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rocksdb/db/forward_iterator.cc
Changyu Bi d5345a8ff7 Introduce a transaction option to skip memtable write during commit (#13144) 
Summary:
add a new transaction option `TransactionOptions::commit_bypass_memtable` that will ingest the transaction into a DB as an immutable memtables, skipping memtable writes during transaction commit. This helps to reduce the blocking time of committing a large transaction, which is mostly spent on memtable writes. The ingestion is done by creating WBWIMemTable using transaction's underlying WBWI, and ingest it as the latest immutable memtable. The feature will be experimental.

Major changes are:
1. write path change to ingest the transaction, mostly in WriteImpl() and IngestWBWI() in db_impl_write.cc.
2. WBWI changes to track some per CF stats like entry count and overwritten single deletion count, and track which keys have overwritten single deletions (see 3.). Per CF stat is used to precompute the number of entries in each WBWIMemTable.
3. WBWIMemTable Iterator changes to emit overwritten single deletions. The motivation is explained in the comment above class WBWIMemTable definition. The rest of the changes in WBWIMemTable are moving the iterator definition around.

Some intended follow ups:
1. support for merge operations
2. stats/logging around this option
3. tests improvement, including stress test support for the more comprehensive no_batched_op_stress.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/13144

Test Plan:
* added new unit tests
* enabled in multi_ops_txns_stress test
* Benchmark: applying the change in 8222c0cafc4c6eb3a0d05807f7014b44998acb7a, I tested txn size of 10k and check perf context for write_memtable_time, write_wal_time and key_lock_wait_time(repurposed for transaction unlock time). Though the benchmark result number can be flaky, this shows memtable write time improved a lot (more than 100 times). The benchmark also shows that the remaining commit latency is from transaction unlock.
```
./db_bench --benchmarks=fillrandom --seed=1727376962 --threads=1 --disable_auto_compactions=1 --max_write_buffer_number=100 --min_write_buffer_number_to_merge=100 --writes=100000 --batch_size=10000 --transaction_db=1 --perf_level=4 --enable_pipelined_write=false --commit_bypass_memtable=1

commit_bypass_memtable = false
fillrandom   :       3.982 micros/op 251119 ops/sec 0.398 seconds 100000 operations;   27.8 MB/s PERF_CONTEXT:
write_memtable_time = 116950422
write_wal_time =      8535565
txn unlock time =     32979883

commit_bypass_memtable = true
fillrandom   :       2.627 micros/op 380559 ops/sec 0.263 seconds 100000 operations;   42.1 MB/s PERF_CONTEXT:
write_memtable_time = 740784
write_wal_time =      11993119
txn unlock time =     21735685
```

Reviewed By: jowlyzhang

Differential Revision: D66307632

Pulled By: cbi42

fbshipit-source-id: 6619af58c4c537aed1f76c4a7e869fb3f5098999
2024-12-05 15:00:17 -08:00

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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).
#include "db/forward_iterator.h"
#include <limits>
#include <string>
#include <utility>
#include "db/column_family.h"
#include "db/db_impl/db_impl.h"
#include "db/db_iter.h"
#include "db/dbformat.h"
#include "db/job_context.h"
#include "db/range_del_aggregator.h"
#include "db/range_tombstone_fragmenter.h"
#include "rocksdb/env.h"
#include "rocksdb/slice.h"
#include "rocksdb/slice_transform.h"
#include "table/merging_iterator.h"
#include "test_util/sync_point.h"
#include "util/string_util.h"
namespace ROCKSDB_NAMESPACE {
// Usage:
// ForwardLevelIterator iter;
// iter.SetFileIndex(file_index);
// iter.Seek(target); // or iter.SeekToFirst();
// iter.Next()
class ForwardLevelIterator : public InternalIterator {
public:
ForwardLevelIterator(const ColumnFamilyData* const cfd,
const ReadOptions& read_options,
const std::vector<FileMetaData*>& files,
const MutableCFOptions& mutable_cf_options,
bool allow_unprepared_value)
: cfd_(cfd),
read_options_(read_options),
files_(files),
valid_(false),
file_index_(std::numeric_limits<uint32_t>::max()),
file_iter_(nullptr),
pinned_iters_mgr_(nullptr),
mutable_cf_options_(mutable_cf_options),
allow_unprepared_value_(allow_unprepared_value) {
status_.PermitUncheckedError(); // Allow uninitialized status through
}
~ForwardLevelIterator() override {
// Reset current pointer
if (pinned_iters_mgr_ && pinned_iters_mgr_->PinningEnabled()) {
pinned_iters_mgr_->PinIterator(file_iter_);
} else {
delete file_iter_;
}
}
void SetFileIndex(uint32_t file_index) {
assert(file_index < files_.size());
status_ = Status::OK();
if (file_index != file_index_) {
file_index_ = file_index;
Reset();
}
}
void Reset() {
assert(file_index_ < files_.size());
// Reset current pointer
if (pinned_iters_mgr_ && pinned_iters_mgr_->PinningEnabled()) {
pinned_iters_mgr_->PinIterator(file_iter_);
} else {
delete file_iter_;
}
ReadRangeDelAggregator range_del_agg(&cfd_->internal_comparator(),
kMaxSequenceNumber /* upper_bound */);
file_iter_ = cfd_->table_cache()->NewIterator(
read_options_, *(cfd_->soptions()), cfd_->internal_comparator(),
*files_[file_index_],
read_options_.ignore_range_deletions ? nullptr : &range_del_agg,
mutable_cf_options_, /*table_reader_ptr=*/nullptr,
/*file_read_hist=*/nullptr, TableReaderCaller::kUserIterator,
/*arena=*/nullptr, /*skip_filters=*/false, /*level=*/-1,
/*max_file_size_for_l0_meta_pin=*/0,
/*smallest_compaction_key=*/nullptr,
/*largest_compaction_key=*/nullptr, allow_unprepared_value_);
file_iter_->SetPinnedItersMgr(pinned_iters_mgr_);
valid_ = false;
if (!range_del_agg.IsEmpty()) {
status_ = Status::NotSupported(
"Range tombstones unsupported with ForwardIterator");
}
}
void SeekToLast() override {
status_ = Status::NotSupported("ForwardLevelIterator::SeekToLast()");
valid_ = false;
}
void Prev() override {
status_ = Status::NotSupported("ForwardLevelIterator::Prev()");
valid_ = false;
}
bool Valid() const override { return valid_; }
void SeekToFirst() override {
assert(file_iter_ != nullptr);
if (!status_.ok()) {
assert(!valid_);
return;
}
file_iter_->SeekToFirst();
valid_ = file_iter_->Valid();
}
void Seek(const Slice& internal_key) override {
assert(file_iter_ != nullptr);
// This deviates from the usual convention for InternalIterator::Seek() in
// that it doesn't discard pre-existing error status. That's because this
// Seek() is only supposed to be called immediately after SetFileIndex()
// (which discards pre-existing error status), and SetFileIndex() may set
// an error status, which we shouldn't discard.
if (!status_.ok()) {
assert(!valid_);
return;
}
file_iter_->Seek(internal_key);
valid_ = file_iter_->Valid();
}
void SeekForPrev(const Slice& /*internal_key*/) override {
status_ = Status::NotSupported("ForwardLevelIterator::SeekForPrev()");
valid_ = false;
}
void Next() override {
assert(valid_);
file_iter_->Next();
for (;;) {
valid_ = file_iter_->Valid();
if (!file_iter_->status().ok()) {
assert(!valid_);
return;
}
if (valid_) {
return;
}
if (file_index_ + 1 >= files_.size()) {
valid_ = false;
return;
}
SetFileIndex(file_index_ + 1);
if (!status_.ok()) {
assert(!valid_);
return;
}
file_iter_->SeekToFirst();
}
}
Slice key() const override {
assert(valid_);
return file_iter_->key();
}
Slice value() const override {
assert(valid_);
return file_iter_->value();
}
uint64_t write_unix_time() const override {
assert(valid_);
return file_iter_->write_unix_time();
}
Status status() const override {
if (!status_.ok()) {
return status_;
} else if (file_iter_) {
return file_iter_->status();
}
return Status::OK();
}
bool PrepareValue() override {
assert(valid_);
if (file_iter_->PrepareValue()) {
return true;
}
assert(!file_iter_->Valid());
valid_ = false;
return false;
}
bool IsKeyPinned() const override {
return pinned_iters_mgr_ && pinned_iters_mgr_->PinningEnabled() &&
file_iter_->IsKeyPinned();
}
bool IsValuePinned() const override {
return pinned_iters_mgr_ && pinned_iters_mgr_->PinningEnabled() &&
file_iter_->IsValuePinned();
}
void SetPinnedItersMgr(PinnedIteratorsManager* pinned_iters_mgr) override {
pinned_iters_mgr_ = pinned_iters_mgr;
if (file_iter_) {
file_iter_->SetPinnedItersMgr(pinned_iters_mgr_);
}
}
private:
const ColumnFamilyData* const cfd_;
const ReadOptions& read_options_;
const std::vector<FileMetaData*>& files_;
bool valid_;
uint32_t file_index_;
Status status_;
InternalIterator* file_iter_;
PinnedIteratorsManager* pinned_iters_mgr_;
const MutableCFOptions& mutable_cf_options_;
const bool allow_unprepared_value_;
};
ForwardIterator::ForwardIterator(DBImpl* db, const ReadOptions& read_options,
ColumnFamilyData* cfd,
SuperVersion* current_sv,
bool allow_unprepared_value)
: db_(db),
read_options_(read_options),
cfd_(cfd),
prefix_extractor_(current_sv->mutable_cf_options.prefix_extractor.get()),
user_comparator_(cfd->user_comparator()),
allow_unprepared_value_(allow_unprepared_value),
immutable_min_heap_(MinIterComparator(&cfd_->internal_comparator())),
sv_(current_sv),
mutable_iter_(nullptr),
current_(nullptr),
valid_(false),
status_(Status::OK()),
immutable_status_(Status::OK()),
has_iter_trimmed_for_upper_bound_(false),
current_over_upper_bound_(false),
is_prev_set_(false),
is_prev_inclusive_(false),
pinned_iters_mgr_(nullptr) {
if (sv_) {
RebuildIterators(false);
}
if (!CheckFSFeatureSupport(cfd_->ioptions()->env->GetFileSystem().get(),
FSSupportedOps::kAsyncIO)) {
read_options_.async_io = false;
}
// immutable_status_ is a local aggregation of the
// status of the immutable Iterators.
// We have to PermitUncheckedError in case it is never
// used, otherwise it will fail ASSERT_STATUS_CHECKED.
immutable_status_.PermitUncheckedError();
}
ForwardIterator::~ForwardIterator() { Cleanup(true); }
void ForwardIterator::SVCleanup(DBImpl* db, SuperVersion* sv,
bool background_purge_on_iterator_cleanup) {
if (sv->Unref()) {
// Job id == 0 means that this is not our background process, but rather
// user thread
JobContext job_context(0);
db->mutex_.Lock();
sv->Cleanup();
db->FindObsoleteFiles(&job_context, false, true);
if (background_purge_on_iterator_cleanup) {
db->ScheduleBgLogWriterClose(&job_context);
db->AddSuperVersionsToFreeQueue(sv);
db->SchedulePurge();
}
db->mutex_.Unlock();
if (!background_purge_on_iterator_cleanup) {
delete sv;
}
if (job_context.HaveSomethingToDelete()) {
db->PurgeObsoleteFiles(job_context, background_purge_on_iterator_cleanup);
}
job_context.Clean();
}
}
namespace {
struct SVCleanupParams {
DBImpl* db;
SuperVersion* sv;
bool background_purge_on_iterator_cleanup;
};
} // anonymous namespace
// Used in PinnedIteratorsManager to release pinned SuperVersion
void ForwardIterator::DeferredSVCleanup(void* arg) {
auto d = static_cast<SVCleanupParams*>(arg);
ForwardIterator::SVCleanup(d->db, d->sv,
d->background_purge_on_iterator_cleanup);
delete d;
}
void ForwardIterator::SVCleanup() {
if (sv_ == nullptr) {
return;
}
bool background_purge =
read_options_.background_purge_on_iterator_cleanup ||
db_->immutable_db_options().avoid_unnecessary_blocking_io;
if (pinned_iters_mgr_ && pinned_iters_mgr_->PinningEnabled()) {
// pinned_iters_mgr_ tells us to make sure that all visited key-value slices
// are alive until pinned_iters_mgr_->ReleasePinnedData() is called.
// The slices may point into some memtables owned by sv_, so we need to keep
// sv_ referenced until pinned_iters_mgr_ unpins everything.
auto p = new SVCleanupParams{db_, sv_, background_purge};
pinned_iters_mgr_->PinPtr(p, &ForwardIterator::DeferredSVCleanup);
} else {
SVCleanup(db_, sv_, background_purge);
}
}
void ForwardIterator::Cleanup(bool release_sv) {
if (mutable_iter_ != nullptr) {
DeleteIterator(mutable_iter_, true /* is_arena */);
}
for (auto* m : imm_iters_) {
DeleteIterator(m, true /* is_arena */);
}
imm_iters_.clear();
for (auto* f : l0_iters_) {
DeleteIterator(f);
}
l0_iters_.clear();
for (auto* l : level_iters_) {
DeleteIterator(l);
}
level_iters_.clear();
if (release_sv) {
SVCleanup();
}
}
bool ForwardIterator::Valid() const {
// See UpdateCurrent().
return valid_ ? !current_over_upper_bound_ : false;
}
void ForwardIterator::SeekToFirst() {
if (sv_ == nullptr) {
RebuildIterators(true);
} else if (sv_->version_number != cfd_->GetSuperVersionNumber()) {
RenewIterators();
} else if (immutable_status_.IsIncomplete()) {
ResetIncompleteIterators();
}
SeekInternal(Slice(), true, false);
}
bool ForwardIterator::IsOverUpperBound(const Slice& internal_key) const {
return !(read_options_.iterate_upper_bound == nullptr ||
cfd_->internal_comparator().user_comparator()->Compare(
ExtractUserKey(internal_key),
*read_options_.iterate_upper_bound) < 0);
}
void ForwardIterator::Seek(const Slice& internal_key) {
if (sv_ == nullptr) {
RebuildIterators(true);
} else if (sv_->version_number != cfd_->GetSuperVersionNumber()) {
RenewIterators();
} else if (immutable_status_.IsIncomplete()) {
ResetIncompleteIterators();
}
SeekInternal(internal_key, false, false);
if (read_options_.async_io) {
SeekInternal(internal_key, false, true);
}
}
// In case of async_io, SeekInternal is called twice with seek_after_async_io
// enabled in second call which only does seeking part to retrieve the blocks.
void ForwardIterator::SeekInternal(const Slice& internal_key,
bool seek_to_first,
bool seek_after_async_io) {
assert(mutable_iter_);
// mutable
if (!seek_after_async_io) {
seek_to_first ? mutable_iter_->SeekToFirst()
: mutable_iter_->Seek(internal_key);
}
// immutable
// TODO(ljin): NeedToSeekImmutable has negative impact on performance
// if it turns to need to seek immutable often. We probably want to have
// an option to turn it off.
if (seek_to_first || seek_after_async_io ||
NeedToSeekImmutable(internal_key)) {
if (!seek_after_async_io) {
immutable_status_ = Status::OK();
if (has_iter_trimmed_for_upper_bound_ &&
(
// prev_ is not set yet
is_prev_set_ == false ||
// We are doing SeekToFirst() and internal_key.size() = 0
seek_to_first ||
// prev_key_ > internal_key
cfd_->internal_comparator().InternalKeyComparator::Compare(
prev_key_.GetInternalKey(), internal_key) > 0)) {
// Some iterators are trimmed. Need to rebuild.
RebuildIterators(true);
// Already seeked mutable iter, so seek again
seek_to_first ? mutable_iter_->SeekToFirst()
: mutable_iter_->Seek(internal_key);
}
{
auto tmp = MinIterHeap(MinIterComparator(&cfd_->internal_comparator()));
immutable_min_heap_.swap(tmp);
}
for (size_t i = 0; i < imm_iters_.size(); i++) {
auto* m = imm_iters_[i];
seek_to_first ? m->SeekToFirst() : m->Seek(internal_key);
if (!m->status().ok()) {
immutable_status_ = m->status();
} else if (m->Valid()) {
immutable_min_heap_.push(m);
}
}
}
Slice target_user_key;
if (!seek_to_first) {
target_user_key = ExtractUserKey(internal_key);
}
const VersionStorageInfo* vstorage = sv_->current->storage_info();
const std::vector<FileMetaData*>& l0 = vstorage->LevelFiles(0);
for (size_t i = 0; i < l0.size(); ++i) {
if (!l0_iters_[i]) {
continue;
}
if (seek_after_async_io) {
if (!l0_iters_[i]->status().IsTryAgain()) {
continue;
}
}
if (seek_to_first) {
l0_iters_[i]->SeekToFirst();
} else {
// If the target key passes over the largest key, we are sure Next()
// won't go over this file.
if (seek_after_async_io == false &&
user_comparator_->Compare(target_user_key,
l0[i]->largest.user_key()) > 0) {
if (read_options_.iterate_upper_bound != nullptr) {
has_iter_trimmed_for_upper_bound_ = true;
DeleteIterator(l0_iters_[i]);
l0_iters_[i] = nullptr;
}
continue;
}
l0_iters_[i]->Seek(internal_key);
}
if (l0_iters_[i]->status().IsTryAgain()) {
assert(!seek_after_async_io);
continue;
} else if (!l0_iters_[i]->status().ok()) {
immutable_status_ = l0_iters_[i]->status();
} else if (l0_iters_[i]->Valid() &&
!IsOverUpperBound(l0_iters_[i]->key())) {
immutable_min_heap_.push(l0_iters_[i]);
} else {
has_iter_trimmed_for_upper_bound_ = true;
DeleteIterator(l0_iters_[i]);
l0_iters_[i] = nullptr;
}
}
for (int32_t level = 1; level < vstorage->num_levels(); ++level) {
const std::vector<FileMetaData*>& level_files =
vstorage->LevelFiles(level);
if (level_files.empty()) {
continue;
}
if (level_iters_[level - 1] == nullptr) {
continue;
}
if (seek_after_async_io) {
if (!level_iters_[level - 1]->status().IsTryAgain()) {
continue;
}
}
uint32_t f_idx = 0;
if (!seek_to_first && !seek_after_async_io) {
f_idx = FindFileInRange(level_files, internal_key, 0,
static_cast<uint32_t>(level_files.size()));
}
// Seek
if (seek_after_async_io || f_idx < level_files.size()) {
if (!seek_after_async_io) {
level_iters_[level - 1]->SetFileIndex(f_idx);
}
seek_to_first ? level_iters_[level - 1]->SeekToFirst()
: level_iters_[level - 1]->Seek(internal_key);
if (level_iters_[level - 1]->status().IsTryAgain()) {
assert(!seek_after_async_io);
continue;
} else if (!level_iters_[level - 1]->status().ok()) {
immutable_status_ = level_iters_[level - 1]->status();
} else if (level_iters_[level - 1]->Valid() &&
!IsOverUpperBound(level_iters_[level - 1]->key())) {
immutable_min_heap_.push(level_iters_[level - 1]);
} else {
// Nothing in this level is interesting. Remove.
has_iter_trimmed_for_upper_bound_ = true;
DeleteIterator(level_iters_[level - 1]);
level_iters_[level - 1] = nullptr;
}
}
}
if (seek_to_first) {
is_prev_set_ = false;
} else {
prev_key_.SetInternalKey(internal_key);
is_prev_set_ = true;
is_prev_inclusive_ = true;
}
TEST_SYNC_POINT_CALLBACK("ForwardIterator::SeekInternal:Immutable", this);
} else if (current_ && current_ != mutable_iter_) {
// current_ is one of immutable iterators, push it back to the heap
immutable_min_heap_.push(current_);
}
// For async_io, it should be updated when seek_after_async_io is true (in
// second call).
if (seek_to_first || !read_options_.async_io || seek_after_async_io) {
UpdateCurrent();
}
TEST_SYNC_POINT_CALLBACK("ForwardIterator::SeekInternal:Return", this);
}
void ForwardIterator::Next() {
assert(valid_);
bool update_prev_key = false;
if (sv_ == nullptr || sv_->version_number != cfd_->GetSuperVersionNumber()) {
std::string current_key = key().ToString();
Slice old_key(current_key.data(), current_key.size());
if (sv_ == nullptr) {
RebuildIterators(true);
} else {
RenewIterators();
}
SeekInternal(old_key, false, false);
if (read_options_.async_io) {
SeekInternal(old_key, false, true);
}
if (!valid_ || key().compare(old_key) != 0) {
return;
}
} else if (current_ != mutable_iter_) {
// It is going to advance immutable iterator
if (is_prev_set_ && prefix_extractor_) {
// advance prev_key_ to current_ only if they share the same prefix
update_prev_key =
prefix_extractor_->Transform(prev_key_.GetUserKey())
.compare(prefix_extractor_->Transform(current_->key())) == 0;
} else {
update_prev_key = true;
}
if (update_prev_key) {
prev_key_.SetInternalKey(current_->key());
is_prev_set_ = true;
is_prev_inclusive_ = false;
}
}
current_->Next();
if (current_ != mutable_iter_) {
if (!current_->status().ok()) {
immutable_status_ = current_->status();
} else if ((current_->Valid()) && (!IsOverUpperBound(current_->key()))) {
immutable_min_heap_.push(current_);
} else {
if ((current_->Valid()) && (IsOverUpperBound(current_->key()))) {
// remove the current iterator
DeleteCurrentIter();
current_ = nullptr;
}
if (update_prev_key) {
mutable_iter_->Seek(prev_key_.GetInternalKey());
}
}
}
UpdateCurrent();
TEST_SYNC_POINT_CALLBACK("ForwardIterator::Next:Return", this);
}
Slice ForwardIterator::key() const {
assert(valid_);
return current_->key();
}
uint64_t ForwardIterator::write_unix_time() const {
assert(valid_);
return current_->write_unix_time();
}
Slice ForwardIterator::value() const {
assert(valid_);
return current_->value();
}
Status ForwardIterator::status() const {
if (!status_.ok()) {
return status_;
} else if (!mutable_iter_->status().ok()) {
return mutable_iter_->status();
}
return immutable_status_;
}
bool ForwardIterator::PrepareValue() {
assert(valid_);
if (current_->PrepareValue()) {
return true;
}
assert(!current_->Valid());
assert(!current_->status().ok());
assert(current_ != mutable_iter_); // memtable iterator can't fail
assert(immutable_status_.ok());
valid_ = false;
immutable_status_ = current_->status();
return false;
}
Status ForwardIterator::GetProperty(std::string prop_name, std::string* prop) {
assert(prop != nullptr);
if (prop_name == "rocksdb.iterator.super-version-number") {
*prop = std::to_string(sv_->version_number);
return Status::OK();
}
return Status::InvalidArgument("Unrecognized property: " + prop_name);
}
void ForwardIterator::SetPinnedItersMgr(
PinnedIteratorsManager* pinned_iters_mgr) {
pinned_iters_mgr_ = pinned_iters_mgr;
UpdateChildrenPinnedItersMgr();
}
void ForwardIterator::UpdateChildrenPinnedItersMgr() {
// Set PinnedIteratorsManager for mutable memtable iterator.
if (mutable_iter_) {
mutable_iter_->SetPinnedItersMgr(pinned_iters_mgr_);
}
// Set PinnedIteratorsManager for immutable memtable iterators.
for (InternalIterator* child_iter : imm_iters_) {
if (child_iter) {
child_iter->SetPinnedItersMgr(pinned_iters_mgr_);
}
}
// Set PinnedIteratorsManager for L0 files iterators.
for (InternalIterator* child_iter : l0_iters_) {
if (child_iter) {
child_iter->SetPinnedItersMgr(pinned_iters_mgr_);
}
}
// Set PinnedIteratorsManager for L1+ levels iterators.
for (ForwardLevelIterator* child_iter : level_iters_) {
if (child_iter) {
child_iter->SetPinnedItersMgr(pinned_iters_mgr_);
}
}
}
bool ForwardIterator::IsKeyPinned() const {
return pinned_iters_mgr_ && pinned_iters_mgr_->PinningEnabled() &&
current_->IsKeyPinned();
}
bool ForwardIterator::IsValuePinned() const {
return pinned_iters_mgr_ && pinned_iters_mgr_->PinningEnabled() &&
current_->IsValuePinned();
}
void ForwardIterator::RebuildIterators(bool refresh_sv) {
// Clean up
Cleanup(refresh_sv);
if (refresh_sv) {
// New
sv_ = cfd_->GetReferencedSuperVersion(db_);
}
ReadRangeDelAggregator range_del_agg(&cfd_->internal_comparator(),
kMaxSequenceNumber /* upper_bound */);
UnownedPtr<const SeqnoToTimeMapping> seqno_to_time_mapping =
sv_->GetSeqnoToTimeMapping();
mutable_iter_ =
sv_->mem->NewIterator(read_options_, seqno_to_time_mapping, &arena_,
sv_->mutable_cf_options.prefix_extractor.get(),
/*for_flush=*/false);
sv_->imm->AddIterators(read_options_, seqno_to_time_mapping,
sv_->mutable_cf_options.prefix_extractor.get(),
&imm_iters_, &arena_);
if (!read_options_.ignore_range_deletions) {
std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter(
sv_->mem->NewRangeTombstoneIterator(
read_options_, sv_->current->version_set()->LastSequence(),
false /* immutable_memtable */));
range_del_agg.AddTombstones(std::move(range_del_iter));
// Always return Status::OK().
Status temp_s = sv_->imm->AddRangeTombstoneIterators(read_options_, &arena_,
&range_del_agg);
assert(temp_s.ok());
}
has_iter_trimmed_for_upper_bound_ = false;
const auto* vstorage = sv_->current->storage_info();
const auto& l0_files = vstorage->LevelFiles(0);
l0_iters_.reserve(l0_files.size());
for (const auto* l0 : l0_files) {
if ((read_options_.iterate_upper_bound != nullptr) &&
cfd_->internal_comparator().user_comparator()->Compare(
l0->smallest.user_key(), *read_options_.iterate_upper_bound) > 0) {
// No need to set has_iter_trimmed_for_upper_bound_: this ForwardIterator
// will never be interested in files with smallest key above
// iterate_upper_bound, since iterate_upper_bound can't be changed.
l0_iters_.push_back(nullptr);
continue;
}
l0_iters_.push_back(cfd_->table_cache()->NewIterator(
read_options_, *cfd_->soptions(), cfd_->internal_comparator(), *l0,
read_options_.ignore_range_deletions ? nullptr : &range_del_agg,
sv_->mutable_cf_options,
/*table_reader_ptr=*/nullptr, /*file_read_hist=*/nullptr,
TableReaderCaller::kUserIterator, /*arena=*/nullptr,
/*skip_filters=*/false, /*level=*/-1,
MaxFileSizeForL0MetaPin(sv_->mutable_cf_options),
/*smallest_compaction_key=*/nullptr,
/*largest_compaction_key=*/nullptr, allow_unprepared_value_));
}
BuildLevelIterators(vstorage, sv_);
current_ = nullptr;
is_prev_set_ = false;
UpdateChildrenPinnedItersMgr();
if (!range_del_agg.IsEmpty()) {
status_ = Status::NotSupported(
"Range tombstones unsupported with ForwardIterator");
valid_ = false;
}
}
void ForwardIterator::RenewIterators() {
SuperVersion* svnew;
assert(sv_);
svnew = cfd_->GetReferencedSuperVersion(db_);
if (mutable_iter_ != nullptr) {
DeleteIterator(mutable_iter_, true /* is_arena */);
}
for (auto* m : imm_iters_) {
DeleteIterator(m, true /* is_arena */);
}
imm_iters_.clear();
UnownedPtr<const SeqnoToTimeMapping> seqno_to_time_mapping =
svnew->GetSeqnoToTimeMapping();
mutable_iter_ =
svnew->mem->NewIterator(read_options_, seqno_to_time_mapping, &arena_,
svnew->mutable_cf_options.prefix_extractor.get(),
/*for_flush=*/false);
svnew->imm->AddIterators(read_options_, seqno_to_time_mapping,
svnew->mutable_cf_options.prefix_extractor.get(),
&imm_iters_, &arena_);
ReadRangeDelAggregator range_del_agg(&cfd_->internal_comparator(),
kMaxSequenceNumber /* upper_bound */);
if (!read_options_.ignore_range_deletions) {
std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter(
svnew->mem->NewRangeTombstoneIterator(
read_options_, sv_->current->version_set()->LastSequence(),
false /* immutable_memtable */));
range_del_agg.AddTombstones(std::move(range_del_iter));
// Always return Status::OK().
Status temp_s = svnew->imm->AddRangeTombstoneIterators(
read_options_, &arena_, &range_del_agg);
assert(temp_s.ok());
}
const auto* vstorage = sv_->current->storage_info();
const auto& l0_files = vstorage->LevelFiles(0);
const auto* vstorage_new = svnew->current->storage_info();
const auto& l0_files_new = vstorage_new->LevelFiles(0);
size_t iold, inew;
bool found;
std::vector<InternalIterator*> l0_iters_new;
l0_iters_new.reserve(l0_files_new.size());
for (inew = 0; inew < l0_files_new.size(); inew++) {
found = false;
for (iold = 0; iold < l0_files.size(); iold++) {
if (l0_files[iold] == l0_files_new[inew]) {
found = true;
break;
}
}
if (found) {
if (l0_iters_[iold] == nullptr) {
l0_iters_new.push_back(nullptr);
TEST_SYNC_POINT_CALLBACK("ForwardIterator::RenewIterators:Null", this);
} else {
l0_iters_new.push_back(l0_iters_[iold]);
l0_iters_[iold] = nullptr;
TEST_SYNC_POINT_CALLBACK("ForwardIterator::RenewIterators:Copy", this);
}
continue;
}
l0_iters_new.push_back(cfd_->table_cache()->NewIterator(
read_options_, *cfd_->soptions(), cfd_->internal_comparator(),
*l0_files_new[inew],
read_options_.ignore_range_deletions ? nullptr : &range_del_agg,
svnew->mutable_cf_options,
/*table_reader_ptr=*/nullptr, /*file_read_hist=*/nullptr,
TableReaderCaller::kUserIterator, /*arena=*/nullptr,
/*skip_filters=*/false, /*level=*/-1,
MaxFileSizeForL0MetaPin(svnew->mutable_cf_options),
/*smallest_compaction_key=*/nullptr,
/*largest_compaction_key=*/nullptr, allow_unprepared_value_));
}
for (auto* f : l0_iters_) {
DeleteIterator(f);
}
l0_iters_.clear();
l0_iters_ = l0_iters_new;
for (auto* l : level_iters_) {
DeleteIterator(l);
}
level_iters_.clear();
BuildLevelIterators(vstorage_new, svnew);
current_ = nullptr;
is_prev_set_ = false;
SVCleanup();
sv_ = svnew;
UpdateChildrenPinnedItersMgr();
if (!range_del_agg.IsEmpty()) {
status_ = Status::NotSupported(
"Range tombstones unsupported with ForwardIterator");
valid_ = false;
}
}
void ForwardIterator::BuildLevelIterators(const VersionStorageInfo* vstorage,
SuperVersion* sv) {
level_iters_.reserve(vstorage->num_levels() - 1);
for (int32_t level = 1; level < vstorage->num_levels(); ++level) {
const auto& level_files = vstorage->LevelFiles(level);
if ((level_files.empty()) ||
((read_options_.iterate_upper_bound != nullptr) &&
(user_comparator_->Compare(*read_options_.iterate_upper_bound,
level_files[0]->smallest.user_key()) <
0))) {
level_iters_.push_back(nullptr);
if (!level_files.empty()) {
has_iter_trimmed_for_upper_bound_ = true;
}
} else {
level_iters_.push_back(new ForwardLevelIterator(
cfd_, read_options_, level_files, sv->mutable_cf_options,
allow_unprepared_value_));
}
}
}
void ForwardIterator::ResetIncompleteIterators() {
const auto& l0_files = sv_->current->storage_info()->LevelFiles(0);
for (size_t i = 0; i < l0_iters_.size(); ++i) {
assert(i < l0_files.size());
if (!l0_iters_[i] || !l0_iters_[i]->status().IsIncomplete()) {
continue;
}
DeleteIterator(l0_iters_[i]);
l0_iters_[i] = cfd_->table_cache()->NewIterator(
read_options_, *cfd_->soptions(), cfd_->internal_comparator(),
*l0_files[i], /*range_del_agg=*/nullptr, sv_->mutable_cf_options,
/*table_reader_ptr=*/nullptr, /*file_read_hist=*/nullptr,
TableReaderCaller::kUserIterator, /*arena=*/nullptr,
/*skip_filters=*/false, /*level=*/-1,
MaxFileSizeForL0MetaPin(sv_->mutable_cf_options),
/*smallest_compaction_key=*/nullptr,
/*largest_compaction_key=*/nullptr, allow_unprepared_value_);
l0_iters_[i]->SetPinnedItersMgr(pinned_iters_mgr_);
}
for (auto* level_iter : level_iters_) {
if (level_iter && level_iter->status().IsIncomplete()) {
level_iter->Reset();
}
}
current_ = nullptr;
is_prev_set_ = false;
}
void ForwardIterator::UpdateCurrent() {
if (immutable_min_heap_.empty() && !mutable_iter_->Valid()) {
current_ = nullptr;
} else if (immutable_min_heap_.empty()) {
current_ = mutable_iter_;
} else if (!mutable_iter_->Valid()) {
current_ = immutable_min_heap_.top();
immutable_min_heap_.pop();
} else {
current_ = immutable_min_heap_.top();
assert(current_ != nullptr);
assert(current_->Valid());
int cmp = cfd_->internal_comparator().InternalKeyComparator::Compare(
mutable_iter_->key(), current_->key());
assert(cmp != 0);
if (cmp > 0) {
immutable_min_heap_.pop();
} else {
current_ = mutable_iter_;
}
}
valid_ = current_ != nullptr && immutable_status_.ok();
if (!status_.ok()) {
status_ = Status::OK();
}
// Upper bound doesn't apply to the memtable iterator. We want Valid() to
// return false when all iterators are over iterate_upper_bound, but can't
// just set valid_ to false, as that would effectively disable the tailing
// optimization (Seek() would be called on all immutable iterators regardless
// of whether the target key is greater than prev_key_).
current_over_upper_bound_ = valid_ && IsOverUpperBound(current_->key());
}
bool ForwardIterator::NeedToSeekImmutable(const Slice& target) {
// We maintain the interval (prev_key_, immutable_min_heap_.top()->key())
// such that there are no records with keys within that range in
// immutable_min_heap_. Since immutable structures (SST files and immutable
// memtables) can't change in this version, we don't need to do a seek if
// 'target' belongs to that interval (immutable_min_heap_.top() is already
// at the correct position).
if (!valid_ || !current_ || !is_prev_set_ || !immutable_status_.ok()) {
return true;
}
Slice prev_key = prev_key_.GetInternalKey();
if (prefix_extractor_ && prefix_extractor_->Transform(target).compare(
prefix_extractor_->Transform(prev_key)) != 0) {
return true;
}
if (cfd_->internal_comparator().InternalKeyComparator::Compare(
prev_key, target) >= (is_prev_inclusive_ ? 1 : 0)) {
return true;
}
if (immutable_min_heap_.empty() && current_ == mutable_iter_) {
// Nothing to seek on.
return false;
}
if (cfd_->internal_comparator().InternalKeyComparator::Compare(
target, current_ == mutable_iter_ ? immutable_min_heap_.top()->key()
: current_->key()) > 0) {
return true;
}
return false;
}
void ForwardIterator::DeleteCurrentIter() {
const VersionStorageInfo* vstorage = sv_->current->storage_info();
const std::vector<FileMetaData*>& l0 = vstorage->LevelFiles(0);
for (size_t i = 0; i < l0.size(); ++i) {
if (!l0_iters_[i]) {
continue;
}
if (l0_iters_[i] == current_) {
has_iter_trimmed_for_upper_bound_ = true;
DeleteIterator(l0_iters_[i]);
l0_iters_[i] = nullptr;
return;
}
}
for (int32_t level = 1; level < vstorage->num_levels(); ++level) {
if (level_iters_[level - 1] == nullptr) {
continue;
}
if (level_iters_[level - 1] == current_) {
has_iter_trimmed_for_upper_bound_ = true;
DeleteIterator(level_iters_[level - 1]);
level_iters_[level - 1] = nullptr;
}
}
}
bool ForwardIterator::TEST_CheckDeletedIters(int* pdeleted_iters,
int* pnum_iters) {
bool retval = false;
int deleted_iters = 0;
int num_iters = 0;
const VersionStorageInfo* vstorage = sv_->current->storage_info();
const std::vector<FileMetaData*>& l0 = vstorage->LevelFiles(0);
for (size_t i = 0; i < l0.size(); ++i) {
if (!l0_iters_[i]) {
retval = true;
deleted_iters++;
} else {
num_iters++;
}
}
for (int32_t level = 1; level < vstorage->num_levels(); ++level) {
if ((level_iters_[level - 1] == nullptr) &&
(!vstorage->LevelFiles(level).empty())) {
retval = true;
deleted_iters++;
} else if (!vstorage->LevelFiles(level).empty()) {
num_iters++;
}
}
if ((!retval) && num_iters <= 1) {
retval = true;
}
if (pdeleted_iters) {
*pdeleted_iters = deleted_iters;
}
if (pnum_iters) {
*pnum_iters = num_iters;
}
return retval;
}
uint32_t ForwardIterator::FindFileInRange(
const std::vector<FileMetaData*>& files, const Slice& internal_key,
uint32_t left, uint32_t right) {
auto cmp = [&](const FileMetaData* f, const Slice& k) -> bool {
return cfd_->internal_comparator().InternalKeyComparator::Compare(
f->largest.Encode(), k) < 0;
};
const auto& b = files.begin();
return static_cast<uint32_t>(
std::lower_bound(b + left, b + right, internal_key, cmp) - b);
}
void ForwardIterator::DeleteIterator(InternalIterator* iter, bool is_arena) {
if (iter == nullptr) {
return;
}
if (pinned_iters_mgr_ && pinned_iters_mgr_->PinningEnabled()) {
pinned_iters_mgr_->PinIterator(iter, is_arena);
} else {
if (is_arena) {
iter->~InternalIterator();
} else {
delete iter;
}
}
}
} // namespace ROCKSDB_NAMESPACE
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