Merge #6247 'api: nvim_get_mode()'

18 files changed, 158 insertions, 97 deletions

diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index da00fbc6e3..11f15b5ad1 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -27,6 +27,7 @@
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"
 #include "nvim/option.h"
+#include "nvim/state.h"
 #include "nvim/syntax.h"
 #include "nvim/getchar.h"
 #include "nvim/os/input.h"
@@ -701,6 +702,24 @@ Dictionary nvim_get_color_map(void)
 }
 
 
+/// Gets the current mode.
+/// mode:     Mode string. |mode()|
+/// blocking: true if Nvim is waiting for input.
+///
+/// @returns Dictionary { "mode": String, "blocking": Boolean }
+Dictionary nvim_get_mode(void)
+  FUNC_API_SINCE(2) FUNC_API_ASYNC
+{
+  Dictionary rv = ARRAY_DICT_INIT;
+  char *modestr = get_mode();
+  bool blocked = input_blocking();
+
+  PUT(rv, "mode", STRING_OBJ(cstr_as_string(modestr)));
+  PUT(rv, "blocking", BOOLEAN_OBJ(blocked));
+
+  return rv;
+}
+
 Array nvim_get_api_info(uint64_t channel_id)
     FUNC_API_SINCE(1) FUNC_API_ASYNC FUNC_API_NOEVAL
 {
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index c02d172458..b0f47d8e45 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -12575,59 +12575,18 @@ static void f_mkdir(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   }
 }
 
-/*
- * "mode()" function
- */
+/// "mode()" function
 static void f_mode(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
-  char_u buf[3];
+  char *mode = get_mode();
 
-  buf[1] = NUL;
-  buf[2] = NUL;
-
-  if (VIsual_active) {
-    if (VIsual_select)
-      buf[0] = VIsual_mode + 's' - 'v';
-    else
-      buf[0] = VIsual_mode;
-  } else if (State == HITRETURN || State == ASKMORE || State == SETWSIZE
-             || State == CONFIRM) {
-    buf[0] = 'r';
-    if (State == ASKMORE)
-      buf[1] = 'm';
-    else if (State == CONFIRM)
-      buf[1] = '?';
-  } else if (State == EXTERNCMD)
-    buf[0] = '!';
-  else if (State & INSERT) {
-    if (State & VREPLACE_FLAG) {
-      buf[0] = 'R';
-      buf[1] = 'v';
-    } else if (State & REPLACE_FLAG)
-      buf[0] = 'R';
-    else
-      buf[0] = 'i';
-  } else if (State & CMDLINE) {
-    buf[0] = 'c';
-    if (exmode_active)
-      buf[1] = 'v';
-  } else if (exmode_active) {
-    buf[0] = 'c';
-    buf[1] = 'e';
-  } else if (State & TERM_FOCUS) {
-    buf[0] = 't';
-  } else {
-    buf[0] = 'n';
-    if (finish_op)
-      buf[1] = 'o';
+  // Clear out the minor mode when the argument is not a non-zero number or
+  // non-empty string.
+  if (!non_zero_arg(&argvars[0])) {
+    mode[1] = NUL;
   }
 
-  /* Clear out the minor mode when the argument is not a non-zero number or
-   * non-empty string.  */
-  if (!non_zero_arg(&argvars[0]))
-    buf[1] = NUL;
-
-  rettv->vval.v_string = vim_strsave(buf);
+  rettv->vval.v_string = (char_u *)mode;
   rettv->v_type = VAR_STRING;
 }
 
diff --git a/src/nvim/event/defs.h b/src/nvim/event/defs.h
index e5335d9f25..cc875d74b9 100644
--- a/src/nvim/event/defs.h
+++ b/src/nvim/event/defs.h
@@ -8,16 +8,14 @@
 
 typedef void (*argv_callback)(void **argv);
 typedef struct message {
-  int priority;
   argv_callback handler;
   void *argv[EVENT_HANDLER_MAX_ARGC];
 } Event;
 typedef void(*event_scheduler)(Event event, void *data);
 
-#define VA_EVENT_INIT(event, p, h, a) \
+#define VA_EVENT_INIT(event, h, a) \
   do { \
     assert(a <= EVENT_HANDLER_MAX_ARGC); \
-    (event)->priority = p; \
     (event)->handler = h; \
     if (a) { \
       va_list args; \
@@ -29,11 +27,11 @@ typedef void(*event_scheduler)(Event event, void *data);
     } \
   } while (0)
 
-static inline Event event_create(int priority, argv_callback cb, int argc, ...)
+static inline Event event_create(argv_callback cb, int argc, ...)
 {
   assert(argc <= EVENT_HANDLER_MAX_ARGC);
   Event event;
-  VA_EVENT_INIT(&event, priority, cb, argc);
+  VA_EVENT_INIT(&event, cb, argc);
   return event;
 }
 
diff --git a/src/nvim/event/loop.c b/src/nvim/event/loop.c
index 6963978581..c709ce9a1c 100644
--- a/src/nvim/event/loop.c
+++ b/src/nvim/event/loop.c
@@ -44,8 +44,7 @@ void loop_poll_events(Loop *loop, int ms)
     // we do not block indefinitely for I/O.
     uv_timer_start(&loop->poll_timer, timer_cb, (uint64_t)ms, (uint64_t)ms);
   } else if (ms == 0) {
-    // For ms == 0, we need to do a non-blocking event poll by
-    // setting the run mode to UV_RUN_NOWAIT.
+    // For ms == 0, do a non-blocking event poll.
     mode = UV_RUN_NOWAIT;
   }
 
diff --git a/src/nvim/event/multiqueue.c b/src/nvim/event/multiqueue.c
index a17bae31e3..ef9f3f1870 100644
--- a/src/nvim/event/multiqueue.c
+++ b/src/nvim/event/multiqueue.c
@@ -126,6 +126,7 @@ void multiqueue_free(MultiQueue *this)
   xfree(this);
 }
 
+/// Removes the next item and returns its Event.
 Event multiqueue_get(MultiQueue *this)
 {
   return multiqueue_empty(this) ? NILEVENT : multiqueue_remove(this);
@@ -144,7 +145,7 @@ void multiqueue_process_events(MultiQueue *this)
 {
   assert(this);
   while (!multiqueue_empty(this)) {
-    Event event = multiqueue_get(this);
+    Event event = multiqueue_remove(this);
     if (event.handler) {
       event.handler(event.argv);
     }
@@ -178,36 +179,48 @@ size_t multiqueue_size(MultiQueue *this)
   return this->size;
 }
 
-static Event multiqueue_remove(MultiQueue *this)
+/// Gets an Event from an item.
+///
+/// @param remove   Remove the node from its queue, and free it.
+static Event multiqueueitem_get_event(MultiQueueItem *item, bool remove)
 {
-  assert(!multiqueue_empty(this));
-  QUEUE *h = QUEUE_HEAD(&this->headtail);
-  QUEUE_REMOVE(h);
-  MultiQueueItem *item = multiqueue_node_data(h);
-  Event rv;
-
+  assert(item != NULL);
+  Event ev;
   if (item->link) {
-    assert(!this->parent);
-    // remove the next node in the linked queue
+    // get the next node in the linked queue
     MultiQueue *linked = item->data.queue;
     assert(!multiqueue_empty(linked));
     MultiQueueItem *child =
       multiqueue_node_data(QUEUE_HEAD(&linked->headtail));
-    QUEUE_REMOVE(&child->node);
-    rv = child->data.item.event;
-    xfree(child);
+    ev = child->data.item.event;
+    // remove the child node
+    if (remove) {
+      QUEUE_REMOVE(&child->node);
+      xfree(child);
+    }
   } else {
-    if (this->parent) {
-      // remove the corresponding link node in the parent queue
+    // remove the corresponding link node in the parent queue
+    if (remove && item->data.item.parent_item) {
       QUEUE_REMOVE(&item->data.item.parent_item->node);
       xfree(item->data.item.parent_item);
+      item->data.item.parent_item = NULL;
     }
-    rv = item->data.item.event;
+    ev = item->data.item.event;
   }
+  return ev;
+}
 
+static Event multiqueue_remove(MultiQueue *this)
+{
+  assert(!multiqueue_empty(this));
+  QUEUE *h = QUEUE_HEAD(&this->headtail);
+  QUEUE_REMOVE(h);
+  MultiQueueItem *item = multiqueue_node_data(h);
+  assert(!item->link || !this->parent);  // Only a parent queue has link-nodes
+  Event ev = multiqueueitem_get_event(item, true);
   this->size--;
   xfree(item);
-  return rv;
+  return ev;
 }
 
 static void multiqueue_push(MultiQueue *this, Event event)
@@ -215,6 +228,7 @@ static void multiqueue_push(MultiQueue *this, Event event)
   MultiQueueItem *item = xmalloc(sizeof(MultiQueueItem));
   item->link = false;
   item->data.item.event = event;
+  item->data.item.parent_item = NULL;
   QUEUE_INSERT_TAIL(&this->headtail, &item->node);
   if (this->parent) {
     // push link node to the parent queue
diff --git a/src/nvim/event/multiqueue.h b/src/nvim/event/multiqueue.h
index def6b95a10..a688107665 100644
--- a/src/nvim/event/multiqueue.h
+++ b/src/nvim/event/multiqueue.h
@@ -10,7 +10,7 @@ typedef struct multiqueue MultiQueue;
 typedef void (*put_callback)(MultiQueue *multiq, void *data);
 
 #define multiqueue_put(q, h, ...) \
-  multiqueue_put_event(q, event_create(1, h, __VA_ARGS__));
+  multiqueue_put_event(q, event_create(h, __VA_ARGS__));
 
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/memory.c b/src/nvim/memory.c
index 0ee4776581..74c58fb203 100644
--- a/src/nvim/memory.c
+++ b/src/nvim/memory.c
@@ -345,10 +345,6 @@ char *xstpcpy(char *restrict dst, const char *restrict src)
 /// WARNING: xstpncpy will ALWAYS write maxlen bytes. If src is shorter than
 /// maxlen, zeroes will be written to the remaining bytes.
 ///
-/// TODO(aktau): I don't see a good reason to have this last behaviour, and
-/// it is potentially wasteful. Could we perhaps deviate from the standard
-/// and not zero the rest of the buffer?
-///
 /// @param dst
 /// @param src
 /// @param maxlen
diff --git a/src/nvim/message.c b/src/nvim/message.c
index 146937c25a..696855e3aa 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -604,7 +604,7 @@ void msg_schedule_emsgf(const char *const fmt, ...)
   va_end(ap);
 
   char *s = xstrdup((char *)IObuff);
-  loop_schedule(&main_loop, event_create(1, msg_emsgf_event, 1, s));
+  loop_schedule(&main_loop, event_create(msg_emsgf_event, 1, s));
 }
 
 /*
diff --git a/src/nvim/msgpack_rpc/channel.c b/src/nvim/msgpack_rpc/channel.c
index 59594357de..911f2a6fa4 100644
--- a/src/nvim/msgpack_rpc/channel.c
+++ b/src/nvim/msgpack_rpc/channel.c
@@ -29,6 +29,7 @@
 #include "nvim/log.h"
 #include "nvim/misc1.h"
 #include "nvim/lib/kvec.h"
+#include "nvim/os/input.h"
 
 #define CHANNEL_BUFFER_SIZE 0xffff
 
@@ -89,6 +90,7 @@ static msgpack_sbuffer out_buffer;
 /// Initializes the module
 void channel_init(void)
 {
+  ch_before_blocking_events = multiqueue_new_child(main_loop.events);
   channels = pmap_new(uint64_t)();
   event_strings = pmap_new(cstr_t)();
   msgpack_sbuffer_init(&out_buffer);
@@ -433,16 +435,25 @@ static void handle_request(Channel *channel, msgpack_object *request)
     handler.async = true;
   }
 
-  RequestEvent *event_data = xmalloc(sizeof(RequestEvent));
-  event_data->channel = channel;
-  event_data->handler = handler;
-  event_data->args = args;
-  event_data->request_id = request_id;
+  RequestEvent *evdata = xmalloc(sizeof(RequestEvent));
+  evdata->channel = channel;
+  evdata->handler = handler;
+  evdata->args = args;
+  evdata->request_id = request_id;
   incref(channel);
   if (handler.async) {
-    on_request_event((void **)&event_data);
+    bool is_get_mode = sizeof("nvim_get_mode") - 1 == method->via.bin.size
+      && !strncmp("nvim_get_mode", method->via.bin.ptr, method->via.bin.size);
+
+    if (is_get_mode && !input_blocking()) {
+      // Defer the event to a special queue used by os/input.c. #6247
+      multiqueue_put(ch_before_blocking_events, on_request_event, 1, evdata);
+    } else {
+      // Invoke immediately.
+      on_request_event((void **)&evdata);
+    }
   } else {
-    multiqueue_put(channel->events, on_request_event, 1, event_data);
+    multiqueue_put(channel->events, on_request_event, 1, evdata);
   }
 }
 
diff --git a/src/nvim/msgpack_rpc/channel.h b/src/nvim/msgpack_rpc/channel.h
index 0d92976d02..f8fe6f129b 100644
--- a/src/nvim/msgpack_rpc/channel.h
+++ b/src/nvim/msgpack_rpc/channel.h
@@ -11,6 +11,11 @@
 
 #define METHOD_MAXLEN 512
 
+/// HACK: os/input.c drains this queue immediately before blocking for input.
+///       Events on this queue are async-safe, but they need the resolved state
+///       of os_inchar(), so they are processed "just-in-time".
+MultiQueue *ch_before_blocking_events;
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "msgpack_rpc/channel.h.generated.h"
 #endif
diff --git a/src/nvim/msgpack_rpc/helpers.c b/src/nvim/msgpack_rpc/helpers.c
index 0228582d37..91ef5524ea 100644
--- a/src/nvim/msgpack_rpc/helpers.c
+++ b/src/nvim/msgpack_rpc/helpers.c
@@ -76,7 +76,7 @@ typedef struct {
   size_t idx;
 } MPToAPIObjectStackItem;
 
-/// Convert type used by msgpack parser to Neovim own API type
+/// Convert type used by msgpack parser to Nvim API type.
 ///
 /// @param[in]  obj  Msgpack value to convert.
 /// @param[out]  arg  Location where result of conversion will be saved.
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index 51da9429b6..f73e3079b9 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -541,7 +541,7 @@ static bool normal_handle_special_visual_command(NormalState *s)
   return false;
 }
 
-static bool normal_need_aditional_char(NormalState *s)
+static bool normal_need_additional_char(NormalState *s)
 {
   int flags = nv_cmds[s->idx].cmd_flags;
   bool pending_op = s->oa.op_type != OP_NOP;
@@ -1083,7 +1083,7 @@ static int normal_execute(VimState *state, int key)
   }
 
   // Get an additional character if we need one.
-  if (normal_need_aditional_char(s)) {
+  if (normal_need_additional_char(s)) {
     normal_get_additional_char(s);
   }
 
diff --git a/src/nvim/os/input.c b/src/nvim/os/input.c
index 7b5e14dd19..31e06ce404 100644
--- a/src/nvim/os/input.c
+++ b/src/nvim/os/input.c
@@ -23,6 +23,7 @@
 #include "nvim/main.h"
 #include "nvim/misc1.h"
 #include "nvim/state.h"
+#include "nvim/msgpack_rpc/channel.h"
 
 #define READ_BUFFER_SIZE 0xfff
 #define INPUT_BUFFER_SIZE (READ_BUFFER_SIZE * 4)
@@ -38,6 +39,7 @@ static RBuffer *input_buffer = NULL;
 static bool input_eof = false;
 static int global_fd = 0;
 static int events_enabled = 0;
+static bool blocking = false;
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "os/input.c.generated.h"
@@ -327,13 +329,25 @@ static unsigned int handle_mouse_event(char **ptr, uint8_t *buf,
   return bufsize;
 }
 
+/// @return true if the main loop is blocked and waiting for input.
+bool input_blocking(void)
+{
+  return blocking;
+}
+
 static bool input_poll(int ms)
 {
   if (do_profiling == PROF_YES && ms) {
     prof_inchar_enter();
   }
 
+  if ((ms == - 1 || ms > 0) && !events_enabled && !input_eof) {
+    // The pending input provoked a blocking wait. Do special events now. #6247
+    blocking = true;
+    multiqueue_process_events(ch_before_blocking_events);
+  }
   LOOP_PROCESS_EVENTS_UNTIL(&main_loop, NULL, ms, input_ready() || input_eof);
+  blocking = false;
 
   if (do_profiling == PROF_YES && ms) {
     prof_inchar_exit();
diff --git a/src/nvim/state.c b/src/nvim/state.c
index 210708c3f4..be6aa21664 100644
--- a/src/nvim/state.c
+++ b/src/nvim/state.c
@@ -98,3 +98,52 @@ int get_real_state(void)
   return State;
 }
 
+/// @returns[allocated] mode string
+char *get_mode(void)
+{
+  char *buf = xcalloc(3, sizeof(char));
+
+  if (VIsual_active) {
+    if (VIsual_select) {
+      buf[0] = (char)(VIsual_mode + 's' - 'v');
+    } else {
+      buf[0] = (char)VIsual_mode;
+    }
+  } else if (State == HITRETURN || State == ASKMORE || State == SETWSIZE
+             || State == CONFIRM) {
+    buf[0] = 'r';
+    if (State == ASKMORE) {
+      buf[1] = 'm';
+    } else if (State == CONFIRM) {
+      buf[1] = '?';
+    }
+  } else if (State == EXTERNCMD) {
+    buf[0] = '!';
+  } else if (State & INSERT) {
+    if (State & VREPLACE_FLAG) {
+      buf[0] = 'R';
+      buf[1] = 'v';
+    } else if (State & REPLACE_FLAG) {
+      buf[0] = 'R';
+    } else {
+      buf[0] = 'i';
+    }
+  } else if (State & CMDLINE) {
+    buf[0] = 'c';
+    if (exmode_active) {
+      buf[1] = 'v';
+    }
+  } else if (exmode_active) {
+    buf[0] = 'c';
+    buf[1] = 'e';
+  } else if (State & TERM_FOCUS) {
+    buf[0] = 't';
+  } else {
+    buf[0] = 'n';
+    if (finish_op) {
+      buf[1] = 'o';
+    }
+  }
+
+  return buf;
+}
diff --git a/src/nvim/tui/input.c b/src/nvim/tui/input.c
index b86ab8cf2f..3d37fabeee 100644
--- a/src/nvim/tui/input.c
+++ b/src/nvim/tui/input.c
@@ -102,7 +102,7 @@ static void flush_input(TermInput *input, bool wait_until_empty)
   size_t drain_boundary = wait_until_empty ? 0 : 0xff;
   do {
     uv_mutex_lock(&input->key_buffer_mutex);
-    loop_schedule(&main_loop, event_create(1, wait_input_enqueue, 1, input));
+    loop_schedule(&main_loop, event_create(wait_input_enqueue, 1, input));
     input->waiting = true;
     while (input->waiting) {
       uv_cond_wait(&input->key_buffer_cond, &input->key_buffer_mutex);
@@ -352,7 +352,7 @@ static void read_cb(Stream *stream, RBuffer *buf, size_t c, void *data,
       stream_close(&input->read_stream, NULL, NULL);
       multiqueue_put(input->loop->fast_events, restart_reading, 1, input);
     } else {
-      loop_schedule(&main_loop, event_create(1, input_done_event, 0));
+      loop_schedule(&main_loop, event_create(input_done_event, 0));
     }
     return;
   }
diff --git a/src/nvim/tui/tui.c b/src/nvim/tui/tui.c
index 21abc19c47..5653924154 100644
--- a/src/nvim/tui/tui.c
+++ b/src/nvim/tui/tui.c
@@ -74,9 +74,6 @@ typedef struct {
   bool out_isatty;
   SignalWatcher winch_handle, cont_handle;
   bool cont_received;
-  // Event scheduled by the ui bridge. Since the main thread suspends until
-  // the event is handled, it is fine to use a single field instead of a queue
-  Event scheduled_event;
   UGrid grid;
   kvec_t(Rect) invalid_regions;
   int out_fd;
@@ -776,7 +773,7 @@ static void tui_suspend(UI *ui)
   // before continuing. This is done in another callback to avoid
   // loop_poll_events recursion
   multiqueue_put_event(data->loop->fast_events,
-                       event_create(1, suspend_event, 1, ui));
+                       event_create(suspend_event, 1, ui));
 }
 
 static void tui_set_title(UI *ui, char *title)
diff --git a/src/nvim/ui.c b/src/nvim/ui.c
index 713dffb46c..924a4192bc 100644
--- a/src/nvim/ui.c
+++ b/src/nvim/ui.c
@@ -198,7 +198,7 @@ static void ui_refresh_event(void **argv)
 
 void ui_schedule_refresh(void)
 {
-  loop_schedule(&main_loop, event_create(1, ui_refresh_event, 0));
+  loop_schedule(&main_loop, event_create(ui_refresh_event, 0));
 }
 
 void ui_resize(int new_width, int new_height)
diff --git a/src/nvim/ui_bridge.c b/src/nvim/ui_bridge.c
index b7b12ae39e..d790770892 100644
--- a/src/nvim/ui_bridge.c
+++ b/src/nvim/ui_bridge.c
@@ -40,13 +40,13 @@ static argv_callback uilog_event = NULL;
       uilog_event = ui_bridge_##name##_event; \
     } \
     ((UIBridgeData *)ui)->scheduler( \
-        event_create(1, ui_bridge_##name##_event, argc, __VA_ARGS__), UI(ui)); \
+        event_create(ui_bridge_##name##_event, argc, __VA_ARGS__), UI(ui)); \
   } while (0)
 #else
 // Schedule a function call on the UI bridge thread.
 #define UI_CALL(ui, name, argc, ...) \
   ((UIBridgeData *)ui)->scheduler( \
-      event_create(1, ui_bridge_##name##_event, argc, __VA_ARGS__), UI(ui))
+      event_create(ui_bridge_##name##_event, argc, __VA_ARGS__), UI(ui))
 #endif
 
 #define INT2PTR(i) ((void *)(uintptr_t)i)