From 3e2d1de21a86e95d82bee50265cd5fc95a0d1969 Mon Sep 17 00:00:00 2001
From: Sebastian Ullrich <sebasti@nullri.ch>
Date: Tue, 27 Dec 2016 20:37:12 +0100
Subject: [PATCH] perf(shell/server,emacs): do not actually compute completions
 during preliminary 'complete' requests

---
 src/emacs/lean-company.el |  7 ++++---
 src/emacs/lean-mode.el    |  2 +-
 src/shell/server.cpp      | 14 ++++++++++----
 3 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/emacs/lean-company.el b/src/emacs/lean-company.el
index 264904ba40..b0ea105140 100644
--- a/src/emacs/lean-company.el
+++ b/src/emacs/lean-company.el
@@ -38,14 +38,15 @@
     (cond ((s-prefix? prefix candidate) candidates)
           (t                            `(,candidate ,prefix)))))
 
-(defun company-lean--exec ()
+(cl-defun company-lean--exec (&key skip-completions)
   "Synchronously queries completions for the current point from server and returns a plist with keys :prefix and :candidates., or nil if no completion should be triggered."
   (lean-server-sync)
   (let* ((col (lean-line-offset))
          (response (lean-server-send-synchronous-command
                     'complete (list :file_name (buffer-file-name)
                                     :line (line-number-at-pos)
-                                    :column col)))
+                                    :column col
+                                    :skip_completions (or skip-completions :json-false))))
          (candidates (plist-get response :completions))
          (prefix (plist-get response :prefix)))
     (when candidates
@@ -92,7 +93,7 @@
 
 (defun company-lean (command &optional arg &rest ignored)
   (cl-case command
-    (prefix (plist-get (company-lean--exec) :prefix))
+    (prefix (plist-get (company-lean--exec :skip-completions t) :prefix))
     (candidates (plist-get (company-lean--exec) :candidates))
     (annotation (company-lean--annotation arg))
     ;(location (cons :async (lambda (cb) (company-lean--findp-location arg cb))))
diff --git a/src/emacs/lean-mode.el b/src/emacs/lean-mode.el
index e41c5858e6..ecd376899e 100644
--- a/src/emacs/lean-mode.el
+++ b/src/emacs/lean-mode.el
@@ -75,7 +75,7 @@
   (interactive)
   (if (minibufferp)
       (minibuffer-complete)
-    (cond ((and lean-company-use (company-lean--exec))
+    (cond ((and lean-company-use (company-lean--exec :skip-completions t))
            (company-complete-common))
           (lean-company-use (lean-tab-indent))
           ((lean-check-expansion)
diff --git a/src/shell/server.cpp b/src/shell/server.cpp
index 5e9b046a8f..29239db18d 100644
--- a/src/shell/server.cpp
+++ b/src/shell/server.cpp
@@ -322,10 +322,12 @@ class server::auto_complete_task : public task<unit> {
     server * m_server;
     unsigned m_seq_num;
     std::shared_ptr<module_info const> m_mod_info;
+    bool     m_skip_completions;
 
 public:
-    auto_complete_task(server * server, unsigned seq_num, std::shared_ptr<module_info const> const & mod_info) :
-        m_server(server), m_seq_num(seq_num), m_mod_info(mod_info) {}
+    auto_complete_task(server * server, unsigned seq_num, std::shared_ptr<module_info const> const & mod_info,
+                       bool skip_completions) :
+        m_server(server), m_seq_num(seq_num), m_mod_info(mod_info), m_skip_completions(skip_completions) {}
 
     // TODO(gabriel): find cleaner way to give it high prio
     task_kind get_kind() const override { return task_kind::parse; }
@@ -355,7 +357,8 @@ public:
                         std::string prefix = e.m_token->to_string();
                         if (auto stop = utf8_char_pos(prefix.c_str(), get_pos().second - e.m_token_pos->second))
                             prefix = prefix.substr(0, *stop);
-                        j["completions"] = get_completions(prefix, snap->m_env, snap->m_options);
+                        if (!m_skip_completions)
+                            j["completions"] = get_completions(prefix, snap->m_env, snap->m_options);
                         j["prefix"] = prefix;
                     }
                 } catch (throwable & ex) {}
@@ -372,13 +375,16 @@ public:
 void server::handle_complete(cmd_req const & req) {
     std::string fn = req.m_payload.at("file_name");
     pos_info pos = {req.m_payload.at("line"), req.m_payload.at("column")};
+    bool skip_completions = false;
+    if (req.m_payload.count("skip_completions"))
+        skip_completions = req.m_payload.at("skip_completions");
 
     scope_message_context scope_msg_ctx(message_bucket_id { "_server", 0 });
     scoped_task_context scope_task_ctx(fn, pos);
 
     auto mod_info = m_mod_mgr->get_module(fn);
 
-    get_global_task_queue()->submit<auto_complete_task>(this, req.m_seq_num, mod_info);
+    get_global_task_queue()->submit<auto_complete_task>(this, req.m_seq_num, mod_info, skip_completions);
 }
 
 class server::info_task : public task<unit> {