rocksdb/db/memtable_list.cc
Yanqin Jin 35c950a94e Refactor atomic flush result installation to MANIFEST (#4791)
Summary:
as titled.
Since different bg flush threads can flush different sets of column families
(due to column family creation and drop), we decide not to let one thread
perform atomic flush result installation for other threads. Bg flush threads
will install their atomic flush results sequentially to MANIFEST, using
a conditional variable, i.e. atomic_flush_install_cv_ to coordinate.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4791

Differential Revision: D13498930

Pulled By: riversand963

fbshipit-source-id: dd7482fc41f4bd22dad1e1ef7d4764ef424688d7
2019-01-07 10:12:51 -08:00

632 lines
22 KiB
C++

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
#include "db/memtable_list.h"
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include <inttypes.h>
#include <limits>
#include <queue>
#include <string>
#include "db/db_impl.h"
#include "db/memtable.h"
#include "db/range_tombstone_fragmenter.h"
#include "db/version_set.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 "util/coding.h"
#include "util/log_buffer.h"
#include "util/sync_point.h"
namespace rocksdb {
class InternalKeyComparator;
class Mutex;
class VersionSet;
void MemTableListVersion::AddMemTable(MemTable* m) {
memlist_.push_front(m);
*parent_memtable_list_memory_usage_ += m->ApproximateMemoryUsage();
}
void MemTableListVersion::UnrefMemTable(autovector<MemTable*>* to_delete,
MemTable* 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, MemTableListVersion* old)
: max_write_buffer_number_to_maintain_(
old->max_write_buffer_number_to_maintain_),
parent_memtable_list_memory_usage_(parent_memtable_list_memory_usage) {
if (old != nullptr) {
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)
: max_write_buffer_number_to_maintain_(max_write_buffer_number_to_maintain),
parent_memtable_list_memory_usage_(parent_memtable_list_memory_usage) {}
void MemTableListVersion::Ref() { ++refs_; }
// called by superversion::clean()
void MemTableListVersion::Unref(autovector<MemTable*>* 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 = static_cast<int>(current_->memlist_.size());
assert(num_flush_not_started_ <= size);
return size;
}
int MemTableList::NumFlushed() const {
return static_cast<int>(current_->memlist_history_.size());
}
// 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,
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, s, merge_context,
max_covering_tombstone_seq, seq, read_opts, callback,
is_blob_index);
}
bool MemTableListVersion::GetFromHistory(
const LookupKey& key, std::string* value, 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, s, merge_context,
max_covering_tombstone_seq, seq, read_opts,
nullptr /*read_callback*/, is_blob_index);
}
bool MemTableListVersion::GetFromList(
std::list<MemTable*>* list, const LookupKey& key, std::string* value,
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) {
SequenceNumber current_seq = kMaxSequenceNumber;
bool done =
memtable->Get(key, value, s, merge_context, max_covering_tombstone_seq,
&current_seq, read_opts, 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->IsNotFound());
return true;
}
if (!done && !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);
for (auto& m : memlist_) {
// Using kMaxSequenceNumber is OK because these are immutable memtables.
std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter(
m->NewRangeTombstoneIterator(read_opts,
kMaxSequenceNumber /* read_seq */));
range_del_agg->AddTombstones(std::move(range_del_iter));
}
return Status::OK();
}
void MemTableListVersion::AddIterators(
const ReadOptions& options, std::vector<InternalIterator*>* iterator_list,
Arena* arena) {
for (auto& m : memlist_) {
iterator_list->push_back(m->NewIterator(options, arena));
}
}
void MemTableListVersion::AddIterators(
const ReadOptions& options, MergeIteratorBuilder* merge_iter_builder) {
for (auto& m : memlist_) {
merge_iter_builder->AddIterator(
m->NewIterator(options, merge_iter_builder->GetArena()));
}
}
uint64_t MemTableListVersion::GetTotalNumEntries() const {
uint64_t total_num = 0;
for (auto& m : memlist_) {
total_num += m->num_entries();
}
return total_num;
}
MemTable::MemTableStats MemTableListVersion::ApproximateStats(
const Slice& start_ikey, const Slice& end_ikey) {
MemTable::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->num_deletes();
}
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;
}
}
// caller is responsible for referencing m
void MemTableListVersion::Add(MemTable* m, autovector<MemTable*>* to_delete) {
assert(refs_ == 1); // only when refs_ == 1 is MemTableListVersion mutable
AddMemTable(m);
TrimHistory(to_delete);
}
// Removes m from list of memtables not flushed. Caller should NOT Unref m.
void MemTableListVersion::Remove(MemTable* m,
autovector<MemTable*>* to_delete) {
assert(refs_ == 1); // only when refs_ == 1 is MemTableListVersion mutable
memlist_.remove(m);
m->MarkFlushed();
if (max_write_buffer_number_to_maintain_ > 0) {
memlist_history_.push_front(m);
TrimHistory(to_delete);
} else {
UnrefMemTable(to_delete, m);
}
}
// Make sure we don't use up too much space in history
void MemTableListVersion::TrimHistory(autovector<MemTable*>* to_delete) {
while (memlist_.size() + memlist_history_.size() >
static_cast<size_t>(max_write_buffer_number_to_maintain_) &&
!memlist_history_.empty()) {
MemTable* x = memlist_history_.back();
memlist_history_.pop_back();
UnrefMemTable(to_delete, x);
}
}
// 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;
}
// Returns the memtables that need to be flushed.
void MemTableList::PickMemtablesToFlush(const uint64_t* max_memtable_id,
autovector<MemTable*>* ret) {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_PICK_MEMTABLES_TO_FLUSH);
const auto& memlist = current_->memlist_;
for (auto it = memlist.rbegin(); it != memlist.rend(); ++it) {
MemTable* m = *it;
if (max_memtable_id != nullptr && 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
ret->push_back(m);
}
}
flush_requested_ = false; // start-flush request is complete
}
void MemTableList::RollbackMemtableFlush(const autovector<MemTable*>& mems,
uint64_t /*file_number*/) {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_MEMTABLE_ROLLBACK);
assert(!mems.empty());
// If the flush was not successful, then just reset state.
// Maybe a succeeding attempt to flush will be successful.
for (MemTable* m : mems) {
assert(m->flush_in_progress_);
assert(m->file_number_ == 0);
m->flush_in_progress_ = false;
m->flush_completed_ = false;
m->edit_.Clear();
num_flush_not_started_++;
}
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<MemTable*>& mems, LogsWithPrepTracker* prep_tracker,
VersionSet* vset, InstrumentedMutex* mu, uint64_t file_number,
autovector<MemTable*>* to_delete, Directory* db_directory,
LogBuffer* log_buffer) {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_MEMTABLE_INSTALL_FLUSH_RESULTS);
mu->AssertHeld();
// 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;
size_t batch_count = 0;
autovector<VersionEdit*> edit_list;
autovector<MemTable*> memtables_to_flush;
// enumerate from the last (earliest) element to see how many batch finished
for (auto it = memlist.rbegin(); it != memlist.rend(); ++it) {
MemTable* m = *it;
if (!m->flush_completed_) {
break;
}
if (it == memlist.rbegin() || batch_file_number != m->file_number_) {
batch_file_number = m->file_number_;
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit table #%" PRIu64 " started",
cfd->GetName().c_str(), m->file_number_);
edit_list.push_back(&m->edit_);
memtables_to_flush.push_back(m);
}
batch_count++;
}
// TODO(myabandeh): Not sure how batch_count could be 0 here.
if (batch_count > 0) {
if (vset->db_options()->allow_2pc) {
assert(edit_list.size() > 0);
// We piggyback the information of earliest log file to keep in the
// manifest entry for the last file flushed.
edit_list.back()->SetMinLogNumberToKeep(PrecomputeMinLogNumberToKeep(
vset, *cfd, edit_list, memtables_to_flush, prep_tracker));
}
// this can release and reacquire the mutex.
s = vset->LogAndApply(cfd, mutable_cf_options, edit_list, mu,
db_directory);
// 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 (batch_count-- > 0) {
MemTable* m = current_->memlist_.back();
ROCKS_LOG_BUFFER(log_buffer, "[%s] Level-0 commit table #%" PRIu64
": memtable #%" PRIu64 " done",
cfd->GetName().c_str(), m->file_number_, mem_id);
assert(m->file_number_ > 0);
current_->Remove(m, to_delete);
++mem_id;
}
} else {
for (auto it = current_->memlist_.rbegin(); batch_count-- > 0; it++) {
MemTable* m = *it;
// commit failed. setup state so that we can flush again.
ROCKS_LOG_BUFFER(log_buffer, "Level-0 commit table #%" PRIu64
": memtable #%" PRIu64 " failed",
m->file_number_, 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;
}
}
}
}
commit_in_progress_ = false;
return s;
}
// New memtables are inserted at the front of the list.
void MemTableList::Add(MemTable* m, autovector<MemTable*>* 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 imutable 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);
}
}
// 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_; }
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_, current_);
current_->Ref();
version->Unref();
}
}
uint64_t MemTableList::PrecomputeMinLogContainingPrepSection(
const autovector<MemTable*>& memtables_to_flush) {
uint64_t min_log = 0;
for (auto& m : current_->memlist_) {
// Assume the list is very short, we can live with O(m*n). We can optimize
// if the performance has some problem.
bool should_skip = false;
for (MemTable* m_to_flush : memtables_to_flush) {
if (m == m_to_flush) {
should_skip = true;
break;
}
}
if (should_skip) {
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<MemTable*>*>& mems_list, VersionSet* vset,
InstrumentedMutex* mu, const autovector<FileMetaData>& file_metas,
autovector<MemTable*>* to_delete, Directory* db_directory,
LogBuffer* log_buffer) {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_MEMTABLE_INSTALL_FLUSH_RESULTS);
mu->AssertHeld();
size_t num = mems_list.size();
assert(cfds.size() == num);
if (imm_lists != nullptr) {
assert(imm_lists->size() == num);
}
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
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());
}
}
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);
}
// Mark the version edits as an atomic group
for (auto& edits : edit_lists) {
assert(edits.size() == 1);
edits[0]->MarkAtomicGroup(--num_entries);
}
assert(0 == num_entries);
// this can release and reacquire the mutex.
s = vset->LogAndApply(cfds, mutable_cf_options_list, 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.IsShutdownInProgress()) {
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();
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit table #%" PRIu64
": memtable #%" PRIu64 " done",
cfds[i]->GetName().c_str(), m->GetFileNumber(),
mem_id);
imm->current_->Remove(m, to_delete);
}
}
} 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();
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Level-0 commit table #%" PRIu64
": memtable #%" PRIu64 " failed",
cfds[i]->GetName().c_str(), m->GetFileNumber(),
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;
}
} // namespace rocksdb