rocksdb/utilities/transactions/write_prepared_transaction_test.cc

570 lines
23 KiB
C++
Raw Normal View History

// Copyright (c) 2011-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).
#ifndef ROCKSDB_LITE
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include "utilities/transactions/transaction_test.h"
#include <inttypes.h>
#include <algorithm>
#include <functional>
#include <string>
#include <thread>
#include "db/db_impl.h"
#include "rocksdb/db.h"
#include "rocksdb/options.h"
#include "rocksdb/utilities/transaction.h"
#include "rocksdb/utilities/transaction_db.h"
#include "table/mock_table.h"
#include "util/fault_injection_test_env.h"
#include "util/random.h"
#include "util/string_util.h"
#include "util/sync_point.h"
#include "util/testharness.h"
#include "util/testutil.h"
#include "util/transaction_test_util.h"
#include "utilities/merge_operators.h"
#include "utilities/merge_operators/string_append/stringappend.h"
#include "utilities/transactions/pessimistic_transaction_db.h"
#include "port/port.h"
using std::string;
namespace rocksdb {
using CommitEntry = PessimisticTransactionDB::CommitEntry;
TEST(PreparedHeap, BasicsTest) {
WritePreparedTxnDB::PreparedHeap heap;
heap.push(14l);
// Test with one element
ASSERT_EQ(14l, heap.top());
heap.push(24l);
heap.push(34l);
// Test that old min is still on top
ASSERT_EQ(14l, heap.top());
heap.push(13l);
// Test that the new min will be on top
ASSERT_EQ(13l, heap.top());
// Test that it is persistent
ASSERT_EQ(13l, heap.top());
heap.push(44l);
heap.push(54l);
heap.push(64l);
heap.push(74l);
heap.push(84l);
// Test that old min is still on top
ASSERT_EQ(13l, heap.top());
heap.erase(24l);
// Test that old min is still on top
ASSERT_EQ(13l, heap.top());
heap.erase(14l);
// Test that old min is still on top
ASSERT_EQ(13l, heap.top());
heap.erase(13l);
// Test that the new comes to the top after multiple erase
ASSERT_EQ(34l, heap.top());
heap.erase(34l);
// Test that the new comes to the top after single erase
ASSERT_EQ(44l, heap.top());
heap.erase(54l);
ASSERT_EQ(44l, heap.top());
heap.pop(); // pop 44l
// Test that the erased items are ignored after pop
ASSERT_EQ(64l, heap.top());
heap.erase(44l);
// Test that erasing an already popped item would work
ASSERT_EQ(64l, heap.top());
heap.erase(84l);
ASSERT_EQ(64l, heap.top());
heap.push(85l);
heap.push(86l);
heap.push(87l);
heap.push(88l);
heap.push(89l);
heap.erase(87l);
heap.erase(85l);
heap.erase(89l);
heap.erase(86l);
heap.erase(88l);
// Test top remians the same after a ranodm order of many erases
ASSERT_EQ(64l, heap.top());
heap.pop();
// Test that pop works with a series of random pending erases
ASSERT_EQ(74l, heap.top());
ASSERT_FALSE(heap.empty());
heap.pop();
// Test that empty works
ASSERT_TRUE(heap.empty());
}
class WritePreparedTransactionTest : public TransactionTest {
protected:
// If expect_update is set, check if it actually updated old_commit_map_. If
// it did not and yet suggested not to check the next snapshot, do the
// opposite to check if it was not a bad suggstion.
void MaybeUpdateOldCommitMapTestWithNext(uint64_t prepare, uint64_t commit,
uint64_t snapshot,
uint64_t next_snapshot,
bool expect_update) {
WritePreparedTxnDB* wp_db = dynamic_cast<WritePreparedTxnDB*>(db);
// reset old_commit_map_empty_ so that its value indicate whether
// old_commit_map_ was updated
wp_db->old_commit_map_empty_ = true;
bool check_next = wp_db->MaybeUpdateOldCommitMap(prepare, commit, snapshot,
snapshot < next_snapshot);
if (expect_update == wp_db->old_commit_map_empty_) {
printf("prepare: %" PRIu64 " commit: %" PRIu64 " snapshot: %" PRIu64
" next: %" PRIu64 "\n",
prepare, commit, snapshot, next_snapshot);
}
EXPECT_EQ(!expect_update, wp_db->old_commit_map_empty_);
if (!check_next && wp_db->old_commit_map_empty_) {
// do the oppotisite to make sure it was not a bad suggestion
const bool dont_care_bool = true;
wp_db->MaybeUpdateOldCommitMap(prepare, commit, next_snapshot,
dont_care_bool);
if (!wp_db->old_commit_map_empty_) {
printf("prepare: %" PRIu64 " commit: %" PRIu64 " snapshot: %" PRIu64
" next: %" PRIu64 "\n",
prepare, commit, snapshot, next_snapshot);
}
EXPECT_TRUE(wp_db->old_commit_map_empty_);
}
}
// Test that a CheckAgainstSnapshots thread reading old_snapshots will not
// miss a snapshot because of a concurrent update by UpdateSnapshots that is
// writing new_snapshots. Both threads are broken at two points. The sync
// points to enforce them are specified by a1, a2, b1, and b2. CommitEntry
// entry is expected to be vital for one of the snapshots that is common
// between the old and new list of snapshots.
void SnapshotConcurrentAccessTestInternal(
WritePreparedTxnDB* wp_db,
const std::vector<SequenceNumber>& old_snapshots,
const std::vector<SequenceNumber>& new_snapshots, CommitEntry& entry,
SequenceNumber& version, size_t a1, size_t a2, size_t b1, size_t b2) {
// First reset the snapshot list
const std::vector<SequenceNumber> empty_snapshots;
wp_db->old_commit_map_empty_ = true;
wp_db->UpdateSnapshots(empty_snapshots, ++version);
// Then initialize it with the old_snapshots
wp_db->UpdateSnapshots(old_snapshots, ++version);
// Starting from the first thread, cut each thread at two points
rocksdb::SyncPoint::GetInstance()->LoadDependency({
{"WritePreparedTxnDB::CheckAgainstSnapshots:p:" + std::to_string(a1),
"WritePreparedTxnDB::UpdateSnapshots:s:start"},
{"WritePreparedTxnDB::UpdateSnapshots:p:" + std::to_string(b1),
"WritePreparedTxnDB::CheckAgainstSnapshots:s:" + std::to_string(a1)},
{"WritePreparedTxnDB::CheckAgainstSnapshots:p:" + std::to_string(a2),
"WritePreparedTxnDB::UpdateSnapshots:s:" + std::to_string(b1)},
{"WritePreparedTxnDB::UpdateSnapshots:p:" + std::to_string(b2),
"WritePreparedTxnDB::CheckAgainstSnapshots:s:" + std::to_string(a2)},
{"WritePreparedTxnDB::CheckAgainstSnapshots:p:end",
"WritePreparedTxnDB::UpdateSnapshots:s:" + std::to_string(b2)},
});
rocksdb::SyncPoint::GetInstance()->EnableProcessing();
{
ASSERT_TRUE(wp_db->old_commit_map_empty_);
rocksdb::port::Thread t1(
[&]() { wp_db->UpdateSnapshots(new_snapshots, version); });
rocksdb::port::Thread t2([&]() { wp_db->CheckAgainstSnapshots(entry); });
t1.join();
t2.join();
ASSERT_FALSE(wp_db->old_commit_map_empty_);
}
rocksdb::SyncPoint::GetInstance()->DisableProcessing();
wp_db->old_commit_map_empty_ = true;
wp_db->UpdateSnapshots(empty_snapshots, ++version);
wp_db->UpdateSnapshots(old_snapshots, ++version);
// Starting from the second thread, cut each thread at two points
rocksdb::SyncPoint::GetInstance()->LoadDependency({
{"WritePreparedTxnDB::UpdateSnapshots:p:" + std::to_string(a1),
"WritePreparedTxnDB::CheckAgainstSnapshots:s:start"},
{"WritePreparedTxnDB::CheckAgainstSnapshots:p:" + std::to_string(b1),
"WritePreparedTxnDB::UpdateSnapshots:s:" + std::to_string(a1)},
{"WritePreparedTxnDB::UpdateSnapshots:p:" + std::to_string(a2),
"WritePreparedTxnDB::CheckAgainstSnapshots:s:" + std::to_string(b1)},
{"WritePreparedTxnDB::CheckAgainstSnapshots:p:" + std::to_string(b2),
"WritePreparedTxnDB::UpdateSnapshots:s:" + std::to_string(a2)},
{"WritePreparedTxnDB::UpdateSnapshots:p:end",
"WritePreparedTxnDB::CheckAgainstSnapshots:s:" + std::to_string(b2)},
});
rocksdb::SyncPoint::GetInstance()->EnableProcessing();
{
ASSERT_TRUE(wp_db->old_commit_map_empty_);
rocksdb::port::Thread t1(
[&]() { wp_db->UpdateSnapshots(new_snapshots, version); });
rocksdb::port::Thread t2([&]() { wp_db->CheckAgainstSnapshots(entry); });
t1.join();
t2.join();
ASSERT_FALSE(wp_db->old_commit_map_empty_);
}
rocksdb::SyncPoint::GetInstance()->DisableProcessing();
}
};
INSTANTIATE_TEST_CASE_P(WritePreparedTransactionTest,
WritePreparedTransactionTest,
::testing::Values(std::make_tuple(false, true,
WRITE_PREPARED)));
TEST_P(WritePreparedTransactionTest, CommitMapTest) {
WritePreparedTxnDB* wp_db = dynamic_cast<WritePreparedTxnDB*>(db);
assert(wp_db);
assert(wp_db->db_impl_);
size_t size = wp_db->COMMIT_CACHE_SIZE;
CommitEntry c = {5, 12}, e;
bool evicted = wp_db->AddCommitEntry(c.prep_seq % size, c, &e);
ASSERT_FALSE(evicted);
// Should be able to read the same value
bool found = wp_db->GetCommitEntry(c.prep_seq % size, &e);
ASSERT_TRUE(found);
ASSERT_EQ(c, e);
// Should be able to distinguish between overlapping entries
found = wp_db->GetCommitEntry((c.prep_seq + size) % size, &e);
ASSERT_TRUE(found);
ASSERT_NE(c.prep_seq + size, e.prep_seq);
// Should be able to detect non-existent entry
found = wp_db->GetCommitEntry((c.prep_seq + 1) % size, &e);
ASSERT_EQ(e.commit_seq, 0);
ASSERT_FALSE(found);
// Reject an invalid exchange
CommitEntry e2 = {c.prep_seq + size, c.commit_seq};
bool exchanged = wp_db->ExchangeCommitEntry(e2.prep_seq % size, e2, e);
ASSERT_FALSE(exchanged);
// check whether it did actually reject that
found = wp_db->GetCommitEntry(e2.prep_seq % size, &e);
ASSERT_TRUE(found);
ASSERT_EQ(c, e);
// Accept a valid exchange
CommitEntry e3 = {c.prep_seq + size, c.commit_seq + size + 1};
exchanged = wp_db->ExchangeCommitEntry(c.prep_seq % size, c, e3);
ASSERT_TRUE(exchanged);
// check whether it did actually accepted that
found = wp_db->GetCommitEntry(c.prep_seq % size, &e);
ASSERT_TRUE(found);
ASSERT_EQ(e3, e);
// Rewrite an entry
CommitEntry e4 = {e3.prep_seq + size, e3.commit_seq + size + 1};
evicted = wp_db->AddCommitEntry(e4.prep_seq % size, e4, &e);
ASSERT_TRUE(evicted);
ASSERT_EQ(e3, e);
found = wp_db->GetCommitEntry(e4.prep_seq % size, &e);
ASSERT_TRUE(found);
ASSERT_EQ(e4, e);
}
TEST_P(WritePreparedTransactionTest, MaybeUpdateOldCommitMap) {
// If prepare <= snapshot < commit we should keep the entry around since its
// nonexistence could be interpreted as committed in the snapshot while it is
// not true. We keep such entries around by adding them to the
// old_commit_map_.
uint64_t p /*prepare*/, c /*commit*/, s /*snapshot*/, ns /*next_snapshot*/;
p = 10l, c = 15l, s = 20l, ns = 21l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
// If we do not expect the old commit map to be updated, try also with a next
// snapshot that is expected to update the old commit map. This would test
// that MaybeUpdateOldCommitMap would not prevent us from checking the next
// snapshot that must be checked.
p = 10l, c = 15l, s = 20l, ns = 11l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
p = 10l, c = 20l, s = 20l, ns = 19l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
p = 10l, c = 20l, s = 20l, ns = 21l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
p = 20l, c = 20l, s = 20l, ns = 21l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
p = 20l, c = 20l, s = 20l, ns = 19l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
p = 10l, c = 25l, s = 20l, ns = 21l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, true);
p = 20l, c = 25l, s = 20l, ns = 21l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, true);
p = 21l, c = 25l, s = 20l, ns = 22l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
p = 21l, c = 25l, s = 20l, ns = 19l;
MaybeUpdateOldCommitMapTestWithNext(p, c, s, ns, false);
}
TEST_P(WritePreparedTransactionTest, CheckAgainstSnapshotsTest) {
std::vector<SequenceNumber> snapshots = {100l, 200l, 300l, 400l,
500l, 600l, 700l};
// will take effect after ReOpen
WritePreparedTxnDB::DEF_SNAPSHOT_CACHE_SIZE = snapshots.size() / 2;
ReOpen(); // to restart the db
WritePreparedTxnDB* wp_db = dynamic_cast<WritePreparedTxnDB*>(db);
assert(wp_db);
assert(wp_db->db_impl_);
SequenceNumber version = 1000l;
ASSERT_EQ(0, wp_db->snapshots_total_);
wp_db->UpdateSnapshots(snapshots, version);
ASSERT_EQ(snapshots.size(), wp_db->snapshots_total_);
// seq numbers are chosen so that we have two of them between each two
// snapshots. If the diff of two consecuitive seq is more than 5, there is a
// snapshot between them.
std::vector<SequenceNumber> seqs = {50l, 55l, 150l, 155l, 250l, 255l,
350l, 355l, 450l, 455l, 550l, 555l,
650l, 655l, 750l, 755l};
assert(seqs.size() > 1);
for (size_t i = 0; i < seqs.size() - 1; i++) {
wp_db->old_commit_map_empty_ = true; // reset
CommitEntry commit_entry = {seqs[i], seqs[i + 1]};
wp_db->CheckAgainstSnapshots(commit_entry);
// Expect update if there is snapshot in between the prepare and commit
bool expect_update = commit_entry.commit_seq - commit_entry.prep_seq > 5 &&
commit_entry.commit_seq >= snapshots.front() &&
commit_entry.prep_seq <= snapshots.back();
ASSERT_EQ(expect_update, !wp_db->old_commit_map_empty_);
}
}
// Return true if the ith bit is set in combination represented by comb
bool IsInCombination(size_t i, size_t comb) { return comb & (1 << i); }
// Test that CheckAgainstSnapshots will not miss a live snapshot if it is run in
// parallel with UpdateSnapshots.
TEST_P(WritePreparedTransactionTest, SnapshotConcurrentAccessTest) {
// We have a sync point in the method under test after checking each snapshot.
// If you increase the max number of snapshots in this test, more sync points
// in the methods must also be added.
const std::vector<SequenceNumber> snapshots = {10l, 20l, 30l, 40l, 50l,
60l, 70l, 80l, 90l, 100l};
SequenceNumber version = 1000l;
// Choose the cache size so that the new snapshot list could replace all the
// existing items in the cache and also have some overflow Will take effect
// after ReOpen
WritePreparedTxnDB::DEF_SNAPSHOT_CACHE_SIZE = (snapshots.size() - 2) / 2;
ReOpen(); // to restart the db
WritePreparedTxnDB* wp_db = dynamic_cast<WritePreparedTxnDB*>(db);
assert(wp_db);
assert(wp_db->db_impl_);
// Add up to 2 items that do not fit into the cache
for (size_t old_size = 1;
old_size <= WritePreparedTxnDB::DEF_SNAPSHOT_CACHE_SIZE + 2;
old_size++) {
const std::vector<SequenceNumber> old_snapshots(
snapshots.begin(), snapshots.begin() + old_size);
// Each member of old snapshot might or might not appear in the new list. We
// create a common_snapshots for each combination.
size_t new_comb_cnt = static_cast<size_t>(1 << old_size);
for (size_t new_comb = 0; new_comb < new_comb_cnt; new_comb++) {
std::vector<SequenceNumber> common_snapshots;
for (size_t i = 0; i < old_snapshots.size(); i++) {
if (IsInCombination(i, new_comb)) {
common_snapshots.push_back(old_snapshots[i]);
}
}
// And add some new snapshots to the common list
for (size_t added_snapshots = 0;
added_snapshots <= snapshots.size() - old_snapshots.size();
added_snapshots++) {
std::vector<SequenceNumber> new_snapshots = common_snapshots;
for (size_t i = 0; i < added_snapshots; i++) {
new_snapshots.push_back(snapshots[old_snapshots.size() + i]);
}
for (auto it = common_snapshots.begin(); it != common_snapshots.end();
it++) {
auto snapshot = *it;
// Create a commit entry that is around the snapshot and thus should
// be not be discarded
CommitEntry entry = {static_cast<uint64_t>(snapshot - 1),
snapshot + 1};
// The critical part is when iterating the snapshot cache. Afterwards,
// we are operating under the lock
size_t a_range =
std::min(old_snapshots.size(),
WritePreparedTxnDB::DEF_SNAPSHOT_CACHE_SIZE) +
1;
size_t b_range =
std::min(new_snapshots.size(),
WritePreparedTxnDB::DEF_SNAPSHOT_CACHE_SIZE) +
1;
// Break each thread at two points
for (size_t a1 = 1; a1 <= a_range; a1++) {
for (size_t a2 = a1 + 1; a2 <= a_range; a2++) {
for (size_t b1 = 1; b1 <= b_range; b1++) {
for (size_t b2 = b1 + 1; b2 <= b_range; b2++) {
SnapshotConcurrentAccessTestInternal(wp_db, old_snapshots,
new_snapshots, entry,
version, a1, a2, b1, b2);
}
}
}
}
}
}
}
}
}
// Test WritePreparedTxnDB's IsInSnapshot against different ordering of
// snapshot, max_committed_seq_, prepared, and commit entries.
TEST_P(WritePreparedTransactionTest, IsInSnapshotTest) {
WriteOptions wo;
// Use small commit cache to trigger lots of eviction and fast advance of
// max_evicted_seq_
// will take effect after ReOpen
WritePreparedTxnDB::DEF_COMMIT_CACHE_SIZE = 8;
// Same for snapshot cache size
WritePreparedTxnDB::DEF_SNAPSHOT_CACHE_SIZE = 5;
// Take some preliminary snapshots first. This is to stress the data structure
// that holds the old snapshots as it will be designed to be efficient when
// only a few snapshots are below the max_evicted_seq_.
for (int max_snapshots = 1; max_snapshots < 20; max_snapshots++) {
// Leave some gap between the preliminary snapshots and the final snapshot
// that we check. This should test for also different overlapping scnearios
// between the last snapshot and the commits.
for (int max_gap = 1; max_gap < 10; max_gap++) {
// Since we do not actually write to db, we mock the seq as it would be
// increaased by the db. The only exception is that we need db seq to
// advance for our snapshots. for which we apply a dummy put each time we
// increase our mock of seq.
uint64_t seq = 0;
// At each step we prepare a txn and then we commit it in the next txn.
// This emulates the consecuitive transactions that write to the same key
uint64_t cur_txn = 0;
// Number of snapshots taken so far
int num_snapshots = 0;
std::vector<const Snapshot*> to_be_released;
// Number of gaps applied so far
int gap_cnt = 0;
// The final snapshot that we will inspect
uint64_t snapshot = 0;
bool found_committed = false;
// To stress the data structure that maintain prepared txns, at each cycle
// we add a new prepare txn. These do not mean to be committed for
// snapshot inspection.
std::set<uint64_t> prepared;
// We keep the list of txns comitted before we take the last snaphot.
// These should be the only seq numbers that will be found in the snapshot
std::set<uint64_t> committed_before;
ReOpen(); // to restart the db
WritePreparedTxnDB* wp_db = dynamic_cast<WritePreparedTxnDB*>(db);
assert(wp_db);
assert(wp_db->db_impl_);
// We continue until max advances a bit beyond the snapshot.
while (!snapshot || wp_db->max_evicted_seq_ < snapshot + 100) {
// do prepare for a transaction
wp_db->db_impl_->Put(wo, "key", "value"); // dummy put to inc db seq
seq++;
ASSERT_EQ(wp_db->db_impl_->GetLatestSequenceNumber(), seq);
wp_db->AddPrepared(seq);
prepared.insert(seq);
// If cur_txn is not started, do prepare for it.
if (!cur_txn) {
wp_db->db_impl_->Put(wo, "key", "value"); // dummy put to inc db seq
seq++;
ASSERT_EQ(wp_db->db_impl_->GetLatestSequenceNumber(), seq);
cur_txn = seq;
wp_db->AddPrepared(cur_txn);
} else { // else commit it
wp_db->db_impl_->Put(wo, "key", "value"); // dummy put to inc db seq
seq++;
ASSERT_EQ(wp_db->db_impl_->GetLatestSequenceNumber(), seq);
wp_db->AddCommitted(cur_txn, seq);
if (!snapshot) {
committed_before.insert(cur_txn);
}
cur_txn = 0;
}
if (num_snapshots < max_snapshots - 1) {
// Take preliminary snapshots
auto tmp_snapshot = db->GetSnapshot();
to_be_released.push_back(tmp_snapshot);
num_snapshots++;
} else if (gap_cnt < max_gap) {
// Wait for some gap before taking the final snapshot
gap_cnt++;
} else if (!snapshot) {
// Take the final snapshot if it is not already taken
auto tmp_snapshot = db->GetSnapshot();
to_be_released.push_back(tmp_snapshot);
snapshot = tmp_snapshot->GetSequenceNumber();
// We increase the db seq artificailly by a dummy Put. Check that this
// technique is effective and db seq is that same as ours.
ASSERT_EQ(snapshot, seq);
num_snapshots++;
}
// If the snapshot is taken, verify seq numbers visible to it. We redo
// it at each cycle to test that the system is still sound when
// max_evicted_seq_ advances.
if (snapshot) {
for (uint64_t s = 0; s <= seq; s++) {
bool was_committed =
(committed_before.find(s) != committed_before.end());
bool is_in_snapshot = wp_db->IsInSnapshot(s, snapshot);
if (was_committed != is_in_snapshot) {
printf("max_snapshots %d max_gap %d seq %" PRIu64 " max %" PRIu64
" snapshot %" PRIu64
" gap_cnt %d num_snapshots %d s %" PRIu64 "\n",
max_snapshots, max_gap, seq,
wp_db->max_evicted_seq_.load(), snapshot, gap_cnt,
num_snapshots, s);
}
ASSERT_EQ(was_committed, is_in_snapshot);
found_committed = found_committed || is_in_snapshot;
}
}
}
// Safety check to make sure the test actually ran
ASSERT_TRUE(found_committed);
// As an extra check, check if prepared set will be properly empty after
// they are committed.
if (cur_txn) {
wp_db->AddCommitted(cur_txn, seq);
}
for (auto p : prepared) {
wp_db->AddCommitted(p, seq);
}
ASSERT_TRUE(wp_db->delayed_prepared_.empty());
ASSERT_TRUE(wp_db->prepared_txns_.empty());
for (auto s : to_be_released) {
db->ReleaseSnapshot(s);
}
}
}
}
} // namespace rocksdb
int main(int argc, char** argv) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
#else
#include <stdio.h>
int main(int argc, char** argv) {
fprintf(stderr,
"SKIPPED as Transactions are not supported in ROCKSDB_LITE\n");
return 0;
}
#endif // ROCKSDB_LITE