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rocksdb/db/version_builder.cc
Levi Tamasi 44d04582cb Aggregate blob file related changes in VersionBuilder as VersionEdits are applied (#9085) 
Summary:
The current VersionBuilder code on mainline keeps track of blob file related
changes ("delta") induced by a series of `VersionEdit`s in the form of
`BlobFileMetaDataDelta` objects. Specifically, `BlobFileMetaDataDelta`
contains the amount of additional garbage generated by compactions, as well
as the set of newly linked/unlinked SSTs. This is very handy for detecting trivial moves,
since in that case the newly linked and unlinked SSTs cancel each other out.
However, this representation does not allow us to easily tell whether a certain
blob file is obsolete after applying a set of `VersionEdit`s or not. In order to
solve this issue, the patch introduces `MutableBlobFileMetaData`, which, in addition
to the delta, also contains the materialized state after applying a set of version edits
(i.e. the total amount of garbage and the resulting set of linked SSTs). This will
enable us to add further consistency checks and to improve certain pieces of
functionality where knowing up front which blob files get obsoleted is beneficial.
(Note: this patch is just the refactoring part; I plan to create separate PRs for
the enhancements.)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9085

Test Plan: Ran `make check` and the stress tests in BlobDB mode.

Reviewed By: riversand963

Differential Revision: D31980867

Pulled By: ltamasi

fbshipit-source-id: cc4286778b10900af720423d6b772c77f28a93e3
2021-10-29 17:47:02 -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;
};
// A class that represents the accumulated changes (like additional garbage or
// newly linked/unlinked SST files) for a given blob file after applying a
// series of VersionEdits.
class BlobFileMetaDataDelta {
public:
bool IsEmpty() const {
return !additional_garbage_count_ && !additional_garbage_bytes_ &&
newly_linked_ssts_.empty() && newly_unlinked_ssts_.empty();
}
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 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:
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_;
};
// A class that represents the state of a blob file after applying a series of
// VersionEdits. In addition to the resulting state, it also contains the
// delta (see BlobFileMetaDataDelta above). The resulting state can be used to
// identify obsolete blob files, while the delta makes it possible to
// efficiently detect trivial moves.
class MutableBlobFileMetaData {
public:
// To be used for brand new blob files
explicit MutableBlobFileMetaData(
std::shared_ptr<SharedBlobFileMetaData>&& shared_meta)
: shared_meta_(std::move(shared_meta)) {}
// To be used for pre-existing blob files
explicit MutableBlobFileMetaData(
const std::shared_ptr<BlobFileMetaData>& meta)
: shared_meta_(meta->GetSharedMeta()),
linked_ssts_(meta->GetLinkedSsts()),
garbage_blob_count_(meta->GetGarbageBlobCount()),
garbage_blob_bytes_(meta->GetGarbageBlobBytes()) {}
const std::shared_ptr<SharedBlobFileMetaData>& GetSharedMeta() const {
return shared_meta_;
}
bool HasDelta() const { return !delta_.IsEmpty(); }
const std::unordered_set<uint64_t>& GetLinkedSsts() const {
return linked_ssts_;
}
uint64_t GetGarbageBlobCount() const { return garbage_blob_count_; }
uint64_t GetGarbageBlobBytes() const { return garbage_blob_bytes_; }
void AddGarbage(uint64_t count, uint64_t bytes) {
delta_.AddGarbage(count, bytes);
garbage_blob_count_ += count;
garbage_blob_bytes_ += bytes;
}
void LinkSst(uint64_t sst_file_number) {
delta_.LinkSst(sst_file_number);
assert(linked_ssts_.find(sst_file_number) == linked_ssts_.end());
linked_ssts_.emplace(sst_file_number);
}
void UnlinkSst(uint64_t sst_file_number) {
delta_.UnlinkSst(sst_file_number);
assert(linked_ssts_.find(sst_file_number) != linked_ssts_.end());
linked_ssts_.erase(sst_file_number);
}
private:
std::shared_ptr<SharedBlobFileMetaData> shared_meta_;
// Accumulated changes
BlobFileMetaDataDelta delta_;
// Resulting state after applying the changes
BlobFileMetaData::LinkedSsts linked_ssts_;
uint64_t garbage_blob_count_ = 0;
uint64_t garbage_blob_bytes_ = 0;
};
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_;
// Mutable metadata objects for all blob files affected by the series of
// version edits.
std::map<uint64_t, MutableBlobFileMetaData> mutable_blob_file_metas_;
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;
}
}
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 CheckConsistencyDetails(VersionStorageInfo* vstorage) {
// 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 " + ToString(f1->fd.smallest_seqno) +
" " + ToString(f1->fd.largest_seqno) +
" vs. file with global_seqno" +
ToString(external_file_seqno) + " with fileNumber " +
ToString(f1->fd.GetNumber()));
}
} else if (f1->fd.smallest_seqno <= f2->fd.smallest_seqno) {
return Status::Corruption("L0 files seqno " +
ToString(f1->fd.smallest_seqno) + " " +
ToString(f1->fd.largest_seqno) + " " +
ToString(f1->fd.GetNumber()) + " vs. " +
ToString(f2->fd.smallest_seqno) + " " +
ToString(f2->fd.largest_seqno) + " " +
ToString(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" + ToString(level) +
" files are not sorted properly: files #" +
ToString(f1->fd.GetNumber()) + ", #" +
ToString(f2->fd.GetNumber()));
}
// Make sure there is no overlap in levels > 0
if (vstorage->InternalComparator()->Compare(f1->largest,
f2->smallest) >= 0) {
return Status::Corruption(
"L" + ToString(level) + " have overlapping ranges: file #" +
ToString(f1->fd.GetNumber()) +
" largest key: " + (f1->largest).DebugString(true) +
" vs. file #" + ToString(f2->fd.GetNumber()) +
" smallest key: " + (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;
}
Status CheckConsistency(VersionStorageInfo* vstorage) {
// Always run consistency checks in debug build
#ifdef NDEBUG
if (!vstorage->force_consistency_checks()) {
return Status::OK();
}
#endif
Status s = CheckConsistencyDetails(vstorage);
if (s.IsCorruption() && s.getState()) {
// Make it clear the error is due to force_consistency_checks = 1 or
// debug build
#ifdef NDEBUG
auto prefix = "force_consistency_checks";
#else
auto prefix = "force_consistency_checks(DEBUG)";
#endif
s = Status::Corruption(prefix, s.getState());
} else {
// was only expecting corruption with message, or OK
assert(s.ok());
}
return 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;
}
bool IsBlobFileInVersion(uint64_t blob_file_number) const {
auto mutable_it = mutable_blob_file_metas_.find(blob_file_number);
if (mutable_it != mutable_blob_file_metas_.end()) {
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()) {
return true;
}
return false;
}
MutableBlobFileMetaData* GetOrCreateMutableBlobFileMetaData(
uint64_t blob_file_number) {
auto mutable_it = mutable_blob_file_metas_.find(blob_file_number);
if (mutable_it != mutable_blob_file_metas_.end()) {
return &mutable_it->second;
}
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);
mutable_it = mutable_blob_file_metas_
.emplace(blob_file_number,
MutableBlobFileMetaData(base_it->second))
.first;
return &mutable_it->second;
}
return nullptr;
}
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);
mutable_blob_file_metas_.emplace(
blob_file_number, MutableBlobFileMetaData(std::move(shared_meta)));
return Status::OK();
}
Status ApplyBlobFileGarbage(const BlobFileGarbage& blob_file_garbage) {
const uint64_t blob_file_number = blob_file_garbage.GetBlobFileNumber();
MutableBlobFileMetaData* const mutable_meta =
GetOrCreateMutableBlobFileMetaData(blob_file_number);
if (!mutable_meta) {
std::ostringstream oss;
oss << "Blob file #" << blob_file_number << " not found";
return Status::Corruption("VersionBuilder", oss.str());
}
mutable_meta->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;
}
uint64_t GetMinOldestBlobFileNumber() const {
uint64_t min_oldest_blob_file_num = std::numeric_limits<uint64_t>::max();
for (int level = 0; level < num_levels_; ++level) {
const auto& base_files = base_vstorage_->LevelFiles(level);
for (const auto* fmeta : base_files) {
assert(fmeta);
min_oldest_blob_file_num =
std::min(min_oldest_blob_file_num, fmeta->oldest_blob_file_number);
}
const auto& added_files = levels_[level].added_files;
for (const auto& elem : added_files) {
assert(elem.second);
min_oldest_blob_file_num = std::min(
min_oldest_blob_file_num, elem.second->oldest_blob_file_number);
}
}
if (min_oldest_blob_file_num == std::numeric_limits<uint64_t>::max()) {
min_oldest_blob_file_num = kInvalidBlobFileNumber;
}
return min_oldest_blob_file_num;
}
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) {
MutableBlobFileMetaData* const mutable_meta =
GetOrCreateMutableBlobFileMetaData(blob_file_number);
if (mutable_meta) {
mutable_meta->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) {
MutableBlobFileMetaData* const mutable_meta =
GetOrCreateMutableBlobFileMetaData(blob_file_number);
if (mutable_meta) {
mutable_meta->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 std::shared_ptr<BlobFileMetaData> CreateBlobFileMetaData(
const MutableBlobFileMetaData& mutable_meta) {
return BlobFileMetaData::Create(
mutable_meta.GetSharedMeta(), mutable_meta.GetLinkedSsts(),
mutable_meta.GetGarbageBlobCount(), mutable_meta.GetGarbageBlobBytes());
}
// 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 mutable_it = mutable_blob_file_metas_.begin();
const auto mutable_it_end = mutable_blob_file_metas_.end();
while (base_it != base_it_end && mutable_it != mutable_it_end) {
const uint64_t base_blob_file_number = base_it->first;
const uint64_t mutable_blob_file_number = mutable_it->first;
if (base_blob_file_number < mutable_blob_file_number) {
const auto& base_meta = base_it->second;
AddBlobFileIfNeeded(vstorage, base_meta, &found_first_non_empty);
++base_it;
} else if (mutable_blob_file_number < base_blob_file_number) {
const auto& mutable_meta = mutable_it->second;
auto meta = CreateBlobFileMetaData(mutable_meta);
AddBlobFileIfNeeded(vstorage, meta, &found_first_non_empty);
++mutable_it;
} else {
assert(base_blob_file_number == mutable_blob_file_number);
const auto& base_meta = base_it->second;
const auto& mutable_meta = mutable_it->second;
assert(base_meta);
assert(base_meta->GetSharedMeta() == mutable_meta.GetSharedMeta());
if (!mutable_meta.HasDelta()) {
assert(base_meta->GetGarbageBlobCount() ==
mutable_meta.GetGarbageBlobCount());
assert(base_meta->GetGarbageBlobBytes() ==
mutable_meta.GetGarbageBlobBytes());
assert(base_meta->GetLinkedSsts() == mutable_meta.GetLinkedSsts());
AddBlobFileIfNeeded(vstorage, base_meta, &found_first_non_empty);
} else {
auto meta = CreateBlobFileMetaData(mutable_meta);
AddBlobFileIfNeeded(vstorage, meta, &found_first_non_empty);
}
++base_it;
++mutable_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 (mutable_it != mutable_it_end) {
const auto& mutable_meta = mutable_it->second;
auto meta = CreateBlobFileMetaData(mutable_meta);
AddBlobFileIfNeeded(vstorage, meta, &found_first_non_empty);
++mutable_it;
}
}
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);
}
}
}
void SaveSSTFilesTo(VersionStorageInfo* vstorage) {
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++);
}
}
}
}
// Save the current state in *vstorage.
Status SaveTo(VersionStorageInfo* vstorage) {
Status s = CheckConsistency(base_vstorage_);
if (!s.ok()) {
return s;
}
s = CheckConsistency(vstorage);
if (!s.ok()) {
return s;
}
SaveSSTFilesTo(vstorage);
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,
file_meta->temperature);
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();
}
Status ret;
for (const auto& s : statuses) {
if (!s.ok()) {
if (ret.ok()) {
ret = s;
}
}
}
return ret;
}
};
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);
}
uint64_t VersionBuilder::GetMinOldestBlobFileNumber() const {
return rep_->GetMinOldestBlobFileNumber();
}
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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