Importing ThreadChecker class from Chromium

The ThreadChecker class is imported/re-implemented from Chromium.
The implementation is changed to depend on WebRTC primitives.

R=andrew@webrtc.org, henrike@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/21649004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@6446 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/base/thread_checker_unittest.cc b/base/thread_checker_unittest.cc
new file mode 100644
index 0000000..13c1da5
--- /dev/null
+++ b/base/thread_checker_unittest.cc
@@ -0,0 +1,205 @@
+/*
+ *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+// Borrowed from Chromium's src/base/threading/thread_checker_unittest.cc.
+
+#include <assert.h>
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/base/thread.h"
+#include "webrtc/base/thread_checker.h"
+#include "webrtc/base/scoped_ptr.h"
+
+// Duplicated from base/threading/thread_checker.h so that we can be
+// good citizens there and undef the macro.
+#if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
+#define ENABLE_THREAD_CHECKER 1
+#else
+#define ENABLE_THREAD_CHECKER 0
+#endif
+
+namespace rtc {
+
+namespace {
+
+// Simple class to exercise the basics of ThreadChecker.
+// Both the destructor and DoStuff should verify that they were
+// called on the same thread as the constructor.
+class ThreadCheckerClass : public ThreadChecker {
+ public:
+  ThreadCheckerClass() {}
+
+  // Verifies that it was called on the same thread as the constructor.
+  void DoStuff() {
+    assert(CalledOnValidThread());
+  }
+
+  void DetachFromThread() {
+    ThreadChecker::DetachFromThread();
+  }
+
+  static void MethodOnDifferentThreadImpl();
+  static void DetachThenCallFromDifferentThreadImpl();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ThreadCheckerClass);
+};
+
+// Calls ThreadCheckerClass::DoStuff on another thread.
+class CallDoStuffOnThread : public Thread {
+ public:
+  explicit CallDoStuffOnThread(ThreadCheckerClass* thread_checker_class)
+      : Thread(),
+        thread_checker_class_(thread_checker_class) {
+    SetName("call_do_stuff_on_thread", NULL);
+  }
+
+  virtual void Run() OVERRIDE {
+    thread_checker_class_->DoStuff();
+  }
+
+  // New method. Needed since Thread::Join is protected, and it is called by
+  // the TEST.
+  void Join() {
+    Thread::Join();
+  }
+
+ private:
+  ThreadCheckerClass* thread_checker_class_;
+
+  DISALLOW_COPY_AND_ASSIGN(CallDoStuffOnThread);
+};
+
+// Deletes ThreadCheckerClass on a different thread.
+class DeleteThreadCheckerClassOnThread : public Thread {
+ public:
+  explicit DeleteThreadCheckerClassOnThread(
+      ThreadCheckerClass* thread_checker_class)
+      : Thread(),
+        thread_checker_class_(thread_checker_class) {
+    SetName("delete_thread_checker_class_on_thread", NULL);
+  }
+
+  virtual void Run() OVERRIDE {
+    thread_checker_class_.reset();
+  }
+
+  // New method. Needed since Thread::Join is protected, and it is called by
+  // the TEST.
+  void Join() {
+    Thread::Join();
+  }
+
+ private:
+  scoped_ptr<ThreadCheckerClass> thread_checker_class_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeleteThreadCheckerClassOnThread);
+};
+
+}  // namespace
+
+TEST(ThreadCheckerTest, CallsAllowedOnSameThread) {
+  scoped_ptr<ThreadCheckerClass> thread_checker_class(
+      new ThreadCheckerClass);
+
+  // Verify that DoStuff doesn't assert.
+  thread_checker_class->DoStuff();
+
+  // Verify that the destructor doesn't assert.
+  thread_checker_class.reset();
+}
+
+TEST(ThreadCheckerTest, DestructorAllowedOnDifferentThread) {
+  scoped_ptr<ThreadCheckerClass> thread_checker_class(
+      new ThreadCheckerClass);
+
+  // Verify that the destructor doesn't assert
+  // when called on a different thread.
+  DeleteThreadCheckerClassOnThread delete_on_thread(
+      thread_checker_class.release());
+
+  delete_on_thread.Start();
+  delete_on_thread.Join();
+}
+
+TEST(ThreadCheckerTest, DetachFromThread) {
+  scoped_ptr<ThreadCheckerClass> thread_checker_class(
+      new ThreadCheckerClass);
+
+  // Verify that DoStuff doesn't assert when called on a different thread after
+  // a call to DetachFromThread.
+  thread_checker_class->DetachFromThread();
+  CallDoStuffOnThread call_on_thread(thread_checker_class.get());
+
+  call_on_thread.Start();
+  call_on_thread.Join();
+}
+
+#if GTEST_HAS_DEATH_TEST || !ENABLE_THREAD_CHECKER
+
+void ThreadCheckerClass::MethodOnDifferentThreadImpl() {
+  scoped_ptr<ThreadCheckerClass> thread_checker_class(
+      new ThreadCheckerClass);
+
+  // DoStuff should assert in debug builds only when called on a
+  // different thread.
+  CallDoStuffOnThread call_on_thread(thread_checker_class.get());
+
+  call_on_thread.Start();
+  call_on_thread.Join();
+}
+
+#if ENABLE_THREAD_CHECKER
+TEST(ThreadCheckerDeathTest, MethodNotAllowedOnDifferentThreadInDebug) {
+  ASSERT_DEATH({
+      ThreadCheckerClass::MethodOnDifferentThreadImpl();
+    }, "");
+}
+#else
+TEST(ThreadCheckerTest, MethodAllowedOnDifferentThreadInRelease) {
+  ThreadCheckerClass::MethodOnDifferentThreadImpl();
+}
+#endif  // ENABLE_THREAD_CHECKER
+
+void ThreadCheckerClass::DetachThenCallFromDifferentThreadImpl() {
+  scoped_ptr<ThreadCheckerClass> thread_checker_class(
+      new ThreadCheckerClass);
+
+  // DoStuff doesn't assert when called on a different thread
+  // after a call to DetachFromThread.
+  thread_checker_class->DetachFromThread();
+  CallDoStuffOnThread call_on_thread(thread_checker_class.get());
+
+  call_on_thread.Start();
+  call_on_thread.Join();
+
+  // DoStuff should assert in debug builds only after moving to
+  // another thread.
+  thread_checker_class->DoStuff();
+}
+
+#if ENABLE_THREAD_CHECKER
+TEST(ThreadCheckerDeathTest, DetachFromThreadInDebug) {
+  ASSERT_DEATH({
+    ThreadCheckerClass::DetachThenCallFromDifferentThreadImpl();
+    }, "");
+}
+#else
+TEST(ThreadCheckerTest, DetachFromThreadInRelease) {
+  ThreadCheckerClass::DetachThenCallFromDifferentThreadImpl();
+}
+#endif  // ENABLE_THREAD_CHECKER
+
+#endif  // GTEST_HAS_DEATH_TEST || !ENABLE_THREAD_CHECKER
+
+// Just in case we ever get lumped together with other compilation units.
+#undef ENABLE_THREAD_CHECKER
+
+}  // namespace rtc