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@6446 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/base/base.gyp

@@ -268,6 +268,9 @@
         'testclient.h',
         'thread.cc',
         'thread.h',
+        'thread_checker.h',
+        'thread_checker_impl.cc',
+        'thread_checker_impl.h',
         'timeutils.cc',
         'timeutils.h',
         'timing.cc',

webrtc/base/base_tests.gyp

@@ -96,6 +96,7 @@
         # 'systeminfo_unittest.cc',
         'task_unittest.cc',
         'testclient_unittest.cc',
+        'thread_checker_unittest.cc',
         'thread_unittest.cc',
         'timeutils_unittest.cc',
         'urlencode_unittest.cc',

webrtc/base/thread_checker.h

@@ -0,0 +1,91 @@
+/*
+ *  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.h.
+
+#ifndef WEBRTC_BASE_THREAD_CHECKER_H_
+#define WEBRTC_BASE_THREAD_CHECKER_H_
+
+// Apart from debug builds, we also enable the thread checker in
+// builds with DCHECK_ALWAYS_ON so that trybots and waterfall bots
+// with this define will get the same level of thread checking as
+// debug bots.
+//
+// Note that this does not perfectly match situations where DCHECK is
+// enabled.  For example a non-official release build may have
+// DCHECK_ALWAYS_ON undefined (and therefore ThreadChecker would be
+// disabled) but have DCHECKs enabled at runtime.
+#if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
+#define ENABLE_THREAD_CHECKER 1
+#else
+#define ENABLE_THREAD_CHECKER 0
+#endif
+
+#include "webrtc/base/thread_checker_impl.h"
+
+namespace rtc {
+
+// Do nothing implementation, for use in release mode.
+//
+// Note: You should almost always use the ThreadChecker class to get the
+// right version for your build configuration.
+class ThreadCheckerDoNothing {
+ public:
+  bool CalledOnValidThread() const {
+    return true;
+  }
+
+  void DetachFromThread() {}
+};
+
+// ThreadChecker is a helper class used to help verify that some methods of a
+// class are called from the same thread. It provides identical functionality to
+// base::NonThreadSafe, but it is meant to be held as a member variable, rather
+// than inherited from base::NonThreadSafe.
+//
+// While inheriting from base::NonThreadSafe may give a clear indication about
+// the thread-safety of a class, it may also lead to violations of the style
+// guide with regard to multiple inheritance. The choice between having a
+// ThreadChecker member and inheriting from base::NonThreadSafe should be based
+// on whether:
+//  - Derived classes need to know the thread they belong to, as opposed to
+//    having that functionality fully encapsulated in the base class.
+//  - Derived classes should be able to reassign the base class to another
+//    thread, via DetachFromThread.
+//
+// If neither of these are true, then having a ThreadChecker member and calling
+// CalledOnValidThread is the preferable solution.
+//
+// Example:
+// class MyClass {
+//  public:
+//   void Foo() {
+//     DCHECK(thread_checker_.CalledOnValidThread());
+//     ... (do stuff) ...
+//   }
+//
+//  private:
+//   ThreadChecker thread_checker_;
+// }
+//
+// In Release mode, CalledOnValidThread will always return true.
+#if ENABLE_THREAD_CHECKER
+class ThreadChecker : public ThreadCheckerImpl {
+};
+#else
+class ThreadChecker : public ThreadCheckerDoNothing {
+};
+#endif  // ENABLE_THREAD_CHECKER
+
+#undef ENABLE_THREAD_CHECKER
+
+}  // namespace rtc
+
+#endif  // WEBRTC_BASE_THREAD_CHECKER_H_

webrtc/base/thread_checker_impl.cc

@@ -0,0 +1,44 @@
+/*
+ *  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_impl.cc.
+
+#include "webrtc/base/thread_checker_impl.h"
+
+#include "webrtc/base/thread.h"
+
+namespace rtc {
+
+ThreadCheckerImpl::ThreadCheckerImpl()
+    : valid_thread_() {
+  EnsureThreadIdAssigned();
+}
+
+ThreadCheckerImpl::~ThreadCheckerImpl() {
+}
+
+bool ThreadCheckerImpl::CalledOnValidThread() const {
+  CritScope scoped_lock(&lock_);
+  EnsureThreadIdAssigned();
+  return valid_thread_->IsCurrent();
+}
+
+void ThreadCheckerImpl::DetachFromThread() {
+  CritScope scoped_lock(&lock_);
+  valid_thread_ = NULL;
+}
+
+void ThreadCheckerImpl::EnsureThreadIdAssigned() const {
+  if (!valid_thread_) {
+    valid_thread_ = Thread::Current();
+  }
+}
+
+}  // namespace rtc

webrtc/base/thread_checker_impl.h

@@ -0,0 +1,51 @@
+/*
+ *  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_impl.h.
+
+#ifndef WEBRTC_BASE_THREAD_CHECKER_IMPL_H_
+#define WEBRTC_BASE_THREAD_CHECKER_IMPL_H_
+
+#include "webrtc/base/criticalsection.h"
+
+namespace rtc {
+
+class Thread;
+
+// Real implementation of ThreadChecker, for use in debug mode, or
+// for temporary use in release mode (e.g. to CHECK on a threading issue
+// seen only in the wild).
+//
+// Note: You should almost always use the ThreadChecker class to get the
+// right version for your build configuration.
+class ThreadCheckerImpl {
+ public:
+  ThreadCheckerImpl();
+  ~ThreadCheckerImpl();
+
+  bool CalledOnValidThread() const;
+
+  // Changes the thread that is checked for in CalledOnValidThread.  This may
+  // be useful when an object may be created on one thread and then used
+  // exclusively on another thread.
+  void DetachFromThread();
+
+ private:
+  void EnsureThreadIdAssigned() const;
+
+  mutable CriticalSection lock_;
+  // This is mutable so that CalledOnValidThread can set it.
+  // It's guarded by |lock_|.
+  mutable const Thread* valid_thread_;
+};
+
+}  // namespace rtc
+
+#endif  // WEBRTC_BASE_THREAD_CHECKER_IMPL_H_

webrtc/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