chromium/base/metrics/histogram_threadsafe_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.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40284755): Remove this and spanify to fix the errors.
#pragma allow_unsafe_buffers
#endif

#include <memory>
#include <set>
#include <string>
#include <vector>

#include "base/atomicops.h"
#include "base/containers/span.h"
#include "base/memory/raw_span.h"
#include "base/metrics/bucket_ranges.h"
#include "base/metrics/histogram.h"
#include "base/metrics/persistent_histogram_allocator.h"
#include "base/metrics/sparse_histogram.h"
#include "base/no_destructor.h"
#include "base/strings/stringprintf.h"
#include "base/test/scoped_feature_list.h"
#include "base/threading/simple_thread.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace base {

namespace {

char const* GetPermanentName(const std::string& name) { … }

size_t GetBucketIndex(HistogramBase::Sample value, const BucketRanges* ranges) { … }

// Runs a task in a thread that will emit |num_emission_| times the passed
// |histograms| and snapshot them. The thread will also keep track of the
// actual samples emitted, as well as the ones found in the snapshots taken, so
// that they can be compared.
class SnapshotDeltaThread : public SimpleThread { … };

}  // namespace

class HistogramThreadsafeTest : public testing::Test { … };

// Verifies that SnapshotDelta() is thread safe. That means 1) a sample emitted
// while a snapshot is taken is not lost, and 2) concurrent calls to
// SnapshotDelta() will not return the same samples. Note that the test makes
// use of ASSERT_* instead EXPECT_* because the test is repeated multiple times,
// and the use of EXPECT_* produces spammy outputs as it does not end the test
// immediately.
TEST_F(HistogramThreadsafeTest, SnapshotDeltaThreadsafe) { … }

}  // namespace base