rocksdb/db/range_tombstone_fragmenter_test.cc
Peter Dillinger e466173d5c Print stack traces on frozen tests in CI (#10828)
Summary:
Instead of existing calls to ps from gnu_parallel, call a new wrapper that does ps, looks for unit test like processes, and uses pstack or gdb to print thread stack traces. Also, using `ps -wwf` instead of `ps -wf` ensures output is not cut off.

For security, CircleCI runs with security restrictions on ptrace (/proc/sys/kernel/yama/ptrace_scope = 1), and this change adds a work-around to `InstallStackTraceHandler()` (only used by testing tools) to allow any process from the same user to debug it. (I've also touched >100 files to ensure all the unit tests call this function.)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10828

Test Plan: local manual + temporary infinite loop in a unit test to observe in CircleCI

Reviewed By: hx235

Differential Revision: D40447634

Pulled By: pdillinger

fbshipit-source-id: 718a4c4a5b54fa0f9af2d01a446162b45e5e84e1
2022-10-18 00:35:35 -07:00

556 lines
24 KiB
C++

// Copyright (c) 2018-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#include "db/range_tombstone_fragmenter.h"
#include "db/db_test_util.h"
#include "db/dbformat.h"
#include "rocksdb/comparator.h"
#include "test_util/testutil.h"
#include "util/vector_iterator.h"
namespace ROCKSDB_NAMESPACE {
class RangeTombstoneFragmenterTest : public testing::Test {};
namespace {
static auto bytewise_icmp = InternalKeyComparator(BytewiseComparator());
std::unique_ptr<InternalIterator> MakeRangeDelIter(
const std::vector<RangeTombstone>& range_dels) {
std::vector<std::string> keys, values;
for (const auto& range_del : range_dels) {
auto key_and_value = range_del.Serialize();
keys.push_back(key_and_value.first.Encode().ToString());
values.push_back(key_and_value.second.ToString());
}
return std::unique_ptr<VectorIterator>(
new VectorIterator(keys, values, &bytewise_icmp));
}
void CheckIterPosition(const RangeTombstone& tombstone,
const FragmentedRangeTombstoneIterator* iter) {
// Test InternalIterator interface.
EXPECT_EQ(tombstone.start_key_, ExtractUserKey(iter->key()));
EXPECT_EQ(tombstone.end_key_, iter->value());
EXPECT_EQ(tombstone.seq_, iter->seq());
// Test FragmentedRangeTombstoneIterator interface.
EXPECT_EQ(tombstone.start_key_, iter->start_key());
EXPECT_EQ(tombstone.end_key_, iter->end_key());
EXPECT_EQ(tombstone.seq_, GetInternalKeySeqno(iter->key()));
}
void VerifyFragmentedRangeDels(
FragmentedRangeTombstoneIterator* iter,
const std::vector<RangeTombstone>& expected_tombstones) {
iter->SeekToFirst();
for (size_t i = 0; i < expected_tombstones.size(); i++, iter->Next()) {
ASSERT_TRUE(iter->Valid());
CheckIterPosition(expected_tombstones[i], iter);
}
EXPECT_FALSE(iter->Valid());
}
void VerifyVisibleTombstones(
FragmentedRangeTombstoneIterator* iter,
const std::vector<RangeTombstone>& expected_tombstones) {
iter->SeekToTopFirst();
for (size_t i = 0; i < expected_tombstones.size(); i++, iter->TopNext()) {
ASSERT_TRUE(iter->Valid());
CheckIterPosition(expected_tombstones[i], iter);
}
EXPECT_FALSE(iter->Valid());
}
struct SeekTestCase {
Slice seek_target;
RangeTombstone expected_position;
bool out_of_range;
};
void VerifySeek(FragmentedRangeTombstoneIterator* iter,
const std::vector<SeekTestCase>& cases) {
for (const auto& testcase : cases) {
iter->Seek(testcase.seek_target);
if (testcase.out_of_range) {
ASSERT_FALSE(iter->Valid());
} else {
ASSERT_TRUE(iter->Valid());
CheckIterPosition(testcase.expected_position, iter);
}
}
}
void VerifySeekForPrev(FragmentedRangeTombstoneIterator* iter,
const std::vector<SeekTestCase>& cases) {
for (const auto& testcase : cases) {
iter->SeekForPrev(testcase.seek_target);
if (testcase.out_of_range) {
ASSERT_FALSE(iter->Valid());
} else {
ASSERT_TRUE(iter->Valid());
CheckIterPosition(testcase.expected_position, iter);
}
}
}
struct MaxCoveringTombstoneSeqnumTestCase {
Slice user_key;
SequenceNumber result;
};
void VerifyMaxCoveringTombstoneSeqnum(
FragmentedRangeTombstoneIterator* iter,
const std::vector<MaxCoveringTombstoneSeqnumTestCase>& cases) {
for (const auto& testcase : cases) {
EXPECT_EQ(testcase.result,
iter->MaxCoveringTombstoneSeqnum(testcase.user_key));
}
}
} // anonymous namespace
TEST_F(RangeTombstoneFragmenterTest, NonOverlappingTombstones) {
auto range_del_iter = MakeRangeDelIter({{"a", "b", 10}, {"c", "d", 5}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter(&fragment_list, bytewise_icmp,
kMaxSequenceNumber);
ASSERT_EQ(0, iter.lower_bound());
ASSERT_EQ(kMaxSequenceNumber, iter.upper_bound());
VerifyFragmentedRangeDels(&iter, {{"a", "b", 10}, {"c", "d", 5}});
VerifyMaxCoveringTombstoneSeqnum(&iter,
{{"", 0}, {"a", 10}, {"b", 0}, {"c", 5}});
}
TEST_F(RangeTombstoneFragmenterTest, OverlappingTombstones) {
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10}, {"c", "g", 15}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter(&fragment_list, bytewise_icmp,
kMaxSequenceNumber);
ASSERT_EQ(0, iter.lower_bound());
ASSERT_EQ(kMaxSequenceNumber, iter.upper_bound());
VerifyFragmentedRangeDels(
&iter, {{"a", "c", 10}, {"c", "e", 15}, {"c", "e", 10}, {"e", "g", 15}});
VerifyMaxCoveringTombstoneSeqnum(&iter,
{{"a", 10}, {"c", 15}, {"e", 15}, {"g", 0}});
}
TEST_F(RangeTombstoneFragmenterTest, ContiguousTombstones) {
auto range_del_iter = MakeRangeDelIter(
{{"a", "c", 10}, {"c", "e", 20}, {"c", "e", 5}, {"e", "g", 15}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter(&fragment_list, bytewise_icmp,
kMaxSequenceNumber);
ASSERT_EQ(0, iter.lower_bound());
ASSERT_EQ(kMaxSequenceNumber, iter.upper_bound());
VerifyFragmentedRangeDels(
&iter, {{"a", "c", 10}, {"c", "e", 20}, {"c", "e", 5}, {"e", "g", 15}});
VerifyMaxCoveringTombstoneSeqnum(&iter,
{{"a", 10}, {"c", 20}, {"e", 15}, {"g", 0}});
}
TEST_F(RangeTombstoneFragmenterTest, RepeatedStartAndEndKey) {
auto range_del_iter =
MakeRangeDelIter({{"a", "c", 10}, {"a", "c", 7}, {"a", "c", 3}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter(&fragment_list, bytewise_icmp,
kMaxSequenceNumber);
ASSERT_EQ(0, iter.lower_bound());
ASSERT_EQ(kMaxSequenceNumber, iter.upper_bound());
VerifyFragmentedRangeDels(&iter,
{{"a", "c", 10}, {"a", "c", 7}, {"a", "c", 3}});
VerifyMaxCoveringTombstoneSeqnum(&iter, {{"a", 10}, {"b", 10}, {"c", 0}});
}
TEST_F(RangeTombstoneFragmenterTest, RepeatedStartKeyDifferentEndKeys) {
auto range_del_iter =
MakeRangeDelIter({{"a", "e", 10}, {"a", "g", 7}, {"a", "c", 3}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter(&fragment_list, bytewise_icmp,
kMaxSequenceNumber);
ASSERT_EQ(0, iter.lower_bound());
ASSERT_EQ(kMaxSequenceNumber, iter.upper_bound());
VerifyFragmentedRangeDels(&iter, {{"a", "c", 10},
{"a", "c", 7},
{"a", "c", 3},
{"c", "e", 10},
{"c", "e", 7},
{"e", "g", 7}});
VerifyMaxCoveringTombstoneSeqnum(&iter,
{{"a", 10}, {"c", 10}, {"e", 7}, {"g", 0}});
}
TEST_F(RangeTombstoneFragmenterTest, RepeatedStartKeyMixedEndKeys) {
auto range_del_iter = MakeRangeDelIter({{"a", "c", 30},
{"a", "g", 20},
{"a", "e", 10},
{"a", "g", 7},
{"a", "c", 3}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter(&fragment_list, bytewise_icmp,
kMaxSequenceNumber);
ASSERT_EQ(0, iter.lower_bound());
ASSERT_EQ(kMaxSequenceNumber, iter.upper_bound());
VerifyFragmentedRangeDels(&iter, {{"a", "c", 30},
{"a", "c", 20},
{"a", "c", 10},
{"a", "c", 7},
{"a", "c", 3},
{"c", "e", 20},
{"c", "e", 10},
{"c", "e", 7},
{"e", "g", 20},
{"e", "g", 7}});
VerifyMaxCoveringTombstoneSeqnum(&iter,
{{"a", 30}, {"c", 20}, {"e", 20}, {"g", 0}});
}
TEST_F(RangeTombstoneFragmenterTest, OverlapAndRepeatedStartKey) {
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"c", "g", 8},
{"c", "i", 6},
{"j", "n", 4},
{"j", "l", 2}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter1(&fragment_list, bytewise_icmp,
kMaxSequenceNumber);
FragmentedRangeTombstoneIterator iter2(&fragment_list, bytewise_icmp,
9 /* upper_bound */);
FragmentedRangeTombstoneIterator iter3(&fragment_list, bytewise_icmp,
7 /* upper_bound */);
FragmentedRangeTombstoneIterator iter4(&fragment_list, bytewise_icmp,
5 /* upper_bound */);
FragmentedRangeTombstoneIterator iter5(&fragment_list, bytewise_icmp,
3 /* upper_bound */);
for (auto* iter : {&iter1, &iter2, &iter3, &iter4, &iter5}) {
VerifyFragmentedRangeDels(iter, {{"a", "c", 10},
{"c", "e", 10},
{"c", "e", 8},
{"c", "e", 6},
{"e", "g", 8},
{"e", "g", 6},
{"g", "i", 6},
{"j", "l", 4},
{"j", "l", 2},
{"l", "n", 4}});
}
ASSERT_EQ(0, iter1.lower_bound());
ASSERT_EQ(kMaxSequenceNumber, iter1.upper_bound());
VerifyVisibleTombstones(&iter1, {{"a", "c", 10},
{"c", "e", 10},
{"e", "g", 8},
{"g", "i", 6},
{"j", "l", 4},
{"l", "n", 4}});
VerifyMaxCoveringTombstoneSeqnum(
&iter1, {{"a", 10}, {"c", 10}, {"e", 8}, {"i", 0}, {"j", 4}, {"m", 4}});
ASSERT_EQ(0, iter2.lower_bound());
ASSERT_EQ(9, iter2.upper_bound());
VerifyVisibleTombstones(&iter2, {{"c", "e", 8},
{"e", "g", 8},
{"g", "i", 6},
{"j", "l", 4},
{"l", "n", 4}});
VerifyMaxCoveringTombstoneSeqnum(
&iter2, {{"a", 0}, {"c", 8}, {"e", 8}, {"i", 0}, {"j", 4}, {"m", 4}});
ASSERT_EQ(0, iter3.lower_bound());
ASSERT_EQ(7, iter3.upper_bound());
VerifyVisibleTombstones(&iter3, {{"c", "e", 6},
{"e", "g", 6},
{"g", "i", 6},
{"j", "l", 4},
{"l", "n", 4}});
VerifyMaxCoveringTombstoneSeqnum(
&iter3, {{"a", 0}, {"c", 6}, {"e", 6}, {"i", 0}, {"j", 4}, {"m", 4}});
ASSERT_EQ(0, iter4.lower_bound());
ASSERT_EQ(5, iter4.upper_bound());
VerifyVisibleTombstones(&iter4, {{"j", "l", 4}, {"l", "n", 4}});
VerifyMaxCoveringTombstoneSeqnum(
&iter4, {{"a", 0}, {"c", 0}, {"e", 0}, {"i", 0}, {"j", 4}, {"m", 4}});
ASSERT_EQ(0, iter5.lower_bound());
ASSERT_EQ(3, iter5.upper_bound());
VerifyVisibleTombstones(&iter5, {{"j", "l", 2}});
VerifyMaxCoveringTombstoneSeqnum(
&iter5, {{"a", 0}, {"c", 0}, {"e", 0}, {"i", 0}, {"j", 2}, {"m", 0}});
}
TEST_F(RangeTombstoneFragmenterTest, OverlapAndRepeatedStartKeyUnordered) {
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"j", "n", 4},
{"c", "i", 6},
{"c", "g", 8},
{"j", "l", 2}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter(&fragment_list, bytewise_icmp,
9 /* upper_bound */);
ASSERT_EQ(0, iter.lower_bound());
ASSERT_EQ(9, iter.upper_bound());
VerifyFragmentedRangeDels(&iter, {{"a", "c", 10},
{"c", "e", 10},
{"c", "e", 8},
{"c", "e", 6},
{"e", "g", 8},
{"e", "g", 6},
{"g", "i", 6},
{"j", "l", 4},
{"j", "l", 2},
{"l", "n", 4}});
VerifyMaxCoveringTombstoneSeqnum(
&iter, {{"a", 0}, {"c", 8}, {"e", 8}, {"i", 0}, {"j", 4}, {"m", 4}});
}
TEST_F(RangeTombstoneFragmenterTest, OverlapAndRepeatedStartKeyForCompaction) {
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"j", "n", 4},
{"c", "i", 6},
{"c", "g", 8},
{"j", "l", 2}});
FragmentedRangeTombstoneList fragment_list(
std::move(range_del_iter), bytewise_icmp, true /* for_compaction */,
{} /* snapshots */);
FragmentedRangeTombstoneIterator iter(&fragment_list, bytewise_icmp,
kMaxSequenceNumber /* upper_bound */);
VerifyFragmentedRangeDels(&iter, {{"a", "c", 10},
{"c", "e", 10},
{"e", "g", 8},
{"g", "i", 6},
{"j", "l", 4},
{"l", "n", 4}});
}
TEST_F(RangeTombstoneFragmenterTest,
OverlapAndRepeatedStartKeyForCompactionWithSnapshot) {
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"j", "n", 4},
{"c", "i", 6},
{"c", "g", 8},
{"j", "l", 2}});
FragmentedRangeTombstoneList fragment_list(
std::move(range_del_iter), bytewise_icmp, true /* for_compaction */,
{20, 9} /* upper_bounds */);
FragmentedRangeTombstoneIterator iter(&fragment_list, bytewise_icmp,
kMaxSequenceNumber /* upper_bound */);
VerifyFragmentedRangeDels(&iter, {{"a", "c", 10},
{"c", "e", 10},
{"c", "e", 8},
{"e", "g", 8},
{"g", "i", 6},
{"j", "l", 4},
{"l", "n", 4}});
}
TEST_F(RangeTombstoneFragmenterTest, IteratorSplitNoSnapshots) {
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"j", "n", 4},
{"c", "i", 6},
{"c", "g", 8},
{"j", "l", 2}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter(&fragment_list, bytewise_icmp,
kMaxSequenceNumber /* upper_bound */);
auto split_iters = iter.SplitBySnapshot({} /* snapshots */);
ASSERT_EQ(1, split_iters.size());
auto* split_iter = split_iters[kMaxSequenceNumber].get();
ASSERT_EQ(0, split_iter->lower_bound());
ASSERT_EQ(kMaxSequenceNumber, split_iter->upper_bound());
VerifyVisibleTombstones(split_iter, {{"a", "c", 10},
{"c", "e", 10},
{"e", "g", 8},
{"g", "i", 6},
{"j", "l", 4},
{"l", "n", 4}});
}
TEST_F(RangeTombstoneFragmenterTest, IteratorSplitWithSnapshots) {
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"j", "n", 4},
{"c", "i", 6},
{"c", "g", 8},
{"j", "l", 2}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter(&fragment_list, bytewise_icmp,
kMaxSequenceNumber /* upper_bound */);
auto split_iters = iter.SplitBySnapshot({3, 5, 7, 9} /* snapshots */);
ASSERT_EQ(5, split_iters.size());
auto* split_iter1 = split_iters[3].get();
ASSERT_EQ(0, split_iter1->lower_bound());
ASSERT_EQ(3, split_iter1->upper_bound());
VerifyVisibleTombstones(split_iter1, {{"j", "l", 2}});
auto* split_iter2 = split_iters[5].get();
ASSERT_EQ(4, split_iter2->lower_bound());
ASSERT_EQ(5, split_iter2->upper_bound());
VerifyVisibleTombstones(split_iter2, {{"j", "l", 4}, {"l", "n", 4}});
auto* split_iter3 = split_iters[7].get();
ASSERT_EQ(6, split_iter3->lower_bound());
ASSERT_EQ(7, split_iter3->upper_bound());
VerifyVisibleTombstones(split_iter3,
{{"c", "e", 6}, {"e", "g", 6}, {"g", "i", 6}});
auto* split_iter4 = split_iters[9].get();
ASSERT_EQ(8, split_iter4->lower_bound());
ASSERT_EQ(9, split_iter4->upper_bound());
VerifyVisibleTombstones(split_iter4, {{"c", "e", 8}, {"e", "g", 8}});
auto* split_iter5 = split_iters[kMaxSequenceNumber].get();
ASSERT_EQ(10, split_iter5->lower_bound());
ASSERT_EQ(kMaxSequenceNumber, split_iter5->upper_bound());
VerifyVisibleTombstones(split_iter5, {{"a", "c", 10}, {"c", "e", 10}});
}
TEST_F(RangeTombstoneFragmenterTest, SeekStartKey) {
// Same tombstones as OverlapAndRepeatedStartKey.
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"c", "g", 8},
{"c", "i", 6},
{"j", "n", 4},
{"j", "l", 2}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter1(&fragment_list, bytewise_icmp,
kMaxSequenceNumber);
VerifySeek(
&iter1,
{{"a", {"a", "c", 10}}, {"e", {"e", "g", 8}}, {"l", {"l", "n", 4}}});
VerifySeekForPrev(
&iter1,
{{"a", {"a", "c", 10}}, {"e", {"e", "g", 8}}, {"l", {"l", "n", 4}}});
FragmentedRangeTombstoneIterator iter2(&fragment_list, bytewise_icmp,
3 /* upper_bound */);
VerifySeek(&iter2, {{"a", {"j", "l", 2}},
{"e", {"j", "l", 2}},
{"l", {}, true /* out of range */}});
VerifySeekForPrev(&iter2, {{"a", {}, true /* out of range */},
{"e", {}, true /* out of range */},
{"l", {"j", "l", 2}}});
}
TEST_F(RangeTombstoneFragmenterTest, SeekCovered) {
// Same tombstones as OverlapAndRepeatedStartKey.
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"c", "g", 8},
{"c", "i", 6},
{"j", "n", 4},
{"j", "l", 2}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter1(&fragment_list, bytewise_icmp,
kMaxSequenceNumber);
VerifySeek(
&iter1,
{{"b", {"a", "c", 10}}, {"f", {"e", "g", 8}}, {"m", {"l", "n", 4}}});
VerifySeekForPrev(
&iter1,
{{"b", {"a", "c", 10}}, {"f", {"e", "g", 8}}, {"m", {"l", "n", 4}}});
FragmentedRangeTombstoneIterator iter2(&fragment_list, bytewise_icmp,
3 /* upper_bound */);
VerifySeek(&iter2, {{"b", {"j", "l", 2}},
{"f", {"j", "l", 2}},
{"m", {}, true /* out of range */}});
VerifySeekForPrev(&iter2, {{"b", {}, true /* out of range */},
{"f", {}, true /* out of range */},
{"m", {"j", "l", 2}}});
}
TEST_F(RangeTombstoneFragmenterTest, SeekEndKey) {
// Same tombstones as OverlapAndRepeatedStartKey.
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"c", "g", 8},
{"c", "i", 6},
{"j", "n", 4},
{"j", "l", 2}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter1(&fragment_list, bytewise_icmp,
kMaxSequenceNumber);
VerifySeek(&iter1, {{"c", {"c", "e", 10}},
{"g", {"g", "i", 6}},
{"i", {"j", "l", 4}},
{"n", {}, true /* out of range */}});
VerifySeekForPrev(&iter1, {{"c", {"c", "e", 10}},
{"g", {"g", "i", 6}},
{"i", {"g", "i", 6}},
{"n", {"l", "n", 4}}});
FragmentedRangeTombstoneIterator iter2(&fragment_list, bytewise_icmp,
3 /* upper_bound */);
VerifySeek(&iter2, {{"c", {"j", "l", 2}},
{"g", {"j", "l", 2}},
{"i", {"j", "l", 2}},
{"n", {}, true /* out of range */}});
VerifySeekForPrev(&iter2, {{"c", {}, true /* out of range */},
{"g", {}, true /* out of range */},
{"i", {}, true /* out of range */},
{"n", {"j", "l", 2}}});
}
TEST_F(RangeTombstoneFragmenterTest, SeekOutOfBounds) {
// Same tombstones as OverlapAndRepeatedStartKey.
auto range_del_iter = MakeRangeDelIter({{"a", "e", 10},
{"c", "g", 8},
{"c", "i", 6},
{"j", "n", 4},
{"j", "l", 2}});
FragmentedRangeTombstoneList fragment_list(std::move(range_del_iter),
bytewise_icmp);
FragmentedRangeTombstoneIterator iter(&fragment_list, bytewise_icmp,
kMaxSequenceNumber);
VerifySeek(&iter, {{"", {"a", "c", 10}}, {"z", {}, true /* out of range */}});
VerifySeekForPrev(&iter,
{{"", {}, true /* out of range */}, {"z", {"l", "n", 4}}});
}
} // namespace ROCKSDB_NAMESPACE
int main(int argc, char** argv) {
ROCKSDB_NAMESPACE::port::InstallStackTraceHandler();
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}