Move non_thread_safe from base to base/threading and into the base namespace.

TEST=it compiles
BUG=none
Review URL: http://codereview.chromium.org/6005010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@70351 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 222 insertions, 0 deletions

diff --git a/base/threading/non_thread_safe.cc b/base/threading/non_thread_safe.cc
new file mode 100644
index 0000000..8b41bc0
--- /dev/null
+++ b/base/threading/non_thread_safe.cc
@@ -0,0 +1,28 @@
+// Copyright (c) 2010 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 "base/threading/non_thread_safe.h"
+
+// These checks are only done in debug builds.
+#ifndef NDEBUG
+
+#include "base/logging.h"
+
+namespace base {
+
+NonThreadSafe::~NonThreadSafe() {
+  DCHECK(CalledOnValidThread());
+}
+
+bool NonThreadSafe::CalledOnValidThread() const {
+  return thread_checker_.CalledOnValidThread();
+}
+
+void NonThreadSafe::DetachFromThread() {
+  thread_checker_.DetachFromThread();
+}
+
+}  // namespace base
+
+#endif  // NDEBUG
diff --git a/base/threading/non_thread_safe.h b/base/threading/non_thread_safe.h
new file mode 100644
index 0000000..868a031
--- /dev/null
+++ b/base/threading/non_thread_safe.h
@@ -0,0 +1,64 @@
+// Copyright (c) 2010 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.
+
+#ifndef BASE_THREADING_NON_THREAD_SAFE_H_
+#define BASE_THREADING_NON_THREAD_SAFE_H_
+#pragma once
+
+#include "base/threading/thread_checker.h"
+
+namespace base {
+
+// A helper class used to help verify that methods of a class are
+// called from the same thread.  One can inherit from this class and use
+// CalledOnValidThread() to verify.
+//
+// This is intended to be used with classes that appear to be thread safe, but
+// aren't.  For example, a service or a singleton like the preferences system.
+//
+// Example:
+// class MyClass : public base::NonThreadSafe {
+//  public:
+//   void Foo() {
+//     DCHECK(CalledOnValidThread());
+//     ... (do stuff) ...
+//   }
+// }
+//
+// In Release mode, CalledOnValidThread will always return true.
+//
+#ifndef NDEBUG
+class NonThreadSafe {
+ public:
+  ~NonThreadSafe();
+
+  bool CalledOnValidThread() const;
+
+ protected:
+  // Changes the thread that is checked for in CalledOnValidThread. The next
+  // call to CalledOnValidThread will attach this class to a new thread. It is
+  // up to the NonThreadSafe derived class to decide to expose this or not.
+  // This may be useful when an object may be created on one thread and then
+  // used exclusively on another thread.
+  void DetachFromThread();
+
+ private:
+  ThreadChecker thread_checker_;
+};
+#else
+// Do nothing in release mode.
+class NonThreadSafe {
+ public:
+  bool CalledOnValidThread() const {
+    return true;
+  }
+
+ protected:
+  void DetachFromThread() {}
+};
+#endif  // NDEBUG
+
+}  // namespace base
+
+#endif  // BASE_NON_THREAD_SAFE_H_
diff --git a/base/threading/non_thread_safe_unittest.cc b/base/threading/non_thread_safe_unittest.cc
new file mode 100644
index 0000000..7d158cf
--- /dev/null
+++ b/base/threading/non_thread_safe_unittest.cc
@@ -0,0 +1,130 @@
+// Copyright (c) 2010 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 "base/basictypes.h"
+#include "base/logging.h"
+#include "base/scoped_ptr.h"
+#include "base/threading/non_thread_safe.h"
+#include "base/threading/simple_thread.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+#ifndef NDEBUG
+
+namespace base {
+
+// Simple class to exersice the basics of NonThreadSafe.
+// Both the destructor and DoStuff should verify that they were
+// called on the same thread as the constructor.
+class NonThreadSafeClass : public NonThreadSafe {
+ public:
+  NonThreadSafeClass() {}
+
+  // Verifies that it was called on the same thread as the constructor.
+  void DoStuff() {
+    DCHECK(CalledOnValidThread());
+  }
+
+  void DetachFromThread() {
+    NonThreadSafe::DetachFromThread();
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(NonThreadSafeClass);
+};
+
+// Calls NonThreadSafeClass::DoStuff on another thread.
+class CallDoStuffOnThread : public SimpleThread {
+ public:
+  CallDoStuffOnThread(NonThreadSafeClass* non_thread_safe_class)
+      : SimpleThread("call_do_stuff_on_thread"),
+        non_thread_safe_class_(non_thread_safe_class) {
+  }
+
+  virtual void Run() {
+    non_thread_safe_class_->DoStuff();
+  }
+
+ private:
+  NonThreadSafeClass* non_thread_safe_class_;
+
+  DISALLOW_COPY_AND_ASSIGN(CallDoStuffOnThread);
+};
+
+// Deletes NonThreadSafeClass on a different thread.
+class DeleteNonThreadSafeClassOnThread : public SimpleThread {
+ public:
+  DeleteNonThreadSafeClassOnThread(NonThreadSafeClass* non_thread_safe_class)
+      : SimpleThread("delete_non_thread_safe_class_on_thread"),
+        non_thread_safe_class_(non_thread_safe_class) {
+  }
+
+  virtual void Run() {
+    non_thread_safe_class_.reset();
+  }
+
+ private:
+  scoped_ptr<NonThreadSafeClass> non_thread_safe_class_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeleteNonThreadSafeClassOnThread);
+};
+
+TEST(NonThreadSafeTest, CallsAllowedOnSameThread) {
+  scoped_ptr<NonThreadSafeClass> non_thread_safe_class(
+      new NonThreadSafeClass);
+
+  // Verify that DoStuff doesn't assert.
+  non_thread_safe_class->DoStuff();
+
+  // Verify that the destructor doesn't assert.
+  non_thread_safe_class.reset();
+}
+
+TEST(NonThreadSafeTest, DetachThenDestructOnDifferentThread) {
+  scoped_ptr<NonThreadSafeClass> non_thread_safe_class(
+      new NonThreadSafeClass);
+
+  // Verify that the destructor doesn't assert when called on a different thread
+  // after a detach.
+  non_thread_safe_class->DetachFromThread();
+  DeleteNonThreadSafeClassOnThread delete_on_thread(
+      non_thread_safe_class.release());
+
+  delete_on_thread.Start();
+  delete_on_thread.Join();
+}
+
+#if GTEST_HAS_DEATH_TEST
+
+TEST(NonThreadSafeDeathTest, MethodNotAllowedOnDifferentThread) {
+  ASSERT_DEBUG_DEATH({
+      scoped_ptr<NonThreadSafeClass> non_thread_safe_class(
+          new NonThreadSafeClass);
+
+      // Verify that DoStuff asserts when called on a different thread.
+      CallDoStuffOnThread call_on_thread(non_thread_safe_class.get());
+
+      call_on_thread.Start();
+      call_on_thread.Join();
+    }, "");
+}
+
+TEST(NonThreadSafeDeathTest, DestructorNotAllowedOnDifferentThread) {
+  ASSERT_DEBUG_DEATH({
+      scoped_ptr<NonThreadSafeClass> non_thread_safe_class(
+          new NonThreadSafeClass);
+
+      // Verify that the destructor asserts when called on a different thread.
+      DeleteNonThreadSafeClassOnThread delete_on_thread(
+          non_thread_safe_class.release());
+
+      delete_on_thread.Start();
+      delete_on_thread.Join();
+    }, "");
+}
+
+#endif  // GTEST_HAS_DEATH_TEST
+
+}  // namespace base
+
+#endif  // NDEBUG