Do not execute two or more setxkbmap commands in parallel.

chrome/browser/chromeos/input_method/xkeyboard.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chromeos/input_method/xkeyboard.h"
 
+#include <queue>
 #include <utility>
 
 #include <X11/XKBlib.h>
 #include <X11/Xlib.h>
 #include <glib.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "base/memory/singleton.h"
 #include "base/logging.h"
@@ skipping 229 matching lines @@
     // Turn off caps lock if there is no kCapsLockKey in the remapped keys.
     if (!ContainsModifierKeyAsReplacement(
             modifier_map, kCapsLockKey)) {
       SetCapsLockEnabled(false);
     }
 
     // TODO(yusukes): Revert to VLOG(1) when crosbug.com/15851 is resolved.
     LOG(WARNING) << (force ? "Reapply" : "Set")
                  << " layout: " << layouts_to_set;
 
-    ExecuteSetLayoutCommand(layouts_to_set);
+    execute_queue_.push(layouts_to_set);

[Daniel Kurtz, 2011/06/07 03:19:38]

Is layouts_to_set a collection or a single layout?
If just one, please rename to layout_to_set.

[Yusuke Sato, 2011/06/07 04:54:58]

Done.

+    if (execute_queue_.size() == 1) {

[satorux1, 2011/06/07 03:19:27]

Checking the size here looks a bit tricky. Maybe better to do this in
ExecuteSetLayoutCommand()?

[Yusuke Sato, 2011/06/07 04:54:58]

Modifed both this function and the callback. PTAL.

On 2011/06/07 03:19:27, satorux1 wrote:

+      ExecuteSetLayoutCommand(layouts_to_set);
+    }
     return true;
   }
 
   // Executes 'setxkbmap -layout ...' command asynchronously.
   // TODO(yusukes): Use libxkbfile.so instead of the command (crosbug.com/13105)
   void ExecuteSetLayoutCommand(const std::string& layouts_to_set) {
     std::vector<std::string> argv;
     base::file_handle_mapping_vector fds_to_remap;
     base::ProcessHandle handle = base::kNullProcessHandle;
 
     argv.push_back(kSetxkbmapCommand);
     argv.push_back("-layout");
     argv.push_back(layouts_to_set);
+    argv.push_back("-synch");
     const bool result = base::LaunchApp(argv,
                                         fds_to_remap,  // No remapping.
                                         false,  // Don't wait.
                                         &handle);
     if (!result) {
       LOG(ERROR) << "Failed to execute setxkbmap: " << layouts_to_set;
       return;
     }
 
     // g_child_watch_add is necessary to prevent the process from becoming a
     // zombie.
     const base::ProcessId pid = base::GetProcId(handle);
     g_child_watch_add(pid,
                       reinterpret_cast<GChildWatchFunc>(OnSetLayoutFinish),
                       this);
+    VLOG(1) << "ExecuteSetLayoutCommand: " << layouts_to_set << ": pid=" << pid;
   }
 
   static void OnSetLayoutFinish(GPid pid, gint status, XKeyboard* self) {
-    DLOG(INFO) << "OnSetLayoutFinish: pid=" << pid;
+    VLOG(1) << "OnSetLayoutFinish: pid=" << pid;
+    DCHECK(!self->execute_queue_.empty());
+    self->execute_queue_.pop();
+    if (!self->execute_queue_.empty()) {
+      self->ExecuteSetLayoutCommand(self->execute_queue_.front());
+    }
   }
 
   // The XKB layout name which we set last time like "us" and "us(dvorak)".
   std::string current_layout_name_;
   // The mapping of modifier keys we set last time.
   ModifierMap current_modifier_map_;
+  // A queue for executing setxkbmap one by one.
+  std::queue<std::string> execute_queue_;
 
   DISALLOW_COPY_AND_ASSIGN(XKeyboard);
 };
 
 }  // namespace
 
 std::string CreateFullXkbLayoutName(const std::string& layout_name,
                                     const ModifierMap& modifier_map) {
   static const char kValidLayoutNameCharacters[] =
       "abcdefghijklmnopqrstuvwxyz0123456789()-_";
@@ skipping 113 matching lines @@
 bool SetAutoRepeatEnabled(bool enabled) {
   return XKeyboard::GetInstance()->SetAutoRepeatEnabled(enabled);
 }
 
 bool SetAutoRepeatRate(const AutoRepeatRate& rate) {
   return XKeyboard::GetInstance()->SetAutoRepeatRate(rate);
 }
 
 }  // namespace input_method
 }  // namespace chromeos