Add a CallbackRegistry class to base/ to manage callbacks

base/callback_list_unittest.cc

+// Copyright 2013 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/callback_list.h"
+
+#include <vector>
+
+#include "base/bind_helpers.h"
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace {
+
+typedef base::Callback<void(void)> TestCallback;

[awong, 2013/08/29 19:30:48]

TestCallback here is just a Closure. Why not use base::Closure?

[Cait (Slow), 2013/08/30 00:28:02]

Done.

+typedef CallbackList TestCallbackList;
+
+typedef base::Callback<void(const int&)> OneParamCallback;
+typedef CallbackListWithDetails<int> TestCallbackListWithParam;
+
+class Listener {
+ public:
+  explicit Listener() : total(0), scaler_(1) {}
+  Listener(int scaler) : total(0), scaler_(scaler) {}
+  virtual ~Listener() {}
+  virtual void OnEvent() {

[awong, 2013/08/29 19:30:48]

Naming the function with what their action is, rather than what they handle is
easier to read.  So

void IncrementTotal()
void MutiplyTotal(const int& x)

or similar.

[Cait (Slow), 2013/08/30 00:28:02]

Done.

+    total++;
+  }
+  virtual void OnEventWithParam(const int& x) {
+    total += x * scaler_;
+  }
+  int total;
+ private:
+  int scaler_;
+};
+
+class Remover : public Listener {

[awong, 2013/08/29 19:30:48]

Is there a reason for the inheritance?

If it'st just to pick up the total, I think it'd be better to avoid the
implementation inheritance.

[Cait (Slow), 2013/08/30 00:28:02]

Done.

+ public:
+  explicit Remover() : removal_cb_(base::Closure()) {}
+  virtual ~Remover() {}
+  virtual void OnEvent() OVERRIDE {
+    Listener::OnEvent();
+    removal_cb_.Run();
+  }
+  virtual void SetCallback(const base::Closure& cb) {
+    removal_cb_ = cb;
+  }
+
+ private:
+  base::Closure removal_cb_;
+};
+
+class Adder : public Listener {
+ public:
+  explicit Adder(TestCallbackList* cb_list)
+      : added(false),
+        cb_list_(cb_list) {}
+  virtual ~Adder() {}
+  virtual void OnAddedEvent() {
+    if (!added) {
+      added = true;
+      cb_list_->Add(
+          base::Bind(&Adder::OnEvent, base::Unretained(this)));
+    }
+  }
+  bool added;

[awong, 2013/08/29 19:30:48]

Should be added_

[Cait (Slow), 2013/08/30 00:28:02]

Done.

+
+ private:
+  TestCallbackList* cb_list_;
+};
+
+class Clearer : public Listener {
+ public:
+  explicit Clearer(TestCallbackList* cb_list)
+      : added(false),
+        cb_list_(cb_list) {}
+  virtual ~Clearer() {}
+  virtual void OnClearAndAddEvent() {
+    cb_list_->Clear();
+    cb_list_->Add(
+        base::Bind(&Clearer::OnEvent, base::Unretained(this)));
+    added = true;
+  }
+  bool added;

[awong, 2013/08/29 19:30:48]

nit: added -> added_

[Cait (Slow), 2013/08/30 00:28:02]

Done.

+
+ private:
+  TestCallbackList* cb_list_;
+};
+
+class ListDestructor {
+ public:
+  explicit ListDestructor(TestCallbackList* cb_list)
+      : cb_list_(cb_list) {}
+  virtual ~ListDestructor() {}
+  virtual void OnEvent() {
+    cb_list_->Clear();
+    delete cb_list_;
+  }
+
+ private:
+  TestCallbackList* cb_list_;
+};
+
+TEST(CallbackListTest, BasicTest) {

[awong, 2013/08/29 19:30:48]

Can you add a comment listing the invariants being asserted by this test?  Look
at comments above the TEST_Fs in base/bind_unittests.cc for examples.

+  TestCallbackList cb_list(TestCallbackList::NOTIFY_ALL);
+  Listener a, b, c;
+  TestCallback a_cb = base::Bind(&Listener::OnEvent, base::Unretained(&a));
+  TestCallback b_cb = base::Bind(&Listener::OnEvent, base::Unretained(&b));
+
+  base::Closure remove_a = cb_list.Add(a_cb);
+  base::Closure remove_b = cb_list.Add(b_cb);
+
+  EXPECT_FALSE(remove_a.is_null());
+  EXPECT_FALSE(remove_b.is_null());
+
+  cb_list.Run();
+
+  EXPECT_EQ(1, a.total);
+  EXPECT_EQ(1, b.total);
+
+  remove_b.Run();
+
+  base::Closure remove_c = cb_list.Add(
+      base::Bind(&Listener::OnEvent, base::Unretained(&c)));
+
+  cb_list.Run();
+
+  EXPECT_EQ(2, a.total);
+  EXPECT_EQ(1, b.total);
+  EXPECT_EQ(1, c.total);
+
+  {
+    scoped_ptr<ScopedClosureRunner> r1;
+    r1.reset(new ScopedClosureRunner(remove_a));
+  }
+
+  //remove_a.Run();

[awong, 2013/08/29 19:30:48]

is this supposed to be commented out?

[Cait (Slow), 2013/08/30 00:28:02]

Done.

+  remove_b.Run();
+  remove_c.Run();
+
+  EXPECT_FALSE(cb_list.might_have_callbacks());
+}
+
+TEST(CallbackListTest, BasicTestWithParams) {
+  TestCallbackListWithParam cb_list(TestCallbackListWithParam::NOTIFY_ALL);
+  Listener a(1), b(-1), c(1);
+  OneParamCallback a_cb =
+      base::Bind(&Listener::OnEventWithParam, base::Unretained(&a));
+
+  OneParamCallback b_cb =
+      base::Bind(&Listener::OnEventWithParam, base::Unretained(&b));
+
+  base::Closure remove_a = cb_list.Add(a_cb);
+

[awong, 2013/08/29 19:30:48]

this newline seems inconsistent with how the previous test was written. remove?

[Cait (Slow), 2013/08/30 00:28:02]

Done.

+  base::Closure remove_b = cb_list.Add(b_cb);
+
+  EXPECT_FALSE(remove_a.is_null());
+  EXPECT_FALSE(remove_b.is_null());
+
+  cb_list.Run(10);
+
+  EXPECT_EQ(10, a.total);
+  EXPECT_EQ(-10, b.total);
+
+  remove_b.Run();
+
+  base::Closure remove_c = cb_list.Add(
+      base::Bind(&Listener::OnEventWithParam, base::Unretained(&c)));
+
+  cb_list.Run(10);
+
+  EXPECT_EQ(20, a.total);
+  EXPECT_EQ(-10, b.total);
+  EXPECT_EQ(10, c.total);
+
+  remove_a.Run();
+  remove_b.Run();
+  remove_c.Run();
+
+  EXPECT_FALSE(cb_list.might_have_callbacks());
+}
+
+TEST(CallbackListTest, RemoveCallbacksDuringIteration) {
+  TestCallbackList cb_list(TestCallbackList::NOTIFY_ALL);
+  Listener a, b;
+  Remover remover_1, remover_2;
+
+  base::Closure remover_1_cb = cb_list.Add(
+      base::Bind(&Remover::OnEvent, base::Unretained(&remover_1)));
+  base::Closure remover_2_cb = cb_list.Add(
+      base::Bind(&Remover::OnEvent, base::Unretained(&remover_2)));
+  base::Closure a_cb = cb_list.Add(
+      base::Bind(&Listener::OnEvent, base::Unretained(&a)));
+  base::Closure b_cb = cb_list.Add(
+      base::Bind(&Listener::OnEvent, base::Unretained(&b)));
+
+  // |remover_1| will remove itself.
+  remover_1.SetCallback(remover_1_cb);
+  // |remover_2| will remove a.
+  remover_2.SetCallback(a_cb);
+
+  cb_list.Run();
+
+  // |remover_1| runs once (and removes itself), |remover_2| runs once (and
+  // removes a), |a| never runs, and |b| runs once.
+  EXPECT_EQ(1, remover_1.total);
+  EXPECT_EQ(1, remover_2.total);
+  EXPECT_EQ(0, a.total);
+  EXPECT_EQ(1, b.total);
+
+  cb_list.Run();
+
+  // Only |remover_2| and |b| run this time.
+  EXPECT_EQ(1, remover_1.total);
+  EXPECT_EQ(2, remover_2.total);
+  EXPECT_EQ(0, a.total);
+  EXPECT_EQ(2, b.total);
+
+  EXPECT_TRUE(cb_list.might_have_callbacks());
+
+  remover_2_cb.Run();
+  b_cb.Run();
+
+  EXPECT_FALSE(cb_list.might_have_callbacks());
+}
+
+TEST(CallbackListTest, AddCallbacksDuringIteration) {
+  TestCallbackList cb_list(TestCallbackList::NOTIFY_ALL);
+  Adder a(&cb_list);
+  Listener b;
+  cb_list.Add(
+      base::Bind(&Adder::OnAddedEvent, base::Unretained(&a)));
+  cb_list.Add(
+      base::Bind(&Listener::OnEvent, base::Unretained(&b)));
+
+  cb_list.Run();
+
+  EXPECT_EQ(1, a.total);
+  EXPECT_EQ(1, b.total);
+  EXPECT_TRUE(a.added);
+
+  cb_list.Run();
+
+  EXPECT_EQ(2, a.total);
+  EXPECT_EQ(2, b.total);
+
+  cb_list.Clear();
+}
+
+TEST(CallbackListTest, AddCallbacksDuringIteration_Existing) {
+  TestCallbackList cb_list(TestCallbackList::NOTIFY_EXISTING_ONLY);
+  Adder a(&cb_list);
+  Listener b;
+  cb_list.Add(
+      base::Bind(&Adder::OnAddedEvent, base::Unretained(&a)));
+  cb_list.Add(
+      base::Bind(&Listener::OnEvent, base::Unretained(&b)));
+
+  cb_list.Run();
+
+  EXPECT_EQ(0, a.total);
+  EXPECT_EQ(1, b.total);
+  EXPECT_TRUE(a.added);
+
+  cb_list.Run();
+
+  EXPECT_EQ(1, a.total);
+  EXPECT_EQ(2, b.total);
+
+  cb_list.Clear();
+}
+
+TEST(CallbackListTest, AddAndRemoveCallbacksDuringIteration_Existing) {
+  TestCallbackList cb_list(TestCallbackList::NOTIFY_EXISTING_ONLY);
+  Adder a(&cb_list);
+  Remover b;
+  Listener c;
+
+  base::Closure c_cb = cb_list.Add(
+      base::Bind(&Listener::OnEvent, base::Unretained(&c)));
+
+  // |b| removes |c|.
+  b.SetCallback(c_cb);
+  cb_list.Add(
+      base::Bind(&Remover::OnEvent, base::Unretained(&b)));
+
+  // |a| adds a new callback.
+  base::Closure a_cb = cb_list.Add(
+      base::Bind(&Adder::OnAddedEvent, base::Unretained(&a)));
+
+  cb_list.Run();
+
+  // |c| ran once, new callback should have been added but not yet run.
+  EXPECT_EQ(1, c.total);
+  EXPECT_EQ(0, a.total);
+  EXPECT_TRUE(a.added);
+
+  cb_list.Run();
+
+  // Now it should have been run.
+  EXPECT_EQ(1, c.total);
+  EXPECT_EQ(1, a.total);
+
+  cb_list.Clear();
+}
+
+TEST(CallbackListTest, ClearCallbacksDuringIteration) {
+  TestCallbackList cb_list(TestCallbackList::NOTIFY_ALL);
+  Clearer a(&cb_list);
+  Listener b;
+  cb_list.Add(
+      base::Bind(&Clearer::OnClearAndAddEvent, base::Unretained(&a)));
+  cb_list.Add(
+      base::Bind(&Listener::OnEvent, base::Unretained(&b)));
+
+  cb_list.Run();
+
+  EXPECT_EQ(1, a.total);
+  EXPECT_EQ(0, b.total);
+  EXPECT_TRUE(a.added);
+
+  cb_list.Clear();
+}
+
+TEST(CallbackListTest, IteratorOutlivesList) {
+  TestCallbackList* cb_list =
+      new TestCallbackList(TestCallbackList::NOTIFY_ALL);
+  ListDestructor destructor(cb_list);
+  cb_list->Add(
+      base::Bind(&ListDestructor::OnEvent, base::Unretained(&destructor)));
+  Listener a;
+  cb_list->Add(
+      base::Bind(&Listener::OnEvent, base::Unretained(&a)));
+
+  cb_list->Run();
+
+  // |a| never gets called, as |cb_list| got deleted first.
+  EXPECT_EQ(0, a.total);
+}
+
+}  // namespace
+}  // namespace base