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rocksdb/db/memtable_list.cc

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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/memtable_list.h"
#include <algorithm>
#include <cinttypes>
#include <limits>
#include <queue>
#include <string>
#include "db/db_impl/db_impl.h"
#include "db/memtable.h"
#include "db/range_tombstone_fragmenter.h"
#include "db/version_set.h"
#include "logging/log_buffer.h"
#include "logging/logging.h"
#include "monitoring/thread_status_util.h"
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include "rocksdb/iterator.h"
#include "table/merging_iterator.h"
#include "test_util/sync_point.h"
#include "util/coding.h"
namespace ROCKSDB_NAMESPACE {
class InternalKeyComparator;
class Mutex;
class VersionSet;
void MemTableListVersion::AddMemTable(ReadOnlyMemTable* m) {
memlist_.push_front(m);
*parent_memtable_list_memory_usage_ += m->ApproximateMemoryUsage();
}
void MemTableListVersion::UnrefMemTable(
autovector<ReadOnlyMemTable*>* to_delete, ReadOnlyMemTable* m) {
if (m->Unref()) {
to_delete->push_back(m);
assert(*parent_memtable_list_memory_usage_ >= m->ApproximateMemoryUsage());
*parent_memtable_list_memory_usage_ -= m->ApproximateMemoryUsage();
}
}
MemTableListVersion::MemTableListVersion(
size_t* parent_memtable_list_memory_usage, const MemTableListVersion& old)
: max_write_buffer_number_to_maintain_(
old.max_write_buffer_number_to_maintain_),
max_write_buffer_size_to_maintain_(
old.max_write_buffer_size_to_maintain_),
parent_memtable_list_memory_usage_(parent_memtable_list_memory_usage) {
memlist_ = old.memlist_;
for (auto& m : memlist_) {
m->Ref();
}
memlist_history_ = old.memlist_history_;
for (auto& m : memlist_history_) {
m->Ref();
}
}
MemTableListVersion::MemTableListVersion(
size_t* parent_memtable_list_memory_usage,
int max_write_buffer_number_to_maintain,
int64_t max_write_buffer_size_to_maintain)
: max_write_buffer_number_to_maintain_(max_write_buffer_number_to_maintain),
max_write_buffer_size_to_maintain_(max_write_buffer_size_to_maintain),
parent_memtable_list_memory_usage_(parent_memtable_list_memory_usage) {}
void MemTableListVersion::Ref() { ++refs_; }
// called by superversion::clean()
void MemTableListVersion::Unref(autovector<ReadOnlyMemTable*>* to_delete) {
assert(refs_ >= 1);
--refs_;
if (refs_ == 0) {
// if to_delete is equal to nullptr it means we're confident
// that refs_ will not be zero
assert(to_delete != nullptr);
for (const auto& m : memlist_) {
UnrefMemTable(to_delete, m);
}
for (const auto& m : memlist_history_) {
UnrefMemTable(to_delete, m);
}
delete this;
}
}
int MemTableList::NumNotFlushed() const {
int size = current_->NumNotFlushed();
assert(num_flush_not_started_ <= size);
return size;
}
int MemTableList::NumFlushed() const { return current_->NumFlushed(); }
// Search all the memtables starting from the most recent one.
// Return the most recent value found, if any.
// Operands stores the list of merge operations to apply, so far.
bool MemTableListVersion::Get(const LookupKey& key, std::string* value,
PinnableWideColumns* columns,
std::string* timestamp, Status* s,
MergeContext* merge_context,
SequenceNumber* max_covering_tombstone_seq,
SequenceNumber* seq, const ReadOptions& read_opts,
ReadCallback* callback, bool* is_blob_index) {
return GetFromList(&memlist_, key, value, columns, timestamp, s,
merge_context, max_covering_tombstone_seq, seq, read_opts,
callback, is_blob_index);
}
void MemTableListVersion::MultiGet(const ReadOptions& read_options,
MultiGetRange* range,
ReadCallback* callback) {
for (auto memtable : memlist_) {
memtable->MultiGet(read_options, range, callback,
true /* immutable_memtable */);
if (range->empty()) {
return;
}
}
}
bool MemTableListVersion::GetMergeOperands(
const LookupKey& key, Status* s, MergeContext* merge_context,
SequenceNumber* max_covering_tombstone_seq, const ReadOptions& read_opts) {
for (ReadOnlyMemTable* memtable : memlist_) {
bool done = memtable->Get(
key, /*value=*/nullptr, /*columns=*/nullptr, /*timestamp=*/nullptr, s,
merge_context, max_covering_tombstone_seq, read_opts,
true /* immutable_memtable */, nullptr, nullptr, false);
if (done) {
return true;
}
}
return false;
}
bool MemTableListVersion::GetFromHistory(
const LookupKey& key, std::string* value, PinnableWideColumns* columns,
std::string* timestamp, Status* s, MergeContext* merge_context,
SequenceNumber* max_covering_tombstone_seq, SequenceNumber* seq,
const ReadOptions& read_opts, bool* is_blob_index) {
return GetFromList(&memlist_history_, key, value, columns, timestamp, s,
merge_context, max_covering_tombstone_seq, seq, read_opts,
nullptr /*read_callback*/, is_blob_index);
}
bool MemTableListVersion::GetFromList(
std::list<ReadOnlyMemTable*>* list, const LookupKey& key,
std::string* value, PinnableWideColumns* columns, std::string* timestamp,
Status* s, MergeContext* merge_context,
SequenceNumber* max_covering_tombstone_seq, SequenceNumber* seq,
const ReadOptions& read_opts, ReadCallback* callback, bool* is_blob_index) {
*seq = kMaxSequenceNumber;
for (auto& memtable : *list) {
assert(memtable->IsFragmentedRangeTombstonesConstructed());
SequenceNumber current_seq = kMaxSequenceNumber;
bool done =
memtable->Get(key, value, columns, timestamp, s, merge_context,
max_covering_tombstone_seq, &current_seq, read_opts,
true /* immutable_memtable */, callback, is_blob_index);
if (*seq == kMaxSequenceNumber) {
// Store the most recent sequence number of any operation on this key.
// Since we only care about the most recent change, we only need to
// return the first operation found when searching memtables in
// reverse-chronological order.
// current_seq would be equal to kMaxSequenceNumber if the value was to be
// skipped. This allows seq to be assigned again when the next value is
// read.
*seq = current_seq;
}
if (done) {
assert(*seq != kMaxSequenceNumber ||
(!s->ok() && !s->IsMergeInProgress()));
return true;
}
if (!s->ok() && !s->IsMergeInProgress() && !s->IsNotFound()) {
return false;
}
}
return false;
}
Status MemTableListVersion::AddRangeTombstoneIterators(
const ReadOptions& read_opts, Arena* /*arena*/,
RangeDelAggregator* range_del_agg) {
assert(range_del_agg != nullptr);
// Except for snapshot read, using kMaxSequenceNumber is OK because these
// are immutable memtables.
SequenceNumber read_seq = read_opts.snapshot != nullptr
? read_opts.snapshot->GetSequenceNumber()
: kMaxSequenceNumber;
for (auto& m : memlist_) {
assert(m->IsFragmentedRangeTombstonesConstructed());
std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter(
m->NewRangeTombstoneIterator(read_opts, read_seq,
true /* immutable_memtable */));
range_del_agg->AddTombstones(std::move(range_del_iter));
}
return Status::OK();
}
void MemTableListVersion::AddIterators(
const ReadOptions& options,
UnownedPtr<const SeqnoToTimeMapping> seqno_to_time_mapping,
const SliceTransform* prefix_extractor,
std::vector<InternalIterator*>* iterator_list, Arena* arena) {
for (auto& m : memlist_) {
iterator_list->push_back(m->NewIterator(options, seqno_to_time_mapping,
arena, prefix_extractor));
}
}
void MemTableListVersion::AddIterators(
const ReadOptions& options,
UnownedPtr<const SeqnoToTimeMapping> seqno_to_time_mapping,
const SliceTransform* prefix_extractor,
MergeIteratorBuilder* merge_iter_builder, bool add_range_tombstone_iter) {
for (auto& m : memlist_) {
auto mem_iter =
m->NewIterator(options, seqno_to_time_mapping,
merge_iter_builder->GetArena(), prefix_extractor);
if (!add_range_tombstone_iter || options.ignore_range_deletions) {
merge_iter_builder->AddIterator(mem_iter);
} else {
// Except for snapshot read, using kMaxSequenceNumber is OK because these
// are immutable memtables.
SequenceNumber read_seq = options.snapshot != nullptr
? options.snapshot->GetSequenceNumber()
: kMaxSequenceNumber;
std::unique_ptr<TruncatedRangeDelIterator> mem_tombstone_iter;
auto range_del_iter = m->NewRangeTombstoneIterator(
options, read_seq, true /* immutale_memtable */);
if (range_del_iter == nullptr || range_del_iter->empty()) {
delete range_del_iter;
} else {
mem_tombstone_iter = std::make_unique<TruncatedRangeDelIterator>(
std::unique_ptr<FragmentedRangeTombstoneIterator>(range_del_iter),
&m->GetInternalKeyComparator(), nullptr /* smallest */,
nullptr /* largest */);
}
merge_iter_builder->AddPointAndTombstoneIterator(
mem_iter, std::move(mem_tombstone_iter));
}
}
}
uint64_t MemTableListVersion::GetTotalNumEntries() const {
uint64_t total_num = 0;
for (auto& m : memlist_) {
total_num += m->NumEntries();
}
return total_num;
}
ReadOnlyMemTable::MemTableStats MemTableListVersion::ApproximateStats(
const Slice& start_ikey, const Slice& end_ikey) const {
ReadOnlyMemTable::MemTableStats total_stats = {0, 0};
for (auto& m : memlist_) {
auto mStats = m->ApproximateStats(start_ikey, end_ikey);
total_stats.size += mStats.size;
total_stats.count += mStats.count;
}
return total_stats;
}
uint64_t MemTableListVersion::GetTotalNumDeletes() const {
uint64_t total_num = 0;
for (auto& m : memlist_) {
total_num += m->NumDeletion();
}
return total_num;
}
SequenceNumber MemTableListVersion::GetEarliestSequenceNumber(
bool include_history) const {
if (include_history && !memlist_history_.empty()) {
return memlist_history_.back()->GetEarliestSequenceNumber();
} else if (!memlist_.empty()) {
return memlist_.back()->GetEarliestSequenceNumber();
} else {
return kMaxSequenceNumber;
}
}
SequenceNumber MemTableListVersion::GetFirstSequenceNumber() const {
SequenceNumber min_first_seqno = kMaxSequenceNumber;
// The first memtable in the list might not be the oldest one with mempurge
for (const auto& m : memlist_) {
min_first_seqno = std::min(m->GetFirstSequenceNumber(), min_first_seqno);
}
return min_first_seqno;
}
// caller is responsible for referencing m
void MemTableListVersion::Add(ReadOnlyMemTable* m,
autovector<ReadOnlyMemTable*>* to_delete) {
assert(refs_ == 1); // only when refs_ == 1 is MemTableListVersion mutable
AddMemTable(m);
// m->MemoryAllocatedBytes() is added in MemoryAllocatedBytesExcludingLast
TrimHistory(to_delete, 0);
}
// Removes m from list of memtables not flushed. Caller should NOT Unref m.
void MemTableListVersion::Remove(ReadOnlyMemTable* m,
autovector<ReadOnlyMemTable*>* to_delete) {
assert(refs_ == 1); // only when refs_ == 1 is MemTableListVersion mutable
memlist_.remove(m);
m->MarkFlushed();
if (max_write_buffer_size_to_maintain_ > 0 ||
max_write_buffer_number_to_maintain_ > 0) {
memlist_history_.push_front(m);
// Unable to get size of mutable memtable at this point, pass 0 to
// TrimHistory as a best effort.
TrimHistory(to_delete, 0);
} else {
UnrefMemTable(to_delete, m);
}
}
// return the total memory usage assuming the oldest flushed memtable is dropped
size_t MemTableListVersion::MemoryAllocatedBytesExcludingLast() const {
size_t total_memtable_size = 0;
for (auto& memtable : memlist_) {
total_memtable_size += memtable->MemoryAllocatedBytes();
}
for (auto& memtable : memlist_history_) {
total_memtable_size += memtable->MemoryAllocatedBytes();
}
if (!memlist_history_.empty()) {
total_memtable_size -= memlist_history_.back()->MemoryAllocatedBytes();
}
return total_memtable_size;
}
bool MemTableListVersion::MemtableLimitExceeded(size_t usage) {
if (max_write_buffer_size_to_maintain_ > 0) {
// calculate the total memory usage after dropping the oldest flushed
// memtable, compare with max_write_buffer_size_to_maintain_ to decide
// whether to trim history
return MemoryAllocatedBytesExcludingLast() + usage >=
static_cast<size_t>(max_write_buffer_size_to_maintain_);
} else if (max_write_buffer_number_to_maintain_ > 0) {
return memlist_.size() + memlist_history_.size() >
static_cast<size_t>(max_write_buffer_number_to_maintain_);
} else {
return false;
}
}
bool MemTableListVersion::HistoryShouldBeTrimmed(size_t usage) {
return MemtableLimitExceeded(usage) && !memlist_history_.empty();
}
// Make sure we don't use up too much space in history
bool MemTableListVersion::TrimHistory(autovector<ReadOnlyMemTable*>* to_delete,
size_t usage) {
bool ret = false;
while (HistoryShouldBeTrimmed(usage)) {
ReadOnlyMemTable* x = memlist_history_.back();
memlist_history_.pop_back();
UnrefMemTable(to_delete, x);
ret = true;
}
return ret;
}
// Returns true if there is at least one memtable on which flush has
// not yet started.
bool MemTableList::IsFlushPending() const {
if ((flush_requested_ && num_flush_not_started_ > 0) ||
(num_flush_not_started_ >= min_write_buffer_number_to_merge_)) {
assert(imm_flush_needed.load(std::memory_order_relaxed));
return true;
}
return false;
}
bool MemTableList::IsFlushPendingOrRunning() const {
if (current_->memlist_.size() - num_flush_not_started_ > 0) {
// Flush is already running on at least one memtable
return true;
}
return IsFlushPending();
}
// Returns the memtables that need to be flushed.
void MemTableList::PickMemtablesToFlush(uint64_t max_memtable_id,
autovector<ReadOnlyMemTable*>* ret,
uint64_t* max_next_log_number) {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_PICK_MEMTABLES_TO_FLUSH);
const auto& memlist = current_->memlist_;
bool atomic_flush = false;
// Note: every time MemTableList::Add(mem) is called, it adds the new mem
// at the FRONT of the memlist (memlist.push_front(mem)). Therefore, by
// iterating through the memlist starting at the end, the vector<MemTable*>
// ret is filled with memtables already sorted in increasing MemTable ID.
// However, when the mempurge feature is activated, new memtables with older
// IDs will be added to the memlist.
for (auto it = memlist.rbegin(); it != memlist.rend(); ++it) {
ReadOnlyMemTable* m = *it;
if (!atomic_flush && m->atomic_flush_seqno_ != kMaxSequenceNumber) {
atomic_flush = true;
}
if (m->GetID() > max_memtable_id) {
break;
}
if (!m->flush_in_progress_) {
assert(!m->flush_completed_);
num_flush_not_started_--;
if (num_flush_not_started_ == 0) {
imm_flush_needed.store(false, std::memory_order_release);
}
m->flush_in_progress_ = true; // flushing will start very soon
if (max_next_log_number) {
*max_next_log_number =
std::max(m->GetNextLogNumber(), *max_next_log_number);
}
ret->push_back(m);
} else if (!ret->empty()) {
// This `break` is necessary to prevent picking non-consecutive memtables
// in case `memlist` has one or more entries with
// `flush_in_progress_ == true` sandwiched between entries with
// `flush_in_progress_ == false`. This could happen after parallel flushes
// are picked and the one flushing older memtables is rolled back.
break;
}
}
if (!atomic_flush || num_flush_not_started_ == 0) {
flush_requested_ = false; // start-flush request is complete
}
}
void MemTableList::RollbackMemtableFlush(
const autovector<ReadOnlyMemTable*>& mems,
bool rollback_succeeding_memtables) {
TEST_SYNC_POINT("RollbackMemtableFlush");
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_MEMTABLE_ROLLBACK);
#ifndef NDEBUG
for (ReadOnlyMemTable* m : mems) {
assert(m->flush_in_progress_);
assert(m->file_number_ == 0);
}
#endif
if (rollback_succeeding_memtables && !mems.empty()) {
std::list<ReadOnlyMemTable*>& memlist = current_->memlist_;
auto it = memlist.rbegin();
for (; *it != mems[0] && it != memlist.rend(); ++it) {
}
// mems should be in memlist
assert(*it == mems[0]);
if (*it == mems[0]) {
++it;
}
while (it != memlist.rend()) {
ReadOnlyMemTable* m = *it;
// Only rollback complete, not in-progress,
// in_progress can be flushes that are still writing SSTs
if (m->flush_completed_) {
m->flush_in_progress_ = false;
m->flush_completed_ = false;
m->edit_.Clear();
m->file_number_ = 0;
num_flush_not_started_++;
++it;
} else {
break;
}
}
}
for (ReadOnlyMemTable* m : mems) {
if (m->flush_in_progress_) {
assert(m->file_number_ == 0);
m->file_number_ = 0;
m->flush_in_progress_ = false;
m->flush_completed_ = false;
m->edit_.Clear();
num_flush_not_started_++;
}
}
if (!mems.empty()) {
imm_flush_needed.store(true, std::memory_order_release);
}
}
// Try record a successful flush in the manifest file. It might just return
// Status::OK letting a concurrent flush to do actual the recording..
Status MemTableList::TryInstallMemtableFlushResults(
ColumnFamilyData* cfd, const MutableCFOptions& mutable_cf_options,
const autovector<ReadOnlyMemTable*>& mems,
LogsWithPrepTracker* prep_tracker, VersionSet* vset, InstrumentedMutex* mu,
uint64_t file_number, autovector<ReadOnlyMemTable*>* to_delete,
FSDirectory* db_directory, LogBuffer* log_buffer,
std::list<std::unique_ptr<FlushJobInfo>>* committed_flush_jobs_info,
bool write_edits) {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_MEMTABLE_INSTALL_FLUSH_RESULTS);
mu->AssertHeld();
const ReadOptions read_options(Env::IOActivity::kFlush);
const WriteOptions write_options(Env::IOActivity::kFlush);
// Flush was successful
// Record the status on the memtable object. Either this call or a call by a
// concurrent flush thread will read the status and write it to manifest.
for (size_t i = 0; i < mems.size(); ++i) {
// All the edits are associated with the first memtable of this batch.
assert(i == 0 || mems[i]->GetEdits()->NumEntries() == 0);
mems[i]->flush_completed_ = true;
mems[i]->file_number_ = file_number;
}
// if some other thread is already committing, then return
Status s;
if (commit_in_progress_) {
TEST_SYNC_POINT("MemTableList::TryInstallMemtableFlushResults:InProgress");
return s;
}
// Only a single thread can be executing this piece of code
commit_in_progress_ = true;
// Retry until all completed flushes are committed. New flushes can finish
// while the current thread is writing manifest where mutex is released.
while (s.ok()) {
auto& memlist = current_->memlist_;
// The back is the oldest; if flush_completed_ is not set to it, it means
// that we were assigned a more recent memtable. The memtables' flushes must
// be recorded in manifest in order. A concurrent flush thread, who is
// assigned to flush the oldest memtable, will later wake up and does all
// the pending writes to manifest, in order.
if (memlist.empty() || !memlist.back()->flush_completed_) {
break;
}
// scan all memtables from the earliest, and commit those
// (in that order) that have finished flushing. Memtables
// are always committed in the order that they were created.
uint64_t batch_file_number = 0;
autovector<VersionEdit*> edit_list;
autovector<ReadOnlyMemTable*> memtables_to_flush;
// enumerate from the last (earliest) element to see how many batch finished
for (auto it = memlist.rbegin(); it != memlist.rend(); ++it) {
ReadOnlyMemTable* m = *it;
if (!m->flush_completed_) {
break;
}
if (it == memlist.rbegin() || batch_file_number != m->file_number_) {
// Oldest memtable in a new batch.
batch_file_number = m->file_number_;
if (m->edit_.GetBlobFileAdditions().empty()) {
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit flush result of table #%" PRIu64
" started",
cfd->GetName().c_str(), m->file_number_);
} else {
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit flush result of table #%" PRIu64
" (+%zu blob files) started",
cfd->GetName().c_str(), m->file_number_,
m->edit_.GetBlobFileAdditions().size());
}
edit_list.push_back(&m->edit_);
std::unique_ptr<FlushJobInfo> info = m->ReleaseFlushJobInfo();
if (info != nullptr) {
committed_flush_jobs_info->push_back(std::move(info));
}
}
memtables_to_flush.push_back(m);
}
size_t num_mem_to_flush = memtables_to_flush.size();
// TODO(myabandeh): Not sure how batch_count could be 0 here.
if (num_mem_to_flush > 0) {
VersionEdit edit;
#ifdef ROCKSDB_ASSERT_STATUS_CHECKED
if (memtables_to_flush.size() == memlist.size()) {
// TODO(yuzhangyu): remove this testing code once the
// `GetEditForDroppingCurrentVersion` API is used by the atomic data
// replacement. This function can get the same edits for wal related
// fields, and some duplicated fields as contained already in edit_list
// for column family's recovery.
edit = GetEditForDroppingCurrentVersion(cfd, vset, prep_tracker);
} else {
edit = GetDBRecoveryEditForObsoletingMemTables(
vset, *cfd, edit_list, memtables_to_flush, prep_tracker);
}
#else
edit = GetDBRecoveryEditForObsoletingMemTables(
vset, *cfd, edit_list, memtables_to_flush, prep_tracker);
#endif // ROCKSDB_ASSERT_STATUS_CHECKED
TEST_SYNC_POINT_CALLBACK(
"MemTableList::TryInstallMemtableFlushResults:"
"AfterComputeMinWalToKeep",
nullptr);
edit_list.push_back(&edit);
const auto manifest_write_cb = [this, cfd, num_mem_to_flush, log_buffer,
to_delete, mu](const Status& status) {
RemoveMemTablesOrRestoreFlags(status, cfd, num_mem_to_flush, log_buffer,
to_delete, mu);
};
if (write_edits) {
// this can release and reacquire the mutex.
s = vset->LogAndApply(
cfd, mutable_cf_options, read_options, write_options, edit_list, mu,
db_directory, /*new_descriptor_log=*/false,
/*column_family_options=*/nullptr, manifest_write_cb);
} else {
// If write_edit is false (e.g: successful mempurge),
// then remove old memtables, wake up manifest write queue threads,
// and don't commit anything to the manifest file.
RemoveMemTablesOrRestoreFlags(s, cfd, num_mem_to_flush, log_buffer,
to_delete, mu);
// Note: cfd->SetLogNumber is only called when a VersionEdit
// is written to MANIFEST. When mempurge is succesful, we skip
// this step, therefore cfd->GetLogNumber is always is
// earliest log with data unflushed.
// Notify new head of manifest write queue.
// wake up all the waiting writers
// TODO(bjlemaire): explain full reason WakeUpWaitingManifestWriters
// needed or investigate more.
vset->WakeUpWaitingManifestWriters();
}
}
}
commit_in_progress_ = false;
return s;
}
// New memtables are inserted at the front of the list.
void MemTableList::Add(ReadOnlyMemTable* m,
autovector<ReadOnlyMemTable*>* to_delete) {
assert(static_cast<int>(current_->memlist_.size()) >= num_flush_not_started_);
InstallNewVersion();
// this method is used to move mutable memtable into an immutable list.
// since mutable memtable is already refcounted by the DBImpl,
// and when moving to the immutable list we don't unref it,
// we don't have to ref the memtable here. we just take over the
// reference from the DBImpl.
current_->Add(m, to_delete);
m->MarkImmutable();
num_flush_not_started_++;
if (num_flush_not_started_ == 1) {
imm_flush_needed.store(true, std::memory_order_release);
}
UpdateCachedValuesFromMemTableListVersion();
ResetTrimHistoryNeeded();
}
bool MemTableList::TrimHistory(autovector<ReadOnlyMemTable*>* to_delete,
size_t usage) {
// Check if history trim is needed first, so that we can avoid installing a
// new MemTableListVersion without installing a SuperVersion (installed based
// on return value of this function).
if (!current_->HistoryShouldBeTrimmed(usage)) {
ResetTrimHistoryNeeded();
return false;
}
InstallNewVersion();
bool ret = current_->TrimHistory(to_delete, usage);
assert(ret);
UpdateCachedValuesFromMemTableListVersion();
ResetTrimHistoryNeeded();
return ret;
}
// Returns an estimate of the number of bytes of data in use.
size_t MemTableList::ApproximateUnflushedMemTablesMemoryUsage() {
size_t total_size = 0;
for (auto& memtable : current_->memlist_) {
total_size += memtable->ApproximateMemoryUsage();
}
return total_size;
}
size_t MemTableList::ApproximateMemoryUsage() { return current_memory_usage_; }
size_t MemTableList::MemoryAllocatedBytesExcludingLast() const {
const size_t usage = current_memory_allocted_bytes_excluding_last_.load(
std::memory_order_relaxed);
return usage;
}
bool MemTableList::HasHistory() const {
const bool has_history = current_has_history_.load(std::memory_order_relaxed);
return has_history;
}
void MemTableList::UpdateCachedValuesFromMemTableListVersion() {
const size_t total_memtable_size =
current_->MemoryAllocatedBytesExcludingLast();
current_memory_allocted_bytes_excluding_last_.store(
total_memtable_size, std::memory_order_relaxed);
const bool has_history = current_->HasHistory();
current_has_history_.store(has_history, std::memory_order_relaxed);
}
uint64_t MemTableList::ApproximateOldestKeyTime() const {
if (!current_->memlist_.empty()) {
return current_->memlist_.back()->ApproximateOldestKeyTime();
}
return std::numeric_limits<uint64_t>::max();
}
void MemTableList::InstallNewVersion() {
if (current_->refs_ == 1) {
// we're the only one using the version, just keep using it
} else {
// somebody else holds the current version, we need to create new one
MemTableListVersion* version = current_;
current_ = new MemTableListVersion(&current_memory_usage_, *version);
current_->SetID(++last_memtable_list_version_id_);
current_->Ref();
version->Unref();
}
}
void MemTableList::RemoveMemTablesOrRestoreFlags(
const Status& s, ColumnFamilyData* cfd, size_t num_mem_to_flush,
LogBuffer* log_buffer, autovector<ReadOnlyMemTable*>* to_delete,
InstrumentedMutex* mu) {
assert(mu);
mu->AssertHeld();
assert(to_delete);
// we will be changing the version in the next code path,
// so we better create a new one, since versions are immutable
InstallNewVersion();
// All the later memtables that have the same filenum
// are part of the same batch. They can be committed now.
uint64_t mem_id = 1; // how many memtables have been flushed.
// commit new state only if the column family is NOT dropped.
// The reason is as follows (refer to
// ColumnFamilyTest.FlushAndDropRaceCondition).
// If the column family is dropped, then according to LogAndApply, its
// corresponding flush operation is NOT written to the MANIFEST. This
// means the DB is not aware of the L0 files generated from the flush.
// By committing the new state, we remove the memtable from the memtable
// list. Creating an iterator on this column family will not be able to
// read full data since the memtable is removed, and the DB is not aware
// of the L0 files, causing MergingIterator unable to build child
// iterators. RocksDB contract requires that the iterator can be created
// on a dropped column family, and we must be able to
// read full data as long as column family handle is not deleted, even if
// the column family is dropped.
if (s.ok() && !cfd->IsDropped()) { // commit new state
while (num_mem_to_flush-- > 0) {
ReadOnlyMemTable* m = current_->memlist_.back();
// TODO: The logging can be redundant when we flush multiple memtables
// into one SST file. We should only check the edit_ of the oldest
// memtable in the group in that case.
if (m->edit_.GetBlobFileAdditions().empty()) {
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit flush result of table #%" PRIu64
": memtable #%" PRIu64 " done",
cfd->GetName().c_str(), m->file_number_, mem_id);
} else {
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit flush result of table #%" PRIu64
" (+%zu blob files)"
": memtable #%" PRIu64 " done",
cfd->GetName().c_str(), m->file_number_,
m->edit_.GetBlobFileAdditions().size(), mem_id);
}
assert(m->file_number_ > 0);
current_->Remove(m, to_delete);
UpdateCachedValuesFromMemTableListVersion();
ResetTrimHistoryNeeded();
++mem_id;
}
} else {
for (auto it = current_->memlist_.rbegin(); num_mem_to_flush-- > 0; ++it) {
ReadOnlyMemTable* m = *it;
// commit failed. setup state so that we can flush again.
if (m->edit_.GetBlobFileAdditions().empty()) {
ROCKS_LOG_BUFFER(log_buffer,
"Level-0 commit table #%" PRIu64 ": memtable #%" PRIu64
" failed",
m->file_number_, mem_id);
} else {
ROCKS_LOG_BUFFER(log_buffer,
"Level-0 commit table #%" PRIu64
" (+%zu blob files)"
": memtable #%" PRIu64 " failed",
m->file_number_,
m->edit_.GetBlobFileAdditions().size(), mem_id);
}
m->flush_completed_ = false;
m->flush_in_progress_ = false;
m->edit_.Clear();
num_flush_not_started_++;
m->file_number_ = 0;
imm_flush_needed.store(true, std::memory_order_release);
++mem_id;
}
}
}
uint64_t MemTableList::PrecomputeMinLogContainingPrepSection(
const std::unordered_set<ReadOnlyMemTable*>* memtables_to_flush) const {
uint64_t min_log = 0;
for (auto& m : current_->memlist_) {
if (memtables_to_flush && memtables_to_flush->count(m)) {
continue;
}
auto log = m->GetMinLogContainingPrepSection();
if (log > 0 && (min_log == 0 || log < min_log)) {
min_log = log;
}
}
return min_log;
}
// Commit a successful atomic flush in the manifest file.
Status InstallMemtableAtomicFlushResults(
const autovector<MemTableList*>* imm_lists,
const autovector<ColumnFamilyData*>& cfds,
const autovector<const MutableCFOptions*>& mutable_cf_options_list,
const autovector<const autovector<ReadOnlyMemTable*>*>& mems_list,
VersionSet* vset, LogsWithPrepTracker* prep_tracker, InstrumentedMutex* mu,
const autovector<FileMetaData*>& file_metas,
const autovector<std::list<std::unique_ptr<FlushJobInfo>>*>&
committed_flush_jobs_info,
autovector<ReadOnlyMemTable*>* to_delete, FSDirectory* db_directory,
LogBuffer* log_buffer) {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_MEMTABLE_INSTALL_FLUSH_RESULTS);
mu->AssertHeld();
const ReadOptions read_options(Env::IOActivity::kFlush);
const WriteOptions write_options(Env::IOActivity::kFlush);
size_t num = mems_list.size();
assert(cfds.size() == num);
if (imm_lists != nullptr) {
assert(imm_lists->size() == num);
}
if (num == 0) {
return Status::OK();
}
for (size_t k = 0; k != num; ++k) {
#ifndef NDEBUG
const auto* imm =
(imm_lists == nullptr) ? cfds[k]->imm() : imm_lists->at(k);
if (!mems_list[k]->empty()) {
assert((*mems_list[k])[0]->GetID() == imm->GetEarliestMemTableID());
}
#endif
assert(nullptr != file_metas[k]);
for (size_t i = 0; i != mems_list[k]->size(); ++i) {
assert(i == 0 || (*mems_list[k])[i]->GetEdits()->NumEntries() == 0);
(*mems_list[k])[i]->SetFlushCompleted(true);
(*mems_list[k])[i]->SetFileNumber(file_metas[k]->fd.GetNumber());
}
if (committed_flush_jobs_info[k]) {
assert(!mems_list[k]->empty());
assert((*mems_list[k])[0]);
std::unique_ptr<FlushJobInfo> flush_job_info =
(*mems_list[k])[0]->ReleaseFlushJobInfo();
committed_flush_jobs_info[k]->push_back(std::move(flush_job_info));
}
}
Status s;
autovector<autovector<VersionEdit*>> edit_lists;
uint32_t num_entries = 0;
for (const auto mems : mems_list) {
assert(mems != nullptr);
autovector<VersionEdit*> edits;
assert(!mems->empty());
edits.emplace_back((*mems)[0]->GetEdits());
++num_entries;
edit_lists.emplace_back(edits);
}
WalNumber min_wal_number_to_keep = 0;
if (vset->db_options()->allow_2pc) {
min_wal_number_to_keep = PrecomputeMinLogNumberToKeep2PC(
vset, cfds, edit_lists, mems_list, prep_tracker);
} else {
min_wal_number_to_keep =
PrecomputeMinLogNumberToKeepNon2PC(vset, cfds, edit_lists);
}
VersionEdit wal_deletion;
wal_deletion.SetMinLogNumberToKeep(min_wal_number_to_keep);
if (vset->db_options()->track_and_verify_wals_in_manifest &&
min_wal_number_to_keep > vset->GetWalSet().GetMinWalNumberToKeep()) {
wal_deletion.DeleteWalsBefore(min_wal_number_to_keep);
}
edit_lists.back().push_back(&wal_deletion);
++num_entries;
// Mark the version edits as an atomic group if the number of version edits
// exceeds 1.
if (cfds.size() > 1) {
for (size_t i = 0; i < edit_lists.size(); i++) {
assert((edit_lists[i].size() == 1) ||
((edit_lists[i].size() == 2) && (i == edit_lists.size() - 1)));
for (auto& e : edit_lists[i]) {
e->MarkAtomicGroup(--num_entries);
}
}
assert(0 == num_entries);
}
// this can release and reacquire the mutex.
s = vset->LogAndApply(cfds, mutable_cf_options_list, read_options,
write_options, edit_lists, mu, db_directory);
for (size_t k = 0; k != cfds.size(); ++k) {
auto* imm = (imm_lists == nullptr) ? cfds[k]->imm() : imm_lists->at(k);
imm->InstallNewVersion();
}
if (s.ok() || s.IsColumnFamilyDropped()) {
for (size_t i = 0; i != cfds.size(); ++i) {
if (cfds[i]->IsDropped()) {
continue;
}
auto* imm = (imm_lists == nullptr) ? cfds[i]->imm() : imm_lists->at(i);
for (auto m : *mems_list[i]) {
assert(m->GetFileNumber() > 0);
uint64_t mem_id = m->GetID();
const VersionEdit* const edit = m->GetEdits();
assert(edit);
if (edit->GetBlobFileAdditions().empty()) {
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit table #%" PRIu64
": memtable #%" PRIu64 " done",
cfds[i]->GetName().c_str(), m->GetFileNumber(),
mem_id);
} else {
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit table #%" PRIu64
" (+%zu blob files)"
": memtable #%" PRIu64 " done",
cfds[i]->GetName().c_str(), m->GetFileNumber(),
edit->GetBlobFileAdditions().size(), mem_id);
}
imm->current_->Remove(m, to_delete);
imm->UpdateCachedValuesFromMemTableListVersion();
imm->ResetTrimHistoryNeeded();
}
}
} else {
for (size_t i = 0; i != cfds.size(); ++i) {
auto* imm = (imm_lists == nullptr) ? cfds[i]->imm() : imm_lists->at(i);
for (auto m : *mems_list[i]) {
uint64_t mem_id = m->GetID();
const VersionEdit* const edit = m->GetEdits();
assert(edit);
if (edit->GetBlobFileAdditions().empty()) {
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit table #%" PRIu64
": memtable #%" PRIu64 " failed",
cfds[i]->GetName().c_str(), m->GetFileNumber(),
mem_id);
} else {
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit table #%" PRIu64
" (+%zu blob files)"
": memtable #%" PRIu64 " failed",
cfds[i]->GetName().c_str(), m->GetFileNumber(),
edit->GetBlobFileAdditions().size(), mem_id);
}
m->SetFlushCompleted(false);
m->SetFlushInProgress(false);
m->GetEdits()->Clear();
m->SetFileNumber(0);
imm->num_flush_not_started_++;
}
imm->imm_flush_needed.store(true, std::memory_order_release);
}
}
return s;
}
void MemTableList::RemoveOldMemTables(
uint64_t log_number, autovector<ReadOnlyMemTable*>* to_delete) {
assert(to_delete != nullptr);
InstallNewVersion();
auto& memlist = current_->memlist_;
autovector<ReadOnlyMemTable*> old_memtables;
for (auto it = memlist.rbegin(); it != memlist.rend(); ++it) {
ReadOnlyMemTable* mem = *it;
if (mem->GetNextLogNumber() > log_number) {
break;
}
old_memtables.push_back(mem);
}
for (auto it = old_memtables.begin(); it != old_memtables.end(); ++it) {
ReadOnlyMemTable* mem = *it;
current_->Remove(mem, to_delete);
--num_flush_not_started_;
if (0 == num_flush_not_started_) {
imm_flush_needed.store(false, std::memory_order_release);
}
}
UpdateCachedValuesFromMemTableListVersion();
ResetTrimHistoryNeeded();
}
VersionEdit MemTableList::GetEditForDroppingCurrentVersion(
const ColumnFamilyData* cfd, VersionSet* vset,
LogsWithPrepTracker* prep_tracker) const {
assert(cfd);
auto& memlist = current_->memlist_;
if (memlist.empty()) {
return VersionEdit();
}
uint64_t max_next_log_number = 0;
autovector<VersionEdit*> edit_list;
autovector<ReadOnlyMemTable*> memtables_to_drop;
for (auto it = memlist.rbegin(); it != memlist.rend(); ++it) {
ReadOnlyMemTable* m = *it;
memtables_to_drop.push_back(m);
max_next_log_number = std::max(m->GetNextLogNumber(), max_next_log_number);
}
// Check the obsoleted MemTables' impact on WALs related to DB's recovery (min
// log number to keep, a delta of WAL files to delete).
VersionEdit edit_with_log_number;
edit_with_log_number.SetPrevLogNumber(0);
edit_with_log_number.SetLogNumber(max_next_log_number);
edit_list.push_back(&edit_with_log_number);
VersionEdit edit = GetDBRecoveryEditForObsoletingMemTables(
vset, *cfd, edit_list, memtables_to_drop, prep_tracker);
// Set fields related to the column family's recovery.
edit.SetColumnFamily(cfd->GetID());
edit.SetPrevLogNumber(0);
edit.SetLogNumber(max_next_log_number);
return edit;
}
} // namespace ROCKSDB_NAMESPACE
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