rocksdb/db/memtable_list_test.cc
Siying Dong d59549298f Skip deleted WALs during recovery
Summary:
This patch record min log number to keep to the manifest while flushing SST files to ignore them and any WAL older than them during recovery. This is to avoid scenarios when we have a gap between the WAL files are fed to the recovery procedure. The gap could happen by for example out-of-order WAL deletion. Such gap could cause problems in 2PC recovery where the prepared and commit entry are placed into two separate WAL and gap in the WALs could result into not processing the WAL with the commit entry and hence breaking the 2PC recovery logic.

Before the commit, for 2PC case, we determined which log number to keep in FindObsoleteFiles(). We looked at the earliest logs with outstanding prepare entries, or prepare entries whose respective commit or abort are in memtable. With the commit, the same calculation is done while we apply the SST flush. Just before installing the flush file, we precompute the earliest log file to keep after the flush finishes using the same logic (but skipping the memtables just flushed), record this information to the manifest entry for this new flushed SST file. This pre-computed value is also remembered in memory, and will later be used to determine whether a log file can be deleted. This value is unlikely to change until next flush because the commit entry will stay in memtable. (In WritePrepared, we could have removed the older log files as soon as all prepared entries are committed. It's not yet done anyway. Even if we do it, the only thing we loss with this new approach is earlier log deletion between two flushes, which does not guarantee to happen anyway because the obsolete file clean-up function is only executed after flush or compaction)

This min log number to keep is stored in the manifest using the safely-ignore customized field of AddFile entry, in order to guarantee that the DB generated using newer release can be opened by previous releases no older than 4.2.
Closes https://github.com/facebook/rocksdb/pull/3765

Differential Revision: D7747618

Pulled By: siying

fbshipit-source-id: d00c92105b4f83852e9754a1b70d6b64cb590729
2018-05-03 15:43:09 -07:00

616 lines
21 KiB
C++

// 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).
#include "db/memtable_list.h"
#include <algorithm>
#include <string>
#include <vector>
#include "db/merge_context.h"
#include "db/range_del_aggregator.h"
#include "db/version_set.h"
#include "db/write_controller.h"
#include "rocksdb/db.h"
#include "rocksdb/status.h"
#include "rocksdb/write_buffer_manager.h"
#include "util/string_util.h"
#include "util/testharness.h"
#include "util/testutil.h"
namespace rocksdb {
class MemTableListTest : public testing::Test {
public:
std::string dbname;
DB* db;
Options options;
MemTableListTest() : db(nullptr) {
dbname = test::TmpDir() + "/memtable_list_test";
}
// Create a test db if not yet created
void CreateDB() {
if (db == nullptr) {
options.create_if_missing = true;
DestroyDB(dbname, options);
Status s = DB::Open(options, dbname, &db);
EXPECT_OK(s);
}
}
~MemTableListTest() {
if (db) {
delete db;
DestroyDB(dbname, options);
}
}
// Calls MemTableList::InstallMemtableFlushResults() and sets up all
// structures needed to call this function.
Status Mock_InstallMemtableFlushResults(
MemTableList* list, const MutableCFOptions& mutable_cf_options,
const autovector<MemTable*>& m, autovector<MemTable*>* to_delete) {
// Create a mock Logger
test::NullLogger logger;
LogBuffer log_buffer(DEBUG_LEVEL, &logger);
// Create a mock VersionSet
DBOptions db_options;
ImmutableDBOptions immutable_db_options(db_options);
EnvOptions env_options;
shared_ptr<Cache> table_cache(NewLRUCache(50000, 16));
WriteBufferManager write_buffer_manager(db_options.db_write_buffer_size);
WriteController write_controller(10000000u);
CreateDB();
VersionSet versions(dbname, &immutable_db_options, env_options,
table_cache.get(), &write_buffer_manager,
&write_controller);
// Create mock default ColumnFamilyData
ColumnFamilyOptions cf_options;
std::vector<ColumnFamilyDescriptor> column_families;
column_families.emplace_back(kDefaultColumnFamilyName, cf_options);
EXPECT_OK(versions.Recover(column_families, false));
auto column_family_set = versions.GetColumnFamilySet();
auto cfd = column_family_set->GetColumnFamily(0);
EXPECT_TRUE(cfd != nullptr);
// Create dummy mutex.
InstrumentedMutex mutex;
InstrumentedMutexLock l(&mutex);
LogsWithPrepTracker dummy_prep_tracker;
return list->InstallMemtableFlushResults(
cfd, mutable_cf_options, m, &dummy_prep_tracker, &versions, &mutex, 1,
to_delete, nullptr, &log_buffer);
}
};
TEST_F(MemTableListTest, Empty) {
// Create an empty MemTableList and validate basic functions.
MemTableList list(1, 0);
ASSERT_EQ(0, list.NumNotFlushed());
ASSERT_FALSE(list.imm_flush_needed.load(std::memory_order_acquire));
ASSERT_FALSE(list.IsFlushPending());
autovector<MemTable*> mems;
list.PickMemtablesToFlush(&mems);
ASSERT_EQ(0, mems.size());
autovector<MemTable*> to_delete;
list.current()->Unref(&to_delete);
ASSERT_EQ(0, to_delete.size());
}
TEST_F(MemTableListTest, GetTest) {
// Create MemTableList
int min_write_buffer_number_to_merge = 2;
int max_write_buffer_number_to_maintain = 0;
MemTableList list(min_write_buffer_number_to_merge,
max_write_buffer_number_to_maintain);
SequenceNumber seq = 1;
std::string value;
Status s;
MergeContext merge_context;
InternalKeyComparator ikey_cmp(options.comparator);
RangeDelAggregator range_del_agg(ikey_cmp, {} /* snapshots */);
autovector<MemTable*> to_delete;
LookupKey lkey("key1", seq);
bool found = list.current()->Get(lkey, &value, &s, &merge_context,
&range_del_agg, ReadOptions());
ASSERT_FALSE(found);
// Create a MemTable
InternalKeyComparator cmp(BytewiseComparator());
auto factory = std::make_shared<SkipListFactory>();
options.memtable_factory = factory;
ImmutableCFOptions ioptions(options);
WriteBufferManager wb(options.db_write_buffer_size);
MemTable* mem = new MemTable(cmp, ioptions, MutableCFOptions(options), &wb,
kMaxSequenceNumber, 0 /* column_family_id */);
mem->Ref();
// Write some keys to this memtable.
mem->Add(++seq, kTypeDeletion, "key1", "");
mem->Add(++seq, kTypeValue, "key2", "value2");
mem->Add(++seq, kTypeValue, "key1", "value1");
mem->Add(++seq, kTypeValue, "key2", "value2.2");
// Fetch the newly written keys
merge_context.Clear();
found = mem->Get(LookupKey("key1", seq), &value, &s, &merge_context,
&range_del_agg, ReadOptions());
ASSERT_TRUE(s.ok() && found);
ASSERT_EQ(value, "value1");
merge_context.Clear();
found = mem->Get(LookupKey("key1", 2), &value, &s, &merge_context,
&range_del_agg, ReadOptions());
// MemTable found out that this key is *not* found (at this sequence#)
ASSERT_TRUE(found && s.IsNotFound());
merge_context.Clear();
found = mem->Get(LookupKey("key2", seq), &value, &s, &merge_context,
&range_del_agg, ReadOptions());
ASSERT_TRUE(s.ok() && found);
ASSERT_EQ(value, "value2.2");
ASSERT_EQ(4, mem->num_entries());
ASSERT_EQ(1, mem->num_deletes());
// Add memtable to list
list.Add(mem, &to_delete);
SequenceNumber saved_seq = seq;
// Create another memtable and write some keys to it
WriteBufferManager wb2(options.db_write_buffer_size);
MemTable* mem2 = new MemTable(cmp, ioptions, MutableCFOptions(options), &wb2,
kMaxSequenceNumber, 0 /* column_family_id */);
mem2->Ref();
mem2->Add(++seq, kTypeDeletion, "key1", "");
mem2->Add(++seq, kTypeValue, "key2", "value2.3");
// Add second memtable to list
list.Add(mem2, &to_delete);
// Fetch keys via MemTableList
merge_context.Clear();
found = list.current()->Get(LookupKey("key1", seq), &value, &s,
&merge_context, &range_del_agg, ReadOptions());
ASSERT_TRUE(found && s.IsNotFound());
merge_context.Clear();
found = list.current()->Get(LookupKey("key1", saved_seq), &value, &s,
&merge_context, &range_del_agg, ReadOptions());
ASSERT_TRUE(s.ok() && found);
ASSERT_EQ("value1", value);
merge_context.Clear();
found = list.current()->Get(LookupKey("key2", seq), &value, &s,
&merge_context, &range_del_agg, ReadOptions());
ASSERT_TRUE(s.ok() && found);
ASSERT_EQ(value, "value2.3");
merge_context.Clear();
found = list.current()->Get(LookupKey("key2", 1), &value, &s, &merge_context,
&range_del_agg, ReadOptions());
ASSERT_FALSE(found);
ASSERT_EQ(2, list.NumNotFlushed());
list.current()->Unref(&to_delete);
for (MemTable* m : to_delete) {
delete m;
}
}
TEST_F(MemTableListTest, GetFromHistoryTest) {
// Create MemTableList
int min_write_buffer_number_to_merge = 2;
int max_write_buffer_number_to_maintain = 2;
MemTableList list(min_write_buffer_number_to_merge,
max_write_buffer_number_to_maintain);
SequenceNumber seq = 1;
std::string value;
Status s;
MergeContext merge_context;
InternalKeyComparator ikey_cmp(options.comparator);
RangeDelAggregator range_del_agg(ikey_cmp, {} /* snapshots */);
autovector<MemTable*> to_delete;
LookupKey lkey("key1", seq);
bool found = list.current()->Get(lkey, &value, &s, &merge_context,
&range_del_agg, ReadOptions());
ASSERT_FALSE(found);
// Create a MemTable
InternalKeyComparator cmp(BytewiseComparator());
auto factory = std::make_shared<SkipListFactory>();
options.memtable_factory = factory;
ImmutableCFOptions ioptions(options);
WriteBufferManager wb(options.db_write_buffer_size);
MemTable* mem = new MemTable(cmp, ioptions, MutableCFOptions(options), &wb,
kMaxSequenceNumber, 0 /* column_family_id */);
mem->Ref();
// Write some keys to this memtable.
mem->Add(++seq, kTypeDeletion, "key1", "");
mem->Add(++seq, kTypeValue, "key2", "value2");
mem->Add(++seq, kTypeValue, "key2", "value2.2");
// Fetch the newly written keys
merge_context.Clear();
found = mem->Get(LookupKey("key1", seq), &value, &s, &merge_context,
&range_del_agg, ReadOptions());
// MemTable found out that this key is *not* found (at this sequence#)
ASSERT_TRUE(found && s.IsNotFound());
merge_context.Clear();
found = mem->Get(LookupKey("key2", seq), &value, &s, &merge_context,
&range_del_agg, ReadOptions());
ASSERT_TRUE(s.ok() && found);
ASSERT_EQ(value, "value2.2");
// Add memtable to list
list.Add(mem, &to_delete);
ASSERT_EQ(0, to_delete.size());
// Fetch keys via MemTableList
merge_context.Clear();
found = list.current()->Get(LookupKey("key1", seq), &value, &s,
&merge_context, &range_del_agg, ReadOptions());
ASSERT_TRUE(found && s.IsNotFound());
merge_context.Clear();
found = list.current()->Get(LookupKey("key2", seq), &value, &s,
&merge_context, &range_del_agg, ReadOptions());
ASSERT_TRUE(s.ok() && found);
ASSERT_EQ("value2.2", value);
// Flush this memtable from the list.
// (It will then be a part of the memtable history).
autovector<MemTable*> to_flush;
list.PickMemtablesToFlush(&to_flush);
ASSERT_EQ(1, to_flush.size());
s = Mock_InstallMemtableFlushResults(&list, MutableCFOptions(options),
to_flush, &to_delete);
ASSERT_OK(s);
ASSERT_EQ(0, list.NumNotFlushed());
ASSERT_EQ(1, list.NumFlushed());
ASSERT_EQ(0, to_delete.size());
// Verify keys are no longer in MemTableList
merge_context.Clear();
found = list.current()->Get(LookupKey("key1", seq), &value, &s,
&merge_context, &range_del_agg, ReadOptions());
ASSERT_FALSE(found);
merge_context.Clear();
found = list.current()->Get(LookupKey("key2", seq), &value, &s,
&merge_context, &range_del_agg, ReadOptions());
ASSERT_FALSE(found);
// Verify keys are present in history
merge_context.Clear();
found = list.current()->GetFromHistory(LookupKey("key1", seq), &value, &s,
&merge_context, &range_del_agg,
ReadOptions());
ASSERT_TRUE(found && s.IsNotFound());
merge_context.Clear();
found = list.current()->GetFromHistory(LookupKey("key2", seq), &value, &s,
&merge_context, &range_del_agg,
ReadOptions());
ASSERT_TRUE(found);
ASSERT_EQ("value2.2", value);
// Create another memtable and write some keys to it
WriteBufferManager wb2(options.db_write_buffer_size);
MemTable* mem2 = new MemTable(cmp, ioptions, MutableCFOptions(options), &wb2,
kMaxSequenceNumber, 0 /* column_family_id */);
mem2->Ref();
mem2->Add(++seq, kTypeDeletion, "key1", "");
mem2->Add(++seq, kTypeValue, "key3", "value3");
// Add second memtable to list
list.Add(mem2, &to_delete);
ASSERT_EQ(0, to_delete.size());
to_flush.clear();
list.PickMemtablesToFlush(&to_flush);
ASSERT_EQ(1, to_flush.size());
// Flush second memtable
s = Mock_InstallMemtableFlushResults(&list, MutableCFOptions(options),
to_flush, &to_delete);
ASSERT_OK(s);
ASSERT_EQ(0, list.NumNotFlushed());
ASSERT_EQ(2, list.NumFlushed());
ASSERT_EQ(0, to_delete.size());
// Add a third memtable to push the first memtable out of the history
WriteBufferManager wb3(options.db_write_buffer_size);
MemTable* mem3 = new MemTable(cmp, ioptions, MutableCFOptions(options), &wb3,
kMaxSequenceNumber, 0 /* column_family_id */);
mem3->Ref();
list.Add(mem3, &to_delete);
ASSERT_EQ(1, list.NumNotFlushed());
ASSERT_EQ(1, list.NumFlushed());
ASSERT_EQ(1, to_delete.size());
// Verify keys are no longer in MemTableList
merge_context.Clear();
found = list.current()->Get(LookupKey("key1", seq), &value, &s,
&merge_context, &range_del_agg, ReadOptions());
ASSERT_FALSE(found);
merge_context.Clear();
found = list.current()->Get(LookupKey("key2", seq), &value, &s,
&merge_context, &range_del_agg, ReadOptions());
ASSERT_FALSE(found);
merge_context.Clear();
found = list.current()->Get(LookupKey("key3", seq), &value, &s,
&merge_context, &range_del_agg, ReadOptions());
ASSERT_FALSE(found);
// Verify that the second memtable's keys are in the history
merge_context.Clear();
found = list.current()->GetFromHistory(LookupKey("key1", seq), &value, &s,
&merge_context, &range_del_agg,
ReadOptions());
ASSERT_TRUE(found && s.IsNotFound());
merge_context.Clear();
found = list.current()->GetFromHistory(LookupKey("key3", seq), &value, &s,
&merge_context, &range_del_agg,
ReadOptions());
ASSERT_TRUE(found);
ASSERT_EQ("value3", value);
// Verify that key2 from the first memtable is no longer in the history
merge_context.Clear();
found = list.current()->Get(LookupKey("key2", seq), &value, &s,
&merge_context, &range_del_agg, ReadOptions());
ASSERT_FALSE(found);
// Cleanup
list.current()->Unref(&to_delete);
ASSERT_EQ(3, to_delete.size());
for (MemTable* m : to_delete) {
delete m;
}
}
TEST_F(MemTableListTest, FlushPendingTest) {
const int num_tables = 5;
SequenceNumber seq = 1;
Status s;
auto factory = std::make_shared<SkipListFactory>();
options.memtable_factory = factory;
ImmutableCFOptions ioptions(options);
InternalKeyComparator cmp(BytewiseComparator());
WriteBufferManager wb(options.db_write_buffer_size);
autovector<MemTable*> to_delete;
// Create MemTableList
int min_write_buffer_number_to_merge = 3;
int max_write_buffer_number_to_maintain = 7;
MemTableList list(min_write_buffer_number_to_merge,
max_write_buffer_number_to_maintain);
// Create some MemTables
std::vector<MemTable*> tables;
MutableCFOptions mutable_cf_options(options);
for (int i = 0; i < num_tables; i++) {
MemTable* mem = new MemTable(cmp, ioptions, mutable_cf_options, &wb,
kMaxSequenceNumber, 0 /* column_family_id */);
mem->Ref();
std::string value;
MergeContext merge_context;
mem->Add(++seq, kTypeValue, "key1", ToString(i));
mem->Add(++seq, kTypeValue, "keyN" + ToString(i), "valueN");
mem->Add(++seq, kTypeValue, "keyX" + ToString(i), "value");
mem->Add(++seq, kTypeValue, "keyM" + ToString(i), "valueM");
mem->Add(++seq, kTypeDeletion, "keyX" + ToString(i), "");
tables.push_back(mem);
}
// Nothing to flush
ASSERT_FALSE(list.IsFlushPending());
ASSERT_FALSE(list.imm_flush_needed.load(std::memory_order_acquire));
autovector<MemTable*> to_flush;
list.PickMemtablesToFlush(&to_flush);
ASSERT_EQ(0, to_flush.size());
// Request a flush even though there is nothing to flush
list.FlushRequested();
ASSERT_FALSE(list.IsFlushPending());
ASSERT_FALSE(list.imm_flush_needed.load(std::memory_order_acquire));
// Attempt to 'flush' to clear request for flush
list.PickMemtablesToFlush(&to_flush);
ASSERT_EQ(0, to_flush.size());
ASSERT_FALSE(list.IsFlushPending());
ASSERT_FALSE(list.imm_flush_needed.load(std::memory_order_acquire));
// Request a flush again
list.FlushRequested();
// No flush pending since the list is empty.
ASSERT_FALSE(list.IsFlushPending());
ASSERT_FALSE(list.imm_flush_needed.load(std::memory_order_acquire));
// Add 2 tables
list.Add(tables[0], &to_delete);
list.Add(tables[1], &to_delete);
ASSERT_EQ(2, list.NumNotFlushed());
ASSERT_EQ(0, to_delete.size());
// Even though we have less than the minimum to flush, a flush is
// pending since we had previously requested a flush and never called
// PickMemtablesToFlush() to clear the flush.
ASSERT_TRUE(list.IsFlushPending());
ASSERT_TRUE(list.imm_flush_needed.load(std::memory_order_acquire));
// Pick tables to flush
list.PickMemtablesToFlush(&to_flush);
ASSERT_EQ(2, to_flush.size());
ASSERT_EQ(2, list.NumNotFlushed());
ASSERT_FALSE(list.IsFlushPending());
ASSERT_FALSE(list.imm_flush_needed.load(std::memory_order_acquire));
// Revert flush
list.RollbackMemtableFlush(to_flush, 0);
ASSERT_FALSE(list.IsFlushPending());
ASSERT_TRUE(list.imm_flush_needed.load(std::memory_order_acquire));
to_flush.clear();
// Add another table
list.Add(tables[2], &to_delete);
// We now have the minimum to flush regardles of whether FlushRequested()
// was called.
ASSERT_TRUE(list.IsFlushPending());
ASSERT_TRUE(list.imm_flush_needed.load(std::memory_order_acquire));
ASSERT_EQ(0, to_delete.size());
// Pick tables to flush
list.PickMemtablesToFlush(&to_flush);
ASSERT_EQ(3, to_flush.size());
ASSERT_EQ(3, list.NumNotFlushed());
ASSERT_FALSE(list.IsFlushPending());
ASSERT_FALSE(list.imm_flush_needed.load(std::memory_order_acquire));
// Pick tables to flush again
autovector<MemTable*> to_flush2;
list.PickMemtablesToFlush(&to_flush2);
ASSERT_EQ(0, to_flush2.size());
ASSERT_EQ(3, list.NumNotFlushed());
ASSERT_FALSE(list.IsFlushPending());
ASSERT_FALSE(list.imm_flush_needed.load(std::memory_order_acquire));
// Add another table
list.Add(tables[3], &to_delete);
ASSERT_FALSE(list.IsFlushPending());
ASSERT_TRUE(list.imm_flush_needed.load(std::memory_order_acquire));
ASSERT_EQ(0, to_delete.size());
// Request a flush again
list.FlushRequested();
ASSERT_TRUE(list.IsFlushPending());
ASSERT_TRUE(list.imm_flush_needed.load(std::memory_order_acquire));
// Pick tables to flush again
list.PickMemtablesToFlush(&to_flush2);
ASSERT_EQ(1, to_flush2.size());
ASSERT_EQ(4, list.NumNotFlushed());
ASSERT_FALSE(list.IsFlushPending());
ASSERT_FALSE(list.imm_flush_needed.load(std::memory_order_acquire));
// Rollback first pick of tables
list.RollbackMemtableFlush(to_flush, 0);
ASSERT_TRUE(list.IsFlushPending());
ASSERT_TRUE(list.imm_flush_needed.load(std::memory_order_acquire));
to_flush.clear();
// Add another tables
list.Add(tables[4], &to_delete);
ASSERT_EQ(5, list.NumNotFlushed());
// We now have the minimum to flush regardles of whether FlushRequested()
ASSERT_TRUE(list.IsFlushPending());
ASSERT_TRUE(list.imm_flush_needed.load(std::memory_order_acquire));
ASSERT_EQ(0, to_delete.size());
// Pick tables to flush
list.PickMemtablesToFlush(&to_flush);
// Should pick 4 of 5 since 1 table has been picked in to_flush2
ASSERT_EQ(4, to_flush.size());
ASSERT_EQ(5, list.NumNotFlushed());
ASSERT_FALSE(list.IsFlushPending());
ASSERT_FALSE(list.imm_flush_needed.load(std::memory_order_acquire));
// Pick tables to flush again
autovector<MemTable*> to_flush3;
ASSERT_EQ(0, to_flush3.size()); // nothing not in progress of being flushed
ASSERT_EQ(5, list.NumNotFlushed());
ASSERT_FALSE(list.IsFlushPending());
ASSERT_FALSE(list.imm_flush_needed.load(std::memory_order_acquire));
// Flush the 4 memtables that were picked in to_flush
s = Mock_InstallMemtableFlushResults(&list, MutableCFOptions(options),
to_flush, &to_delete);
ASSERT_OK(s);
// Note: now to_flush contains tables[0,1,2,4]. to_flush2 contains
// tables[3].
// Current implementation will only commit memtables in the order they were
// created. So InstallMemtableFlushResults will install the first 3 tables
// in to_flush and stop when it encounters a table not yet flushed.
ASSERT_EQ(2, list.NumNotFlushed());
int num_in_history = std::min(3, max_write_buffer_number_to_maintain);
ASSERT_EQ(num_in_history, list.NumFlushed());
ASSERT_EQ(5 - list.NumNotFlushed() - num_in_history, to_delete.size());
// Request a flush again. Should be nothing to flush
list.FlushRequested();
ASSERT_FALSE(list.IsFlushPending());
ASSERT_FALSE(list.imm_flush_needed.load(std::memory_order_acquire));
// Flush the 1 memtable that was picked in to_flush2
s = MemTableListTest::Mock_InstallMemtableFlushResults(
&list, MutableCFOptions(options), to_flush2, &to_delete);
ASSERT_OK(s);
// This will actually install 2 tables. The 1 we told it to flush, and also
// tables[4] which has been waiting for tables[3] to commit.
ASSERT_EQ(0, list.NumNotFlushed());
num_in_history = std::min(5, max_write_buffer_number_to_maintain);
ASSERT_EQ(num_in_history, list.NumFlushed());
ASSERT_EQ(5 - list.NumNotFlushed() - num_in_history, to_delete.size());
for (const auto& m : to_delete) {
// Refcount should be 0 after calling InstallMemtableFlushResults.
// Verify this, by Ref'ing then UnRef'ing:
m->Ref();
ASSERT_EQ(m, m->Unref());
delete m;
}
to_delete.clear();
list.current()->Unref(&to_delete);
int to_delete_size = std::min(5, max_write_buffer_number_to_maintain);
ASSERT_EQ(to_delete_size, to_delete.size());
for (const auto& m : to_delete) {
// Refcount should be 0 after calling InstallMemtableFlushResults.
// Verify this, by Ref'ing then UnRef'ing:
m->Ref();
ASSERT_EQ(m, m->Unref());
delete m;
}
to_delete.clear();
}
} // namespace rocksdb
int main(int argc, char** argv) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}