absl/strings/internal/cordz_info_test.cc - external/github.com/abseil/abseil-cpp - Git at Google

 // Copyright 2019 The Abseil Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //      https://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 #include "absl/strings/internal/cordz_info.h"

 #include <vector>

 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include "absl/base/config.h"
 #include "absl/debugging/stacktrace.h"
 #include "absl/debugging/symbolize.h"
 #include "absl/strings/cordz_test_helpers.h"
 #include "absl/strings/internal/cord_rep_flat.h"
 #include "absl/strings/internal/cordz_handle.h"
 #include "absl/strings/internal/cordz_statistics.h"
 #include "absl/strings/internal/cordz_update_tracker.h"
 #include "absl/strings/str_cat.h"
 #include "absl/types/span.h"

 namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace cord_internal {
 namespace {

 using ::testing::ElementsAre;
 using ::testing::Eq;
 using ::testing::HasSubstr;
 using ::testing::Ne;
 using ::testing::SizeIs;

 // Used test values
 auto constexpr kUnknownMethod = CordzUpdateTracker::kUnknown;
 auto constexpr kTrackCordMethod = CordzUpdateTracker::kConstructorString;
 auto constexpr kChildMethod = CordzUpdateTracker::kConstructorCord;
 auto constexpr kUpdateMethod = CordzUpdateTracker::kAppendString;

 // Local less verbose helper
 std::vector<const CordzHandle*> DeleteQueue() {
   return CordzHandle::DiagnosticsGetDeleteQueue();
 }

 std::string FormatStack(absl::Span<void* const> raw_stack) {
   static constexpr size_t buf_size = 1 << 14;
   std::unique_ptr<char[]> buf(new char[buf_size]);
   std::string output;
   for (void* stackp : raw_stack) {
     if (absl::Symbolize(stackp, buf.get(), buf_size)) {
       absl::StrAppend(&output, "    ", buf.get(), "\n");
     }
   }
   return output;
 }

 TEST(CordzInfoTest, TrackCord) {
   TestCordData data;
   CordzInfo::TrackCord(data.data, kTrackCordMethod);
   CordzInfo* info = data.data.cordz_info();
   ASSERT_THAT(info, Ne(nullptr));
   EXPECT_FALSE(info->is_snapshot());
   EXPECT_THAT(CordzInfo::Head(CordzSnapshot()), Eq(info));
   EXPECT_THAT(info->GetCordRepForTesting(), Eq(data.rep.rep));
   info->Untrack();
 }

 TEST(CordzInfoTest, MaybeTrackChildCordWithoutSampling) {
   CordzSamplingIntervalHelper sample_none(99999);
   TestCordData parent, child;
   CordzInfo::MaybeTrackCord(child.data, parent.data, kTrackCordMethod);
   EXPECT_THAT(child.data.cordz_info(), Eq(nullptr));
 }

 TEST(CordzInfoTest, MaybeTrackChildCordWithSampling) {
   CordzSamplingIntervalHelper sample_all(1);
   TestCordData parent, child;
   CordzInfo::MaybeTrackCord(child.data, parent.data, kTrackCordMethod);
   EXPECT_THAT(child.data.cordz_info(), Eq(nullptr));
 }

 TEST(CordzInfoTest, MaybeTrackChildCordWithoutSamplingParentSampled) {
   CordzSamplingIntervalHelper sample_none(99999);
   TestCordData parent, child;
   CordzInfo::TrackCord(parent.data, kTrackCordMethod);
   CordzInfo::MaybeTrackCord(child.data, parent.data, kTrackCordMethod);
   CordzInfo* parent_info = parent.data.cordz_info();
   CordzInfo* child_info = child.data.cordz_info();
   ASSERT_THAT(child_info, Ne(nullptr));
   EXPECT_THAT(child_info->GetCordRepForTesting(), Eq(child.rep.rep));
   EXPECT_THAT(child_info->GetParentStack(), parent_info->GetStack());
   parent_info->Untrack();
   child_info->Untrack();
 }

 TEST(CordzInfoTest, MaybeTrackChildCordWithoutSamplingChildSampled) {
   CordzSamplingIntervalHelper sample_none(99999);
   TestCordData parent, child;
   CordzInfo::TrackCord(child.data, kTrackCordMethod);
   CordzInfo::MaybeTrackCord(child.data, parent.data, kTrackCordMethod);
   EXPECT_THAT(child.data.cordz_info(), Eq(nullptr));
 }

 TEST(CordzInfoTest, MaybeTrackChildCordWithSamplingChildSampled) {
   CordzSamplingIntervalHelper sample_all(1);
   TestCordData parent, child;
   CordzInfo::TrackCord(child.data, kTrackCordMethod);
   CordzInfo::MaybeTrackCord(child.data, parent.data, kTrackCordMethod);
   EXPECT_THAT(child.data.cordz_info(), Eq(nullptr));
 }

 TEST(CordzInfoTest, UntrackCord) {
   TestCordData data;
   CordzInfo::TrackCord(data.data, kTrackCordMethod);
   CordzInfo* info = data.data.cordz_info();

   info->Untrack();
   EXPECT_THAT(DeleteQueue(), SizeIs(0));
 }

 TEST(CordzInfoTest, UntrackCordWithSnapshot) {
   TestCordData data;
   CordzInfo::TrackCord(data.data, kTrackCordMethod);
   CordzInfo* info = data.data.cordz_info();

   CordzSnapshot snapshot;
   info->Untrack();
   EXPECT_THAT(CordzInfo::Head(CordzSnapshot()), Eq(nullptr));
   EXPECT_THAT(info->GetCordRepForTesting(), Eq(data.rep.rep));
   EXPECT_THAT(DeleteQueue(), ElementsAre(info, &snapshot));
 }

 TEST(CordzInfoTest, SetCordRep) {
   TestCordData data;
   CordzInfo::TrackCord(data.data, kTrackCordMethod);
   CordzInfo* info = data.data.cordz_info();

   TestCordRep rep;
   info->Lock(CordzUpdateTracker::kAppendCord);
   info->SetCordRep(rep.rep);
   info->Unlock();
   EXPECT_THAT(info->GetCordRepForTesting(), Eq(rep.rep));

   info->Untrack();
 }

 TEST(CordzInfoTest, SetCordRepNullUntracksCordOnUnlock) {
   TestCordData data;
   CordzInfo::TrackCord(data.data, kTrackCordMethod);
   CordzInfo* info = data.data.cordz_info();

   info->Lock(CordzUpdateTracker::kAppendString);
   info->SetCordRep(nullptr);
   EXPECT_THAT(info->GetCordRepForTesting(), Eq(nullptr));
   EXPECT_THAT(CordzInfo::Head(CordzSnapshot()), Eq(info));

   info->Unlock();
   EXPECT_THAT(CordzInfo::Head(CordzSnapshot()), Eq(nullptr));
 }

 TEST(CordzInfoTest, RefCordRep) {
   TestCordData data;
   CordzInfo::TrackCord(data.data, kTrackCordMethod);
   CordzInfo* info = data.data.cordz_info();

   size_t refcount = data.rep.rep->refcount.Get();
   EXPECT_THAT(info->RefCordRep(), Eq(data.rep.rep));
   EXPECT_THAT(data.rep.rep->refcount.Get(), Eq(refcount + 1));
   CordRep::Unref(data.rep.rep);
   info->Untrack();
 }

 #if GTEST_HAS_DEATH_TEST

 TEST(CordzInfoTest, SetCordRepRequiresMutex) {
   TestCordData data;
   CordzInfo::TrackCord(data.data, kTrackCordMethod);
   CordzInfo* info = data.data.cordz_info();
   TestCordRep rep;
   EXPECT_DEBUG_DEATH(info->SetCordRep(rep.rep), ".*");
   info->Untrack();
 }

 #endif  // GTEST_HAS_DEATH_TEST

 TEST(CordzInfoTest, TrackUntrackHeadFirstV2) {
   CordzSnapshot snapshot;
   EXPECT_THAT(CordzInfo::Head(snapshot), Eq(nullptr));

   TestCordData data;
   CordzInfo::TrackCord(data.data, kTrackCordMethod);
   CordzInfo* info1 = data.data.cordz_info();
   ASSERT_THAT(CordzInfo::Head(snapshot), Eq(info1));
   EXPECT_THAT(info1->Next(snapshot), Eq(nullptr));

   TestCordData data2;
   CordzInfo::TrackCord(data2.data, kTrackCordMethod);
   CordzInfo* info2 = data2.data.cordz_info();
   ASSERT_THAT(CordzInfo::Head(snapshot), Eq(info2));
   EXPECT_THAT(info2->Next(snapshot), Eq(info1));
   EXPECT_THAT(info1->Next(snapshot), Eq(nullptr));

   info2->Untrack();
   ASSERT_THAT(CordzInfo::Head(snapshot), Eq(info1));
   EXPECT_THAT(info1->Next(snapshot), Eq(nullptr));

   info1->Untrack();
   ASSERT_THAT(CordzInfo::Head(snapshot), Eq(nullptr));
 }

 TEST(CordzInfoTest, TrackUntrackTailFirstV2) {
   CordzSnapshot snapshot;
   EXPECT_THAT(CordzInfo::Head(snapshot), Eq(nullptr));

   TestCordData data;
   CordzInfo::TrackCord(data.data, kTrackCordMethod);
   CordzInfo* info1 = data.data.cordz_info();
   ASSERT_THAT(CordzInfo::Head(snapshot), Eq(info1));
   EXPECT_THAT(info1->Next(snapshot), Eq(nullptr));

   TestCordData data2;
   CordzInfo::TrackCord(data2.data, kTrackCordMethod);
   CordzInfo* info2 = data2.data.cordz_info();
   ASSERT_THAT(CordzInfo::Head(snapshot), Eq(info2));
   EXPECT_THAT(info2->Next(snapshot), Eq(info1));
   EXPECT_THAT(info1->Next(snapshot), Eq(nullptr));

   info1->Untrack();
   ASSERT_THAT(CordzInfo::Head(snapshot), Eq(info2));
   EXPECT_THAT(info2->Next(snapshot), Eq(nullptr));

   info2->Untrack();
   ASSERT_THAT(CordzInfo::Head(snapshot), Eq(nullptr));
 }

 TEST(CordzInfoTest, StackV2) {
   TestCordData data;
   // kMaxStackDepth is intentionally less than 64 (which is the max depth that
   // Cordz will record) because if the actual stack depth is over 64
   // (which it is on Apple platforms) then the expected_stack will end up
   // catching a few frames at the end that the actual_stack didn't get and
   // it will no longer be subset. At the time of this writing 58 is the max
   // that will allow this test to pass (with a minimum os version of iOS 9), so
   // rounded down to 50 to hopefully not run into this in the future if Apple
   // makes small modifications to its testing stack. 50 is sufficient to prove
   // that we got a decent stack.
   static constexpr int kMaxStackDepth = 50;
   CordzInfo::TrackCord(data.data, kTrackCordMethod);
   CordzInfo* info = data.data.cordz_info();
   std::vector<void*> local_stack;
   local_stack.resize(kMaxStackDepth);
   // In some environments we don't get stack traces. For example in Android
   // absl::GetStackTrace will return 0 indicating it didn't find any stack. The
   // resultant formatted stack will be "", but that still equals the stack
   // recorded in CordzInfo, which is also empty. The skip_count is 1 so that the
   // line number of the current stack isn't included in the HasSubstr check.
   local_stack.resize(absl::GetStackTrace(local_stack.data(), kMaxStackDepth,
                                          /*skip_count=*/1));

   std::string got_stack = FormatStack(info->GetStack());
   std::string expected_stack = FormatStack(local_stack);
   // If TrackCord is inlined, got_stack should match expected_stack. If it isn't
   // inlined, got_stack should include an additional frame not present in
   // expected_stack. Either way, expected_stack should be a substring of
   // got_stack.
   EXPECT_THAT(got_stack, HasSubstr(expected_stack));

   info->Untrack();
 }

 // Local helper functions to get different stacks for child and parent.
 CordzInfo* TrackChildCord(InlineData& data, const InlineData& parent) {
   CordzInfo::TrackCord(data, parent, kChildMethod);
   return data.cordz_info();
 }
 CordzInfo* TrackParentCord(InlineData& data) {
   CordzInfo::TrackCord(data, kTrackCordMethod);
   return data.cordz_info();
 }

 TEST(CordzInfoTest, GetStatistics) {
   TestCordData data;
   CordzInfo* info = TrackParentCord(data.data);

   CordzStatistics statistics = info->GetCordzStatistics();
   EXPECT_THAT(statistics.size, Eq(data.rep.rep->length));
   EXPECT_THAT(statistics.method, Eq(kTrackCordMethod));
   EXPECT_THAT(statistics.parent_method, Eq(kUnknownMethod));
   EXPECT_THAT(statistics.update_tracker.Value(kTrackCordMethod), Eq(1));

   info->Untrack();
 }

 TEST(CordzInfoTest, LockCountsMethod) {
   TestCordData data;
   CordzInfo* info = TrackParentCord(data.data);

   info->Lock(kUpdateMethod);
   info->Unlock();
   info->Lock(kUpdateMethod);
   info->Unlock();

   CordzStatistics statistics = info->GetCordzStatistics();
   EXPECT_THAT(statistics.update_tracker.Value(kUpdateMethod), Eq(2));

   info->Untrack();
 }

 TEST(CordzInfoTest, FromParent) {
   TestCordData parent;
   TestCordData child;
   CordzInfo* info_parent = TrackParentCord(parent.data);
   CordzInfo* info_child = TrackChildCord(child.data, parent.data);

   std::string stack = FormatStack(info_parent->GetStack());
   std::string parent_stack = FormatStack(info_child->GetParentStack());
   EXPECT_THAT(stack, Eq(parent_stack));

   CordzStatistics statistics = info_child->GetCordzStatistics();
   EXPECT_THAT(statistics.size, Eq(child.rep.rep->length));
   EXPECT_THAT(statistics.method, Eq(kChildMethod));
   EXPECT_THAT(statistics.parent_method, Eq(kTrackCordMethod));
   EXPECT_THAT(statistics.update_tracker.Value(kChildMethod), Eq(1));

   info_parent->Untrack();
   info_child->Untrack();
 }

 }  // namespace
 }  // namespace cord_internal
 ABSL_NAMESPACE_END
 }  // namespace absl
	// Copyright 2019 The Abseil Authors
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// https://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	#include "absl/strings/internal/cordz_info.h"

	#include <vector>

	#include "gmock/gmock.h"
	#include "gtest/gtest.h"
	#include "absl/base/config.h"
	#include "absl/debugging/stacktrace.h"
	#include "absl/debugging/symbolize.h"
	#include "absl/strings/cordz_test_helpers.h"
	#include "absl/strings/internal/cord_rep_flat.h"
	#include "absl/strings/internal/cordz_handle.h"
	#include "absl/strings/internal/cordz_statistics.h"
	#include "absl/strings/internal/cordz_update_tracker.h"
	#include "absl/strings/str_cat.h"
	#include "absl/types/span.h"

	namespace absl {
	ABSL_NAMESPACE_BEGIN
	namespace cord_internal {
	namespace {

	using ::testing::ElementsAre;
	using ::testing::Eq;
	using ::testing::HasSubstr;
	using ::testing::Ne;
	using ::testing::SizeIs;

	// Used test values
	auto constexpr kUnknownMethod = CordzUpdateTracker::kUnknown;
	auto constexpr kTrackCordMethod = CordzUpdateTracker::kConstructorString;
	auto constexpr kChildMethod = CordzUpdateTracker::kConstructorCord;
	auto constexpr kUpdateMethod = CordzUpdateTracker::kAppendString;

	// Local less verbose helper
	std::vector<const CordzHandle*> DeleteQueue() {
	return CordzHandle::DiagnosticsGetDeleteQueue();
	}

	std::string FormatStack(absl::Span<void* const> raw_stack) {
	static constexpr size_t buf_size = 1 << 14;
	std::unique_ptr<char[]> buf(new char[buf_size]);
	std::string output;
	for (void* stackp : raw_stack) {
	if (absl::Symbolize(stackp, buf.get(), buf_size)) {
	absl::StrAppend(&output, " ", buf.get(), "\n");
	}
	}
	return output;
	}

	TEST(CordzInfoTest, TrackCord) {
	TestCordData data;
	CordzInfo::TrackCord(data.data, kTrackCordMethod);
	CordzInfo* info = data.data.cordz_info();
	ASSERT_THAT(info, Ne(nullptr));
	EXPECT_FALSE(info->is_snapshot());
	EXPECT_THAT(CordzInfo::Head(CordzSnapshot()), Eq(info));
	EXPECT_THAT(info->GetCordRepForTesting(), Eq(data.rep.rep));
	info->Untrack();
	}

	TEST(CordzInfoTest, MaybeTrackChildCordWithoutSampling) {
	CordzSamplingIntervalHelper sample_none(99999);
	TestCordData parent, child;
	CordzInfo::MaybeTrackCord(child.data, parent.data, kTrackCordMethod);
	EXPECT_THAT(child.data.cordz_info(), Eq(nullptr));
	}

	TEST(CordzInfoTest, MaybeTrackChildCordWithSampling) {
	CordzSamplingIntervalHelper sample_all(1);
	TestCordData parent, child;
	CordzInfo::MaybeTrackCord(child.data, parent.data, kTrackCordMethod);
	EXPECT_THAT(child.data.cordz_info(), Eq(nullptr));
	}

	TEST(CordzInfoTest, MaybeTrackChildCordWithoutSamplingParentSampled) {
	CordzSamplingIntervalHelper sample_none(99999);
	TestCordData parent, child;
	CordzInfo::TrackCord(parent.data, kTrackCordMethod);
	CordzInfo::MaybeTrackCord(child.data, parent.data, kTrackCordMethod);
	CordzInfo* parent_info = parent.data.cordz_info();
	CordzInfo* child_info = child.data.cordz_info();
	ASSERT_THAT(child_info, Ne(nullptr));
	EXPECT_THAT(child_info->GetCordRepForTesting(), Eq(child.rep.rep));
	EXPECT_THAT(child_info->GetParentStack(), parent_info->GetStack());
	parent_info->Untrack();
	child_info->Untrack();
	}

	TEST(CordzInfoTest, MaybeTrackChildCordWithoutSamplingChildSampled) {
	CordzSamplingIntervalHelper sample_none(99999);
	TestCordData parent, child;
	CordzInfo::TrackCord(child.data, kTrackCordMethod);
	CordzInfo::MaybeTrackCord(child.data, parent.data, kTrackCordMethod);
	EXPECT_THAT(child.data.cordz_info(), Eq(nullptr));
	}

	TEST(CordzInfoTest, MaybeTrackChildCordWithSamplingChildSampled) {
	CordzSamplingIntervalHelper sample_all(1);
	TestCordData parent, child;
	CordzInfo::TrackCord(child.data, kTrackCordMethod);
	CordzInfo::MaybeTrackCord(child.data, parent.data, kTrackCordMethod);
	EXPECT_THAT(child.data.cordz_info(), Eq(nullptr));
	}

	TEST(CordzInfoTest, UntrackCord) {
	TestCordData data;
	CordzInfo::TrackCord(data.data, kTrackCordMethod);
	CordzInfo* info = data.data.cordz_info();

	info->Untrack();
	EXPECT_THAT(DeleteQueue(), SizeIs(0));
	}

	TEST(CordzInfoTest, UntrackCordWithSnapshot) {
	TestCordData data;
	CordzInfo::TrackCord(data.data, kTrackCordMethod);
	CordzInfo* info = data.data.cordz_info();

	CordzSnapshot snapshot;
	info->Untrack();
	EXPECT_THAT(CordzInfo::Head(CordzSnapshot()), Eq(nullptr));
	EXPECT_THAT(info->GetCordRepForTesting(), Eq(data.rep.rep));
	EXPECT_THAT(DeleteQueue(), ElementsAre(info, &snapshot));
	}

	TEST(CordzInfoTest, SetCordRep) {
	TestCordData data;
	CordzInfo::TrackCord(data.data, kTrackCordMethod);
	CordzInfo* info = data.data.cordz_info();

	TestCordRep rep;
	info->Lock(CordzUpdateTracker::kAppendCord);
	info->SetCordRep(rep.rep);
	info->Unlock();
	EXPECT_THAT(info->GetCordRepForTesting(), Eq(rep.rep));

	info->Untrack();
	}

	TEST(CordzInfoTest, SetCordRepNullUntracksCordOnUnlock) {
	TestCordData data;
	CordzInfo::TrackCord(data.data, kTrackCordMethod);
	CordzInfo* info = data.data.cordz_info();

	info->Lock(CordzUpdateTracker::kAppendString);
	info->SetCordRep(nullptr);
	EXPECT_THAT(info->GetCordRepForTesting(), Eq(nullptr));
	EXPECT_THAT(CordzInfo::Head(CordzSnapshot()), Eq(info));

	info->Unlock();
	EXPECT_THAT(CordzInfo::Head(CordzSnapshot()), Eq(nullptr));
	}

	TEST(CordzInfoTest, RefCordRep) {
	TestCordData data;
	CordzInfo::TrackCord(data.data, kTrackCordMethod);
	CordzInfo* info = data.data.cordz_info();

	size_t refcount = data.rep.rep->refcount.Get();
	EXPECT_THAT(info->RefCordRep(), Eq(data.rep.rep));
	EXPECT_THAT(data.rep.rep->refcount.Get(), Eq(refcount + 1));
	CordRep::Unref(data.rep.rep);
	info->Untrack();
	}

	#if GTEST_HAS_DEATH_TEST

	TEST(CordzInfoTest, SetCordRepRequiresMutex) {
	TestCordData data;
	CordzInfo::TrackCord(data.data, kTrackCordMethod);
	CordzInfo* info = data.data.cordz_info();
	TestCordRep rep;
	EXPECT_DEBUG_DEATH(info->SetCordRep(rep.rep), ".*");
	info->Untrack();
	}

	#endif // GTEST_HAS_DEATH_TEST

	TEST(CordzInfoTest, TrackUntrackHeadFirstV2) {
	CordzSnapshot snapshot;
	EXPECT_THAT(CordzInfo::Head(snapshot), Eq(nullptr));

	TestCordData data;
	CordzInfo::TrackCord(data.data, kTrackCordMethod);
	CordzInfo* info1 = data.data.cordz_info();
	ASSERT_THAT(CordzInfo::Head(snapshot), Eq(info1));
	EXPECT_THAT(info1->Next(snapshot), Eq(nullptr));

	TestCordData data2;
	CordzInfo::TrackCord(data2.data, kTrackCordMethod);
	CordzInfo* info2 = data2.data.cordz_info();
	ASSERT_THAT(CordzInfo::Head(snapshot), Eq(info2));
	EXPECT_THAT(info2->Next(snapshot), Eq(info1));
	EXPECT_THAT(info1->Next(snapshot), Eq(nullptr));

	info2->Untrack();
	ASSERT_THAT(CordzInfo::Head(snapshot), Eq(info1));
	EXPECT_THAT(info1->Next(snapshot), Eq(nullptr));

	info1->Untrack();
	ASSERT_THAT(CordzInfo::Head(snapshot), Eq(nullptr));
	}

	TEST(CordzInfoTest, TrackUntrackTailFirstV2) {
	CordzSnapshot snapshot;
	EXPECT_THAT(CordzInfo::Head(snapshot), Eq(nullptr));

	TestCordData data;
	CordzInfo::TrackCord(data.data, kTrackCordMethod);
	CordzInfo* info1 = data.data.cordz_info();
	ASSERT_THAT(CordzInfo::Head(snapshot), Eq(info1));
	EXPECT_THAT(info1->Next(snapshot), Eq(nullptr));

	TestCordData data2;
	CordzInfo::TrackCord(data2.data, kTrackCordMethod);
	CordzInfo* info2 = data2.data.cordz_info();
	ASSERT_THAT(CordzInfo::Head(snapshot), Eq(info2));
	EXPECT_THAT(info2->Next(snapshot), Eq(info1));
	EXPECT_THAT(info1->Next(snapshot), Eq(nullptr));

	info1->Untrack();
	ASSERT_THAT(CordzInfo::Head(snapshot), Eq(info2));
	EXPECT_THAT(info2->Next(snapshot), Eq(nullptr));

	info2->Untrack();
	ASSERT_THAT(CordzInfo::Head(snapshot), Eq(nullptr));
	}

	TEST(CordzInfoTest, StackV2) {
	TestCordData data;
	// kMaxStackDepth is intentionally less than 64 (which is the max depth that
	// Cordz will record) because if the actual stack depth is over 64
	// (which it is on Apple platforms) then the expected_stack will end up
	// catching a few frames at the end that the actual_stack didn't get and
	// it will no longer be subset. At the time of this writing 58 is the max
	// that will allow this test to pass (with a minimum os version of iOS 9), so
	// rounded down to 50 to hopefully not run into this in the future if Apple
	// makes small modifications to its testing stack. 50 is sufficient to prove
	// that we got a decent stack.
	static constexpr int kMaxStackDepth = 50;
	CordzInfo::TrackCord(data.data, kTrackCordMethod);
	CordzInfo* info = data.data.cordz_info();
	std::vector<void*> local_stack;
	local_stack.resize(kMaxStackDepth);
	// In some environments we don't get stack traces. For example in Android
	// absl::GetStackTrace will return 0 indicating it didn't find any stack. The
	// resultant formatted stack will be "", but that still equals the stack
	// recorded in CordzInfo, which is also empty. The skip_count is 1 so that the
	// line number of the current stack isn't included in the HasSubstr check.
	local_stack.resize(absl::GetStackTrace(local_stack.data(), kMaxStackDepth,
	/skip_count=/1));

	std::string got_stack = FormatStack(info->GetStack());
	std::string expected_stack = FormatStack(local_stack);
	// If TrackCord is inlined, got_stack should match expected_stack. If it isn't
	// inlined, got_stack should include an additional frame not present in
	// expected_stack. Either way, expected_stack should be a substring of
	// got_stack.
	EXPECT_THAT(got_stack, HasSubstr(expected_stack));

	info->Untrack();
	}

	// Local helper functions to get different stacks for child and parent.
	CordzInfo* TrackChildCord(InlineData& data, const InlineData& parent) {
	CordzInfo::TrackCord(data, parent, kChildMethod);
	return data.cordz_info();
	}
	CordzInfo* TrackParentCord(InlineData& data) {
	CordzInfo::TrackCord(data, kTrackCordMethod);
	return data.cordz_info();
	}

	TEST(CordzInfoTest, GetStatistics) {
	TestCordData data;
	CordzInfo* info = TrackParentCord(data.data);

	CordzStatistics statistics = info->GetCordzStatistics();
	EXPECT_THAT(statistics.size, Eq(data.rep.rep->length));
	EXPECT_THAT(statistics.method, Eq(kTrackCordMethod));
	EXPECT_THAT(statistics.parent_method, Eq(kUnknownMethod));
	EXPECT_THAT(statistics.update_tracker.Value(kTrackCordMethod), Eq(1));

	info->Untrack();
	}

	TEST(CordzInfoTest, LockCountsMethod) {
	TestCordData data;
	CordzInfo* info = TrackParentCord(data.data);

	info->Lock(kUpdateMethod);
	info->Unlock();
	info->Lock(kUpdateMethod);
	info->Unlock();

	CordzStatistics statistics = info->GetCordzStatistics();
	EXPECT_THAT(statistics.update_tracker.Value(kUpdateMethod), Eq(2));

	info->Untrack();
	}

	TEST(CordzInfoTest, FromParent) {
	TestCordData parent;
	TestCordData child;
	CordzInfo* info_parent = TrackParentCord(parent.data);
	CordzInfo* info_child = TrackChildCord(child.data, parent.data);

	std::string stack = FormatStack(info_parent->GetStack());
	std::string parent_stack = FormatStack(info_child->GetParentStack());
	EXPECT_THAT(stack, Eq(parent_stack));

	CordzStatistics statistics = info_child->GetCordzStatistics();
	EXPECT_THAT(statistics.size, Eq(child.rep.rep->length));
	EXPECT_THAT(statistics.method, Eq(kChildMethod));
	EXPECT_THAT(statistics.parent_method, Eq(kTrackCordMethod));
	EXPECT_THAT(statistics.update_tracker.Value(kChildMethod), Eq(1));

	info_parent->Untrack();
	info_child->Untrack();
	}

	} // namespace
	} // namespace cord_internal
	ABSL_NAMESPACE_END
	} // namespace absl