4 files changed, 188 insertions, 170 deletions

diff --git a/crates/rust-analyzer/src/global_state.rs b/crates/rust-analyzer/src/global_state.rs
index 1527c9947..d1897bf50 100644
--- a/crates/rust-analyzer/src/global_state.rs
+++ b/crates/rust-analyzer/src/global_state.rs
@@ -20,7 +20,7 @@ use stdx::format_to;
 use crate::{
     config::{Config, FilesWatcher},
     diagnostics::{CheckFixes, DiagnosticCollection},
-    main_loop::pending_requests::{CompletedRequest, LatestRequests},
+    main_loop::req_queue::{CompletedInRequest, LatestRequests},
     to_proto::url_from_abs_path,
     vfs_glob::{Glob, RustPackageFilterBuilder},
     LspError, Result,
@@ -236,7 +236,7 @@ impl GlobalState {
         self.analysis_host.collect_garbage()
     }
 
-    pub fn complete_request(&mut self, request: CompletedRequest) {
+    pub(crate) fn complete_request(&mut self, request: CompletedInRequest) {
         self.latest_requests.write().record(request)
     }
 }
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index f0aaaa21e..fd40b2443 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -3,7 +3,7 @@
 
 mod handlers;
 mod subscriptions;
-pub(crate) mod pending_requests;
+pub(crate) mod req_queue;
 
 use std::{
     borrow::Cow,
@@ -28,7 +28,6 @@ use ra_ide::{Canceled, FileId, LineIndex};
 use ra_prof::profile;
 use ra_project_model::{PackageRoot, ProjectWorkspace};
 use ra_vfs::VfsTask;
-use rustc_hash::FxHashSet;
 use serde::{de::DeserializeOwned, Serialize};
 use threadpool::ThreadPool;
 
@@ -38,12 +37,10 @@ use crate::{
     from_proto,
     global_state::{file_id_to_url, GlobalState, GlobalStateSnapshot},
     lsp_ext,
-    main_loop::{
-        pending_requests::{PendingRequest, PendingRequests},
-        subscriptions::Subscriptions,
-    },
+    main_loop::subscriptions::Subscriptions,
     Result,
 };
+use req_queue::ReqQueue;
 
 #[derive(Debug)]
 pub struct LspError {
@@ -153,10 +150,10 @@ pub fn main_loop(config: Config, connection: Connection) -> Result<()> {
                 register_options: Some(serde_json::to_value(registration_options).unwrap()),
             };
             let params = lsp_types::RegistrationParams { registrations: vec![registration] };
-            let request = request_new::<lsp_types::request::RegisterCapability>(
-                loop_state.next_request_id(),
-                params,
-            );
+            let request = loop_state
+                .req_queue
+                .outgoing
+                .register::<lsp_types::request::RegisterCapability>(params, |_, _| ());
             connection.sender.send(request.into()).unwrap();
         }
 
@@ -199,7 +196,7 @@ pub fn main_loop(config: Config, connection: Connection) -> Result<()> {
     global_state.analysis_host.request_cancellation();
     log::info!("waiting for tasks to finish...");
     task_receiver.into_iter().for_each(|task| {
-        on_task(task, &connection.sender, &mut loop_state.pending_requests, &mut global_state)
+        on_task(task, &connection.sender, &mut loop_state.req_queue.incoming, &mut global_state)
     });
     log::info!("...tasks have finished");
     log::info!("joining threadpool...");
@@ -264,27 +261,14 @@ impl fmt::Debug for Event {
     }
 }
 
-#[derive(Debug, Default)]
+#[derive(Default)]
 struct LoopState {
-    next_request_id: u64,
-    pending_responses: FxHashSet<RequestId>,
-    pending_requests: PendingRequests,
+    req_queue: ReqQueue<fn(&mut GlobalState, lsp_server::Response)>,
     subscriptions: Subscriptions,
     workspace_loaded: bool,
     roots_progress_reported: Option<usize>,
     roots_scanned: usize,
     roots_total: usize,
-    configuration_request_id: Option<RequestId>,
-}
-
-impl LoopState {
-    fn next_request_id(&mut self) -> RequestId {
-        self.next_request_id += 1;
-        let res: RequestId = self.next_request_id.into();
-        let inserted = self.pending_responses.insert(res.clone());
-        assert!(inserted);
-        res
-    }
 }
 
 fn loop_turn(
@@ -307,7 +291,7 @@ fn loop_turn(
 
     match event {
         Event::Task(task) => {
-            on_task(task, &connection.sender, &mut loop_state.pending_requests, global_state);
+            on_task(task, &connection.sender, &mut loop_state.req_queue.incoming, global_state);
             global_state.maybe_collect_garbage();
         }
         Event::Vfs(task) => {
@@ -317,7 +301,7 @@ fn loop_turn(
         Event::Msg(msg) => match msg {
             Message::Request(req) => on_request(
                 global_state,
-                &mut loop_state.pending_requests,
+                &mut loop_state.req_queue.incoming,
                 pool,
                 task_sender,
                 &connection.sender,
@@ -328,32 +312,8 @@ fn loop_turn(
                 on_notification(&connection.sender, global_state, loop_state, not)?;
             }
             Message::Response(resp) => {
-                let removed = loop_state.pending_responses.remove(&resp.id);
-                if !removed {
-                    log::error!("unexpected response: {:?}", resp)
-                }
-
-                if Some(&resp.id) == loop_state.configuration_request_id.as_ref() {
-                    loop_state.configuration_request_id = None;
-                    log::debug!("config update response: '{:?}", resp);
-                    let Response { error, result, .. } = resp;
-
-                    match (error, result) {
-                        (Some(err), _) => {
-                            log::error!("failed to fetch the server settings: {:?}", err)
-                        }
-                        (None, Some(configs)) => {
-                            if let Some(new_config) = configs.get(0) {
-                                let mut config = global_state.config.clone();
-                                config.update(&new_config);
-                                global_state.update_configuration(config);
-                            }
-                        }
-                        (None, None) => {
-                            log::error!("received empty server settings response from the client")
-                        }
-                    }
-                }
+                let handler = loop_state.req_queue.outgoing.complete(resp.id.clone());
+                handler(global_state, resp)
             }
         },
     };
@@ -407,12 +367,12 @@ fn loop_turn(
 fn on_task(
     task: Task,
     msg_sender: &Sender<Message>,
-    pending_requests: &mut PendingRequests,
+    incoming_requests: &mut req_queue::Incoming,
     state: &mut GlobalState,
 ) {
     match task {
         Task::Respond(response) => {
-            if let Some(completed) = pending_requests.finish(&response.id) {
+            if let Some(completed) = incoming_requests.complete(response.id.clone()) {
                 log::info!("handled req#{} in {:?}", completed.id, completed.duration);
                 state.complete_request(completed);
                 msg_sender.send(response.into()).unwrap();
@@ -427,7 +387,7 @@ fn on_task(
 
 fn on_request(
     global_state: &mut GlobalState,
-    pending_requests: &mut PendingRequests,
+    incoming_requests: &mut req_queue::Incoming,
     pool: &ThreadPool,
     task_sender: &Sender<Task>,
     msg_sender: &Sender<Message>,
@@ -440,7 +400,7 @@ fn on_request(
         global_state,
         task_sender,
         msg_sender,
-        pending_requests,
+        incoming_requests,
         request_received,
     };
     pool_dispatcher
@@ -504,12 +464,7 @@ fn on_notification(
                 NumberOrString::Number(id) => id.into(),
                 NumberOrString::String(id) => id.into(),
             };
-            if loop_state.pending_requests.cancel(&id) {
-                let response = Response::new_err(
-                    id,
-                    ErrorCode::RequestCanceled as i32,
-                    "canceled by client".to_string(),
-                );
+            if let Some(response) = loop_state.req_queue.incoming.cancel(id) {
                 msg_sender.send(response.into()).unwrap()
             }
             return Ok(());
@@ -572,18 +527,38 @@ fn on_notification(
         Ok(_) => {
             // As stated in https://github.com/microsoft/language-server-protocol/issues/676,
             // this notification's parameters should be ignored and the actual config queried separately.
-            let request_id = loop_state.next_request_id();
-            let request = request_new::<lsp_types::request::WorkspaceConfiguration>(
-                request_id.clone(),
-                lsp_types::ConfigurationParams {
-                    items: vec![lsp_types::ConfigurationItem {
-                        scope_uri: None,
-                        section: Some("rust-analyzer".to_string()),
-                    }],
-                },
-            );
+            let request = loop_state
+                .req_queue
+                .outgoing
+                .register::<lsp_types::request::WorkspaceConfiguration>(
+                    lsp_types::ConfigurationParams {
+                        items: vec![lsp_types::ConfigurationItem {
+                            scope_uri: None,
+                            section: Some("rust-analyzer".to_string()),
+                        }],
+                    },
+                    |global_state, resp| {
+                        log::debug!("config update response: '{:?}", resp);
+                        let Response { error, result, .. } = resp;
+
+                        match (error, result) {
+                            (Some(err), _) => {
+                                log::error!("failed to fetch the server settings: {:?}", err)
+                            }
+                            (None, Some(configs)) => {
+                                if let Some(new_config) = configs.get(0) {
+                                    let mut config = global_state.config.clone();
+                                    config.update(&new_config);
+                                    global_state.update_configuration(config);
+                                }
+                            }
+                            (None, None) => log::error!(
+                                "received empty server settings response from the client"
+                            ),
+                        }
+                    },
+                );
             msg_sender.send(request.into())?;
-            loop_state.configuration_request_id = Some(request_id);
 
             return Ok(());
         }
@@ -752,13 +727,16 @@ fn send_startup_progress(sender: &Sender<Message>, loop_state: &mut LoopState) {
 
     match (prev, loop_state.workspace_loaded) {
         (None, false) => {
-            let work_done_progress_create = request_new::<lsp_types::request::WorkDoneProgressCreate>(
-                loop_state.next_request_id(),
-                WorkDoneProgressCreateParams {
-                    token: lsp_types::ProgressToken::String("rustAnalyzer/startup".into()),
-                },
-            );
-            sender.send(work_done_progress_create.into()).unwrap();
+            let request = loop_state
+                .req_queue
+                .outgoing
+                .register::<lsp_types::request::WorkDoneProgressCreate>(
+                    WorkDoneProgressCreateParams {
+                        token: lsp_types::ProgressToken::String("rustAnalyzer/startup".into()),
+                    },
+                    |_, _| (),
+                );
+            sender.send(request.into()).unwrap();
             send_startup_progress_notif(
                 sender,
                 WorkDoneProgress::Begin(WorkDoneProgressBegin {
@@ -800,7 +778,7 @@ struct PoolDispatcher<'a> {
     req: Option<Request>,
     pool: &'a ThreadPool,
     global_state: &'a mut GlobalState,
-    pending_requests: &'a mut PendingRequests,
+    incoming_requests: &'a mut req_queue::Incoming,
     msg_sender: &'a Sender<Message>,
     task_sender: &'a Sender<Task>,
     request_received: Instant,
@@ -829,7 +807,7 @@ impl<'a> PoolDispatcher<'a> {
             result_to_task::<R>(id, result)
         })
         .map_err(|_| format!("sync task {:?} panicked", R::METHOD))?;
-        on_task(task, self.msg_sender, self.pending_requests, self.global_state);
+        on_task(task, self.msg_sender, self.incoming_requests, self.global_state);
         Ok(self)
     }
 
@@ -876,7 +854,7 @@ impl<'a> PoolDispatcher<'a> {
                 return None;
             }
         };
-        self.pending_requests.start(PendingRequest {
+        self.incoming_requests.register(req_queue::PendingInRequest {
             id: id.clone(),
             method: R::METHOD.to_string(),
             received: self.request_received,
@@ -993,14 +971,6 @@ where
     Notification::new(N::METHOD.to_string(), params)
 }
 
-fn request_new<R>(id: RequestId, params: R::Params) -> Request
-where
-    R: lsp_types::request::Request,
-    R::Params: Serialize,
-{
-    Request::new(id, R::METHOD.to_string(), params)
-}
-
 #[cfg(test)]
 mod tests {
     use std::borrow::Cow;
diff --git a/crates/rust-analyzer/src/main_loop/pending_requests.rs b/crates/rust-analyzer/src/main_loop/pending_requests.rs
deleted file mode 100644
index 73b33e419..000000000
--- a/crates/rust-analyzer/src/main_loop/pending_requests.rs
+++ /dev/null
@@ -1,75 +0,0 @@
-//! Data structures that keep track of inflight requests.
-
-use std::time::{Duration, Instant};
-
-use lsp_server::RequestId;
-use rustc_hash::FxHashMap;
-
-#[derive(Debug)]
-pub struct CompletedRequest {
-    pub id: RequestId,
-    pub method: String,
-    pub duration: Duration,
-}
-
-#[derive(Debug)]
-pub(crate) struct PendingRequest {
-    pub(crate) id: RequestId,
-    pub(crate) method: String,
-    pub(crate) received: Instant,
-}
-
-impl From<PendingRequest> for CompletedRequest {
-    fn from(pending: PendingRequest) -> CompletedRequest {
-        CompletedRequest {
-            id: pending.id,
-            method: pending.method,
-            duration: pending.received.elapsed(),
-        }
-    }
-}
-
-#[derive(Debug, Default)]
-pub(crate) struct PendingRequests {
-    map: FxHashMap<RequestId, PendingRequest>,
-}
-
-impl PendingRequests {
-    pub(crate) fn start(&mut self, request: PendingRequest) {
-        let id = request.id.clone();
-        let prev = self.map.insert(id.clone(), request);
-        assert!(prev.is_none(), "duplicate request with id {}", id);
-    }
-    pub(crate) fn cancel(&mut self, id: &RequestId) -> bool {
-        self.map.remove(id).is_some()
-    }
-    pub(crate) fn finish(&mut self, id: &RequestId) -> Option<CompletedRequest> {
-        self.map.remove(id).map(CompletedRequest::from)
-    }
-}
-
-const N_COMPLETED_REQUESTS: usize = 10;
-
-#[derive(Debug, Default)]
-pub struct LatestRequests {
-    // hand-rolling VecDeque here to print things in a nicer way
-    buf: [Option<CompletedRequest>; N_COMPLETED_REQUESTS],
-    idx: usize,
-}
-
-impl LatestRequests {
-    pub(crate) fn record(&mut self, request: CompletedRequest) {
-        // special case: don't track status request itself
-        if request.method == "rust-analyzer/analyzerStatus" {
-            return;
-        }
-        let idx = self.idx;
-        self.buf[idx] = Some(request);
-        self.idx = (idx + 1) % N_COMPLETED_REQUESTS;
-    }
-
-    pub(crate) fn iter(&self) -> impl Iterator<Item = (bool, &CompletedRequest)> {
-        let idx = self.idx;
-        self.buf.iter().enumerate().filter_map(move |(i, req)| Some((i == idx, req.as_ref()?)))
-    }
-}
diff --git a/crates/rust-analyzer/src/main_loop/req_queue.rs b/crates/rust-analyzer/src/main_loop/req_queue.rs
new file mode 100644
index 000000000..5cf6d916b
--- /dev/null
+++ b/crates/rust-analyzer/src/main_loop/req_queue.rs
@@ -0,0 +1,123 @@
+//! Manages the set of in-flight requests in both directions.
+use std::time::{Duration, Instant};
+
+use lsp_server::RequestId;
+use rustc_hash::FxHashMap;
+use serde::Serialize;
+
+#[derive(Debug)]
+pub(crate) struct ReqQueue<H> {
+    pub(crate) incoming: Incoming,
+    pub(crate) outgoing: Outgoing<H>,
+}
+
+impl<H> Default for ReqQueue<H> {
+    fn default() -> Self {
+        ReqQueue { incoming: Incoming::default(), outgoing: Outgoing::default() }
+    }
+}
+
+#[derive(Debug)]
+pub(crate) struct Outgoing<H> {
+    next: u64,
+    pending: FxHashMap<RequestId, H>,
+}
+
+impl<H> Default for Outgoing<H> {
+    fn default() -> Self {
+        Outgoing { next: 0, pending: FxHashMap::default() }
+    }
+}
+
+impl<H> Outgoing<H> {
+    pub(crate) fn register<R>(&mut self, params: R::Params, handler: H) -> lsp_server::Request
+    where
+        R: lsp_types::request::Request,
+        R::Params: Serialize,
+    {
+        let id = RequestId::from(self.next);
+        self.next += 1;
+        self.pending.insert(id.clone(), handler);
+        lsp_server::Request::new(id, R::METHOD.to_string(), params)
+    }
+    pub(crate) fn complete(&mut self, id: RequestId) -> H {
+        self.pending.remove(&id).unwrap()
+    }
+}
+
+#[derive(Debug)]
+pub(crate) struct CompletedInRequest {
+    pub(crate) id: RequestId,
+    pub(crate) method: String,
+    pub(crate) duration: Duration,
+}
+
+#[derive(Debug)]
+pub(crate) struct PendingInRequest {
+    pub(crate) id: RequestId,
+    pub(crate) method: String,
+    pub(crate) received: Instant,
+}
+
+impl From<PendingInRequest> for CompletedInRequest {
+    fn from(pending: PendingInRequest) -> CompletedInRequest {
+        CompletedInRequest {
+            id: pending.id,
+            method: pending.method,
+            duration: pending.received.elapsed(),
+        }
+    }
+}
+
+#[derive(Debug, Default)]
+pub(crate) struct Incoming {
+    pending: FxHashMap<RequestId, PendingInRequest>,
+}
+
+impl Incoming {
+    pub(crate) fn register(&mut self, request: PendingInRequest) {
+        let id = request.id.clone();
+        let prev = self.pending.insert(id.clone(), request);
+        assert!(prev.is_none(), "duplicate request with id {}", id);
+    }
+    pub(crate) fn cancel(&mut self, id: RequestId) -> Option<lsp_server::Response> {
+        if self.pending.remove(&id).is_some() {
+            Some(lsp_server::Response::new_err(
+                id,
+                lsp_server::ErrorCode::RequestCanceled as i32,
+                "canceled by client".to_string(),
+            ))
+        } else {
+            None
+        }
+    }
+    pub(crate) fn complete(&mut self, id: RequestId) -> Option<CompletedInRequest> {
+        self.pending.remove(&id).map(CompletedInRequest::from)
+    }
+}
+
+const N_COMPLETED_REQUESTS: usize = 10;
+
+#[derive(Debug, Default)]
+pub struct LatestRequests {
+    // hand-rolling VecDeque here to print things in a nicer way
+    buf: [Option<CompletedInRequest>; N_COMPLETED_REQUESTS],
+    idx: usize,
+}
+
+impl LatestRequests {
+    pub(crate) fn record(&mut self, request: CompletedInRequest) {
+        // special case: don't track status request itself
+        if request.method == "rust-analyzer/analyzerStatus" {
+            return;
+        }
+        let idx = self.idx;
+        self.buf[idx] = Some(request);
+        self.idx = (idx + 1) % N_COMPLETED_REQUESTS;
+    }
+
+    pub(crate) fn iter(&self) -> impl Iterator<Item = (bool, &CompletedInRequest)> {
+        let idx = self.idx;
+        self.buf.iter().enumerate().filter_map(move |(i, req)| Some((i == idx, req.as_ref()?)))
+    }
+}