rocksdb/db/table_cache.cc
Levi Tamasi 6301dbe7a7 Use function objects as deleters in the block cache (#6545)
Summary:
As the first step of reintroducing eviction statistics for the block
cache, the patch switches from using simple function pointers as deleters
to function objects implementing an interface. This will enable using
deleters that have state, like a smart pointer to the statistics object
that is to be updated when an entry is removed from the cache. For now,
the patch adds a deleter template class `SimpleDeleter`, which simply
casts the `value` pointer to its original type and calls `delete` or
`delete[]` on it as appropriate. Note: to prevent object lifecycle
issues, deleters must outlive the cache entries referring to them;
`SimpleDeleter` ensures this by using the ("leaky") Meyers singleton
pattern.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6545

Test Plan: `make asan_check`

Reviewed By: siying

Differential Revision: D20475823

Pulled By: ltamasi

fbshipit-source-id: fe354c33dd96d9bafc094605462352305449a22a
2020-03-26 16:19:58 -07:00

664 lines
25 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).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/table_cache.h"
#include "cache/simple_deleter.h"
#include "db/dbformat.h"
#include "db/range_tombstone_fragmenter.h"
#include "db/snapshot_impl.h"
#include "db/version_edit.h"
#include "file/filename.h"
#include "file/random_access_file_reader.h"
#include "monitoring/perf_context_imp.h"
#include "rocksdb/statistics.h"
#include "table/block_based/block_based_table_reader.h"
#include "table/get_context.h"
#include "table/internal_iterator.h"
#include "table/iterator_wrapper.h"
#include "table/multiget_context.h"
#include "table/table_builder.h"
#include "table/table_reader.h"
#include "test_util/sync_point.h"
#include "util/cast_util.h"
#include "util/coding.h"
#include "util/stop_watch.h"
namespace ROCKSDB_NAMESPACE {
namespace {
static void UnrefEntry(void* arg1, void* arg2) {
Cache* cache = reinterpret_cast<Cache*>(arg1);
Cache::Handle* h = reinterpret_cast<Cache::Handle*>(arg2);
cache->Release(h);
}
static Slice GetSliceForFileNumber(const uint64_t* file_number) {
return Slice(reinterpret_cast<const char*>(file_number),
sizeof(*file_number));
}
#ifndef ROCKSDB_LITE
void AppendVarint64(IterKey* key, uint64_t v) {
char buf[10];
auto ptr = EncodeVarint64(buf, v);
key->TrimAppend(key->Size(), buf, ptr - buf);
}
#endif // ROCKSDB_LITE
} // namespace
TableCache::TableCache(const ImmutableCFOptions& ioptions,
const FileOptions& file_options, Cache* const cache,
BlockCacheTracer* const block_cache_tracer)
: ioptions_(ioptions),
file_options_(file_options),
cache_(cache),
immortal_tables_(false),
block_cache_tracer_(block_cache_tracer) {
if (ioptions_.row_cache) {
// If the same cache is shared by multiple instances, we need to
// disambiguate its entries.
PutVarint64(&row_cache_id_, ioptions_.row_cache->NewId());
}
}
TableCache::~TableCache() {
}
TableReader* TableCache::GetTableReaderFromHandle(Cache::Handle* handle) {
return reinterpret_cast<TableReader*>(cache_->Value(handle));
}
void TableCache::ReleaseHandle(Cache::Handle* handle) {
cache_->Release(handle);
}
Status TableCache::GetTableReader(
const FileOptions& file_options,
const InternalKeyComparator& internal_comparator, const FileDescriptor& fd,
bool sequential_mode, bool record_read_stats, HistogramImpl* file_read_hist,
std::unique_ptr<TableReader>* table_reader,
const SliceTransform* prefix_extractor, bool skip_filters, int level,
bool prefetch_index_and_filter_in_cache) {
std::string fname =
TableFileName(ioptions_.cf_paths, fd.GetNumber(), fd.GetPathId());
std::unique_ptr<FSRandomAccessFile> file;
Status s = ioptions_.fs->NewRandomAccessFile(fname, file_options, &file,
nullptr);
RecordTick(ioptions_.statistics, NO_FILE_OPENS);
if (s.IsPathNotFound()) {
fname = Rocks2LevelTableFileName(fname);
s = ioptions_.fs->NewRandomAccessFile(fname, file_options, &file, nullptr);
RecordTick(ioptions_.statistics, NO_FILE_OPENS);
}
if (s.ok()) {
if (!sequential_mode && ioptions_.advise_random_on_open) {
file->Hint(FSRandomAccessFile::kRandom);
}
StopWatch sw(ioptions_.env, ioptions_.statistics, TABLE_OPEN_IO_MICROS);
std::unique_ptr<RandomAccessFileReader> file_reader(
new RandomAccessFileReader(
std::move(file), fname, ioptions_.env,
record_read_stats ? ioptions_.statistics : nullptr, SST_READ_MICROS,
file_read_hist, ioptions_.rate_limiter, ioptions_.listeners));
s = ioptions_.table_factory->NewTableReader(
TableReaderOptions(ioptions_, prefix_extractor, file_options,
internal_comparator, skip_filters, immortal_tables_,
level, fd.largest_seqno, block_cache_tracer_),
std::move(file_reader), fd.GetFileSize(), table_reader,
prefetch_index_and_filter_in_cache);
TEST_SYNC_POINT("TableCache::GetTableReader:0");
}
return s;
}
void TableCache::EraseHandle(const FileDescriptor& fd, Cache::Handle* handle) {
ReleaseHandle(handle);
uint64_t number = fd.GetNumber();
Slice key = GetSliceForFileNumber(&number);
cache_->Erase(key);
}
Status TableCache::FindTable(const FileOptions& file_options,
const InternalKeyComparator& internal_comparator,
const FileDescriptor& fd, Cache::Handle** handle,
const SliceTransform* prefix_extractor,
const bool no_io, bool record_read_stats,
HistogramImpl* file_read_hist, bool skip_filters,
int level,
bool prefetch_index_and_filter_in_cache) {
PERF_TIMER_GUARD_WITH_ENV(find_table_nanos, ioptions_.env);
Status s;
uint64_t number = fd.GetNumber();
Slice key = GetSliceForFileNumber(&number);
*handle = cache_->Lookup(key);
TEST_SYNC_POINT_CALLBACK("TableCache::FindTable:0",
const_cast<bool*>(&no_io));
if (*handle == nullptr) {
if (no_io) { // Don't do IO and return a not-found status
return Status::Incomplete("Table not found in table_cache, no_io is set");
}
std::unique_ptr<TableReader> table_reader;
s = GetTableReader(file_options, internal_comparator, fd,
false /* sequential mode */, record_read_stats,
file_read_hist, &table_reader, prefix_extractor,
skip_filters, level, prefetch_index_and_filter_in_cache);
if (!s.ok()) {
assert(table_reader == nullptr);
RecordTick(ioptions_.statistics, NO_FILE_ERRORS);
// We do not cache error results so that if the error is transient,
// or somebody repairs the file, we recover automatically.
} else {
s = cache_->Insert(key, table_reader.get(), 1,
SimpleDeleter<TableReader>::GetInstance(), handle);
if (s.ok()) {
// Release ownership of table reader.
table_reader.release();
}
}
}
return s;
}
InternalIterator* TableCache::NewIterator(
const ReadOptions& options, const FileOptions& file_options,
const InternalKeyComparator& icomparator, const FileMetaData& file_meta,
RangeDelAggregator* range_del_agg, const SliceTransform* prefix_extractor,
TableReader** table_reader_ptr, HistogramImpl* file_read_hist,
TableReaderCaller caller, Arena* arena, bool skip_filters, int level,
const InternalKey* smallest_compaction_key,
const InternalKey* largest_compaction_key) {
PERF_TIMER_GUARD(new_table_iterator_nanos);
Status s;
TableReader* table_reader = nullptr;
Cache::Handle* handle = nullptr;
if (table_reader_ptr != nullptr) {
*table_reader_ptr = nullptr;
}
bool for_compaction = caller == TableReaderCaller::kCompaction;
auto& fd = file_meta.fd;
table_reader = fd.table_reader;
if (table_reader == nullptr) {
s = FindTable(file_options, icomparator, fd, &handle, prefix_extractor,
options.read_tier == kBlockCacheTier /* no_io */,
!for_compaction /* record_read_stats */, file_read_hist,
skip_filters, level);
if (s.ok()) {
table_reader = GetTableReaderFromHandle(handle);
}
}
InternalIterator* result = nullptr;
if (s.ok()) {
if (options.table_filter &&
!options.table_filter(*table_reader->GetTableProperties())) {
result = NewEmptyInternalIterator<Slice>(arena);
} else {
result = table_reader->NewIterator(options, prefix_extractor, arena,
skip_filters, caller,
file_options.compaction_readahead_size);
}
if (handle != nullptr) {
result->RegisterCleanup(&UnrefEntry, cache_, handle);
handle = nullptr; // prevent from releasing below
}
if (for_compaction) {
table_reader->SetupForCompaction();
}
if (table_reader_ptr != nullptr) {
*table_reader_ptr = table_reader;
}
}
if (s.ok() && range_del_agg != nullptr && !options.ignore_range_deletions) {
if (range_del_agg->AddFile(fd.GetNumber())) {
std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter(
static_cast<FragmentedRangeTombstoneIterator*>(
table_reader->NewRangeTombstoneIterator(options)));
if (range_del_iter != nullptr) {
s = range_del_iter->status();
}
if (s.ok()) {
const InternalKey* smallest = &file_meta.smallest;
const InternalKey* largest = &file_meta.largest;
if (smallest_compaction_key != nullptr) {
smallest = smallest_compaction_key;
}
if (largest_compaction_key != nullptr) {
largest = largest_compaction_key;
}
range_del_agg->AddTombstones(std::move(range_del_iter), smallest,
largest);
}
}
}
if (handle != nullptr) {
ReleaseHandle(handle);
}
if (!s.ok()) {
assert(result == nullptr);
result = NewErrorInternalIterator<Slice>(s, arena);
}
return result;
}
Status TableCache::GetRangeTombstoneIterator(
const ReadOptions& options,
const InternalKeyComparator& internal_comparator,
const FileMetaData& file_meta,
std::unique_ptr<FragmentedRangeTombstoneIterator>* out_iter) {
const FileDescriptor& fd = file_meta.fd;
Status s;
TableReader* t = fd.table_reader;
Cache::Handle* handle = nullptr;
if (t == nullptr) {
s = FindTable(file_options_, internal_comparator, fd, &handle);
if (s.ok()) {
t = GetTableReaderFromHandle(handle);
}
}
if (s.ok()) {
out_iter->reset(t->NewRangeTombstoneIterator(options));
assert(out_iter);
}
return s;
}
#ifndef ROCKSDB_LITE
void TableCache::CreateRowCacheKeyPrefix(const ReadOptions& options,
const FileDescriptor& fd,
const Slice& internal_key,
GetContext* get_context,
IterKey& row_cache_key) {
uint64_t fd_number = fd.GetNumber();
// We use the user key as cache key instead of the internal key,
// otherwise the whole cache would be invalidated every time the
// sequence key increases. However, to support caching snapshot
// reads, we append the sequence number (incremented by 1 to
// distinguish from 0) only in this case.
// If the snapshot is larger than the largest seqno in the file,
// all data should be exposed to the snapshot, so we treat it
// the same as there is no snapshot. The exception is that if
// a seq-checking callback is registered, some internal keys
// may still be filtered out.
uint64_t seq_no = 0;
// Maybe we can include the whole file ifsnapshot == fd.largest_seqno.
if (options.snapshot != nullptr &&
(get_context->has_callback() ||
static_cast_with_check<const SnapshotImpl, const Snapshot>(
options.snapshot)
->GetSequenceNumber() <= fd.largest_seqno)) {
// We should consider to use options.snapshot->GetSequenceNumber()
// instead of GetInternalKeySeqno(k), which will make the code
// easier to understand.
seq_no = 1 + GetInternalKeySeqno(internal_key);
}
// Compute row cache key.
row_cache_key.TrimAppend(row_cache_key.Size(), row_cache_id_.data(),
row_cache_id_.size());
AppendVarint64(&row_cache_key, fd_number);
AppendVarint64(&row_cache_key, seq_no);
}
bool TableCache::GetFromRowCache(const Slice& user_key, IterKey& row_cache_key,
size_t prefix_size, GetContext* get_context) {
bool found = false;
row_cache_key.TrimAppend(prefix_size, user_key.data(), user_key.size());
if (auto row_handle =
ioptions_.row_cache->Lookup(row_cache_key.GetUserKey())) {
// Cleanable routine to release the cache entry
Cleanable value_pinner;
auto release_cache_entry_func = [](void* cache_to_clean,
void* cache_handle) {
((Cache*)cache_to_clean)->Release((Cache::Handle*)cache_handle);
};
auto found_row_cache_entry =
static_cast<const std::string*>(ioptions_.row_cache->Value(row_handle));
// If it comes here value is located on the cache.
// found_row_cache_entry points to the value on cache,
// and value_pinner has cleanup procedure for the cached entry.
// After replayGetContextLog() returns, get_context.pinnable_slice_
// will point to cache entry buffer (or a copy based on that) and
// cleanup routine under value_pinner will be delegated to
// get_context.pinnable_slice_. Cache entry is released when
// get_context.pinnable_slice_ is reset.
value_pinner.RegisterCleanup(release_cache_entry_func,
ioptions_.row_cache.get(), row_handle);
replayGetContextLog(*found_row_cache_entry, user_key, get_context,
&value_pinner);
RecordTick(ioptions_.statistics, ROW_CACHE_HIT);
found = true;
} else {
RecordTick(ioptions_.statistics, ROW_CACHE_MISS);
}
return found;
}
#endif // ROCKSDB_LITE
Status TableCache::Get(const ReadOptions& options,
const InternalKeyComparator& internal_comparator,
const FileMetaData& file_meta, const Slice& k,
GetContext* get_context,
const SliceTransform* prefix_extractor,
HistogramImpl* file_read_hist, bool skip_filters,
int level) {
auto& fd = file_meta.fd;
std::string* row_cache_entry = nullptr;
bool done = false;
#ifndef ROCKSDB_LITE
IterKey row_cache_key;
std::string row_cache_entry_buffer;
// Check row cache if enabled. Since row cache does not currently store
// sequence numbers, we cannot use it if we need to fetch the sequence.
if (ioptions_.row_cache && !get_context->NeedToReadSequence()) {
auto user_key = ExtractUserKey(k);
CreateRowCacheKeyPrefix(options, fd, k, get_context, row_cache_key);
done = GetFromRowCache(user_key, row_cache_key, row_cache_key.Size(),
get_context);
if (!done) {
row_cache_entry = &row_cache_entry_buffer;
}
}
#endif // ROCKSDB_LITE
Status s;
TableReader* t = fd.table_reader;
Cache::Handle* handle = nullptr;
if (!done && s.ok()) {
if (t == nullptr) {
s = FindTable(
file_options_, internal_comparator, fd, &handle, prefix_extractor,
options.read_tier == kBlockCacheTier /* no_io */,
true /* record_read_stats */, file_read_hist, skip_filters, level);
if (s.ok()) {
t = GetTableReaderFromHandle(handle);
}
}
SequenceNumber* max_covering_tombstone_seq =
get_context->max_covering_tombstone_seq();
if (s.ok() && max_covering_tombstone_seq != nullptr &&
!options.ignore_range_deletions) {
std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter(
t->NewRangeTombstoneIterator(options));
if (range_del_iter != nullptr) {
*max_covering_tombstone_seq = std::max(
*max_covering_tombstone_seq,
range_del_iter->MaxCoveringTombstoneSeqnum(ExtractUserKey(k)));
}
}
if (s.ok()) {
get_context->SetReplayLog(row_cache_entry); // nullptr if no cache.
s = t->Get(options, k, get_context, prefix_extractor, skip_filters);
get_context->SetReplayLog(nullptr);
} else if (options.read_tier == kBlockCacheTier && s.IsIncomplete()) {
// Couldn't find Table in cache but treat as kFound if no_io set
get_context->MarkKeyMayExist();
s = Status::OK();
done = true;
}
}
#ifndef ROCKSDB_LITE
// Put the replay log in row cache only if something was found.
if (!done && s.ok() && row_cache_entry && !row_cache_entry->empty()) {
size_t charge =
row_cache_key.Size() + row_cache_entry->size() + sizeof(std::string);
void* row_ptr = new std::string(std::move(*row_cache_entry));
ioptions_.row_cache->Insert(row_cache_key.GetUserKey(), row_ptr, charge,
SimpleDeleter<std::string>::GetInstance());
}
#endif // ROCKSDB_LITE
if (handle != nullptr) {
ReleaseHandle(handle);
}
return s;
}
// Batched version of TableCache::MultiGet.
Status TableCache::MultiGet(const ReadOptions& options,
const InternalKeyComparator& internal_comparator,
const FileMetaData& file_meta,
const MultiGetContext::Range* mget_range,
const SliceTransform* prefix_extractor,
HistogramImpl* file_read_hist, bool skip_filters,
int level) {
auto& fd = file_meta.fd;
Status s;
TableReader* t = fd.table_reader;
Cache::Handle* handle = nullptr;
MultiGetRange table_range(*mget_range, mget_range->begin(),
mget_range->end());
#ifndef ROCKSDB_LITE
autovector<std::string, MultiGetContext::MAX_BATCH_SIZE> row_cache_entries;
IterKey row_cache_key;
size_t row_cache_key_prefix_size = 0;
KeyContext& first_key = *table_range.begin();
bool lookup_row_cache =
ioptions_.row_cache && !first_key.get_context->NeedToReadSequence();
// Check row cache if enabled. Since row cache does not currently store
// sequence numbers, we cannot use it if we need to fetch the sequence.
if (lookup_row_cache) {
GetContext* first_context = first_key.get_context;
CreateRowCacheKeyPrefix(options, fd, first_key.ikey, first_context,
row_cache_key);
row_cache_key_prefix_size = row_cache_key.Size();
for (auto miter = table_range.begin(); miter != table_range.end();
++miter) {
const Slice& user_key = miter->ukey;
;
GetContext* get_context = miter->get_context;
if (GetFromRowCache(user_key, row_cache_key, row_cache_key_prefix_size,
get_context)) {
table_range.SkipKey(miter);
} else {
row_cache_entries.emplace_back();
get_context->SetReplayLog(&(row_cache_entries.back()));
}
}
}
#endif // ROCKSDB_LITE
// Check that table_range is not empty. Its possible all keys may have been
// found in the row cache and thus the range may now be empty
if (s.ok() && !table_range.empty()) {
if (t == nullptr) {
s = FindTable(
file_options_, internal_comparator, fd, &handle, prefix_extractor,
options.read_tier == kBlockCacheTier /* no_io */,
true /* record_read_stats */, file_read_hist, skip_filters, level);
TEST_SYNC_POINT_CALLBACK("TableCache::MultiGet:FindTable", &s);
if (s.ok()) {
t = GetTableReaderFromHandle(handle);
assert(t);
}
}
if (s.ok() && !options.ignore_range_deletions) {
std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter(
t->NewRangeTombstoneIterator(options));
if (range_del_iter != nullptr) {
for (auto iter = table_range.begin(); iter != table_range.end();
++iter) {
SequenceNumber* max_covering_tombstone_seq =
iter->get_context->max_covering_tombstone_seq();
*max_covering_tombstone_seq =
std::max(*max_covering_tombstone_seq,
range_del_iter->MaxCoveringTombstoneSeqnum(iter->ukey));
}
}
}
if (s.ok()) {
t->MultiGet(options, &table_range, prefix_extractor, skip_filters);
} else if (options.read_tier == kBlockCacheTier && s.IsIncomplete()) {
for (auto iter = table_range.begin(); iter != table_range.end(); ++iter) {
Status* status = iter->s;
if (status->IsIncomplete()) {
// Couldn't find Table in cache but treat as kFound if no_io set
iter->get_context->MarkKeyMayExist();
s = Status::OK();
}
}
}
}
#ifndef ROCKSDB_LITE
if (lookup_row_cache) {
size_t row_idx = 0;
for (auto miter = table_range.begin(); miter != table_range.end();
++miter) {
std::string& row_cache_entry = row_cache_entries[row_idx++];
const Slice& user_key = miter->ukey;
;
GetContext* get_context = miter->get_context;
get_context->SetReplayLog(nullptr);
// Compute row cache key.
row_cache_key.TrimAppend(row_cache_key_prefix_size, user_key.data(),
user_key.size());
// Put the replay log in row cache only if something was found.
if (s.ok() && !row_cache_entry.empty()) {
size_t charge =
row_cache_key.Size() + row_cache_entry.size() + sizeof(std::string);
void* row_ptr = new std::string(std::move(row_cache_entry));
ioptions_.row_cache->Insert(row_cache_key.GetUserKey(), row_ptr, charge,
SimpleDeleter<std::string>::GetInstance());
}
}
}
#endif // ROCKSDB_LITE
if (handle != nullptr) {
ReleaseHandle(handle);
}
return s;
}
Status TableCache::GetTableProperties(
const FileOptions& file_options,
const InternalKeyComparator& internal_comparator, const FileDescriptor& fd,
std::shared_ptr<const TableProperties>* properties,
const SliceTransform* prefix_extractor, bool no_io) {
Status s;
auto table_reader = fd.table_reader;
// table already been pre-loaded?
if (table_reader) {
*properties = table_reader->GetTableProperties();
return s;
}
Cache::Handle* table_handle = nullptr;
s = FindTable(file_options, internal_comparator, fd, &table_handle,
prefix_extractor, no_io);
if (!s.ok()) {
return s;
}
assert(table_handle);
auto table = GetTableReaderFromHandle(table_handle);
*properties = table->GetTableProperties();
ReleaseHandle(table_handle);
return s;
}
size_t TableCache::GetMemoryUsageByTableReader(
const FileOptions& file_options,
const InternalKeyComparator& internal_comparator, const FileDescriptor& fd,
const SliceTransform* prefix_extractor) {
Status s;
auto table_reader = fd.table_reader;
// table already been pre-loaded?
if (table_reader) {
return table_reader->ApproximateMemoryUsage();
}
Cache::Handle* table_handle = nullptr;
s = FindTable(file_options, internal_comparator, fd, &table_handle,
prefix_extractor, true);
if (!s.ok()) {
return 0;
}
assert(table_handle);
auto table = GetTableReaderFromHandle(table_handle);
auto ret = table->ApproximateMemoryUsage();
ReleaseHandle(table_handle);
return ret;
}
void TableCache::Evict(Cache* cache, uint64_t file_number) {
cache->Erase(GetSliceForFileNumber(&file_number));
}
uint64_t TableCache::ApproximateOffsetOf(
const Slice& key, const FileDescriptor& fd, TableReaderCaller caller,
const InternalKeyComparator& internal_comparator,
const SliceTransform* prefix_extractor) {
uint64_t result = 0;
TableReader* table_reader = fd.table_reader;
Cache::Handle* table_handle = nullptr;
if (table_reader == nullptr) {
const bool for_compaction = (caller == TableReaderCaller::kCompaction);
Status s = FindTable(file_options_, internal_comparator, fd, &table_handle,
prefix_extractor, false /* no_io */,
!for_compaction /* record_read_stats */);
if (s.ok()) {
table_reader = GetTableReaderFromHandle(table_handle);
}
}
if (table_reader != nullptr) {
result = table_reader->ApproximateOffsetOf(key, caller);
}
if (table_handle != nullptr) {
ReleaseHandle(table_handle);
}
return result;
}
uint64_t TableCache::ApproximateSize(
const Slice& start, const Slice& end, const FileDescriptor& fd,
TableReaderCaller caller, const InternalKeyComparator& internal_comparator,
const SliceTransform* prefix_extractor) {
uint64_t result = 0;
TableReader* table_reader = fd.table_reader;
Cache::Handle* table_handle = nullptr;
if (table_reader == nullptr) {
const bool for_compaction = (caller == TableReaderCaller::kCompaction);
Status s = FindTable(file_options_, internal_comparator, fd, &table_handle,
prefix_extractor, false /* no_io */,
!for_compaction /* record_read_stats */);
if (s.ok()) {
table_reader = GetTableReaderFromHandle(table_handle);
}
}
if (table_reader != nullptr) {
result = table_reader->ApproximateSize(start, end, caller);
}
if (table_handle != nullptr) {
ReleaseHandle(table_handle);
}
return result;
}
} // namespace ROCKSDB_NAMESPACE