Display a status line message when Kakoune is waiting on a shell to complete

If a shell commands takes more than 1s to execute, a message will appear
on the status line notifying the user, along with the time Kakoune has
been waiting for.

src/client.cc

@@ -98,10 +98,18 @@ void Client::handle_available_input(EventMode mode)
     }
 }
 
-void Client::print_status(DisplayLine status_line)
+void Client::print_status(DisplayLine status_line, bool immediate)
 {
     m_status_line = std::move(status_line);
-    m_ui_pending |= StatusLine;
+    if (immediate)
+    {
+        m_ui->draw_status(m_status_line, m_mode_line, get_face("StatusLine"));
+        m_ui->refresh(true);
+    }
+    else
+    {
+        m_ui_pending |= StatusLine;
+    }
 }
 
 DisplayLine Client::generate_mode_line() const

src/client.hh

@@ -41,7 +41,7 @@ public:
     void info_show(String title, String content, BufferCoord anchor, InfoStyle style);
     void info_hide();
 
-    void print_status(DisplayLine status_line);
+    void print_status(DisplayLine status_line, bool immediate = false);
 
     DisplayCoord dimensions() const { return m_ui->dimensions(); }
 

src/context.cc

@@ -69,10 +69,10 @@ void Context::set_window(Window& window)
     m_window.reset(&window);
 }
 
-void Context::print_status(DisplayLine status) const
+void Context::print_status(DisplayLine status, bool immediate) const
 {
     if (has_client())
-        client().print_status(std::move(status));
+        client().print_status(std::move(status), immediate);
 }
 
 void JumpList::push(SelectionList jump)

src/context.hh

@@ -128,7 +128,7 @@ public:
     KeymapManager& keymaps() const { return scope().keymaps(); }
     AliasRegistry& aliases() const { return scope().aliases(); }
 
-    void print_status(DisplayLine status) const;
+    void print_status(DisplayLine status, bool immediate = false) const;
 
     StringView main_sel_register_value(StringView reg) const;
 

src/shell_manager.cc

@@ -5,6 +5,8 @@
 #include "buffer_utils.hh"
 #include "event_manager.hh"
 #include "file.hh"
+#include "face_registry.hh"
+#include "display_buffer.hh"
 
 #include <cstring>
 #include <sys/types.h>
@@ -150,7 +152,7 @@ std::pair<String, int> ShellManager::eval(
     write(child_stdin.write_fd(), input);
     child_stdin.close_write_fd();
 
-    auto wait_time = profile ? Clock::now() : Clock::time_point{};
+    auto wait_time = Clock::now();
 
     struct PipeReader : FDWatcher
     {
@@ -186,6 +188,10 @@ std::pair<String, int> ShellManager::eval(
     // check for termination now that SIGCHLD is blocked
     bool terminated = waitpid(pid, &status, WNOHANG);
 
+    using namespace std::chrono;
+    static constexpr seconds wait_timeout{1};
+    auto next_wait_notification = duration_cast<milliseconds>(wait_timeout);
+
     while (not terminated or
            ((flags & Flags::WaitForStdout) and
             (child_stdout.read_fd() != -1 or child_stderr.read_fd() != -1)))
@@ -193,6 +199,15 @@ std::pair<String, int> ShellManager::eval(
         EventManager::instance().handle_next_events(EventMode::Urgent, &orig_mask);
         if (not terminated)
             terminated = waitpid(pid, &status, WNOHANG);
+
+        auto wait_duration = Clock::now() - wait_time;
+        if (wait_duration > next_wait_notification)
+        {
+            next_wait_notification = duration_cast<milliseconds>(wait_duration + wait_timeout);
+            context.print_status({ format("waiting for shell command to finish ({}s)",
+                                          duration_cast<seconds>(wait_duration).count()),
+                                    get_face("Information") }, true);
+        }
     }
 
     if (not stderr_contents.empty())
@@ -200,7 +215,6 @@ std::pair<String, int> ShellManager::eval(
 
     if (profile)
     {
-        using namespace std::chrono;
         auto end_time = Clock::now();
         auto full = duration_cast<milliseconds>(end_time - start_time);
         auto spawn = duration_cast<milliseconds>(wait_time - spawn_time);