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rocksdb/db/version_builder.cc
Levi Tamasi 7b1d6c438a Fix the handling of the case when a blob file with a lower number gets added in VersionBuilder (#7349) 
Summary:
When multiple background jobs are generating blob files in parallel, it is actually
possible for a blob file to be added with a file number that is lower than the
highest one in the base version. (This is a harmless race condition.) The patch
fixes the handling of this case and adds a unit test.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7349

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D23542453

Pulled By: ltamasi

fbshipit-source-id: 4ff6f3654bc58c391d10b9870e1cc40b5e3fa8e4
2020-09-09 10:25:12 -07:00

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// 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/version_builder.h"
#include <algorithm>
#include <atomic>
#include <cinttypes>
#include <functional>
#include <map>
#include <memory>
#include <set>
#include <sstream>
#include <thread>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
#include "db/blob/blob_file_meta.h"
#include "db/dbformat.h"
#include "db/internal_stats.h"
#include "db/table_cache.h"
#include "db/version_set.h"
#include "port/port.h"
#include "table/table_reader.h"
#include "util/string_util.h"
namespace ROCKSDB_NAMESPACE {
bool NewestFirstBySeqNo(FileMetaData* a, FileMetaData* b) {
if (a->fd.largest_seqno != b->fd.largest_seqno) {
return a->fd.largest_seqno > b->fd.largest_seqno;
}
if (a->fd.smallest_seqno != b->fd.smallest_seqno) {
return a->fd.smallest_seqno > b->fd.smallest_seqno;
}
// Break ties by file number
return a->fd.GetNumber() > b->fd.GetNumber();
}
namespace {
bool BySmallestKey(FileMetaData* a, FileMetaData* b,
const InternalKeyComparator* cmp) {
int r = cmp->Compare(a->smallest, b->smallest);
if (r != 0) {
return (r < 0);
}
// Break ties by file number
return (a->fd.GetNumber() < b->fd.GetNumber());
}
} // namespace
class VersionBuilder::Rep {
private:
// Helper to sort files_ in v
// kLevel0 -- NewestFirstBySeqNo
// kLevelNon0 -- BySmallestKey
struct FileComparator {
enum SortMethod { kLevel0 = 0, kLevelNon0 = 1, } sort_method;
const InternalKeyComparator* internal_comparator;
FileComparator() : internal_comparator(nullptr) {}
bool operator()(FileMetaData* f1, FileMetaData* f2) const {
switch (sort_method) {
case kLevel0:
return NewestFirstBySeqNo(f1, f2);
case kLevelNon0:
return BySmallestKey(f1, f2, internal_comparator);
}
assert(false);
return false;
}
};
struct LevelState {
std::unordered_set<uint64_t> deleted_files;
// Map from file number to file meta data.
std::unordered_map<uint64_t, FileMetaData*> added_files;
};
class BlobFileMetaDataDelta {
public:
bool IsEmpty() const {
return !shared_meta_ && !additional_garbage_count_ &&
!additional_garbage_bytes_ && newly_linked_ssts_.empty() &&
newly_unlinked_ssts_.empty();
}
std::shared_ptr<SharedBlobFileMetaData> GetSharedMeta() const {
return shared_meta_;
}
uint64_t GetAdditionalGarbageCount() const {
return additional_garbage_count_;
}
uint64_t GetAdditionalGarbageBytes() const {
return additional_garbage_bytes_;
}
const std::unordered_set<uint64_t>& GetNewlyLinkedSsts() const {
return newly_linked_ssts_;
}
const std::unordered_set<uint64_t>& GetNewlyUnlinkedSsts() const {
return newly_unlinked_ssts_;
}
void SetSharedMeta(std::shared_ptr<SharedBlobFileMetaData> shared_meta) {
assert(!shared_meta_);
assert(shared_meta);
shared_meta_ = std::move(shared_meta);
}
void AddGarbage(uint64_t count, uint64_t bytes) {
additional_garbage_count_ += count;
additional_garbage_bytes_ += bytes;
}
void LinkSst(uint64_t sst_file_number) {
assert(newly_linked_ssts_.find(sst_file_number) ==
newly_linked_ssts_.end());
// Reconcile with newly unlinked SSTs on the fly. (Note: an SST can be
// linked to and unlinked from the same blob file in the case of a trivial
// move.)
auto it = newly_unlinked_ssts_.find(sst_file_number);
if (it != newly_unlinked_ssts_.end()) {
newly_unlinked_ssts_.erase(it);
} else {
newly_linked_ssts_.emplace(sst_file_number);
}
}
void UnlinkSst(uint64_t sst_file_number) {
assert(newly_unlinked_ssts_.find(sst_file_number) ==
newly_unlinked_ssts_.end());
// Reconcile with newly linked SSTs on the fly. (Note: an SST can be
// linked to and unlinked from the same blob file in the case of a trivial
// move.)
auto it = newly_linked_ssts_.find(sst_file_number);
if (it != newly_linked_ssts_.end()) {
newly_linked_ssts_.erase(it);
} else {
newly_unlinked_ssts_.emplace(sst_file_number);
}
}
private:
std::shared_ptr<SharedBlobFileMetaData> shared_meta_;
uint64_t additional_garbage_count_ = 0;
uint64_t additional_garbage_bytes_ = 0;
std::unordered_set<uint64_t> newly_linked_ssts_;
std::unordered_set<uint64_t> newly_unlinked_ssts_;
};
const FileOptions& file_options_;
const ImmutableCFOptions* const ioptions_;
TableCache* table_cache_;
VersionStorageInfo* base_vstorage_;
VersionSet* version_set_;
int num_levels_;
LevelState* levels_;
// Store sizes of levels larger than num_levels_. We do this instead of
// storing them in levels_ to avoid regression in case there are no files
// on invalid levels. The version is not consistent if in the end the files
// on invalid levels don't cancel out.
std::unordered_map<int, size_t> invalid_level_sizes_;
// Whether there are invalid new files or invalid deletion on levels larger
// than num_levels_.
bool has_invalid_levels_;
// Current levels of table files affected by additions/deletions.
std::unordered_map<uint64_t, int> table_file_levels_;
FileComparator level_zero_cmp_;
FileComparator level_nonzero_cmp_;
// Metadata delta for all blob files affected by the series of version edits.
std::map<uint64_t, BlobFileMetaDataDelta> blob_file_meta_deltas_;
public:
Rep(const FileOptions& file_options, const ImmutableCFOptions* ioptions,
TableCache* table_cache, VersionStorageInfo* base_vstorage,
VersionSet* version_set)
: file_options_(file_options),
ioptions_(ioptions),
table_cache_(table_cache),
base_vstorage_(base_vstorage),
version_set_(version_set),
num_levels_(base_vstorage->num_levels()),
has_invalid_levels_(false) {
assert(ioptions_);
levels_ = new LevelState[num_levels_];
level_zero_cmp_.sort_method = FileComparator::kLevel0;
level_nonzero_cmp_.sort_method = FileComparator::kLevelNon0;
level_nonzero_cmp_.internal_comparator =
base_vstorage_->InternalComparator();
}
~Rep() {
for (int level = 0; level < num_levels_; level++) {
const auto& added = levels_[level].added_files;
for (auto& pair : added) {
UnrefFile(pair.second);
}
}
delete[] levels_;
}
void UnrefFile(FileMetaData* f) {
f->refs--;
if (f->refs <= 0) {
if (f->table_reader_handle) {
assert(table_cache_ != nullptr);
table_cache_->ReleaseHandle(f->table_reader_handle);
f->table_reader_handle = nullptr;
}
delete f;
}
}
bool IsBlobFileInVersion(uint64_t blob_file_number) const {
auto delta_it = blob_file_meta_deltas_.find(blob_file_number);
if (delta_it != blob_file_meta_deltas_.end()) {
if (delta_it->second.GetSharedMeta()) {
return true;
}
}
assert(base_vstorage_);
const auto& base_blob_files = base_vstorage_->GetBlobFiles();
auto base_it = base_blob_files.find(blob_file_number);
if (base_it != base_blob_files.end()) {
assert(base_it->second);
assert(base_it->second->GetSharedMeta());
return true;
}
return false;
}
using ExpectedLinkedSsts =
std::unordered_map<uint64_t, BlobFileMetaData::LinkedSsts>;
static void UpdateExpectedLinkedSsts(
uint64_t table_file_number, uint64_t blob_file_number,
ExpectedLinkedSsts* expected_linked_ssts) {
assert(expected_linked_ssts);
if (blob_file_number == kInvalidBlobFileNumber) {
return;
}
(*expected_linked_ssts)[blob_file_number].emplace(table_file_number);
}
Status CheckConsistency(VersionStorageInfo* vstorage) {
#ifdef NDEBUG
if (!vstorage->force_consistency_checks()) {
// Dont run consistency checks in release mode except if
// explicitly asked to
return Status::OK();
}
#endif
// Make sure the files are sorted correctly and that the links between
// table files and blob files are consistent. The latter is checked using
// the following mapping, which is built using the forward links
// (table file -> blob file), and is subsequently compared with the inverse
// mapping stored in the BlobFileMetaData objects.
ExpectedLinkedSsts expected_linked_ssts;
for (int level = 0; level < num_levels_; level++) {
auto& level_files = vstorage->LevelFiles(level);
if (level_files.empty()) {
continue;
}
assert(level_files[0]);
UpdateExpectedLinkedSsts(level_files[0]->fd.GetNumber(),
level_files[0]->oldest_blob_file_number,
&expected_linked_ssts);
for (size_t i = 1; i < level_files.size(); i++) {
assert(level_files[i]);
UpdateExpectedLinkedSsts(level_files[i]->fd.GetNumber(),
level_files[i]->oldest_blob_file_number,
&expected_linked_ssts);
auto f1 = level_files[i - 1];
auto f2 = level_files[i];
if (level == 0) {
#ifndef NDEBUG
auto pair = std::make_pair(&f1, &f2);
TEST_SYNC_POINT_CALLBACK("VersionBuilder::CheckConsistency0", &pair);
#endif
if (!level_zero_cmp_(f1, f2)) {
return Status::Corruption("L0 files are not sorted properly");
}
if (f2->fd.smallest_seqno == f2->fd.largest_seqno) {
// This is an external file that we ingested
SequenceNumber external_file_seqno = f2->fd.smallest_seqno;
if (!(external_file_seqno < f1->fd.largest_seqno ||
external_file_seqno == 0)) {
return Status::Corruption(
"L0 file with seqno " +
NumberToString(f1->fd.smallest_seqno) + " " +
NumberToString(f1->fd.largest_seqno) +
" vs. file with global_seqno" +
NumberToString(external_file_seqno) + " with fileNumber " +
NumberToString(f1->fd.GetNumber()));
}
} else if (f1->fd.smallest_seqno <= f2->fd.smallest_seqno) {
return Status::Corruption(
"L0 files seqno " + NumberToString(f1->fd.smallest_seqno) +
" " + NumberToString(f1->fd.largest_seqno) + " " +
NumberToString(f1->fd.GetNumber()) + " vs. " +
NumberToString(f2->fd.smallest_seqno) + " " +
NumberToString(f2->fd.largest_seqno) + " " +
NumberToString(f2->fd.GetNumber()));
}
} else {
#ifndef NDEBUG
auto pair = std::make_pair(&f1, &f2);
TEST_SYNC_POINT_CALLBACK("VersionBuilder::CheckConsistency1", &pair);
#endif
if (!level_nonzero_cmp_(f1, f2)) {
return Status::Corruption("L" + NumberToString(level) +
" files are not sorted properly");
}
// Make sure there is no overlap in levels > 0
if (vstorage->InternalComparator()->Compare(f1->largest,
f2->smallest) >= 0) {
return Status::Corruption(
"L" + NumberToString(level) + " have overlapping ranges " +
(f1->largest).DebugString(true) + " vs. " +
(f2->smallest).DebugString(true));
}
}
}
}
// Make sure that all blob files in the version have non-garbage data.
const auto& blob_files = vstorage->GetBlobFiles();
for (const auto& pair : blob_files) {
const uint64_t blob_file_number = pair.first;
const auto& blob_file_meta = pair.second;
assert(blob_file_meta);
if (blob_file_meta->GetGarbageBlobCount() >=
blob_file_meta->GetTotalBlobCount()) {
std::ostringstream oss;
oss << "Blob file #" << blob_file_number
<< " consists entirely of garbage";
return Status::Corruption("VersionBuilder", oss.str());
}
if (blob_file_meta->GetLinkedSsts() !=
expected_linked_ssts[blob_file_number]) {
std::ostringstream oss;
oss << "Links are inconsistent between table files and blob file #"
<< blob_file_number;
return Status::Corruption("VersionBuilder", oss.str());
}
}
Status ret_s;
TEST_SYNC_POINT_CALLBACK("VersionBuilder::CheckConsistencyBeforeReturn",
&ret_s);
return ret_s;
}
bool CheckConsistencyForNumLevels() const {
// Make sure there are no files on or beyond num_levels().
if (has_invalid_levels_) {
return false;
}
for (const auto& pair : invalid_level_sizes_) {
const size_t level_size = pair.second;
if (level_size != 0) {
return false;
}
}
return true;
}
Status ApplyBlobFileAddition(const BlobFileAddition& blob_file_addition) {
const uint64_t blob_file_number = blob_file_addition.GetBlobFileNumber();
if (IsBlobFileInVersion(blob_file_number)) {
std::ostringstream oss;
oss << "Blob file #" << blob_file_number << " already added";
return Status::Corruption("VersionBuilder", oss.str());
}
// Note: we use C++11 for now but in C++14, this could be done in a more
// elegant way using generalized lambda capture.
VersionSet* const vs = version_set_;
const ImmutableCFOptions* const ioptions = ioptions_;
auto deleter = [vs, ioptions](SharedBlobFileMetaData* shared_meta) {
if (vs) {
assert(ioptions);
assert(!ioptions->cf_paths.empty());
assert(shared_meta);
vs->AddObsoleteBlobFile(shared_meta->GetBlobFileNumber(),
ioptions->cf_paths.front().path);
}
delete shared_meta;
};
auto shared_meta = SharedBlobFileMetaData::Create(
blob_file_number, blob_file_addition.GetTotalBlobCount(),
blob_file_addition.GetTotalBlobBytes(),
blob_file_addition.GetChecksumMethod(),
blob_file_addition.GetChecksumValue(), deleter);
blob_file_meta_deltas_[blob_file_number].SetSharedMeta(
std::move(shared_meta));
return Status::OK();
}
Status ApplyBlobFileGarbage(const BlobFileGarbage& blob_file_garbage) {
const uint64_t blob_file_number = blob_file_garbage.GetBlobFileNumber();
if (!IsBlobFileInVersion(blob_file_number)) {
std::ostringstream oss;
oss << "Blob file #" << blob_file_number << " not found";
return Status::Corruption("VersionBuilder", oss.str());
}
blob_file_meta_deltas_[blob_file_number].AddGarbage(
blob_file_garbage.GetGarbageBlobCount(),
blob_file_garbage.GetGarbageBlobBytes());
return Status::OK();
}
int GetCurrentLevelForTableFile(uint64_t file_number) const {
auto it = table_file_levels_.find(file_number);
if (it != table_file_levels_.end()) {
return it->second;
}
assert(base_vstorage_);
return base_vstorage_->GetFileLocation(file_number).GetLevel();
}
uint64_t GetOldestBlobFileNumberForTableFile(int level,
uint64_t file_number) const {
assert(level < num_levels_);
const auto& added_files = levels_[level].added_files;
auto it = added_files.find(file_number);
if (it != added_files.end()) {
const FileMetaData* const meta = it->second;
assert(meta);
return meta->oldest_blob_file_number;
}
assert(base_vstorage_);
const FileMetaData* const meta =
base_vstorage_->GetFileMetaDataByNumber(file_number);
assert(meta);
return meta->oldest_blob_file_number;
}
Status ApplyFileDeletion(int level, uint64_t file_number) {
assert(level != VersionStorageInfo::FileLocation::Invalid().GetLevel());
const int current_level = GetCurrentLevelForTableFile(file_number);
if (level != current_level) {
if (level >= num_levels_) {
has_invalid_levels_ = true;
}
std::ostringstream oss;
oss << "Cannot delete table file #" << file_number << " from level "
<< level << " since it is ";
if (current_level ==
VersionStorageInfo::FileLocation::Invalid().GetLevel()) {
oss << "not in the LSM tree";
} else {
oss << "on level " << current_level;
}
return Status::Corruption("VersionBuilder", oss.str());
}
if (level >= num_levels_) {
assert(invalid_level_sizes_[level] > 0);
--invalid_level_sizes_[level];
table_file_levels_[file_number] =
VersionStorageInfo::FileLocation::Invalid().GetLevel();
return Status::OK();
}
const uint64_t blob_file_number =
GetOldestBlobFileNumberForTableFile(level, file_number);
if (blob_file_number != kInvalidBlobFileNumber &&
IsBlobFileInVersion(blob_file_number)) {
blob_file_meta_deltas_[blob_file_number].UnlinkSst(file_number);
}
auto& level_state = levels_[level];
auto& add_files = level_state.added_files;
auto add_it = add_files.find(file_number);
if (add_it != add_files.end()) {
UnrefFile(add_it->second);
add_files.erase(add_it);
}
auto& del_files = level_state.deleted_files;
assert(del_files.find(file_number) == del_files.end());
del_files.emplace(file_number);
table_file_levels_[file_number] =
VersionStorageInfo::FileLocation::Invalid().GetLevel();
return Status::OK();
}
Status ApplyFileAddition(int level, const FileMetaData& meta) {
assert(level != VersionStorageInfo::FileLocation::Invalid().GetLevel());
const uint64_t file_number = meta.fd.GetNumber();
const int current_level = GetCurrentLevelForTableFile(file_number);
if (current_level !=
VersionStorageInfo::FileLocation::Invalid().GetLevel()) {
if (level >= num_levels_) {
has_invalid_levels_ = true;
}
std::ostringstream oss;
oss << "Cannot add table file #" << file_number << " to level " << level
<< " since it is already in the LSM tree on level " << current_level;
return Status::Corruption("VersionBuilder", oss.str());
}
if (level >= num_levels_) {
++invalid_level_sizes_[level];
table_file_levels_[file_number] = level;
return Status::OK();
}
auto& level_state = levels_[level];
auto& del_files = level_state.deleted_files;
auto del_it = del_files.find(file_number);
if (del_it != del_files.end()) {
del_files.erase(del_it);
}
FileMetaData* const f = new FileMetaData(meta);
f->refs = 1;
auto& add_files = level_state.added_files;
assert(add_files.find(file_number) == add_files.end());
add_files.emplace(file_number, f);
const uint64_t blob_file_number = f->oldest_blob_file_number;
if (blob_file_number != kInvalidBlobFileNumber &&
IsBlobFileInVersion(blob_file_number)) {
blob_file_meta_deltas_[blob_file_number].LinkSst(file_number);
}
table_file_levels_[file_number] = level;
return Status::OK();
}
// Apply all of the edits in *edit to the current state.
Status Apply(VersionEdit* edit) {
{
const Status s = CheckConsistency(base_vstorage_);
if (!s.ok()) {
return s;
}
}
// Note: we process the blob file related changes first because the
// table file addition/deletion logic depends on the blob files
// already being there.
// Add new blob files
for (const auto& blob_file_addition : edit->GetBlobFileAdditions()) {
const Status s = ApplyBlobFileAddition(blob_file_addition);
if (!s.ok()) {
return s;
}
}
// Increase the amount of garbage for blob files affected by GC
for (const auto& blob_file_garbage : edit->GetBlobFileGarbages()) {
const Status s = ApplyBlobFileGarbage(blob_file_garbage);
if (!s.ok()) {
return s;
}
}
// Delete table files
for (const auto& deleted_file : edit->GetDeletedFiles()) {
const int level = deleted_file.first;
const uint64_t file_number = deleted_file.second;
const Status s = ApplyFileDeletion(level, file_number);
if (!s.ok()) {
return s;
}
}
// Add new table files
for (const auto& new_file : edit->GetNewFiles()) {
const int level = new_file.first;
const FileMetaData& meta = new_file.second;
const Status s = ApplyFileAddition(level, meta);
if (!s.ok()) {
return s;
}
}
return Status::OK();
}
static BlobFileMetaData::LinkedSsts ApplyLinkedSstChanges(
const BlobFileMetaData::LinkedSsts& base,
const std::unordered_set<uint64_t>& newly_linked,
const std::unordered_set<uint64_t>& newly_unlinked) {
BlobFileMetaData::LinkedSsts result(base);
for (uint64_t sst_file_number : newly_unlinked) {
assert(result.find(sst_file_number) != result.end());
result.erase(sst_file_number);
}
for (uint64_t sst_file_number : newly_linked) {
assert(result.find(sst_file_number) == result.end());
result.emplace(sst_file_number);
}
return result;
}
static std::shared_ptr<BlobFileMetaData> CreateMetaDataForNewBlobFile(
const BlobFileMetaDataDelta& delta) {
auto shared_meta = delta.GetSharedMeta();
assert(shared_meta);
assert(delta.GetNewlyUnlinkedSsts().empty());
auto meta = BlobFileMetaData::Create(
std::move(shared_meta), delta.GetNewlyLinkedSsts(),
delta.GetAdditionalGarbageCount(), delta.GetAdditionalGarbageBytes());
return meta;
}
static std::shared_ptr<BlobFileMetaData>
GetOrCreateMetaDataForExistingBlobFile(
const std::shared_ptr<BlobFileMetaData>& base_meta,
const BlobFileMetaDataDelta& delta) {
assert(base_meta);
assert(!delta.GetSharedMeta());
if (delta.IsEmpty()) {
return base_meta;
}
auto shared_meta = base_meta->GetSharedMeta();
assert(shared_meta);
auto linked_ssts = ApplyLinkedSstChanges(base_meta->GetLinkedSsts(),
delta.GetNewlyLinkedSsts(),
delta.GetNewlyUnlinkedSsts());
auto meta = BlobFileMetaData::Create(
std::move(shared_meta), std::move(linked_ssts),
base_meta->GetGarbageBlobCount() + delta.GetAdditionalGarbageCount(),
base_meta->GetGarbageBlobBytes() + delta.GetAdditionalGarbageBytes());
return meta;
}
// Add the blob file specified by meta to *vstorage if it is determined to
// contain valid data (blobs). We make this decision based on the amount
// of garbage in the file, and whether the file or any lower-numbered blob
// files have any linked SSTs. The latter condition is tracked using the
// flag *found_first_non_empty.
void AddBlobFileIfNeeded(VersionStorageInfo* vstorage,
const std::shared_ptr<BlobFileMetaData>& meta,
bool* found_first_non_empty) const {
assert(vstorage);
assert(meta);
assert(found_first_non_empty);
if (!meta->GetLinkedSsts().empty()) {
(*found_first_non_empty) = true;
} else if (!(*found_first_non_empty) ||
meta->GetGarbageBlobCount() >= meta->GetTotalBlobCount()) {
return;
}
vstorage->AddBlobFile(meta);
}
// Merge the blob file metadata from the base version with the changes (edits)
// applied, and save the result into *vstorage.
void SaveBlobFilesTo(VersionStorageInfo* vstorage) const {
assert(base_vstorage_);
assert(vstorage);
bool found_first_non_empty = false;
const auto& base_blob_files = base_vstorage_->GetBlobFiles();
auto base_it = base_blob_files.begin();
const auto base_it_end = base_blob_files.end();
auto delta_it = blob_file_meta_deltas_.begin();
const auto delta_it_end = blob_file_meta_deltas_.end();
while (base_it != base_it_end && delta_it != delta_it_end) {
const uint64_t base_blob_file_number = base_it->first;
const uint64_t delta_blob_file_number = delta_it->first;
if (base_blob_file_number < delta_blob_file_number) {
const auto& base_meta = base_it->second;
AddBlobFileIfNeeded(vstorage, base_meta, &found_first_non_empty);
++base_it;
} else if (delta_blob_file_number < base_blob_file_number) {
const auto& delta = delta_it->second;
auto meta = CreateMetaDataForNewBlobFile(delta);
AddBlobFileIfNeeded(vstorage, meta, &found_first_non_empty);
++delta_it;
} else {
assert(base_blob_file_number == delta_blob_file_number);
const auto& base_meta = base_it->second;
const auto& delta = delta_it->second;
auto meta = GetOrCreateMetaDataForExistingBlobFile(base_meta, delta);
AddBlobFileIfNeeded(vstorage, meta, &found_first_non_empty);
++base_it;
++delta_it;
}
}
while (base_it != base_it_end) {
const auto& base_meta = base_it->second;
AddBlobFileIfNeeded(vstorage, base_meta, &found_first_non_empty);
++base_it;
}
while (delta_it != delta_it_end) {
const auto& delta = delta_it->second;
auto meta = CreateMetaDataForNewBlobFile(delta);
AddBlobFileIfNeeded(vstorage, meta, &found_first_non_empty);
++delta_it;
}
}
// Save the current state in *v.
Status SaveTo(VersionStorageInfo* vstorage) {
Status s = CheckConsistency(base_vstorage_);
if (!s.ok()) {
return s;
}
s = CheckConsistency(vstorage);
if (!s.ok()) {
return s;
}
for (int level = 0; level < num_levels_; level++) {
const auto& cmp = (level == 0) ? level_zero_cmp_ : level_nonzero_cmp_;
// Merge the set of added files with the set of pre-existing files.
// Drop any deleted files. Store the result in *v.
const auto& base_files = base_vstorage_->LevelFiles(level);
const auto& unordered_added_files = levels_[level].added_files;
vstorage->Reserve(level,
base_files.size() + unordered_added_files.size());
// Sort added files for the level.
std::vector<FileMetaData*> added_files;
added_files.reserve(unordered_added_files.size());
for (const auto& pair : unordered_added_files) {
added_files.push_back(pair.second);
}
std::sort(added_files.begin(), added_files.end(), cmp);
#ifndef NDEBUG
FileMetaData* prev_added_file = nullptr;
for (const auto& added : added_files) {
if (level > 0 && prev_added_file != nullptr) {
assert(base_vstorage_->InternalComparator()->Compare(
prev_added_file->smallest, added->smallest) <= 0);
}
prev_added_file = added;
}
#endif
auto base_iter = base_files.begin();
auto base_end = base_files.end();
auto added_iter = added_files.begin();
auto added_end = added_files.end();
while (added_iter != added_end || base_iter != base_end) {
if (base_iter == base_end ||
(added_iter != added_end && cmp(*added_iter, *base_iter))) {
MaybeAddFile(vstorage, level, *added_iter++);
} else {
MaybeAddFile(vstorage, level, *base_iter++);
}
}
}
SaveBlobFilesTo(vstorage);
s = CheckConsistency(vstorage);
return s;
}
Status LoadTableHandlers(InternalStats* internal_stats, int max_threads,
bool prefetch_index_and_filter_in_cache,
bool is_initial_load,
const SliceTransform* prefix_extractor,
size_t max_file_size_for_l0_meta_pin) {
assert(table_cache_ != nullptr);
size_t table_cache_capacity = table_cache_->get_cache()->GetCapacity();
bool always_load = (table_cache_capacity == TableCache::kInfiniteCapacity);
size_t max_load = port::kMaxSizet;
if (!always_load) {
// If it is initial loading and not set to always loading all the
// files, we only load up to kInitialLoadLimit files, to limit the
// time reopening the DB.
const size_t kInitialLoadLimit = 16;
size_t load_limit;
// If the table cache is not 1/4 full, we pin the table handle to
// file metadata to avoid the cache read costs when reading the file.
// The downside of pinning those files is that LRU won't be followed
// for those files. This doesn't matter much because if number of files
// of the DB excceeds table cache capacity, eventually no table reader
// will be pinned and LRU will be followed.
if (is_initial_load) {
load_limit = std::min(kInitialLoadLimit, table_cache_capacity / 4);
} else {
load_limit = table_cache_capacity / 4;
}
size_t table_cache_usage = table_cache_->get_cache()->GetUsage();
if (table_cache_usage >= load_limit) {
// TODO (yanqin) find a suitable status code.
return Status::OK();
} else {
max_load = load_limit - table_cache_usage;
}
}
// <file metadata, level>
std::vector<std::pair<FileMetaData*, int>> files_meta;
std::vector<Status> statuses;
for (int level = 0; level < num_levels_; level++) {
for (auto& file_meta_pair : levels_[level].added_files) {
auto* file_meta = file_meta_pair.second;
// If the file has been opened before, just skip it.
if (!file_meta->table_reader_handle) {
files_meta.emplace_back(file_meta, level);
statuses.emplace_back(Status::OK());
}
if (files_meta.size() >= max_load) {
break;
}
}
if (files_meta.size() >= max_load) {
break;
}
}
std::atomic<size_t> next_file_meta_idx(0);
std::function<void()> load_handlers_func([&]() {
while (true) {
size_t file_idx = next_file_meta_idx.fetch_add(1);
if (file_idx >= files_meta.size()) {
break;
}
auto* file_meta = files_meta[file_idx].first;
int level = files_meta[file_idx].second;
statuses[file_idx] = table_cache_->FindTable(
ReadOptions(), file_options_,
*(base_vstorage_->InternalComparator()), file_meta->fd,
&file_meta->table_reader_handle, prefix_extractor, false /*no_io */,
true /* record_read_stats */,
internal_stats->GetFileReadHist(level), false, level,
prefetch_index_and_filter_in_cache, max_file_size_for_l0_meta_pin);
if (file_meta->table_reader_handle != nullptr) {
// Load table_reader
file_meta->fd.table_reader = table_cache_->GetTableReaderFromHandle(
file_meta->table_reader_handle);
}
}
});
std::vector<port::Thread> threads;
for (int i = 1; i < max_threads; i++) {
threads.emplace_back(load_handlers_func);
}
load_handlers_func();
for (auto& t : threads) {
t.join();
}
for (const auto& s : statuses) {
if (!s.ok()) {
return s;
}
}
return Status::OK();
}
void MaybeAddFile(VersionStorageInfo* vstorage, int level, FileMetaData* f) {
const uint64_t file_number = f->fd.GetNumber();
const auto& level_state = levels_[level];
const auto& del_files = level_state.deleted_files;
const auto del_it = del_files.find(file_number);
if (del_it != del_files.end()) {
// f is to-be-deleted table file
vstorage->RemoveCurrentStats(f);
} else {
const auto& add_files = level_state.added_files;
const auto add_it = add_files.find(file_number);
// Note: if the file appears both in the base version and in the added
// list, the added FileMetaData supersedes the one in the base version.
if (add_it != add_files.end() && add_it->second != f) {
vstorage->RemoveCurrentStats(f);
} else {
vstorage->AddFile(level, f);
}
}
}
};
VersionBuilder::VersionBuilder(const FileOptions& file_options,
const ImmutableCFOptions* ioptions,
TableCache* table_cache,
VersionStorageInfo* base_vstorage,
VersionSet* version_set)
: rep_(new Rep(file_options, ioptions, table_cache, base_vstorage,
version_set)) {}
VersionBuilder::~VersionBuilder() = default;
bool VersionBuilder::CheckConsistencyForNumLevels() {
return rep_->CheckConsistencyForNumLevels();
}
Status VersionBuilder::Apply(VersionEdit* edit) { return rep_->Apply(edit); }
Status VersionBuilder::SaveTo(VersionStorageInfo* vstorage) {
return rep_->SaveTo(vstorage);
}
Status VersionBuilder::LoadTableHandlers(
InternalStats* internal_stats, int max_threads,
bool prefetch_index_and_filter_in_cache, bool is_initial_load,
const SliceTransform* prefix_extractor,
size_t max_file_size_for_l0_meta_pin) {
return rep_->LoadTableHandlers(
internal_stats, max_threads, prefetch_index_and_filter_in_cache,
is_initial_load, prefix_extractor, max_file_size_for_l0_meta_pin);
}
BaseReferencedVersionBuilder::BaseReferencedVersionBuilder(
ColumnFamilyData* cfd)
: version_builder_(new VersionBuilder(
cfd->current()->version_set()->file_options(), cfd->ioptions(),
cfd->table_cache(), cfd->current()->storage_info(),
cfd->current()->version_set())),
version_(cfd->current()) {
version_->Ref();
}
BaseReferencedVersionBuilder::BaseReferencedVersionBuilder(
ColumnFamilyData* cfd, Version* v)
: version_builder_(new VersionBuilder(
cfd->current()->version_set()->file_options(), cfd->ioptions(),
cfd->table_cache(), v->storage_info(), v->version_set())),
version_(v) {
assert(version_ != cfd->current());
}
BaseReferencedVersionBuilder::~BaseReferencedVersionBuilder() {
version_->Unref();
}
} // namespace ROCKSDB_NAMESPACE
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