4 files changed, 106 insertions, 50 deletions

diff --git a/crates/server/src/dispatch.rs b/crates/server/src/dispatch.rs
index d8cca48d0..806534944 100644
--- a/crates/server/src/dispatch.rs
+++ b/crates/server/src/dispatch.rs
@@ -58,20 +58,18 @@ fn parse_request_as<R: ClientRequest>(raw: RawRequest)
     Ok(Ok((params, responder)))
 }
 
-pub fn handle_request<R, F>(req: &mut Option<RawRequest>, f: F) -> Result<()>
+pub fn handle_request<R, F>(req: RawRequest, f: F) -> Result<::std::result::Result<u64, RawRequest>>
     where
         R: ClientRequest,
         F: FnOnce(R::Params, Responder<R>) -> Result<()>
 {
-    match req.take() {
-        None => Ok(()),
-        Some(r) => match parse_request_as::<R>(r)? {
-            Ok((params, responder)) => f(params, responder),
-            Err(r) => {
-                *req = Some(r);
-                Ok(())
-            }
-        }
+    let id = req.id;
+    match parse_request_as::<R>(req)? {
+        Ok((params, responder)) => {
+            let () = f(params, responder)?;
+            Ok(Ok(id))
+        },
+        Err(r) => Ok(Err(r)),
     }
 }
 
diff --git a/crates/server/src/main.rs b/crates/server/src/main.rs
index 6af8bf81b..eeb343b80 100644
--- a/crates/server/src/main.rs
+++ b/crates/server/src/main.rs
@@ -84,14 +84,13 @@ fn initialize(io: &mut Io) -> Result<()> {
             bail!("expected initialize request, got {:?}", res),
 
         RawMsg::Request(req) => {
-            let mut req = Some(req);
-            dispatch::handle_request::<req::Initialize, _>(&mut req, |_params, resp| {
+            let req = dispatch::handle_request::<req::Initialize, _>(req, |_params, resp| {
                 let res = req::InitializeResult { capabilities: caps::server_capabilities() };
                 let resp = resp.into_response(Ok(res))?;
                 io.send(RawMsg::Response(resp));
                 Ok(())
             })?;
-            if let Some(req) = req {
+            if let Err(req) = req {
                 bail!("expected initialize request, got {:?}", req)
             }
             match io.recv()? {
diff --git a/crates/server/src/main_loop/handlers.rs b/crates/server/src/main_loop/handlers.rs
index 6b70399b0..ab8b6f799 100644
--- a/crates/server/src/main_loop/handlers.rs
+++ b/crates/server/src/main_loop/handlers.rs
@@ -7,7 +7,7 @@ use languageserver_types::{
     CompletionItem, InsertTextFormat, CompletionItemKind,
 };
 use serde_json::to_value;
-use libanalysis::{Query, FileId, RunnableKind};
+use libanalysis::{Query, FileId, RunnableKind, JobToken};
 use libsyntax2::{
     text_utils::contains_offset_nonstrict,
 };
@@ -21,6 +21,7 @@ use ::{
 pub fn handle_syntax_tree(
     world: ServerWorld,
     params: req::SyntaxTreeParams,
+    _token: JobToken,
 ) -> Result<String> {
     let id = params.text_document.try_conv_with(&world)?;
     let res = world.analysis().syntax_tree(id);
@@ -30,6 +31,7 @@ pub fn handle_syntax_tree(
 pub fn handle_extend_selection(
     world: ServerWorld,
     params: req::ExtendSelectionParams,
+    _token: JobToken,
 ) -> Result<req::ExtendSelectionResult> {
     let file_id = params.text_document.try_conv_with(&world)?;
     let file = world.analysis().file_syntax(file_id);
@@ -45,6 +47,7 @@ pub fn handle_extend_selection(
 pub fn handle_find_matching_brace(
     world: ServerWorld,
     params: req::FindMatchingBraceParams,
+    _token: JobToken,
 ) -> Result<Vec<Position>> {
     let file_id = params.text_document.try_conv_with(&world)?;
     let file = world.analysis().file_syntax(file_id);
@@ -63,6 +66,7 @@ pub fn handle_find_matching_brace(
 pub fn handle_join_lines(
     world: ServerWorld,
     params: req::JoinLinesParams,
+    _token: JobToken,
 ) -> Result<req::SourceChange> {
     let file_id = params.text_document.try_conv_with(&world)?;
     let line_index = world.analysis().file_line_index(file_id);
@@ -74,6 +78,7 @@ pub fn handle_join_lines(
 pub fn handle_on_type_formatting(
     world: ServerWorld,
     params: req::DocumentOnTypeFormattingParams,
+    _token: JobToken,
 ) -> Result<Option<Vec<TextEdit>>> {
     if params.ch != "=" {
         return Ok(None);
@@ -93,6 +98,7 @@ pub fn handle_on_type_formatting(
 pub fn handle_document_symbol(
     world: ServerWorld,
     params: req::DocumentSymbolParams,
+    _token: JobToken,
 ) -> Result<Option<req::DocumentSymbolResponse>> {
     let file_id = params.text_document.try_conv_with(&world)?;
     let line_index = world.analysis().file_line_index(file_id);
@@ -131,6 +137,7 @@ pub fn handle_document_symbol(
 pub fn handle_workspace_symbol(
     world: ServerWorld,
     params: req::WorkspaceSymbolParams,
+    token: JobToken,
 ) -> Result<Option<Vec<SymbolInformation>>> {
     let all_symbols = params.query.contains("#");
     let query = {
@@ -144,18 +151,18 @@ pub fn handle_workspace_symbol(
         q.limit(128);
         q
     };
-    let mut res = exec_query(&world, query)?;
+    let mut res = exec_query(&world, query, &token)?;
     if res.is_empty() && !all_symbols {
         let mut query = Query::new(params.query);
         query.limit(128);
-        res = exec_query(&world, query)?;
+        res = exec_query(&world, query, &token)?;
     }
 
     return Ok(Some(res));
 
-    fn exec_query(world: &ServerWorld, query: Query) -> Result<Vec<SymbolInformation>> {
+    fn exec_query(world: &ServerWorld, query: Query, token: &JobToken) -> Result<Vec<SymbolInformation>> {
         let mut res = Vec::new();
-        for (file_id, symbol) in world.analysis().symbol_search(query) {
+        for (file_id, symbol) in world.analysis().symbol_search(query, token) {
             let line_index = world.analysis().file_line_index(file_id);
             let info = SymbolInformation {
                 name: symbol.name.to_string(),
@@ -175,12 +182,13 @@ pub fn handle_workspace_symbol(
 pub fn handle_goto_definition(
     world: ServerWorld,
     params: req::TextDocumentPositionParams,
+    token: JobToken,
 ) -> Result<Option<req::GotoDefinitionResponse>> {
     let file_id = params.text_document.try_conv_with(&world)?;
     let line_index = world.analysis().file_line_index(file_id);
     let offset = params.position.conv_with(&line_index);
     let mut res = Vec::new();
-    for (file_id, symbol) in world.analysis().approximately_resolve_symbol(file_id, offset) {
+    for (file_id, symbol) in world.analysis().approximately_resolve_symbol(file_id, offset, &token) {
         let line_index = world.analysis().file_line_index(file_id);
         let location = to_location(
             file_id, symbol.node_range,
@@ -194,6 +202,7 @@ pub fn handle_goto_definition(
 pub fn handle_parent_module(
     world: ServerWorld,
     params: TextDocumentIdentifier,
+    _token: JobToken,
 ) -> Result<Vec<Location>> {
     let file_id = params.try_conv_with(&world)?;
     let mut res = Vec::new();
@@ -211,6 +220,7 @@ pub fn handle_parent_module(
 pub fn handle_runnables(
     world: ServerWorld,
     params: req::RunnablesParams,
+    _token: JobToken,
 ) -> Result<Vec<req::Runnable>> {
     let file_id = params.text_document.try_conv_with(&world)?;
     let line_index = world.analysis().file_line_index(file_id);
@@ -260,6 +270,7 @@ pub fn handle_runnables(
 pub fn handle_decorations(
     world: ServerWorld,
     params: TextDocumentIdentifier,
+    _token: JobToken,
 ) -> Result<Vec<Decoration>> {
     let file_id = params.try_conv_with(&world)?;
     Ok(highlight(&world, file_id))
@@ -268,6 +279,7 @@ pub fn handle_decorations(
 pub fn handle_completion(
     world: ServerWorld,
     params: req::CompletionParams,
+    _token: JobToken,
 ) -> Result<Option<req::CompletionResponse>> {
     let file_id = params.text_document.try_conv_with(&world)?;
     let line_index = world.analysis().file_line_index(file_id);
@@ -297,6 +309,7 @@ pub fn handle_completion(
 pub fn handle_code_action(
     world: ServerWorld,
     params: req::CodeActionParams,
+    _token: JobToken,
 ) -> Result<Option<Vec<Command>>> {
     let file_id = params.text_document.try_conv_with(&world)?;
     let line_index = world.analysis().file_line_index(file_id);
diff --git a/crates/server/src/main_loop/mod.rs b/crates/server/src/main_loop/mod.rs
index cd17cab56..db7d5ae34 100644
--- a/crates/server/src/main_loop/mod.rs
+++ b/crates/server/src/main_loop/mod.rs
@@ -2,12 +2,13 @@ mod handlers;
 mod subscriptions;
 
 use std::{
-    collections::{HashSet},
+    collections::{HashMap},
 };
 
 use threadpool::ThreadPool;
 use crossbeam_channel::{Sender, Receiver};
-use libanalysis::FileId;
+use languageserver_types::{NumberOrString};
+use libanalysis::{FileId, JobHandle, JobToken};
 
 use {
     req, dispatch,
@@ -28,7 +29,7 @@ pub(super) fn main_loop(
     info!("server initialized, serving requests");
     let mut state = ServerWorldState::new();
 
-    let mut pending_requests: HashSet<u64> = HashSet::new();
+    let mut pending_requests: HashMap<u64, JobHandle> = HashMap::new();
     let mut fs_events_receiver = Some(&fs_events_receiver);
     let mut subs = Subscriptions::new();
     loop {
@@ -61,8 +62,12 @@ pub(super) fn main_loop(
             }
             Event::Task(task) => {
                 match task {
-                    Task::Respond(response) =>
-                        io.send(RawMsg::Response(response)),
+                    Task::Respond(response) => {
+                        if let Some(handle) = pending_requests.remove(&response.id) {
+                            assert!(handle.has_completed());
+                        }
+                        io.send(RawMsg::Response(response))
+                    }
                     Task::Notify(n) =>
                         io.send(RawMsg::Notification(n)),
                     Task::Die(error) =>
@@ -78,18 +83,16 @@ pub(super) fn main_loop(
             Event::Msg(msg) => {
                 match msg {
                     RawMsg::Request(req) => {
-                        if !on_request(io, &mut state, pool, &task_sender, req)? {
+                        if !on_request(io, &mut state, &mut pending_requests, pool, &task_sender, req)? {
                             return Ok(());
                         }
                     }
                     RawMsg::Notification(not) => {
-                        on_notification(io, &mut state, &mut subs, not)?;
+                        on_notification(io, &mut state, &mut pending_requests, &mut subs, not)?;
                         state_changed = true;
                     }
                     RawMsg::Response(resp) => {
-                        if !pending_requests.remove(&resp.id) {
-                            error!("unexpected response: {:?}", resp)
-                        }
+                        error!("unexpected response: {:?}", resp)
                     }
                 }
             }
@@ -109,15 +112,17 @@ pub(super) fn main_loop(
 fn on_request(
     io: &mut Io,
     world: &mut ServerWorldState,
+    pending_requests: &mut HashMap<u64, JobHandle>,
     pool: &ThreadPool,
     sender: &Sender<Task>,
     req: RawRequest,
 ) -> Result<bool> {
     let mut pool_dispatcher = PoolDispatcher {
         req: Some(req),
+        res: None,
         pool, world, sender
     };
-    pool_dispatcher
+    let req = pool_dispatcher
         .on::<req::SyntaxTree>(handlers::handle_syntax_tree)?
         .on::<req::ExtendSelection>(handlers::handle_extend_selection)?
         .on::<req::FindMatchingBrace>(handlers::handle_find_matching_brace)?
@@ -130,23 +135,30 @@ fn on_request(
         .on::<req::Runnables>(handlers::handle_runnables)?
         .on::<req::DecorationsRequest>(handlers::handle_decorations)?
         .on::<req::Completion>(handlers::handle_completion)?
-        .on::<req::CodeActionRequest>(handlers::handle_code_action)?;
-
-    let mut req = pool_dispatcher.req;
-    let mut shutdown = false;
-    dispatch::handle_request::<req::Shutdown, _>(&mut req, |(), resp| {
-        let resp = resp.into_response(Ok(()))?;
-        io.send(RawMsg::Response(resp));
-        shutdown = true;
-        Ok(())
-    })?;
-    if shutdown {
-        info!("lifecycle: initiating shutdown");
-        return Ok(false);
-    }
-    if let Some(req) = req {
-        error!("unknown method: {:?}", req);
-        io.send(RawMsg::Response(dispatch::unknown_method(req.id)?));
+        .on::<req::CodeActionRequest>(handlers::handle_code_action)?
+        .finish();
+    match req {
+        Ok((id, handle)) => {
+            let inserted = pending_requests.insert(id, handle).is_none();
+            assert!(inserted, "duplicate request: {}", id);
+        },
+        Err(req) => {
+            let req = dispatch::handle_request::<req::Shutdown, _>(req, |(), resp| {
+                let resp = resp.into_response(Ok(()))?;
+                io.send(RawMsg::Response(resp));
+                Ok(())
+            })?;
+            match req {
+                Ok(_id) => {
+                    info!("lifecycle: initiating shutdown");
+                    return Ok(false);
+                }
+                Err(req) => {
+                    error!("unknown method: {:?}", req);
+                    io.send(RawMsg::Response(dispatch::unknown_method(req.id)?));
+                }
+            }
+        }
     }
     Ok(true)
 }
@@ -154,10 +166,23 @@ fn on_request(
 fn on_notification(
     io: &mut Io,
     state: &mut ServerWorldState,
+    pending_requests: &mut HashMap<u64, JobHandle>,
     subs: &mut Subscriptions,
     not: RawNotification,
 ) -> Result<()> {
     let mut not = Some(not);
+    dispatch::handle_notification::<req::Cancel, _>(&mut not, |params| {
+        let id = match params.id {
+            NumberOrString::Number(id) => id,
+            NumberOrString::String(id) => {
+                panic!("string id's not supported: {:?}", id);
+            }
+        };
+        if let Some(handle) = pending_requests.remove(&id) {
+            handle.cancel();
+        }
+        Ok(())
+    })?;
     dispatch::handle_notification::<req::DidOpenTextDocument, _>(&mut not, |params| {
         let uri = params.text_document.uri;
         let path = uri.to_file_path()
@@ -196,21 +221,30 @@ fn on_notification(
 
 struct PoolDispatcher<'a> {
     req: Option<RawRequest>,
+    res: Option<(u64, JobHandle)>,
     pool: &'a ThreadPool,
     world: &'a ServerWorldState,
     sender: &'a Sender<Task>,
 }
 
 impl<'a> PoolDispatcher<'a> {
-    fn on<'b, R: req::ClientRequest>(&'b mut self, f: fn(ServerWorld, R::Params) -> Result<R::Result>) -> Result<&'b mut Self> {
+    fn on<'b, R: req::ClientRequest>(
+        &'b mut self,
+        f: fn(ServerWorld, R::Params, JobToken) -> Result<R::Result>
+    ) -> Result<&'b mut Self> {
+        let req = match self.req.take() {
+            None => return Ok(self),
+            Some(req) => req,
+        };
         let world = self.world;
         let sender = self.sender;
         let pool = self.pool;
-        dispatch::handle_request::<R, _>(&mut self.req, |params, resp| {
+        let (handle, token) = JobHandle::new();
+        let req = dispatch::handle_request::<R, _>(req, |params, resp| {
             let world = world.snapshot();
             let sender = sender.clone();
             pool.execute(move || {
-                let res = f(world, params);
+                let res = f(world, params, token);
                 let task = match resp.into_response(res) {
                     Ok(resp) => Task::Respond(resp),
                     Err(e) => Task::Die(e),
@@ -219,8 +253,20 @@ impl<'a> PoolDispatcher<'a> {
             });
             Ok(())
         })?;
+        match req {
+            Ok(id) => self.res = Some((id, handle)),
+            Err(req) => self.req = Some(req),
+        }
         Ok(self)
     }
+
+    fn finish(&mut self) -> ::std::result::Result<(u64, JobHandle), RawRequest> {
+        match (self.res.take(), self.req.take()) {
+            (Some(res), None) => Ok(res),
+            (None, Some(req)) => Err(req),
+            _ => unreachable!(),
+        }
+    }
 }
 
 fn update_file_notifications_on_threadpool(