        #[derive(Serialize)]
-        struct JsonRpc {
-            jsonrpc: &'static str,
-            #[serde(flatten)]
-            msg: Message,
-        }
-        let text = serde_json::to_string(&JsonRpc { jsonrpc: "2.0", msg: self })?;
-        write_msg_text(w, &text)
+    fn write(self, w: &mut impl Write) -> io::Result<()> {
+        let text = serde_json::to_string(&self)?;
+        write_json(w, &text)
     }
 }
 
-impl Response {
-    pub fn new_ok<R: Serialize>(id: RequestId, result: R) -> Response {
-        Response { id, result: Some(serde_json::to_value(result).unwrap()), error: None }
-    }
-    pub fn new_err(id: RequestId, code: i32, message: String) -> Response {
-        let error = ResponseError { code, message, data: None };
-        Response { id, result: None, error: Some(error) }
-    }
-}
+impl Message for Request {}
+impl Message for Response {}
 
-impl Request {
-    pub fn new<P: Serialize>(id: RequestId, method: String, params: P) -> Request {
-        Request { id, method, params: serde_json::to_value(params).unwrap() }
-    }
-    pub fn extract<P: DeserializeOwned>(self, method: &str) -> Result<(RequestId, P), Request> {
-        if self.method == method {
-            let params = serde_json::from_value(self.params).unwrap_or_else(|err| {
-                panic!("Invalid request\nMethod: {}\n error: {}", method, err)
-            });
-            Ok((self.id, params))
-        } else {
-            Err(self)
-        }
-    }
-}
-
-impl Notification {
-    pub fn new(method: String, params: impl Serialize) -> Notification {
-        Notification { method, params: serde_json::to_value(params).unwrap() }
-    }
-    pub fn extract<P: DeserializeOwned>(self, method: &str) -> Result<P, Notification> {
-        if self.method == method {
-            let params = serde_json::from_value(self.params).unwrap();
-            Ok(params)
-        } else {
-            Err(self)
-        }
-    }
-}
-
-fn read_msg_text(inp: &mut impl BufRead) -> io::Result<Option<String>> {
-    fn invalid_data(error: impl Into<Box<dyn std::error::Error + Send + Sync>>) -> io::Error {
-        io::Error::new(io::ErrorKind::InvalidData, error)
-    }
-    macro_rules! invalid_data {
-        ($($tt:tt)*) => (invalid_data(format!($($tt)*)))
-    }
-
-    let mut size = None;
+fn read_json(inp: &mut impl BufRead) -> io::Result<Option<String>> {
     let mut buf = String::new();
-    loop {
-        buf.clear();
-        if inp.read_line(&mut buf)? == 0 {
-            return Ok(None);
-        }
-        if !buf.ends_with("\r\n") {
-            return Err(invalid_data!("malformed header: {:?}", buf));
-        }
-        let buf = &buf[..buf.len() - 2];
-        if buf.is_empty() {
-            break;
-        }
-        let mut parts = buf.splitn(2, ": ");
-        let header_name = parts.next().unwrap();
-        let header_value =
-            parts.next().ok_or_else(|| invalid_data!("malformed header: {:?}", buf))?;
-        if header_name == "Content-Length" {
-            size = Some(header_value.parse::<usize>().map_err(invalid_data)?);
-        }
+    if inp.read_line(&mut buf)? == 0 {
+        return Ok(None);
+    }
+    // Remove ending '\n'
+    let buf = &buf[..buf.len() - 1];
+    if buf.is_empty() {
+        return Ok(None);
     }
-    let size: usize = size.ok_or_else(|| invalid_data!("no Content-Length"))?;
-    let mut buf = buf.into_bytes();
-    buf.resize(size, 0);
-    inp.read_exact(&mut buf)?;
-    let buf = String::from_utf8(buf).map_err(invalid_data)?;
-    log::debug!("< {}", buf);
-    Ok(Some(buf))
+    Ok(Some(buf.to_string()))
 }
 
-fn write_msg_text(out: &mut impl Write, msg: &str) -> io::Result<()> {
+fn write_json(out: &mut impl Write, msg: &str) -> io::Result<()> {
     log::debug!("> {}", msg);
-    write!(out, "Content-Length: {}\r\n\r\n", msg.len())?;
     out.write_all(msg.as_bytes())?;
+    out.write_all(b"\n")?;
     out.flush()?;
     Ok(())
 }
diff --git a/crates/ra_proc_macro/src/process.rs b/crates/ra_proc_macro/src/process.rs
index daae9a7e0..2b1f8535a 100644
--- a/crates/ra_proc_macro/src/process.rs
+++ b/crates/ra_proc_macro/src/process.rs
@@ -3,11 +3,12 @@
 use crossbeam_channel::{bounded, Receiver, Sender};
 use ra_tt::Subtree;
 
-use crate::msg::{ErrorCode, Message, Request, Response, ResponseError};
+use crate::msg::{ErrorCode, Request, Response, ResponseError, Message};
 use crate::rpc::{ExpansionResult, ExpansionTask, ListMacrosResult, ListMacrosTask, ProcMacroKind};
 
 use io::{BufRead, BufReader};
 use std::{
+    convert::{TryFrom, TryInto},
     io::{self, Write},
     path::{Path, PathBuf},
     process::{Child, Command, Stdio},
@@ -26,7 +27,7 @@ pub(crate) struct ProcMacroProcessThread {
 }
 
 enum Task {
-    Request { req: Message, result_tx: Sender<Message> },
+    Request { req: Request, result_tx: Sender<Response> },
     Close,
 }
 
@@ -96,7 +97,7 @@ impl ProcMacroProcessSrv {
     ) -> Result<Vec<(String, ProcMacroKind)>, ra_tt::ExpansionError> {
         let task = ListMacrosTask { lib: dylib_path.to_path_buf() };
 
-        let result: ListMacrosResult = self.send_task("list_macros", task)?;
+        let result: ListMacrosResult = self.send_task(Request::ListMacro(task))?;
         Ok(result.macros)
     }
 
@@ -113,26 +114,19 @@ impl ProcMacroProcessSrv {
             lib: dylib_path.to_path_buf(),
         };
 
-        let result: ExpansionResult = self.send_task("custom_derive", task)?;
+        let result: ExpansionResult = self.send_task(Request::ExpansionMacro(task))?;
         Ok(result.expansion)
     }
 
-    pub fn send_task<'a, T, R>(&self, method: &str, task: T) -> Result<R, ra_tt::ExpansionError>
+    pub fn send_task<R>(&self, req: Request) -> Result<R, ra_tt::ExpansionError>
     where
-        T: serde::Serialize,
-        R: serde::de::DeserializeOwned + Default,
+        R: TryFrom<Response, Error = &'static str>,
     {
         let sender = match &self.inner {
             None => return Err(ra_tt::ExpansionError::Unknown("No sender is found.".to_string())),
             Some(it) => it,
         };
 
-        let msg = serde_json::to_value(task).unwrap();
-
-        // FIXME: use a proper request id
-        let id = 0;
-        let req = Request { id: id.into(), method: method.into(), params: msg };
-
         let (result_tx, result_rx) = bounded(0);
 
         sender.send(Task::Request { req: req.into(), result_tx }).map_err(|err| {
@@ -141,27 +135,18 @@ impl ProcMacroProcessSrv {
                 err
             ))
         })?;
-        let response = result_rx.recv().unwrap();
 
-        match response {
-            Message::Request(_) => {
-                return Err(ra_tt::ExpansionError::Unknown(
-                    "Return request from ra_proc_srv".into(),
-                ))
-            }
-            Message::Response(res) => {
-                if let Some(err) = res.error {
-                    return Err(ra_tt::ExpansionError::ExpansionError(err.message));
-                }
-                match res.result {
-                    None => Ok(R::default()),
-                    Some(res) => {
-                        let result: R = serde_json::from_value(res)
-                            .map_err(|err| ra_tt::ExpansionError::JsonError(err.to_string()))?;
-                        Ok(result)
-                    }
-                }
+        let res = result_rx.recv().unwrap();
+        match res {
+            Response::Error(err) => {
+                return Err(ra_tt::ExpansionError::ExpansionError(err.message));
             }
+            _ => Ok(res.try_into().map_err(|err| {
+                ra_tt::ExpansionError::Unknown(format!(
+                    "Fail to get response, reason : {:#?} ",
+                    err
+                ))
+            })?),
         }
     }
 }
@@ -183,18 +168,13 @@ fn client_loop(task_rx: Receiver<Task>, mut process: Process) {
             Task::Close => break,
         };
 
-        let res = match send_message(&mut stdin, &mut stdout, req) {
+        let res = match send_request(&mut stdin, &mut stdout, req) {
             Ok(res) => res,
             Err(_err) => {
-                let res = Response {
-                    id: 0.into(),
-                    result: None,
-                    error: Some(ResponseError {
-                        code: ErrorCode::ServerErrorEnd as i32,
-                        message: "Server closed".into(),
-                        data: None,
-                    }),
-                };
+                let res = Response::Error(ResponseError {
+                    code: ErrorCode::ServerErrorEnd,
+                    message: "Server closed".into(),
+                });
                 if result_tx.send(res.into()).is_err() {
                     break;
                 }
@@ -222,11 +202,11 @@ fn client_loop(task_rx: Receiver<Task>, mut process: Process) {
     let _ = process.child.kill();
 }
 
-fn send_message(
+fn send_request(
     mut writer: &mut impl Write,
     mut reader: &mut impl BufRead,
-    msg: Message,
-) -> Result<Option<Message>, io::Error> {
-    msg.write(&mut writer)?;
-    Ok(Message::read(&mut reader)?)
+    req: Request,
+) -> Result<Option<Response>, io::Error> {
+    req.write(&mut writer)?;
+    Ok(Response::read(&mut reader)?)
 }
diff --git a/crates/ra_proc_macro/src/rpc.rs b/crates/ra_proc_macro/src/rpc.rs
index f88d91f78..fc8b04e28 100644
--- a/crates/ra_proc_macro/src/rpc.rs
+++ b/crates/ra_proc_macro/src/rpc.rs
@@ -1,4 +1,10 @@
 //! Data struture serialization related stuffs for RPC
+//! 
+//! Define all necessary rpc serialization data structure, 
+//! which include ra_tt related data and some task messages. 
+//! Although adding Serialize and Deserialize trait to ra_tt directly seem to be much easier, 
+//! we deliberately duplicate the ra_tt struct with #[serde(with = "XXDef")] 
+//! for separation of code responsibility.
 
 use ra_tt::{
     Delimiter, DelimiterKind, Ident, Leaf, Literal, Punct, SmolStr, Spacing, Subtree, TokenId,