1 // Copyright 2018 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #include "base/observer_list.h"
9 #include "base/check_op.h"
10 #include "base/strings/stringprintf.h"
11 #include "base/time/time.h"
12 #include "testing/gtest/include/gtest/gtest.h"
13 #include "testing/perf/perf_result_reporter.h"
15 // Ask the compiler not to use a register for this counter, in case it decides
16 // to do magic optimizations like |counter += kLaps|.
17 volatile int g_observer_list_perf_test_counter;
21 constexpr char kMetricPrefixObserverList[] = "ObserverList.";
22 constexpr char kMetricNotifyTimePerObserver[] = "notify_time_per_observer";
26 perf_test::PerfResultReporter SetUpReporter(const std::string& story_name) {
27 perf_test::PerfResultReporter reporter(kMetricPrefixObserverList, story_name);
28 reporter.RegisterImportantMetric(kMetricNotifyTimePerObserver, "ns");
34 class ObserverInterface {
36 ObserverInterface() = default;
37 ObserverInterface(const ObserverInterface&) = delete;
38 ObserverInterface& operator=(const ObserverInterface&) = delete;
39 virtual ~ObserverInterface() = default;
40 virtual void Observe() const {
41 g_observer_list_perf_test_counter = g_observer_list_perf_test_counter + 1;
45 class UnsafeObserver : public ObserverInterface {};
47 class TestCheckedObserver : public CheckedObserver, public ObserverInterface {};
49 template <class ObserverType>
51 // The ObserverList type to use. Checked observers need to be in a checked
53 using ObserverListType = ObserverList<ObserverType>;
54 static const char* GetName() { return "CheckedObserver"; }
57 struct Pick<UnsafeObserver> {
58 using ObserverListType = ObserverList<ObserverInterface>::Unchecked;
59 static const char* GetName() { return "UnsafeObserver"; }
62 template <class ObserverType>
63 class ObserverListPerfTest : public ::testing::Test {
65 using ObserverListType = typename Pick<ObserverType>::ObserverListType;
67 ObserverListPerfTest() = default;
68 ObserverListPerfTest(const ObserverListPerfTest&) = delete;
69 ObserverListPerfTest& operator=(const ObserverListPerfTest&) = delete;
72 typedef ::testing::Types<UnsafeObserver, TestCheckedObserver> ObserverTypes;
73 TYPED_TEST_SUITE(ObserverListPerfTest, ObserverTypes);
75 // Performance test for base::ObserverList and Checked Observers.
76 TYPED_TEST(ObserverListPerfTest, NotifyPerformance) {
77 constexpr int kMaxObservers = 128;
79 // The test takes about 100x longer in debug builds, mostly due to sequence
80 // checker overheads when WeakPtr gets involved.
81 constexpr int kLaps = 1000000;
83 constexpr int kLaps = 100000000;
85 constexpr int kWarmupLaps = 100;
86 std::vector<std::unique_ptr<TypeParam>> observers;
88 for (int observer_count = 0; observer_count <= kMaxObservers;
89 observer_count = observer_count ? observer_count * 2 : 1) {
90 typename TestFixture::ObserverListType list;
91 for (int i = 0; i < observer_count; ++i)
92 observers.push_back(std::make_unique<TypeParam>());
93 for (auto& o : observers)
94 list.AddObserver(o.get());
96 for (int i = 0; i < kWarmupLaps; ++i) {
100 g_observer_list_perf_test_counter = 0;
101 const int weighted_laps = kLaps / (observer_count + 1);
103 TimeTicks start = TimeTicks::Now();
104 for (int i = 0; i < weighted_laps; ++i) {
108 TimeDelta duration = TimeTicks::Now() - start;
112 EXPECT_EQ(observer_count * weighted_laps,
113 g_observer_list_perf_test_counter);
114 EXPECT_TRUE(observer_count == 0 || !list.empty());
116 std::string story_name =
117 base::StringPrintf("%s_%d", Pick<TypeParam>::GetName(), observer_count);
119 // A typical value is 3-20 nanoseconds per observe in Release, 1000-2000ns
120 // in an optimized build with DCHECKs and 3000-6000ns in debug builds.
121 auto reporter = SetUpReporter(story_name);
123 kMetricNotifyTimePerObserver,
124 duration.InNanoseconds() /
125 static_cast<double>(g_observer_list_perf_test_counter +