Merge pull request #12348 from tjdevries/luawait

[RFC] lua: Add vim.wait()

runtime/doc/lua.txt

@@ -827,6 +827,62 @@ vim.schedule({callback})				*vim.schedule()*
         Schedules {callback} to be invoked soon by the main event-loop. Useful
         to avoid |textlock| or other temporary restrictions.
 
+
+vim.defer_fn({fn}, {timeout})                                    *vim.defer_fn*
+    Defers calling {fn} until {timeout} ms passes.  Use to do a one-shot timer
+    that calls {fn}.
+
+    Parameters: ~
+        {fn}        Callback to call once {timeout} expires
+        {timeout}   Time in ms to wait before calling {fn}
+
+    Returns: ~
+        |vim.loop|.new_timer() object
+
+vim.wait({time}, {callback} [, {interval}])                         *vim.wait()*
+        Wait for {time} in milliseconds until {callback} returns `true`.
+
+        Executes {callback} immediately and at approximately {interval}
+        milliseconds (default 200). Nvim still processes other events during
+        this time.
+
+
+    Returns: ~
+        If {callback} returns `true` during the {time}:
+            `true, nil`
+
+        If {callback} never returns `true` during the {time}:
+            `false, -1`
+
+        If {callback} is interrupted during the {time}:
+            `false, -2`
+
+        If {callback} errors, the error is raised.
+
+        Examples: >
+
+    ---
+    -- Wait for 100 ms, allowing other events to process
+    vim.wait(100, function() end)
+
+    ---
+    -- Wait for 100 ms or until global variable set.
+    vim.wait(100, function() return vim.g.waiting_for_var end)
+
+    ---
+    -- Wait for 1 second or until global variable set, checking every ~500 ms
+    vim.wait(1000, function() return vim.g.waiting_for_var end, 500)
+
+    ---
+    -- Schedule a function to set a value in 100ms
+    vim.defer_fn(function() vim.g.timer_result = true end, 100)
+
+    -- Would wait ten seconds if results blocked. Actually only waits  100 ms
+    if vim.wait(10000, function() return vim.g.timer_result end) then
+      print('Only waiting a little bit of time!')
+    end
+<
+
 vim.fn.{func}({...})					*vim.fn*
         Invokes |vim-function| or |user-function| {func} with arguments {...}.
         To call autoload functions, use the syntax: >

runtime/lua/vim/lsp.lua

@@ -46,31 +46,6 @@ local function is_dir(filename)
   return stat and stat.type == 'directory' or false
 end
 
--- TODO Use vim.wait when that is available, but provide an alternative for now.
-local wait = vim.wait or function(timeout_ms, condition, interval)
-  validate {
-    timeout_ms = { timeout_ms, 'n' };
-    condition = { condition, 'f' };
-    interval = { interval, 'n', true };
-  }
-  assert(timeout_ms > 0, "timeout_ms must be > 0")
-  local _ = log.debug() and log.debug("wait.fallback", timeout_ms)
-  interval = interval or 200
-  local interval_cmd = "sleep "..interval.."m"
-  local timeout = timeout_ms + uv.now()
-  -- TODO is there a better way to sync this?
-  while true do
-    uv.update_time()
-    if condition() then
-      return 0
-    end
-    if uv.now() >= timeout then
-      return -1
-    end
-    nvim_command(interval_cmd)
-    -- vim.loop.sleep(10)
-  end
-end
 local wait_result_reason = { [-1] = "timeout"; [-2] = "interrupted"; [-3] = "error" }
 
 local valid_encodings = {
@@ -810,8 +785,8 @@ function lsp._vim_exit_handler()
   for _, client in pairs(active_clients) do
     client.stop()
   end
-  local wait_result = wait(500, function() return tbl_isempty(active_clients) end, 50)
+
-  if wait_result ~= 0 then
+  if not vim.wait(500, function() return tbl_isempty(active_clients) end, 50) then
     for _, client in pairs(active_clients) do
       client.stop(true)
     end
@@ -889,12 +864,14 @@ function lsp.buf_request_sync(bufnr, method, params, timeout_ms)
   for _ in pairs(client_request_ids) do
     expected_result_count = expected_result_count + 1
   end
-  local wait_result = wait(timeout_ms or 100, function()
+
+  local wait_result, reason = vim.wait(timeout_ms or 100, function()
     return result_count >= expected_result_count
   end, 10)
-  if wait_result ~= 0 then
+
+  if not wait_result then
     cancel()
-    return nil, wait_result_reason[wait_result]
+    return nil, wait_result_reason[reason]
   end
   return request_results
 end

src/nvim/lua/executor.c

@@ -28,6 +28,8 @@
 #include "nvim/ascii.h"
 #include "nvim/change.h"
 #include "nvim/eval/userfunc.h"
+#include "nvim/event/time.h"
+#include "nvim/event/loop.h"
 
 #ifdef WIN32
 #include "nvim/os/os.h"
@@ -255,6 +257,101 @@ static struct luaL_Reg regex_meta[] = {
   { NULL, NULL }
 };
 
+// Dummy timer callback. Used by f_wait().
+static void dummy_timer_due_cb(TimeWatcher *tw, void *data)
+{
+}
+
+// Dummy timer close callback. Used by f_wait().
+static void dummy_timer_close_cb(TimeWatcher *tw, void *data)
+{
+  xfree(tw);
+}
+
+static bool nlua_wait_condition(lua_State *lstate, int *status,
+                                bool *callback_result)
+{
+  lua_pushvalue(lstate, 2);
+  *status = lua_pcall(lstate, 0, 1, 0);
+  if (*status) {
+    return true;  // break on error, but keep error on stack
+  }
+  *callback_result = lua_toboolean(lstate, -1);
+  lua_pop(lstate, 1);
+  return *callback_result;  // break if true
+}
+
+/// "vim.wait(timeout, condition[, interval])" function
+static int nlua_wait(lua_State *lstate)
+  FUNC_ATTR_NONNULL_ALL
+{
+  intptr_t timeout = luaL_checkinteger(lstate, 1);
+  if (timeout < 0) {
+    return luaL_error(lstate, "timeout must be > 0");
+  }
+
+  // Check if condition can be called.
+  bool is_function = (lua_type(lstate, 2) == LUA_TFUNCTION);
+
+  // Check if condition is callable table
+  if (!is_function && luaL_getmetafield(lstate, 2, "__call") != 0) {
+    is_function = (lua_type(lstate, -1) == LUA_TFUNCTION);
+    lua_pop(lstate, 1);
+  }
+
+  if (!is_function) {
+    lua_pushliteral(lstate, "vim.wait: condition must be a function");
+    return lua_error(lstate);
+  }
+
+  intptr_t interval = 200;
+  if (lua_gettop(lstate) >= 3) {
+    interval = luaL_checkinteger(lstate, 3);
+    if (interval < 0) {
+      return luaL_error(lstate, "interval must be > 0");
+    }
+  }
+
+  TimeWatcher *tw = xmalloc(sizeof(TimeWatcher));
+
+  // Start dummy timer.
+  time_watcher_init(&main_loop, tw, NULL);
+  tw->events = main_loop.events;
+  tw->blockable = true;
+  time_watcher_start(tw, dummy_timer_due_cb,
+                     (uint64_t)interval, (uint64_t)interval);
+
+  int pcall_status = 0;
+  bool callback_result = false;
+
+  LOOP_PROCESS_EVENTS_UNTIL(
+      &main_loop,
+      main_loop.events,
+      (int)timeout,
+      nlua_wait_condition(lstate, &pcall_status, &callback_result) || got_int);
+
+  // Stop dummy timer
+  time_watcher_stop(tw);
+  time_watcher_close(tw, dummy_timer_close_cb);
+
+  if (pcall_status) {
+    return lua_error(lstate);
+  } else if (callback_result) {
+    lua_pushboolean(lstate, 1);
+    lua_pushnil(lstate);
+  } else if (got_int) {
+    got_int = false;
+    vgetc();
+    lua_pushboolean(lstate, 0);
+    lua_pushinteger(lstate, -2);
+  } else {
+    lua_pushboolean(lstate, 0);
+    lua_pushinteger(lstate, -1);
+  }
+
+  return 2;
+}
+
 /// Initialize lua interpreter state
 ///
 /// Called by lua interpreter itself to initialize state.
@@ -305,7 +402,6 @@ static int nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   // regex
   lua_pushcfunction(lstate, &nlua_regex);
   lua_setfield(lstate, -2, "regex");
-
   luaL_newmetatable(lstate, "nvim_regex");
   luaL_register(lstate, NULL, regex_meta);
   lua_pushvalue(lstate, -1);  // [meta, meta]
@@ -320,6 +416,10 @@ static int nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   lua_pushcfunction(lstate, &nlua_rpcnotify);
   lua_setfield(lstate, -2, "rpcnotify");
 
+  // wait
+  lua_pushcfunction(lstate, &nlua_wait);
+  lua_setfield(lstate, -2, "wait");
+
   // vim.loop
   luv_set_loop(lstate, &main_loop.uv);
   luv_set_callback(lstate, nlua_luv_cfpcall);

test/functional/lua/vim_spec.lua

@@ -1048,13 +1048,13 @@ describe('lua stdlib', function()
   end)
 
   it('vim.defer_fn', function()
-    exec_lua [[
+    eq(false, exec_lua [[
-    vim.g.test = 0
+      vim.g.test = false
-    vim.defer_fn(function() vim.g.test = 1 end, 50)
+      vim.defer_fn(function() vim.g.test = true end, 150)
-    ]]
+      return vim.g.test
-    eq(0, exec_lua[[return vim.g.test]])
+    ]])
-    exec_lua [[vim.cmd("sleep 1000m")]]
+    exec_lua [[vim.wait(1000, function() return vim.g.test end)]]
-    eq(1, exec_lua[[return vim.g.test]])
+    eq(true, exec_lua[[return vim.g.test]])
   end)
 
   it('vim.region', function()
@@ -1066,4 +1066,176 @@ describe('lua stdlib', function()
     eq({5,15}, exec_lua[[ return vim.region(0,{1,5},{1,14},'v',true)[1] ]])
   end)
 
+  describe('vim.wait', function()
+    before_each(function()
+      exec_lua[[
+        -- high precision timer
+        get_time = function()
+          return vim.fn.reltimefloat(vim.fn.reltime())
+        end
+      ]]
+    end)
+
+    it('should run from lua', function()
+      exec_lua[[vim.wait(100, function() return true end)]]
+    end)
+
+    it('should wait the expected time if false', function()
+      eq({time = true, wait_result = {false, -1}}, exec_lua[[
+        start_time = get_time()
+        wait_succeed, wait_fail_val = vim.wait(200, function() return false end)
+
+        return {
+          -- 150ms waiting or more results in true. Flaky tests are bad.
+          time = (start_time + 0.15) < get_time(),
+          wait_result = {wait_succeed, wait_fail_val}
+        }
+      ]])
+    end)
+
+
+    it('should not block other events', function()
+      eq({time = true, wait_result = true}, exec_lua[[
+        start_time = get_time()
+
+        vim.g.timer_result = false
+        timer = vim.loop.new_timer()
+        timer:start(100, 0, vim.schedule_wrap(function()
+          vim.g.timer_result = true
+        end))
+
+        -- Would wait ten seconds if results blocked.
+        wait_result = vim.wait(10000, function() return vim.g.timer_result end)
+
+        return {
+          time = (start_time + 5) > get_time(),
+          wait_result = wait_result,
+        }
+      ]])
+    end)
+
+    it('should work with vim.defer_fn', function()
+      eq({time = true, wait_result = true}, exec_lua[[
+        start_time = get_time()
+
+        vim.defer_fn(function() vim.g.timer_result = true end, 100)
+        wait_result = vim.wait(10000, function() return vim.g.timer_result end)
+
+        return {
+          time = (start_time + 5) > get_time(),
+          wait_result = wait_result,
+        }
+      ]])
+    end)
+
+    it('should require functions to be passed', function()
+      local pcall_result = exec_lua [[
+        return {pcall(function() vim.wait(1000, 13) end)}
+      ]]
+
+      eq(pcall_result[1], false)
+      matches('condition must be a function', pcall_result[2])
+    end)
+
+    it('should not crash when callback errors', function()
+      local pcall_result = exec_lua [[
+        return {pcall(function() vim.wait(1000, function() error("As Expected") end) end)}
+      ]]
+
+      eq(pcall_result[1], false)
+      matches('As Expected', pcall_result[2])
+    end)
+
+    it('should call callbacks exactly once if they return true immediately', function()
+      eq(true, exec_lua [[
+        vim.g.wait_count = 0
+        vim.wait(1000, function()
+          vim.g.wait_count = vim.g.wait_count + 1
+          return true
+        end, 20)
+        return vim.g.wait_count == 1
+      ]])
+    end)
+
+    it('should call callbacks few times with large `interval`', function()
+      eq(true, exec_lua [[
+        vim.g.wait_count = 0
+        vim.wait(50, function() vim.g.wait_count = vim.g.wait_count + 1 end, 200)
+        return vim.g.wait_count < 5
+      ]])
+    end)
+
+    it('should call callbacks more times with small `interval`', function()
+      eq(true, exec_lua [[
+        vim.g.wait_count = 0
+        vim.wait(50, function() vim.g.wait_count = vim.g.wait_count + 1 end, 5)
+        return vim.g.wait_count > 5
+      ]])
+    end)
+
+    it('should play nice with `not` when fails', function()
+      eq(true, exec_lua [[
+        if not vim.wait(50, function() end) then
+          return true
+        end
+
+        return false
+      ]])
+    end)
+
+    it('should play nice with `if` when success', function()
+      eq(true, exec_lua [[
+        if vim.wait(50, function() return true end) then
+          return true
+        end
+
+        return false
+      ]])
+    end)
+
+    it('should return immediately with false if timeout is 0', function()
+      eq({false, -1}, exec_lua [[
+        return {
+          vim.wait(0, function() return false end)
+        }
+      ]])
+    end)
+
+    it('should work with tables with __call', function()
+      eq(true, exec_lua [[
+        local t = setmetatable({}, {__call = function(...) return true end})
+        return vim.wait(100, t, 10)
+      ]])
+    end)
+
+    it('should work with tables with __call that change', function()
+      eq(true, exec_lua [[
+        local t = {count = 0}
+        setmetatable(t, {
+          __call = function()
+            t.count = t.count + 1
+            return t.count > 3
+          end
+        })
+
+        return vim.wait(1000, t, 10)
+      ]])
+    end)
+
+    it('should not work with negative intervals', function()
+      local pcall_result = exec_lua [[
+        return pcall(function() vim.wait(1000, function() return false end, -1) end)
+      ]]
+
+      eq(false, pcall_result)
+    end)
+
+    it('should not work with weird intervals', function()
+      local pcall_result = exec_lua [[
+        return pcall(function() vim.wait(1000, function() return false end, 'a string value') end)
+      ]]
+
+      eq(false, pcall_result)
+    end)
   end)
+end)