Merge pull request #13686 from bfredl/fastevent

state: throttle batched event processing when input is available

src/nvim/edit.c

@@ -1024,7 +1024,7 @@ static int insert_handle_key(InsertState *s)
     break;
 
   case K_EVENT:       // some event
-    multiqueue_process_events(main_loop.events);
+    state_handle_k_event();
     goto check_pum;
 
   case K_COMMAND:       // some command

src/nvim/eval/funcs.c

@@ -3029,10 +3029,11 @@ static void f_getchar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 
     if (argvars[0].v_type == VAR_UNKNOWN) {
       // getchar(): blocking wait.
+      // TODO(bfredl): deduplicate shared logic with state_enter ?
       if (!(char_avail() || using_script() || input_available())) {
         (void)os_inchar(NULL, 0, -1, 0, main_loop.events);
         if (!multiqueue_empty(main_loop.events)) {
-          multiqueue_process_events(main_loop.events);
+          state_handle_k_event();
           continue;
         }
       }

src/nvim/ex_getln.c

@@ -935,7 +935,7 @@ static int command_line_execute(VimState *state, int key)
 
   if (s->c == K_EVENT || s->c == K_COMMAND) {
     if (s->c == K_EVENT) {
-      multiqueue_process_events(main_loop.events);
+      state_handle_k_event();
     } else {
       do_cmdline(NULL, getcmdkeycmd, NULL, DOCMD_NOWAIT);
     }

src/nvim/normal.c

@@ -8103,7 +8103,7 @@ static void nv_event(cmdarg_T *cap)
   // lists or dicts being used.
   may_garbage_collect = false;
   bool may_restart = (restart_edit != 0);
-  multiqueue_process_events(main_loop.events);
+  state_handle_k_event();
   finish_op = false;
   if (may_restart) {
     // Tricky: if restart_edit was set before the handler we are in ctrl-o mode,

src/nvim/os/input.c

@@ -159,16 +159,28 @@ bool os_char_avail(void)
   return inbuf_poll(0, NULL) == kInputAvail;
 }
 
-// Check for CTRL-C typed by reading all available characters.
+/// Poll for fast events. `got_int` will be set to `true` if CTRL-C was typed.
+///
+/// This invokes a full libuv loop iteration which can be quite costly.
+/// Prefer `line_breakcheck()` if called in a busy inner loop.
+///
+/// Caller must at least check `got_int` before calling this function again.
+/// checking for other low-level input state like `input_available()` might
+/// also be relevant (i e to throttle idle processing when user input is
+/// available)
 void os_breakcheck(void)
 {
+  if (got_int) {
+    return;
+  }
+
   int save_us = updating_screen;
   // We do not want screen_resize() to redraw here.
+  // TODO(bfredl): we are already special casing redraw events, is this
+  // hack still needed?
   updating_screen++;
 
-  if (!got_int) {
-    loop_poll_events(&main_loop, 0);
-  }
+  loop_poll_events(&main_loop, 0);
 
   updating_screen = save_us;
 }

src/nvim/state.c

@@ -75,6 +75,34 @@ void state_enter(VimState *s)
   }
 }
 
+/// process events on main_loop, but interrupt if input is available
+///
+/// This should be used to handle K_EVENT in states accepting input
+/// otherwise bursts of events can block break checking indefinitely.
+void state_handle_k_event(void)
+{
+  while (true) {
+    Event event = multiqueue_get(main_loop.events);
+    if (event.handler) {
+      event.handler(event.argv);
+    }
+
+    if (multiqueue_empty(main_loop.events)) {
+      // don't breakcheck before return, caller should return to main-loop
+      // and handle input already.
+      return;
+    }
+
+    // TODO(bfredl): as an further micro-optimization, we could check whether
+    // event.handler already checked input.
+    os_breakcheck();
+    if (input_available() || got_int) {
+      return;
+    }
+  }
+}
+
+
 /// Return true if in the current mode we need to use virtual.
 bool virtual_active(void)
 {

src/nvim/terminal.c

@@ -457,7 +457,7 @@ static int terminal_execute(VimState *state, int key)
     case K_EVENT:
       // We cannot let an event free the terminal yet. It is still needed.
       s->term->refcount++;
-      multiqueue_process_events(main_loop.events);
+      state_handle_k_event();
       s->term->refcount--;
       if (s->term->buf_handle == 0) {
         s->close = true;

test/functional/plugin/lsp_spec.lua

@@ -257,6 +257,7 @@ describe('LSP', function()
           eq(0, client.resolved_capabilities().text_document_did_change)
           client.request('shutdown')
           client.notify('exit')
+          client.stop()
         end;
         on_exit = function(code, signal)
           eq(0, code, "exit code", fake_lsp_logfile)

test/functional/ui/input_spec.lua

@@ -1,16 +1,18 @@
 local helpers = require('test.functional.helpers')(after_each)
-local clear, feed_command, nvim = helpers.clear, helpers.feed_command, helpers.nvim
+local clear, feed_command = helpers.clear, helpers.feed_command
 local feed, next_msg, eq = helpers.feed, helpers.next_msg, helpers.eq
 local command = helpers.command
 local expect = helpers.expect
+local meths = helpers.meths
+local exec_lua = helpers.exec_lua
 local write_file = helpers.write_file
 local Screen = require('test.functional.ui.screen')
 
-describe('mappings', function()
-  local cid
+before_each(clear)
 
+describe('mappings', function()
   local add_mapping = function(mapping, send)
-    local cmd = "nnoremap "..mapping.." :call rpcnotify("..cid..", 'mapped', '"
+    local cmd = "nnoremap "..mapping.." :call rpcnotify(1, 'mapped', '"
                 ..send:gsub('<', '<lt>').."')<cr>"
     feed_command(cmd)
   end
@@ -21,8 +23,6 @@ describe('mappings', function()
   end
 
   before_each(function()
-    clear()
-    cid = nvim('get_api_info')[1]
     add_mapping('<C-L>', '<C-L>')
     add_mapping('<C-S-L>', '<C-S-L>')
     add_mapping('<s-up>', '<s-up>')
@@ -115,7 +115,6 @@ describe('mappings', function()
 end)
 
 describe('input utf sequences that contain CSI/K_SPECIAL', function()
-  before_each(clear)
   it('ok', function()
     feed('i…<esc>')
     expect('…')
@@ -129,7 +128,6 @@ describe('input non-printable chars', function()
 
   it("doesn't crash when echoing them back", function()
     write_file("Xtest-overwrite", [[foobar]])
-    clear()
     local screen = Screen.new(60,8)
     screen:set_default_attr_ids({
       [1] = {bold = true, foreground = Screen.colors.Blue1},
@@ -215,3 +213,27 @@ describe('input non-printable chars', function()
     ]])
   end)
 end)
+
+describe("event processing and input", function()
+  it('not blocked by event bursts', function()
+    meths.set_keymap('', '<f2>', "<cmd>lua vim.rpcnotify(1, 'stop') winning = true <cr>", {noremap=true})
+
+    exec_lua [[
+      winning = false
+      burst = vim.schedule_wrap(function(tell)
+        if tell then
+          vim.rpcnotify(1, 'start')
+        end
+        -- Are we winning, son?
+        if not winning then
+          burst(false)
+        end
+      end)
+      burst(true)
+    ]]
+
+    eq({'notification', 'start', {}}, next_msg())
+    feed '<f2>'
+    eq({'notification', 'stop', {}}, next_msg())
+  end)
+end)