1 files changed, 65 insertions, 0 deletions
diff --git a/clang-tools-extra/unittests/clangd/ThreadingTests.cpp b/clang-tools-extra/unittests/clangd/ThreadingTests.cpp
new file mode 100644
index 00000000000..84e6512fe43
--- /dev/null
+++ b/clang-tools-extra/unittests/clangd/ThreadingTests.cpp
@@ -0,0 +1,65 @@
+//===-- ThreadingTests.cpp --------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Threading.h"
+#include "gtest/gtest.h"
+#include <mutex>
+
+namespace clang {
+namespace clangd {
+class ThreadingTest : public ::testing::Test {};
+
+TEST_F(ThreadingTest, TaskRunner) {
+  const int TasksCnt = 100;
+  // This should be const, but MSVC does not allow to use const vars in lambdas
+  // without capture. On the other hand, clang gives a warning that capture of
+  // const var is not required.
+  // Making it non-const makes both compilers happy.
+  int IncrementsPerTask = 1000;
+
+  std::mutex Mutex;
+  int Counter(0); /* GUARDED_BY(Mutex) */
+  {
+    AsyncTaskRunner Tasks;
+    auto scheduleIncrements = [&]() {
+      for (int TaskI = 0; TaskI < TasksCnt; ++TaskI) {
+        Tasks.runAsync([&Counter, &Mutex, IncrementsPerTask]() {
+          for (int Increment = 0; Increment < IncrementsPerTask; ++Increment) {
+            std::lock_guard<std::mutex> Lock(Mutex);
+            ++Counter;
+          }
+        });
+      }
+    };
+
+    {
+      // Make sure runAsync is not running tasks synchronously on the same
+      // thread by locking the Mutex used for increments.
+      std::lock_guard<std::mutex> Lock(Mutex);
+      scheduleIncrements();
+    }
+
+    Tasks.waitForAll();
+    {
+      std::lock_guard<std::mutex> Lock(Mutex);
+      ASSERT_EQ(Counter, TasksCnt * IncrementsPerTask);
+    }
+
+    {
+      std::lock_guard<std::mutex> Lock(Mutex);
+      Counter = 0;
+      scheduleIncrements();
+    }
+  }
+  // Check that destructor has waited for tasks to finish.
+  std::lock_guard<std::mutex> Lock(Mutex);
+  ASSERT_EQ(Counter, TasksCnt * IncrementsPerTask);
+}
+} // namespace clangd
+} // namespace clang