base::Bind: Implement CancelableCallback to replace CancelableTask.

Designed by groby,binji,csilv,jhawkins.

BUG=96749
TEST=CancelableCallbackTest.*

R=ajwong@chromium.org,darin@chromium.org

Review URL: http://codereview.chromium.org/8673008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@111493 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 182 insertions, 0 deletions

diff --git a/base/cancelable_callback_unittest.cc b/base/cancelable_callback_unittest.cc
new file mode 100644
index 0000000..980359b
--- /dev/null
+++ b/base/cancelable_callback_unittest.cc
@@ -0,0 +1,182 @@
+// Copyright (c) 2011 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/cancelable_callback.h"
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/memory/ref_counted.h"
+#include "base/message_loop.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace {
+
+class TestRefCounted : public RefCountedThreadSafe<TestRefCounted> {
+ private:
+  friend class RefCountedThreadSafe<TestRefCounted>;
+  ~TestRefCounted() {};
+};
+
+void Increment(int* count) { (*count)++; }
+void IncrementBy(int* count, int n) { (*count) += n; }
+void RefCountedParam(const scoped_refptr<TestRefCounted>& ref_counted) {}
+
+// Cancel().
+//  - Callback can be run multiple times.
+//  - After Cancel(), Run() completes but has no effect.
+TEST(CancelableCallbackTest, Cancel) {
+  int count = 0;
+  CancelableCallback cancelable(
+      base::Bind(&Increment, base::Unretained(&count)));
+
+  base::Closure callback = cancelable.callback();
+  callback.Run();
+  EXPECT_EQ(1, count);
+
+  callback.Run();
+  EXPECT_EQ(2, count);
+
+  cancelable.Cancel();
+  callback.Run();
+  EXPECT_EQ(2, count);
+}
+
+// Cancel() called multiple times.
+//  - Cancel() cancels all copies of the wrapped callback.
+TEST(CancelableCallbackTest, MultipleCancel) {
+  int count = 0;
+  CancelableCallback cancelable(
+      base::Bind(&Increment, base::Unretained(&count)));
+
+  base::Closure callback1 = cancelable.callback();
+  cancelable.Cancel();
+
+  callback1.Run();
+  EXPECT_EQ(0, count);
+
+  base::Closure callback2 = cancelable.callback();
+  callback2.Run();
+  EXPECT_EQ(0, count);
+
+  // Cancel() should have no effect, but callback() is still runnable.
+  base::Closure callback3 = cancelable.callback();
+  cancelable.Cancel();
+  callback3.Run();
+  EXPECT_EQ(0, count);
+}
+
+// CancelableCallback destroyed before callback is run.
+//  - Destruction of CancelableCallback cancels outstanding callbacks.
+TEST(CancelableCallbackTest, CallbackCanceledOnDestruction) {
+  int count = 0;
+  base::Closure callback;
+
+  {
+    CancelableCallback cancelable(
+        base::Bind(&Increment, base::Unretained(&count)));
+
+    callback = cancelable.callback();
+    callback.Run();
+    EXPECT_EQ(1, count);
+  }
+
+  callback.Run();
+  EXPECT_EQ(1, count);
+}
+
+// Cancel() called on bound closure with a RefCounted parameter.
+//  - Cancel drops wrapped callback (and, implicitly, its bound arguments).
+TEST(CancelableCallbackTest, CancelDropsCallback) {
+  scoped_refptr<TestRefCounted> ref_counted = new TestRefCounted;
+  EXPECT_TRUE(ref_counted->HasOneRef());
+
+  CancelableCallback cancelable(base::Bind(RefCountedParam, ref_counted));
+  EXPECT_FALSE(cancelable.IsCancelled());
+  EXPECT_TRUE(ref_counted.get());
+  EXPECT_FALSE(ref_counted->HasOneRef());
+
+  // There is only one reference to |ref_counted| after the Cancel().
+  cancelable.Cancel();
+  EXPECT_TRUE(cancelable.IsCancelled());
+  EXPECT_TRUE(ref_counted.get());
+  EXPECT_TRUE(ref_counted->HasOneRef());
+}
+
+// Reset().
+//  - Reset() replaces the existing wrapped callback with a new callback.
+//  - Reset() deactivates outstanding callbacks.
+TEST(CancelableCallbackTest, Reset) {
+  int count = 0;
+  CancelableCallback cancelable(
+      base::Bind(&Increment, base::Unretained(&count)));
+
+  base::Closure callback = cancelable.callback();
+  callback.Run();
+  EXPECT_EQ(1, count);
+
+  callback.Run();
+  EXPECT_EQ(2, count);
+
+  cancelable.Reset(
+      base::Bind(&IncrementBy, base::Unretained(&count), 3));
+  EXPECT_FALSE(cancelable.IsCancelled());
+
+  // The stale copy of the cancelable callback is non-null.
+  ASSERT_FALSE(callback.is_null());
+
+  // The stale copy of the cancelable callback is no longer active.
+  callback.Run();
+  EXPECT_EQ(2, count);
+
+  base::Closure callback2 = cancelable.callback();
+  ASSERT_FALSE(callback2.is_null());
+
+  callback2.Run();
+  EXPECT_EQ(5, count);
+}
+
+// IsCanceled().
+//  - Cancel() transforms the CancelableCallback into a cancelled state.
+TEST(CancelableCallbackTest, IsNull) {
+  CancelableCallback cancelable;
+  EXPECT_TRUE(cancelable.IsCancelled());
+
+  int count = 0;
+  cancelable.Reset(base::Bind(&Increment,
+                              base::Unretained(&count)));
+  EXPECT_FALSE(cancelable.IsCancelled());
+
+  cancelable.Cancel();
+  EXPECT_TRUE(cancelable.IsCancelled());
+}
+
+// CancelableCallback posted to a MessageLoop with PostTask.
+//  - Callbacks posted to a MessageLoop can be cancelled.
+TEST(CancelableCallbackTest, PostTask) {
+  MessageLoop loop(MessageLoop::TYPE_DEFAULT);
+
+  int count = 0;
+  CancelableCallback cancelable(base::Bind(&Increment,
+                                           base::Unretained(&count)));
+
+  MessageLoop::current()->PostTask(FROM_HERE, cancelable.callback());
+  MessageLoop::current()->PostTask(FROM_HERE, MessageLoop::QuitClosure());
+  MessageLoop::current()->Run();
+
+  EXPECT_EQ(1, count);
+
+  MessageLoop::current()->PostTask(FROM_HERE, cancelable.callback());
+  MessageLoop::current()->PostTask(FROM_HERE, MessageLoop::QuitClosure());
+
+  // Cancel before running the message loop.
+  cancelable.Cancel();
+  MessageLoop::current()->Run();
+
+  // Callback never ran due to cancellation; count is the same.
+  EXPECT_EQ(1, count);
+}
+
+}  // namespace
+}  // namespace base