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// Copyright 2018 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/observer_list.h"
#include <memory>
#include "base/logging.h"
#include "base/observer_list.h"
#include "base/strings/stringprintf.h"
#include "base/time/time.h"
#include "testing/gtest/include/gtest/gtest.h"
#include "testing/perf/perf_test.h"
// Ask the compiler not to use a register for this counter, in case it decides
// to do magic optimizations like |counter += kLaps|.
volatile int g_observer_list_perf_test_counter;
namespace base {
class ObserverInterface {
public:
ObserverInterface() {}
virtual ~ObserverInterface() {}
virtual void Observe() const { ++g_observer_list_perf_test_counter; }
private:
DISALLOW_COPY_AND_ASSIGN(ObserverInterface);
};
class UnsafeObserver : public ObserverInterface {};
class TestCheckedObserver : public CheckedObserver, public ObserverInterface {};
template <class ObserverType>
struct Pick {
// The ObserverList type to use. Checked observers need to be in a checked
// ObserverList.
using ObserverListType = ObserverList<ObserverType>;
static const char* GetName() { return "CheckedObserver"; }
};
template <>
struct Pick<UnsafeObserver> {
using ObserverListType = ObserverList<ObserverInterface>::Unchecked;
static const char* GetName() { return "UnsafeObserver"; }
};
template <class ObserverType>
class ObserverListPerfTest : public ::testing::Test {
public:
using ObserverListType = typename Pick<ObserverType>::ObserverListType;
ObserverListPerfTest() {}
private:
DISALLOW_COPY_AND_ASSIGN(ObserverListPerfTest);
};
typedef ::testing::Types<UnsafeObserver, TestCheckedObserver> ObserverTypes;
TYPED_TEST_SUITE(ObserverListPerfTest, ObserverTypes);
// Performance test for base::ObserverList and Checked Observers.
TYPED_TEST(ObserverListPerfTest, NotifyPerformance) {
constexpr int kMaxObservers = 128;
#if DCHECK_IS_ON()
// The test takes about 100x longer in debug builds, mostly due to sequence
// checker overheads when WeakPtr gets involved.
constexpr int kLaps = 1000000;
#else
constexpr int kLaps = 100000000;
#endif
constexpr int kWarmupLaps = 100;
std::vector<std::unique_ptr<TypeParam>> observers;
for (int observer_count = 0; observer_count <= kMaxObservers;
observer_count = observer_count ? observer_count * 2 : 1) {
typename TestFixture::ObserverListType list;
for (int i = 0; i < observer_count; ++i)
observers.push_back(std::make_unique<TypeParam>());
for (auto& o : observers)
list.AddObserver(o.get());
for (int i = 0; i < kWarmupLaps; ++i) {
for (auto& o : list)
o.Observe();
}
g_observer_list_perf_test_counter = 0;
const int weighted_laps = kLaps / (observer_count + 1);
TimeTicks start = TimeTicks::Now();
for (int i = 0; i < weighted_laps; ++i) {
for (auto& o : list)
o.Observe();
}
TimeDelta duration = TimeTicks::Now() - start;
const char* name = Pick<TypeParam>::GetName();
observers.clear();
EXPECT_EQ(observer_count * weighted_laps,
g_observer_list_perf_test_counter);
EXPECT_TRUE(observer_count == 0 || list.might_have_observers());
std::string prefix =
base::StringPrintf("ObserverListPerfTest_%d.", observer_count);
// A typical value is 3-20 nanoseconds per observe in Release, 1000-2000ns
// in an optimized build with DCHECKs and 3000-6000ns in debug builds.
perf_test::PrintResult(
prefix, name, "NotifyPerformance",
duration.InNanoseconds() /
static_cast<double>(g_observer_list_perf_test_counter +
weighted_laps),
"ns/observe", true);
}
}
} // namespace base