diff --git a/autoload/langserver/lock.vim b/autoload/langserver/lock.vim
new file mode 100644
index 0000000..83c6cdb
--- /dev/null
+++ b/autoload/langserver/lock.vim
@@ -0,0 +1,16 @@
+
+function! s:dict_lock() dict
+  let self.locked = v:true
+endfunction
+
+function! s:dict_unlock() dict
+  let self.locked = v:false
+endfunction
+
+function! langserver#lock#semaphore() abort
+  let l:ret = {}
+  let l:ret.locked = v:false
+  let l:ret.lock = function('s:dict_lock')
+  let l:ret.unlock = function('s:dict_unlock')
+  return l:ret
+endfunction
diff --git a/tests/test_lock.vader b/tests/test_lock.vader
new file mode 100644
index 0000000..b6cdad1
--- /dev/null
+++ b/tests/test_lock.vader
@@ -0,0 +1,10 @@
+Execute (Test Lock):
+  let my_lock = langserver#lock#semaphore()
+
+  AssertEqual v:false, my_lock.locked
+
+  call my_lock.lock()
+  AssertEqual v:true, my_lock.locked
+
+  call my_lock.unlock()
+  AssertEqual v:false, my_lock.locked