Drop old completion requests.

Also increase xref limit.

src/clang_complete.cc

@@ -440,6 +440,14 @@ void CompletionQueryMain(ClangCompleteManager* completion_manager) {
     // Fetching the completion request blocks until we have a request.
     std::unique_ptr<ClangCompleteManager::CompletionRequest> request =
         completion_manager->completion_request_.Dequeue();
+
+    // Drop older requests if we're not buffering.
+    while (completion_manager->config_->completion.dropOldRequests &&
+           !completion_manager->completion_request_.IsEmpty()) {
+      completion_manager->on_dropped_(request->id);
+      request = completion_manager->completion_request_.Dequeue();
+    }
+
     std::string path = request->document.uri.GetPath();
 
     std::shared_ptr<CompletionSession> session =
@@ -625,25 +633,35 @@ CompletionSession::~CompletionSession() {}
 ClangCompleteManager::ParseRequest::ParseRequest(const std::string& path)
     : request_time(std::chrono::high_resolution_clock::now()), path(path) {}
 
-ClangCompleteManager::CompletionRequest::CompletionRequest(const lsTextDocumentIdentifier& document,
-                                                              const bool& emit_diagnostics)
-    : document(document), emit_diagnostics(emit_diagnostics) {}
-ClangCompleteManager::CompletionRequest::CompletionRequest(const lsTextDocumentIdentifier& document,
+ClangCompleteManager::CompletionRequest::CompletionRequest(
+    const lsRequestId& id,
+    const lsTextDocumentIdentifier& document,
+    bool emit_diagnostics)
+    : id(id), document(document), emit_diagnostics(emit_diagnostics) {}
+ClangCompleteManager::CompletionRequest::CompletionRequest(
+    const lsRequestId& id,
+    const lsTextDocumentIdentifier& document,
     const lsPosition& position,
     const OnComplete& on_complete,
-                                                              const bool& emit_diagnostics)
-    : document(document), position(position), on_complete(on_complete), emit_diagnostics(emit_diagnostics) {}
+    bool emit_diagnostics)
+    : id(id),
+      document(document),
+      position(position),
+      on_complete(on_complete),
+      emit_diagnostics(emit_diagnostics) {}
 
 ClangCompleteManager::ClangCompleteManager(Config* config,
                                            Project* project,
                                            WorkingFiles* working_files,
                                            OnDiagnostic on_diagnostic,
-                                           OnIndex on_index)
+                                           OnIndex on_index,
+                                           OnDropped on_dropped)
     : config_(config),
       project_(project),
       working_files_(working_files),
       on_diagnostic_(on_diagnostic),
       on_index_(on_index),
+      on_dropped_(on_dropped),
       preloaded_sessions_(kMaxPreloadedSessions),
       completion_sessions_(kMaxCompletionSessions) {
   new std::thread([&]() {
@@ -660,16 +678,19 @@ ClangCompleteManager::ClangCompleteManager(Config* config,
 ClangCompleteManager::~ClangCompleteManager() {}
 
 void ClangCompleteManager::CodeComplete(
+    const lsRequestId& id,
     const lsTextDocumentPositionParams& completion_location,
     const OnComplete& on_complete) {
   completion_request_.PushBack(MakeUnique<CompletionRequest>(
-      completion_location.textDocument, completion_location.position,
+      id, completion_location.textDocument, completion_location.position,
       on_complete, false));
 }
 
 void ClangCompleteManager::DiagnosticsUpdate(
+    const lsRequestId& id,
     const lsTextDocumentIdentifier& document) {
-  completion_request_.PushBack(MakeUnique<CompletionRequest>(document, true));
+  completion_request_.PushBack(
+      MakeUnique<CompletionRequest>(id, document, true));
 }
 
 void ClangCompleteManager::NotifyView(const std::string& filename) {

src/clang_complete.h

@@ -47,6 +47,7 @@ struct ClangCompleteManager {
   using OnComplete =
       std::function<void(const std::vector<lsCompletionItem>& results,
                          bool is_cached_result)>;
+  using OnDropped = std::function<void(lsRequestId request_id)>;
 
   struct ParseRequest {
     ParseRequest(const std::string& path);
@@ -55,13 +56,16 @@ struct ClangCompleteManager {
     std::string path;
   };
   struct CompletionRequest {
-    CompletionRequest(const lsTextDocumentIdentifier& document,
-                      const bool& emit_diagnostics);
-    CompletionRequest(const lsTextDocumentIdentifier& document,
+    CompletionRequest(const lsRequestId& id,
+                      const lsTextDocumentIdentifier& document,
+                      bool emit_diagnostics);
+    CompletionRequest(const lsRequestId& id,
+                      const lsTextDocumentIdentifier& document,
                       const lsPosition& position,
                       const OnComplete& on_complete,
-                      const bool& emit_diagnostics);
+                      bool emit_diagnostics);
 
+    lsRequestId id;
     lsTextDocumentIdentifier document;
     optional<lsPosition> position;
     OnComplete on_complete;  // May be null/empty.
@@ -72,15 +76,18 @@ struct ClangCompleteManager {
                        Project* project,
                        WorkingFiles* working_files,
                        OnDiagnostic on_diagnostic,
-                       OnIndex on_index);
+                       OnIndex on_index,
+                       OnDropped on_dropped);
   ~ClangCompleteManager();
 
   // Start a code completion at the given location. |on_complete| will run when
   // completion results are available. |on_complete| may run on any thread.
-  void CodeComplete(const lsTextDocumentPositionParams& completion_location,
+  void CodeComplete(const lsRequestId& request_id,
+                    const lsTextDocumentPositionParams& completion_location,
                     const OnComplete& on_complete);
   // Request a diagnostics update.
-  void DiagnosticsUpdate(const lsTextDocumentIdentifier& document);
+  void DiagnosticsUpdate(const lsRequestId& request_id,
+                         const lsTextDocumentIdentifier& document);
 
   // Notify the completion manager that |filename| has been viewed and we
   // should begin preloading completion data.
@@ -113,6 +120,7 @@ struct ClangCompleteManager {
   WorkingFiles* working_files_;
   OnDiagnostic on_diagnostic_;
   OnIndex on_index_;
+  OnDropped on_dropped_;
 
   using LruSessionCache = LruCache<std::string, CompletionSession>;
 

src/command_line.cc

@@ -71,7 +71,8 @@ bool ShouldDisplayIpcTiming(IpcId id) {
 REGISTER_IPC_MESSAGE(Ipc_CancelRequest);
 
 void PrintHelp() {
-  std::cout << R"help(cquery is a low-latency C/C++/Objective-C language server.
+  std::cout
+      << R"help(cquery is a low-latency C/C++/Objective-C language server.
 
 Mode:
   --clang-sanity-check
@@ -186,6 +187,15 @@ void RunQueryDbThread(const std::string& bin_name,
           const std::string& path, const std::vector<std::string>& args) {
         IndexWithTuFromCodeCompletion(config, &file_consumer_shared, tu,
                                       unsaved, path, args);
+      },
+      [](lsRequestId id) {
+        if (!std::holds_alternative<std::monostate>(id)) {
+          Out_Error out;
+          out.id = id;
+          out.error.code = lsErrorCodes::InternalError;
+          out.error.message = "Dropped completion request";
+          QueueManager::WriteStdout(IpcId::Unknown, out);
+        }
       });
 
   IncludeComplete include_complete(config, &project);

src/config.h

@@ -110,6 +110,12 @@ struct Config {
     // items can end up truncated by the UIs.
     bool detailedLabel = false;
 
+    // On large projects, completion can take a long time. By default if cquery
+    // receives multiple completion requests while completion is still running
+    // it will only service the newest request. If this is set to false then all
+    // completion requests will be serviced.
+    bool dropOldRequests = true;
+
     // If true, filter and sort completion response. cquery filters and sorts
     // completions to try to be nicer to clients that can't handle big numbers
     // of completion candidates. This behaviour can be disabled by specifying

src/messages/text_document_completion.cc

@@ -223,7 +223,8 @@ struct TextDocumentCompletionHandler : MessageHandler {
       std::string character = *request->params.context->triggerCharacter;
       int preceding_index = request->params.position.character - 2;
 
-      // If the character is '"', '<' or '/', make sure that the line starts with '#'.
+      // If the character is '"', '<' or '/', make sure that the line starts
+      // with '#'.
       if (character == "\"" || character == "<" || character == "/") {
         size_t i = 0;
         while (i < buffer_line.size() && isspace(buffer_line[i]))
@@ -361,7 +362,8 @@ struct TextDocumentCompletionHandler : MessageHandler {
           callback(global_code_complete_cache->cached_results_,
                    true /*is_cached_result*/);
         });
-        clang_complete->CodeComplete(request->params, freshen_global);
+        clang_complete->CodeComplete(request->id, request->params,
+                                     freshen_global);
       } else if (non_global_code_complete_cache->IsCacheValid(
                      request->params)) {
         non_global_code_complete_cache->WithLock([&]() {
@@ -369,7 +371,7 @@ struct TextDocumentCompletionHandler : MessageHandler {
                    true /*is_cached_result*/);
         });
       } else {
-        clang_complete->CodeComplete(request->params, callback);
+        clang_complete->CodeComplete(request->id, request->params, callback);
       }
     }
   }

src/messages/text_document_did_change.cc

@@ -19,6 +19,7 @@ struct TextDocumentDidChangeHandler
     working_files->OnChange(request->params);
     clang_complete->NotifyEdit(path);
     clang_complete->DiagnosticsUpdate(
+        std::monostate(),
         request->params.textDocument.AsTextDocumentIdentifier());
   }
 };

src/messages/text_document_signature_help.cc

@@ -164,7 +164,7 @@ struct TextDocumentSignatureHelpHandler : MessageHandler {
         callback(signature_cache->cached_results_, true /*is_cached_result*/);
       });
     } else {
-      clang_complete->CodeComplete(params, std::move(callback));
+      clang_complete->CodeComplete(request->id, params, std::move(callback));
     }
   }
 };