statistics_recorder_starvation_unittest.cc

// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/metrics/statistics_recorder.h"

#include <atomic>

#include "base/containers/span.h"
#include "base/logging.h"
#include "base/metrics/histogram_functions.h"
#include "base/metrics/persistent_histogram_allocator.h"
#include "base/strings/strcat.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "base/threading/platform_thread.h"
#include "base/threading/simple_thread.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace base {

namespace {

constexpr TimeDelta kTestRunningTime = …;
constexpr char kHistogramNamePrefix[] = …;

class BaseThread : public SimpleThread { … };

class ReadThread : public BaseThread { … };

class WriteThread : public BaseThread { … };

}  // namespace

// Determines the number of reader and writer threads to run in the test.
struct StarvationTestParams { … };

// Determines which threads should start running first.
enum class FirstThreadsToStart { … };

class StatisticsRecorderStarvationTest
    : public testing::TestWithParam<
          std::tuple<StarvationTestParams, FirstThreadsToStart>> { … };

// Verifies that there are no starvation issues when emitting histograms (since
// it may be done from any thread). In particular, emitting a histogram requires
// a lock to look up (and sometimes write to) an internal map in the
// StatisticsRecorder. When switching to a Read/Write lock (see crbug/1123627),
// we encountered such a starvation issue, where a thread trying to write to the
// internal map was starved out for 10+ seconds by readers on iOS.
// TODO(crbug.com/41489801): StatisticsRecorderNoStarvation continuously emits a
// new histogram which can cause the app memory footprint to grow unbounded and
// watchdog kill the unit test on iOS devices.
TEST_P(StatisticsRecorderStarvationTest, StatisticsRecorderNoStarvation) { … }

INSTANTIATE_TEST_SUITE_P(…);

}  // namespace base
chromium/base/metrics/statistics_recorder_starvation_unittest.cc
