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rocksdb/db/memtable.cc
Yu Zhang 8592517c89 Remove stale entries from L0 files when UDT is not persisted (#13035) 
Summary:
When user-defined timestamps are not persisted, currently we replace the actual timestamp with min timestamp after an entry is output from compaction iterator. Compaction iterator won't be able to help with removing stale entries this way. This PR adds a wrapper iterator `TimestampStrippingIterator` for `MemTableIterator` that does the min timestamp replacement at the memtable iteration step. It is used by flush and can help remove stale entries from landing in L0 files.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/13035

Test Plan: Added unit test

Reviewed By: pdillinger, cbi42

Differential Revision: D63423682

Pulled By: jowlyzhang

fbshipit-source-id: 087dcc9cee97b9ea51b8d2b88dc91c2984d54e55
2024-10-14 12:28:35 -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/memtable.h"
#include <algorithm>
#include <array>
#include <limits>
#include <memory>
#include <optional>
#include "db/dbformat.h"
#include "db/kv_checksum.h"
#include "db/merge_context.h"
#include "db/merge_helper.h"
#include "db/pinned_iterators_manager.h"
#include "db/range_tombstone_fragmenter.h"
#include "db/read_callback.h"
#include "db/wide/wide_column_serialization.h"
#include "logging/logging.h"
#include "memory/arena.h"
#include "memory/memory_usage.h"
#include "monitoring/perf_context_imp.h"
#include "monitoring/statistics_impl.h"
#include "port/lang.h"
#include "port/port.h"
#include "rocksdb/comparator.h"
#include "rocksdb/env.h"
#include "rocksdb/iterator.h"
#include "rocksdb/merge_operator.h"
#include "rocksdb/slice_transform.h"
#include "rocksdb/types.h"
#include "rocksdb/write_buffer_manager.h"
#include "table/internal_iterator.h"
#include "table/iterator_wrapper.h"
#include "table/merging_iterator.h"
#include "util/autovector.h"
#include "util/coding.h"
#include "util/mutexlock.h"
namespace ROCKSDB_NAMESPACE {
ImmutableMemTableOptions::ImmutableMemTableOptions(
const ImmutableOptions& ioptions,
const MutableCFOptions& mutable_cf_options)
: arena_block_size(mutable_cf_options.arena_block_size),
memtable_prefix_bloom_bits(
static_cast<uint32_t>(
static_cast<double>(mutable_cf_options.write_buffer_size) *
mutable_cf_options.memtable_prefix_bloom_size_ratio) *
8u),
memtable_huge_page_size(mutable_cf_options.memtable_huge_page_size),
memtable_whole_key_filtering(
mutable_cf_options.memtable_whole_key_filtering),
inplace_update_support(ioptions.inplace_update_support),
inplace_update_num_locks(mutable_cf_options.inplace_update_num_locks),
inplace_callback(ioptions.inplace_callback),
max_successive_merges(mutable_cf_options.max_successive_merges),
strict_max_successive_merges(
mutable_cf_options.strict_max_successive_merges),
statistics(ioptions.stats),
merge_operator(ioptions.merge_operator.get()),
info_log(ioptions.logger),
protection_bytes_per_key(
mutable_cf_options.memtable_protection_bytes_per_key),
allow_data_in_errors(ioptions.allow_data_in_errors),
paranoid_memory_checks(mutable_cf_options.paranoid_memory_checks) {}
MemTable::MemTable(const InternalKeyComparator& cmp,
const ImmutableOptions& ioptions,
const MutableCFOptions& mutable_cf_options,
WriteBufferManager* write_buffer_manager,
SequenceNumber latest_seq, uint32_t column_family_id)
: comparator_(cmp),
moptions_(ioptions, mutable_cf_options),
refs_(0),
kArenaBlockSize(Arena::OptimizeBlockSize(moptions_.arena_block_size)),
mem_tracker_(write_buffer_manager),
arena_(moptions_.arena_block_size,
(write_buffer_manager != nullptr &&
(write_buffer_manager->enabled() ||
write_buffer_manager->cost_to_cache()))
? &mem_tracker_
: nullptr,
mutable_cf_options.memtable_huge_page_size),
table_(ioptions.memtable_factory->CreateMemTableRep(
comparator_, &arena_, mutable_cf_options.prefix_extractor.get(),
ioptions.logger, column_family_id)),
range_del_table_(SkipListFactory().CreateMemTableRep(
comparator_, &arena_, nullptr /* transform */, ioptions.logger,
column_family_id)),
is_range_del_table_empty_(true),
data_size_(0),
num_entries_(0),
num_deletes_(0),
num_range_deletes_(0),
write_buffer_size_(mutable_cf_options.write_buffer_size),
flush_in_progress_(false),
flush_completed_(false),
file_number_(0),
first_seqno_(0),
earliest_seqno_(latest_seq),
creation_seq_(latest_seq),
mem_next_logfile_number_(0),
min_prep_log_referenced_(0),
locks_(moptions_.inplace_update_support
? moptions_.inplace_update_num_locks
: 0),
prefix_extractor_(mutable_cf_options.prefix_extractor.get()),
flush_state_(FLUSH_NOT_REQUESTED),
clock_(ioptions.clock),
insert_with_hint_prefix_extractor_(
ioptions.memtable_insert_with_hint_prefix_extractor.get()),
oldest_key_time_(std::numeric_limits<uint64_t>::max()),
atomic_flush_seqno_(kMaxSequenceNumber),
approximate_memory_usage_(0),
memtable_max_range_deletions_(
mutable_cf_options.memtable_max_range_deletions) {
UpdateFlushState();
// something went wrong if we need to flush before inserting anything
assert(!ShouldScheduleFlush());
// use bloom_filter_ for both whole key and prefix bloom filter
if ((prefix_extractor_ || moptions_.memtable_whole_key_filtering) &&
moptions_.memtable_prefix_bloom_bits > 0) {
bloom_filter_.reset(
new DynamicBloom(&arena_, moptions_.memtable_prefix_bloom_bits,
6 /* hard coded 6 probes */,
moptions_.memtable_huge_page_size, ioptions.logger));
}
// Initialize cached_range_tombstone_ here since it could
// be read before it is constructed in MemTable::Add(), which could also lead
// to a data race on the global mutex table backing atomic shared_ptr.
auto new_cache = std::make_shared<FragmentedRangeTombstoneListCache>();
size_t size = cached_range_tombstone_.Size();
for (size_t i = 0; i < size; ++i) {
std::shared_ptr<FragmentedRangeTombstoneListCache>* local_cache_ref_ptr =
cached_range_tombstone_.AccessAtCore(i);
auto new_local_cache_ref = std::make_shared<
const std::shared_ptr<FragmentedRangeTombstoneListCache>>(new_cache);
std::atomic_store_explicit(
local_cache_ref_ptr,
std::shared_ptr<FragmentedRangeTombstoneListCache>(new_local_cache_ref,
new_cache.get()),
std::memory_order_relaxed);
}
const Comparator* ucmp = cmp.user_comparator();
assert(ucmp);
ts_sz_ = ucmp->timestamp_size();
persist_user_defined_timestamps_ = ioptions.persist_user_defined_timestamps;
}
MemTable::~MemTable() {
mem_tracker_.FreeMem();
assert(refs_ == 0);
}
size_t MemTable::ApproximateMemoryUsage() {
autovector<size_t> usages = {
arena_.ApproximateMemoryUsage(), table_->ApproximateMemoryUsage(),
range_del_table_->ApproximateMemoryUsage(),
ROCKSDB_NAMESPACE::ApproximateMemoryUsage(insert_hints_)};
size_t total_usage = 0;
for (size_t usage : usages) {
// If usage + total_usage >= kMaxSizet, return kMaxSizet.
// the following variation is to avoid numeric overflow.
if (usage >= std::numeric_limits<size_t>::max() - total_usage) {
return std::numeric_limits<size_t>::max();
}
total_usage += usage;
}
approximate_memory_usage_.store(total_usage, std::memory_order_relaxed);
// otherwise, return the actual usage
return total_usage;
}
bool MemTable::ShouldFlushNow() {
// This is set if memtable_max_range_deletions is > 0,
// and that many range deletions are done
if (memtable_max_range_deletions_ > 0 &&
num_range_deletes_.load(std::memory_order_relaxed) >=
static_cast<uint64_t>(memtable_max_range_deletions_)) {
return true;
}
size_t write_buffer_size = write_buffer_size_.load(std::memory_order_relaxed);
// In a lot of times, we cannot allocate arena blocks that exactly matches the
// buffer size. Thus we have to decide if we should over-allocate or
// under-allocate.
// This constant variable can be interpreted as: if we still have more than
// "kAllowOverAllocationRatio * kArenaBlockSize" space left, we'd try to over
// allocate one more block.
const double kAllowOverAllocationRatio = 0.6;
// If arena still have room for new block allocation, we can safely say it
// shouldn't flush.
auto allocated_memory = table_->ApproximateMemoryUsage() +
range_del_table_->ApproximateMemoryUsage() +
arena_.MemoryAllocatedBytes();
approximate_memory_usage_.store(allocated_memory, std::memory_order_relaxed);
// if we can still allocate one more block without exceeding the
// over-allocation ratio, then we should not flush.
if (allocated_memory + kArenaBlockSize <
write_buffer_size + kArenaBlockSize * kAllowOverAllocationRatio) {
return false;
}
// if user keeps adding entries that exceeds write_buffer_size, we need to
// flush earlier even though we still have much available memory left.
if (allocated_memory >
write_buffer_size + kArenaBlockSize * kAllowOverAllocationRatio) {
return true;
}
// In this code path, Arena has already allocated its "last block", which
// means the total allocatedmemory size is either:
// (1) "moderately" over allocated the memory (no more than `0.6 * arena
// block size`. Or,
// (2) the allocated memory is less than write buffer size, but we'll stop
// here since if we allocate a new arena block, we'll over allocate too much
// more (half of the arena block size) memory.
//
// In either case, to avoid over-allocate, the last block will stop allocation
// when its usage reaches a certain ratio, which we carefully choose "0.75
// full" as the stop condition because it addresses the following issue with
// great simplicity: What if the next inserted entry's size is
// bigger than AllocatedAndUnused()?
//
// The answer is: if the entry size is also bigger than 0.25 *
// kArenaBlockSize, a dedicated block will be allocated for it; otherwise
// arena will anyway skip the AllocatedAndUnused() and allocate a new, empty
// and regular block. In either case, we *overly* over-allocated.
//
// Therefore, setting the last block to be at most "0.75 full" avoids both
// cases.
//
// NOTE: the average percentage of waste space of this approach can be counted
// as: "arena block size * 0.25 / write buffer size". User who specify a small
// write buffer size and/or big arena block size may suffer.
return arena_.AllocatedAndUnused() < kArenaBlockSize / 4;
}
void MemTable::UpdateFlushState() {
auto state = flush_state_.load(std::memory_order_relaxed);
if (state == FLUSH_NOT_REQUESTED && ShouldFlushNow()) {
// ignore CAS failure, because that means somebody else requested
// a flush
flush_state_.compare_exchange_strong(state, FLUSH_REQUESTED,
std::memory_order_relaxed,
std::memory_order_relaxed);
}
}
void MemTable::UpdateOldestKeyTime() {
uint64_t oldest_key_time = oldest_key_time_.load(std::memory_order_relaxed);
if (oldest_key_time == std::numeric_limits<uint64_t>::max()) {
int64_t current_time = 0;
auto s = clock_->GetCurrentTime(&current_time);
if (s.ok()) {
assert(current_time >= 0);
// If fail, the timestamp is already set.
oldest_key_time_.compare_exchange_strong(
oldest_key_time, static_cast<uint64_t>(current_time),
std::memory_order_relaxed, std::memory_order_relaxed);
}
}
}
Status MemTable::VerifyEntryChecksum(const char* entry,
uint32_t protection_bytes_per_key,
bool allow_data_in_errors) {
if (protection_bytes_per_key == 0) {
return Status::OK();
}
uint32_t key_length;
const char* key_ptr = GetVarint32Ptr(entry, entry + 5, &key_length);
if (key_ptr == nullptr) {
return Status::Corruption("Unable to parse internal key length");
}
if (key_length < 8) {
return Status::Corruption("Memtable entry internal key length too short.");
}
Slice user_key = Slice(key_ptr, key_length - 8);
const uint64_t tag = DecodeFixed64(key_ptr + key_length - 8);
ValueType type;
SequenceNumber seq;
UnPackSequenceAndType(tag, &seq, &type);
uint32_t value_length = 0;
const char* value_ptr = GetVarint32Ptr(
key_ptr + key_length, key_ptr + key_length + 5, &value_length);
if (value_ptr == nullptr) {
return Status::Corruption("Unable to parse internal key value");
}
Slice value = Slice(value_ptr, value_length);
const char* checksum_ptr = value_ptr + value_length;
bool match =
ProtectionInfo64()
.ProtectKVO(user_key, value, type)
.ProtectS(seq)
.Verify(static_cast<uint8_t>(protection_bytes_per_key), checksum_ptr);
if (!match) {
std::string msg(
"Corrupted memtable entry, per key-value checksum verification "
"failed.");
if (allow_data_in_errors) {
msg.append("Unrecognized value type: " +
std::to_string(static_cast<int>(type)) + ". ");
msg.append("User key: " + user_key.ToString(/*hex=*/true) + ". ");
msg.append("seq: " + std::to_string(seq) + ".");
}
return Status::Corruption(msg.c_str());
}
return Status::OK();
}
int MemTable::KeyComparator::operator()(const char* prefix_len_key1,
const char* prefix_len_key2) const {
// Internal keys are encoded as length-prefixed strings.
Slice k1 = GetLengthPrefixedSlice(prefix_len_key1);
Slice k2 = GetLengthPrefixedSlice(prefix_len_key2);
return comparator.CompareKeySeq(k1, k2);
}
int MemTable::KeyComparator::operator()(
const char* prefix_len_key, const KeyComparator::DecodedType& key) const {
// Internal keys are encoded as length-prefixed strings.
Slice a = GetLengthPrefixedSlice(prefix_len_key);
return comparator.CompareKeySeq(a, key);
}
void MemTableRep::InsertConcurrently(KeyHandle /*handle*/) {
throw std::runtime_error("concurrent insert not supported");
}
Slice MemTableRep::UserKey(const char* key) const {
Slice slice = GetLengthPrefixedSlice(key);
return Slice(slice.data(), slice.size() - 8);
}
KeyHandle MemTableRep::Allocate(const size_t len, char** buf) {
*buf = allocator_->Allocate(len);
return static_cast<KeyHandle>(*buf);
}
// Encode a suitable internal key target for "target" and return it.
// Uses *scratch as scratch space, and the returned pointer will point
// into this scratch space.
const char* EncodeKey(std::string* scratch, const Slice& target) {
scratch->clear();
PutVarint32(scratch, static_cast<uint32_t>(target.size()));
scratch->append(target.data(), target.size());
return scratch->data();
}
class MemTableIterator : public InternalIterator {
public:
enum Kind { kPointEntries, kRangeDelEntries };
MemTableIterator(
Kind kind, const MemTable& mem, const ReadOptions& read_options,
UnownedPtr<const SeqnoToTimeMapping> seqno_to_time_mapping = nullptr,
Arena* arena = nullptr,
const SliceTransform* cf_prefix_extractor = nullptr)
: bloom_(nullptr),
prefix_extractor_(mem.prefix_extractor_),
comparator_(mem.comparator_),
seqno_to_time_mapping_(seqno_to_time_mapping),
status_(Status::OK()),
logger_(mem.moptions_.info_log),
ts_sz_(mem.ts_sz_),
protection_bytes_per_key_(mem.moptions_.protection_bytes_per_key),
valid_(false),
value_pinned_(
!mem.GetImmutableMemTableOptions()->inplace_update_support),
arena_mode_(arena != nullptr),
paranoid_memory_checks_(mem.moptions_.paranoid_memory_checks),
allow_data_in_error(mem.moptions_.allow_data_in_errors) {
if (kind == kRangeDelEntries) {
iter_ = mem.range_del_table_->GetIterator(arena);
} else if (prefix_extractor_ != nullptr &&
// NOTE: checking extractor equivalence when not pointer
// equivalent is arguably too expensive for memtable
prefix_extractor_ == cf_prefix_extractor &&
(read_options.prefix_same_as_start ||
(!read_options.total_order_seek &&
!read_options.auto_prefix_mode))) {
// Auto prefix mode is not implemented in memtable yet.
assert(kind == kPointEntries);
bloom_ = mem.bloom_filter_.get();
iter_ = mem.table_->GetDynamicPrefixIterator(arena);
} else {
assert(kind == kPointEntries);
iter_ = mem.table_->GetIterator(arena);
}
status_.PermitUncheckedError();
}
// No copying allowed
MemTableIterator(const MemTableIterator&) = delete;
void operator=(const MemTableIterator&) = delete;
~MemTableIterator() override {
#ifndef NDEBUG
// Assert that the MemTableIterator is never deleted while
// Pinning is Enabled.
assert(!pinned_iters_mgr_ || !pinned_iters_mgr_->PinningEnabled());
#endif
if (arena_mode_) {
iter_->~Iterator();
} else {
delete iter_;
}
status_.PermitUncheckedError();
}
#ifndef NDEBUG
void SetPinnedItersMgr(PinnedIteratorsManager* pinned_iters_mgr) override {
pinned_iters_mgr_ = pinned_iters_mgr;
}
PinnedIteratorsManager* pinned_iters_mgr_ = nullptr;
#endif
bool Valid() const override {
// If inner iter_ is not valid, then this iter should also not be valid.
assert(iter_->Valid() || !(valid_ && status_.ok()));
return valid_ && status_.ok();
}
void Seek(const Slice& k) override {
PERF_TIMER_GUARD(seek_on_memtable_time);
PERF_COUNTER_ADD(seek_on_memtable_count, 1);
status_ = Status::OK();
if (bloom_) {
// iterator should only use prefix bloom filter
Slice user_k_without_ts(ExtractUserKeyAndStripTimestamp(k, ts_sz_));
if (prefix_extractor_->InDomain(user_k_without_ts)) {
Slice prefix = prefix_extractor_->Transform(user_k_without_ts);
if (!bloom_->MayContain(prefix)) {
PERF_COUNTER_ADD(bloom_memtable_miss_count, 1);
valid_ = false;
return;
} else {
PERF_COUNTER_ADD(bloom_memtable_hit_count, 1);
}
}
}
if (paranoid_memory_checks_) {
status_ = iter_->SeekAndValidate(k, nullptr, allow_data_in_error);
} else {
iter_->Seek(k, nullptr);
}
valid_ = iter_->Valid();
VerifyEntryChecksum();
}
void SeekForPrev(const Slice& k) override {
PERF_TIMER_GUARD(seek_on_memtable_time);
PERF_COUNTER_ADD(seek_on_memtable_count, 1);
status_ = Status::OK();
if (bloom_) {
Slice user_k_without_ts(ExtractUserKeyAndStripTimestamp(k, ts_sz_));
if (prefix_extractor_->InDomain(user_k_without_ts)) {
if (!bloom_->MayContain(
prefix_extractor_->Transform(user_k_without_ts))) {
PERF_COUNTER_ADD(bloom_memtable_miss_count, 1);
valid_ = false;
return;
} else {
PERF_COUNTER_ADD(bloom_memtable_hit_count, 1);
}
}
}
if (paranoid_memory_checks_) {
status_ = iter_->SeekAndValidate(k, nullptr, allow_data_in_error);
} else {
iter_->Seek(k, nullptr);
}
valid_ = iter_->Valid();
VerifyEntryChecksum();
if (!Valid() && status().ok()) {
SeekToLast();
}
while (Valid() && comparator_.comparator.Compare(k, key()) < 0) {
Prev();
}
}
void SeekToFirst() override {
status_ = Status::OK();
iter_->SeekToFirst();
valid_ = iter_->Valid();
VerifyEntryChecksum();
}
void SeekToLast() override {
status_ = Status::OK();
iter_->SeekToLast();
valid_ = iter_->Valid();
VerifyEntryChecksum();
}
void Next() override {
PERF_COUNTER_ADD(next_on_memtable_count, 1);
assert(Valid());
if (paranoid_memory_checks_) {
status_ = iter_->NextAndValidate(allow_data_in_error);
} else {
iter_->Next();
TEST_SYNC_POINT_CALLBACK("MemTableIterator::Next:0", iter_);
}
valid_ = iter_->Valid();
VerifyEntryChecksum();
}
bool NextAndGetResult(IterateResult* result) override {
Next();
bool is_valid = Valid();
if (is_valid) {
result->key = key();
result->bound_check_result = IterBoundCheck::kUnknown;
result->value_prepared = true;
}
return is_valid;
}
void Prev() override {
PERF_COUNTER_ADD(prev_on_memtable_count, 1);
assert(Valid());
if (paranoid_memory_checks_) {
status_ = iter_->PrevAndValidate(allow_data_in_error);
} else {
iter_->Prev();
}
valid_ = iter_->Valid();
VerifyEntryChecksum();
}
Slice key() const override {
assert(Valid());
return GetLengthPrefixedSlice(iter_->key());
}
uint64_t write_unix_time() const override {
assert(Valid());
ParsedInternalKey pikey;
Status s = ParseInternalKey(key(), &pikey, /*log_err_key=*/false);
if (!s.ok()) {
return std::numeric_limits<uint64_t>::max();
} else if (kTypeValuePreferredSeqno == pikey.type) {
return ParsePackedValueForWriteTime(value());
} else if (!seqno_to_time_mapping_ || seqno_to_time_mapping_->Empty()) {
return std::numeric_limits<uint64_t>::max();
}
return seqno_to_time_mapping_->GetProximalTimeBeforeSeqno(pikey.sequence);
}
Slice value() const override {
assert(Valid());
Slice key_slice = GetLengthPrefixedSlice(iter_->key());
return GetLengthPrefixedSlice(key_slice.data() + key_slice.size());
}
Status status() const override { return status_; }
bool IsKeyPinned() const override {
// memtable data is always pinned
return true;
}
bool IsValuePinned() const override {
// memtable value is always pinned, except if we allow inplace update.
return value_pinned_;
}
private:
DynamicBloom* bloom_;
const SliceTransform* const prefix_extractor_;
const MemTable::KeyComparator comparator_;
MemTableRep::Iterator* iter_;
// The seqno to time mapping is owned by the SuperVersion.
UnownedPtr<const SeqnoToTimeMapping> seqno_to_time_mapping_;
Status status_;
Logger* logger_;
size_t ts_sz_;
uint32_t protection_bytes_per_key_;
bool valid_;
bool value_pinned_;
bool arena_mode_;
const bool paranoid_memory_checks_;
const bool allow_data_in_error;
void VerifyEntryChecksum() {
if (protection_bytes_per_key_ > 0 && Valid()) {
status_ = MemTable::VerifyEntryChecksum(iter_->key(),
protection_bytes_per_key_);
if (!status_.ok()) {
ROCKS_LOG_ERROR(logger_, "In MemtableIterator: %s", status_.getState());
}
}
}
};
InternalIterator* MemTable::NewIterator(
const ReadOptions& read_options,
UnownedPtr<const SeqnoToTimeMapping> seqno_to_time_mapping, Arena* arena,
const SliceTransform* prefix_extractor) {
assert(arena != nullptr);
auto mem = arena->AllocateAligned(sizeof(MemTableIterator));
return new (mem)
MemTableIterator(MemTableIterator::kPointEntries, *this, read_options,
seqno_to_time_mapping, arena, prefix_extractor);
}
// An iterator wrapper that wraps a MemTableIterator and logically strips each
// key's user-defined timestamp.
class TimestampStrippingIterator : public InternalIterator {
public:
TimestampStrippingIterator(
MemTableIterator::Kind kind, const MemTable& memtable,
const ReadOptions& read_options,
UnownedPtr<const SeqnoToTimeMapping> seqno_to_time_mapping, Arena* arena,
const SliceTransform* cf_prefix_extractor, size_t ts_sz)
: arena_mode_(arena != nullptr), kind_(kind), ts_sz_(ts_sz) {
assert(ts_sz_ != 0);
void* mem = arena ? arena->AllocateAligned(sizeof(MemTableIterator)) :
operator new(sizeof(MemTableIterator));
iter_ = new (mem)
MemTableIterator(kind, memtable, read_options, seqno_to_time_mapping,
arena, cf_prefix_extractor);
}
// No copying allowed
TimestampStrippingIterator(const TimestampStrippingIterator&) = delete;
void operator=(const TimestampStrippingIterator&) = delete;
~TimestampStrippingIterator() override {
if (arena_mode_) {
iter_->~MemTableIterator();
} else {
delete iter_;
}
}
void SetPinnedItersMgr(PinnedIteratorsManager* pinned_iters_mgr) override {
iter_->SetPinnedItersMgr(pinned_iters_mgr);
}
bool Valid() const override { return iter_->Valid(); }
void Seek(const Slice& k) override {
iter_->Seek(k);
UpdateKeyAndValueBuffer();
}
void SeekForPrev(const Slice& k) override {
iter_->SeekForPrev(k);
UpdateKeyAndValueBuffer();
}
void SeekToFirst() override {
iter_->SeekToFirst();
UpdateKeyAndValueBuffer();
}
void SeekToLast() override {
iter_->SeekToLast();
UpdateKeyAndValueBuffer();
}
void Next() override {
iter_->Next();
UpdateKeyAndValueBuffer();
}
bool NextAndGetResult(IterateResult* result) override {
iter_->Next();
UpdateKeyAndValueBuffer();
bool is_valid = Valid();
if (is_valid) {
result->key = key();
result->bound_check_result = IterBoundCheck::kUnknown;
result->value_prepared = true;
}
return is_valid;
}
void Prev() override {
iter_->Prev();
UpdateKeyAndValueBuffer();
}
Slice key() const override {
assert(Valid());
return key_buf_;
}
uint64_t write_unix_time() const override { return iter_->write_unix_time(); }
Slice value() const override {
if (kind_ == MemTableIterator::Kind::kRangeDelEntries) {
return value_buf_;
}
return iter_->value();
}
Status status() const override { return iter_->status(); }
bool IsKeyPinned() const override {
// Key is only in a buffer that is updated in each iteration.
return false;
}
bool IsValuePinned() const override {
if (kind_ == MemTableIterator::Kind::kRangeDelEntries) {
return false;
}
return iter_->IsValuePinned();
}
private:
void UpdateKeyAndValueBuffer() {
key_buf_.clear();
if (kind_ == MemTableIterator::Kind::kRangeDelEntries) {
value_buf_.clear();
}
if (!Valid()) {
return;
}
Slice original_key = iter_->key();
ReplaceInternalKeyWithMinTimestamp(&key_buf_, original_key, ts_sz_);
if (kind_ == MemTableIterator::Kind::kRangeDelEntries) {
Slice original_value = iter_->value();
AppendUserKeyWithMinTimestamp(&value_buf_, original_value, ts_sz_);
}
}
bool arena_mode_;
MemTableIterator::Kind kind_;
size_t ts_sz_;
MemTableIterator* iter_;
std::string key_buf_;
std::string value_buf_;
};
InternalIterator* MemTable::NewTimestampStrippingIterator(
const ReadOptions& read_options,
UnownedPtr<const SeqnoToTimeMapping> seqno_to_time_mapping, Arena* arena,
const SliceTransform* prefix_extractor, size_t ts_sz) {
assert(arena != nullptr);
auto mem = arena->AllocateAligned(sizeof(TimestampStrippingIterator));
return new (mem) TimestampStrippingIterator(
MemTableIterator::kPointEntries, *this, read_options,
seqno_to_time_mapping, arena, prefix_extractor, ts_sz);
}
FragmentedRangeTombstoneIterator* MemTable::NewRangeTombstoneIterator(
const ReadOptions& read_options, SequenceNumber read_seq,
bool immutable_memtable) {
if (read_options.ignore_range_deletions ||
is_range_del_table_empty_.load(std::memory_order_relaxed)) {
return nullptr;
}
return NewRangeTombstoneIteratorInternal(read_options, read_seq,
immutable_memtable);
}
FragmentedRangeTombstoneIterator*
MemTable::NewTimestampStrippingRangeTombstoneIterator(
const ReadOptions& read_options, SequenceNumber read_seq, size_t ts_sz) {
if (read_options.ignore_range_deletions ||
is_range_del_table_empty_.load(std::memory_order_relaxed)) {
return nullptr;
}
if (!timestamp_stripping_fragmented_range_tombstone_list_) {
// TODO: plumb Env::IOActivity, Env::IOPriority
auto* unfragmented_iter = new TimestampStrippingIterator(
MemTableIterator::kRangeDelEntries, *this, ReadOptions(),
/*seqno_to_time_mapping*/ nullptr, /* arena */ nullptr,
/* prefix_extractor */ nullptr, ts_sz);
timestamp_stripping_fragmented_range_tombstone_list_ =
std::make_unique<FragmentedRangeTombstoneList>(
std::unique_ptr<InternalIterator>(unfragmented_iter),
comparator_.comparator);
}
return new FragmentedRangeTombstoneIterator(
timestamp_stripping_fragmented_range_tombstone_list_.get(),
comparator_.comparator, read_seq, read_options.timestamp);
}
FragmentedRangeTombstoneIterator* MemTable::NewRangeTombstoneIteratorInternal(
const ReadOptions& read_options, SequenceNumber read_seq,
bool immutable_memtable) {
if (immutable_memtable) {
// Note that caller should already have verified that
// !is_range_del_table_empty_
assert(IsFragmentedRangeTombstonesConstructed());
return new FragmentedRangeTombstoneIterator(
fragmented_range_tombstone_list_.get(), comparator_.comparator,
read_seq, read_options.timestamp);
}
// takes current cache
std::shared_ptr<FragmentedRangeTombstoneListCache> cache =
std::atomic_load_explicit(cached_range_tombstone_.Access(),
std::memory_order_relaxed);
// construct fragmented tombstone list if necessary
if (!cache->initialized.load(std::memory_order_acquire)) {
cache->reader_mutex.lock();
if (!cache->tombstones) {
auto* unfragmented_iter = new MemTableIterator(
MemTableIterator::kRangeDelEntries, *this, read_options);
cache->tombstones.reset(new FragmentedRangeTombstoneList(
std::unique_ptr<InternalIterator>(unfragmented_iter),
comparator_.comparator));
cache->initialized.store(true, std::memory_order_release);
}
cache->reader_mutex.unlock();
}
auto* fragmented_iter = new FragmentedRangeTombstoneIterator(
cache, comparator_.comparator, read_seq, read_options.timestamp);
return fragmented_iter;
}
void MemTable::ConstructFragmentedRangeTombstones() {
// There should be no concurrent Construction.
// We could also check fragmented_range_tombstone_list_ to avoid repeate
// constructions. We just construct them here again to be safe.
if (!is_range_del_table_empty_.load(std::memory_order_relaxed)) {
// TODO: plumb Env::IOActivity, Env::IOPriority
auto* unfragmented_iter = new MemTableIterator(
MemTableIterator::kRangeDelEntries, *this, ReadOptions());
fragmented_range_tombstone_list_ =
std::make_unique<FragmentedRangeTombstoneList>(
std::unique_ptr<InternalIterator>(unfragmented_iter),
comparator_.comparator);
}
}
port::RWMutex* MemTable::GetLock(const Slice& key) {
return &locks_[GetSliceRangedNPHash(key, locks_.size())];
}
MemTable::MemTableStats MemTable::ApproximateStats(const Slice& start_ikey,
const Slice& end_ikey) {
uint64_t entry_count = table_->ApproximateNumEntries(start_ikey, end_ikey);
entry_count += range_del_table_->ApproximateNumEntries(start_ikey, end_ikey);
if (entry_count == 0) {
return {0, 0};
}
uint64_t n = num_entries_.load(std::memory_order_relaxed);
if (n == 0) {
return {0, 0};
}
if (entry_count > n) {
// (range_del_)table_->ApproximateNumEntries() is just an estimate so it can
// be larger than actual entries we have. Cap it to entries we have to limit
// the inaccuracy.
entry_count = n;
}
uint64_t data_size = data_size_.load(std::memory_order_relaxed);
return {entry_count * (data_size / n), entry_count};
}
Status MemTable::VerifyEncodedEntry(Slice encoded,
const ProtectionInfoKVOS64& kv_prot_info) {
uint32_t ikey_len = 0;
if (!GetVarint32(&encoded, &ikey_len)) {
return Status::Corruption("Unable to parse internal key length");
}
if (ikey_len < 8 + ts_sz_) {
return Status::Corruption("Internal key length too short");
}
if (ikey_len > encoded.size()) {
return Status::Corruption("Internal key length too long");
}
uint32_t value_len = 0;
const size_t user_key_len = ikey_len - 8;
Slice key(encoded.data(), user_key_len);
encoded.remove_prefix(user_key_len);
uint64_t packed = DecodeFixed64(encoded.data());
ValueType value_type = kMaxValue;
SequenceNumber sequence_number = kMaxSequenceNumber;
UnPackSequenceAndType(packed, &sequence_number, &value_type);
encoded.remove_prefix(8);
if (!GetVarint32(&encoded, &value_len)) {
return Status::Corruption("Unable to parse value length");
}
if (value_len < encoded.size()) {
return Status::Corruption("Value length too short");
}
if (value_len > encoded.size()) {
return Status::Corruption("Value length too long");
}
Slice value(encoded.data(), value_len);
return kv_prot_info.StripS(sequence_number)
.StripKVO(key, value, value_type)
.GetStatus();
}
void MemTable::UpdateEntryChecksum(const ProtectionInfoKVOS64* kv_prot_info,
const Slice& key, const Slice& value,
ValueType type, SequenceNumber s,
char* checksum_ptr) {
if (moptions_.protection_bytes_per_key == 0) {
return;
}
if (kv_prot_info == nullptr) {
ProtectionInfo64()
.ProtectKVO(key, value, type)
.ProtectS(s)
.Encode(static_cast<uint8_t>(moptions_.protection_bytes_per_key),
checksum_ptr);
} else {
kv_prot_info->Encode(
static_cast<uint8_t>(moptions_.protection_bytes_per_key), checksum_ptr);
}
}
Status MemTable::Add(SequenceNumber s, ValueType type,
const Slice& key, /* user key */
const Slice& value,
const ProtectionInfoKVOS64* kv_prot_info,
bool allow_concurrent,
MemTablePostProcessInfo* post_process_info, void** hint) {
// Format of an entry is concatenation of:
// key_size : varint32 of internal_key.size()
// key bytes : char[internal_key.size()]
// value_size : varint32 of value.size()
// value bytes : char[value.size()]
// checksum : char[moptions_.protection_bytes_per_key]
uint32_t key_size = static_cast<uint32_t>(key.size());
uint32_t val_size = static_cast<uint32_t>(value.size());
uint32_t internal_key_size = key_size + 8;
const uint32_t encoded_len = VarintLength(internal_key_size) +
internal_key_size + VarintLength(val_size) +
val_size + moptions_.protection_bytes_per_key;
char* buf = nullptr;
std::unique_ptr<MemTableRep>& table =
type == kTypeRangeDeletion ? range_del_table_ : table_;
KeyHandle handle = table->Allocate(encoded_len, &buf);
char* p = EncodeVarint32(buf, internal_key_size);
memcpy(p, key.data(), key_size);
Slice key_slice(p, key_size);
p += key_size;
uint64_t packed = PackSequenceAndType(s, type);
EncodeFixed64(p, packed);
p += 8;
p = EncodeVarint32(p, val_size);
memcpy(p, value.data(), val_size);
assert((unsigned)(p + val_size - buf + moptions_.protection_bytes_per_key) ==
(unsigned)encoded_len);
UpdateEntryChecksum(kv_prot_info, key, value, type, s,
buf + encoded_len - moptions_.protection_bytes_per_key);
Slice encoded(buf, encoded_len - moptions_.protection_bytes_per_key);
if (kv_prot_info != nullptr) {
TEST_SYNC_POINT_CALLBACK("MemTable::Add:Encoded", &encoded);
Status status = VerifyEncodedEntry(encoded, *kv_prot_info);
if (!status.ok()) {
return status;
}
}
Slice key_without_ts = StripTimestampFromUserKey(key, ts_sz_);
if (!allow_concurrent) {
// Extract prefix for insert with hint. Hints are for point key table
// (`table_`) only, not `range_del_table_`.
if (table == table_ && insert_with_hint_prefix_extractor_ != nullptr &&
insert_with_hint_prefix_extractor_->InDomain(key_slice)) {
Slice prefix = insert_with_hint_prefix_extractor_->Transform(key_slice);
bool res = table->InsertKeyWithHint(handle, &insert_hints_[prefix]);
if (UNLIKELY(!res)) {
return Status::TryAgain("key+seq exists");
}
} else {
bool res = table->InsertKey(handle);
if (UNLIKELY(!res)) {
return Status::TryAgain("key+seq exists");
}
}
// this is a bit ugly, but is the way to avoid locked instructions
// when incrementing an atomic
num_entries_.store(num_entries_.load(std::memory_order_relaxed) + 1,
std::memory_order_relaxed);
data_size_.store(data_size_.load(std::memory_order_relaxed) + encoded_len,
std::memory_order_relaxed);
if (type == kTypeDeletion || type == kTypeSingleDeletion ||
type == kTypeDeletionWithTimestamp) {
num_deletes_.store(num_deletes_.load(std::memory_order_relaxed) + 1,
std::memory_order_relaxed);
} else if (type == kTypeRangeDeletion) {
uint64_t val = num_range_deletes_.load(std::memory_order_relaxed) + 1;
num_range_deletes_.store(val, std::memory_order_relaxed);
}
if (bloom_filter_ && prefix_extractor_ &&
prefix_extractor_->InDomain(key_without_ts)) {
bloom_filter_->Add(prefix_extractor_->Transform(key_without_ts));
}
if (bloom_filter_ && moptions_.memtable_whole_key_filtering) {
bloom_filter_->Add(key_without_ts);
}
// The first sequence number inserted into the memtable
assert(first_seqno_ == 0 || s >= first_seqno_);
if (first_seqno_ == 0) {
first_seqno_.store(s, std::memory_order_relaxed);
if (earliest_seqno_ == kMaxSequenceNumber) {
earliest_seqno_.store(GetFirstSequenceNumber(),
std::memory_order_relaxed);
}
assert(first_seqno_.load() >= earliest_seqno_.load());
}
assert(post_process_info == nullptr);
// TODO(yuzhangyu): support updating newest UDT for when `allow_concurrent`
// is true.
MaybeUpdateNewestUDT(key_slice);
UpdateFlushState();
} else {
bool res = (hint == nullptr)
? table->InsertKeyConcurrently(handle)
: table->InsertKeyWithHintConcurrently(handle, hint);
if (UNLIKELY(!res)) {
return Status::TryAgain("key+seq exists");
}
assert(post_process_info != nullptr);
post_process_info->num_entries++;
post_process_info->data_size += encoded_len;
if (type == kTypeDeletion) {
post_process_info->num_deletes++;
}
if (bloom_filter_ && prefix_extractor_ &&
prefix_extractor_->InDomain(key_without_ts)) {
bloom_filter_->AddConcurrently(
prefix_extractor_->Transform(key_without_ts));
}
if (bloom_filter_ && moptions_.memtable_whole_key_filtering) {
bloom_filter_->AddConcurrently(key_without_ts);
}
// atomically update first_seqno_ and earliest_seqno_.
uint64_t cur_seq_num = first_seqno_.load(std::memory_order_relaxed);
while ((cur_seq_num == 0 || s < cur_seq_num) &&
!first_seqno_.compare_exchange_weak(cur_seq_num, s)) {
}
uint64_t cur_earliest_seqno =
earliest_seqno_.load(std::memory_order_relaxed);
while (
(cur_earliest_seqno == kMaxSequenceNumber || s < cur_earliest_seqno) &&
!earliest_seqno_.compare_exchange_weak(cur_earliest_seqno, s)) {
}
}
if (type == kTypeRangeDeletion) {
auto new_cache = std::make_shared<FragmentedRangeTombstoneListCache>();
size_t size = cached_range_tombstone_.Size();
if (allow_concurrent) {
post_process_info->num_range_deletes++;
range_del_mutex_.lock();
}
for (size_t i = 0; i < size; ++i) {
std::shared_ptr<FragmentedRangeTombstoneListCache>* local_cache_ref_ptr =
cached_range_tombstone_.AccessAtCore(i);
auto new_local_cache_ref = std::make_shared<
const std::shared_ptr<FragmentedRangeTombstoneListCache>>(new_cache);
// It is okay for some reader to load old cache during invalidation as
// the new sequence number is not published yet.
// Each core will have a shared_ptr to a shared_ptr to the cached
// fragmented range tombstones, so that ref count is maintianed locally
// per-core using the per-core shared_ptr.
std::atomic_store_explicit(
local_cache_ref_ptr,
std::shared_ptr<FragmentedRangeTombstoneListCache>(
new_local_cache_ref, new_cache.get()),
std::memory_order_relaxed);
}
if (allow_concurrent) {
range_del_mutex_.unlock();
}
is_range_del_table_empty_.store(false, std::memory_order_relaxed);
}
UpdateOldestKeyTime();
TEST_SYNC_POINT_CALLBACK("MemTable::Add:BeforeReturn:Encoded", &encoded);
return Status::OK();
}
// Callback from MemTable::Get()
namespace {
struct Saver {
Status* status;
const LookupKey* key;
bool* found_final_value; // Is value set correctly? Used by KeyMayExist
bool* merge_in_progress;
std::string* value;
PinnableWideColumns* columns;
SequenceNumber seq;
std::string* timestamp;
const MergeOperator* merge_operator;
// the merge operations encountered;
MergeContext* merge_context;
SequenceNumber max_covering_tombstone_seq;
MemTable* mem;
Logger* logger;
Statistics* statistics;
bool inplace_update_support;
bool do_merge;
SystemClock* clock;
ReadCallback* callback_;
bool* is_blob_index;
bool allow_data_in_errors;
uint32_t protection_bytes_per_key;
bool CheckCallback(SequenceNumber _seq) {
if (callback_) {
return callback_->IsVisible(_seq);
}
return true;
}
};
} // anonymous namespace
static bool SaveValue(void* arg, const char* entry) {
Saver* s = static_cast<Saver*>(arg);
assert(s != nullptr);
assert(!s->value || !s->columns);
assert(!*(s->found_final_value));
assert(s->status->ok() || s->status->IsMergeInProgress());
MergeContext* merge_context = s->merge_context;
SequenceNumber max_covering_tombstone_seq = s->max_covering_tombstone_seq;
const MergeOperator* merge_operator = s->merge_operator;
assert(merge_context != nullptr);
// Refer to comments under MemTable::Add() for entry format.
// Check that it belongs to same user key.
uint32_t key_length = 0;
const char* key_ptr = GetVarint32Ptr(entry, entry + 5, &key_length);
assert(key_length >= 8);
Slice user_key_slice = Slice(key_ptr, key_length - 8);
const Comparator* user_comparator =
s->mem->GetInternalKeyComparator().user_comparator();
size_t ts_sz = user_comparator->timestamp_size();
if (ts_sz && s->timestamp && max_covering_tombstone_seq > 0) {
// timestamp should already be set to range tombstone timestamp
assert(s->timestamp->size() == ts_sz);
}
if (user_comparator->EqualWithoutTimestamp(user_key_slice,
s->key->user_key())) {
// Correct user key
TEST_SYNC_POINT_CALLBACK("Memtable::SaveValue:Found:entry", &entry);
std::optional<ReadLock> read_lock;
if (s->inplace_update_support) {
read_lock.emplace(s->mem->GetLock(s->key->user_key()));
}
if (s->protection_bytes_per_key > 0) {
*(s->status) = MemTable::VerifyEntryChecksum(
entry, s->protection_bytes_per_key, s->allow_data_in_errors);
if (!s->status->ok()) {
*(s->found_final_value) = true;
ROCKS_LOG_ERROR(s->logger, "In SaveValue: %s", s->status->getState());
// Memtable entry corrupted
return false;
}
}
const uint64_t tag = DecodeFixed64(key_ptr + key_length - 8);
ValueType type;
SequenceNumber seq;
UnPackSequenceAndType(tag, &seq, &type);
// If the value is not in the snapshot, skip it
if (!s->CheckCallback(seq)) {
return true; // to continue to the next seq
}
if (s->seq == kMaxSequenceNumber) {
s->seq = seq;
if (s->seq > max_covering_tombstone_seq) {
if (ts_sz && s->timestamp != nullptr) {
// `timestamp` was set to range tombstone's timestamp before
// `SaveValue` is ever called. This key has a higher sequence number
// than range tombstone, and is the key with the highest seqno across
// all keys with this user_key, so we update timestamp here.
Slice ts = ExtractTimestampFromUserKey(user_key_slice, ts_sz);
s->timestamp->assign(ts.data(), ts_sz);
}
} else {
s->seq = max_covering_tombstone_seq;
}
}
if (ts_sz > 0 && s->timestamp != nullptr) {
if (!s->timestamp->empty()) {
assert(ts_sz == s->timestamp->size());
}
// TODO optimize for smaller size ts
const std::string kMaxTs(ts_sz, '\xff');
if (s->timestamp->empty() ||
user_comparator->CompareTimestamp(*(s->timestamp), kMaxTs) == 0) {
Slice ts = ExtractTimestampFromUserKey(user_key_slice, ts_sz);
s->timestamp->assign(ts.data(), ts_sz);
}
}
if ((type == kTypeValue || type == kTypeMerge || type == kTypeBlobIndex ||
type == kTypeWideColumnEntity || type == kTypeDeletion ||
type == kTypeSingleDeletion || type == kTypeDeletionWithTimestamp ||
type == kTypeValuePreferredSeqno) &&
max_covering_tombstone_seq > seq) {
type = kTypeRangeDeletion;
}
switch (type) {
case kTypeBlobIndex: {
if (!s->do_merge) {
*(s->status) = Status::NotSupported(
"GetMergeOperands not supported by stacked BlobDB");
*(s->found_final_value) = true;
return false;
}
if (*(s->merge_in_progress)) {
*(s->status) = Status::NotSupported(
"Merge operator not supported by stacked BlobDB");
*(s->found_final_value) = true;
return false;
}
if (s->is_blob_index == nullptr) {
ROCKS_LOG_ERROR(s->logger, "Encountered unexpected blob index.");
*(s->status) = Status::NotSupported(
"Encountered unexpected blob index. Please open DB with "
"ROCKSDB_NAMESPACE::blob_db::BlobDB.");
*(s->found_final_value) = true;
return false;
}
Slice v = GetLengthPrefixedSlice(key_ptr + key_length);
*(s->status) = Status::OK();
if (s->value) {
s->value->assign(v.data(), v.size());
} else if (s->columns) {
s->columns->SetPlainValue(v);
}
*(s->found_final_value) = true;
*(s->is_blob_index) = true;
return false;
}
case kTypeValue:
case kTypeValuePreferredSeqno: {
Slice v = GetLengthPrefixedSlice(key_ptr + key_length);
if (type == kTypeValuePreferredSeqno) {
v = ParsePackedValueForValue(v);
}
*(s->status) = Status::OK();
if (!s->do_merge) {
// Preserve the value with the goal of returning it as part of
// raw merge operands to the user
// TODO(yanqin) update MergeContext so that timestamps information
// can also be retained.
merge_context->PushOperand(
v, s->inplace_update_support == false /* operand_pinned */);
} else if (*(s->merge_in_progress)) {
assert(s->do_merge);
if (s->value || s->columns) {
// `op_failure_scope` (an output parameter) is not provided (set to
// nullptr) since a failure must be propagated regardless of its
// value.
*(s->status) = MergeHelper::TimedFullMerge(
merge_operator, s->key->user_key(),
MergeHelper::kPlainBaseValue, v, merge_context->GetOperands(),
s->logger, s->statistics, s->clock,
/* update_num_ops_stats */ true, /* op_failure_scope */ nullptr,
s->value, s->columns);
}
} else if (s->value) {
s->value->assign(v.data(), v.size());
} else if (s->columns) {
s->columns->SetPlainValue(v);
}
*(s->found_final_value) = true;
if (s->is_blob_index != nullptr) {
*(s->is_blob_index) = false;
}
return false;
}
case kTypeWideColumnEntity: {
Slice v = GetLengthPrefixedSlice(key_ptr + key_length);
*(s->status) = Status::OK();
if (!s->do_merge) {
// Preserve the value with the goal of returning it as part of
// raw merge operands to the user
Slice value_of_default;
*(s->status) = WideColumnSerialization::GetValueOfDefaultColumn(
v, value_of_default);
if (s->status->ok()) {
merge_context->PushOperand(
value_of_default,
s->inplace_update_support == false /* operand_pinned */);
}
} else if (*(s->merge_in_progress)) {
assert(s->do_merge);
if (s->value || s->columns) {
// `op_failure_scope` (an output parameter) is not provided (set
// to nullptr) since a failure must be propagated regardless of
// its value.
*(s->status) = MergeHelper::TimedFullMerge(
merge_operator, s->key->user_key(), MergeHelper::kWideBaseValue,
v, merge_context->GetOperands(), s->logger, s->statistics,
s->clock, /* update_num_ops_stats */ true,
/* op_failure_scope */ nullptr, s->value, s->columns);
}
} else if (s->value) {
Slice value_of_default;
*(s->status) = WideColumnSerialization::GetValueOfDefaultColumn(
v, value_of_default);
if (s->status->ok()) {
s->value->assign(value_of_default.data(), value_of_default.size());
}
} else if (s->columns) {
*(s->status) = s->columns->SetWideColumnValue(v);
}
*(s->found_final_value) = true;
if (s->is_blob_index != nullptr) {
*(s->is_blob_index) = false;
}
return false;
}
case kTypeDeletion:
case kTypeDeletionWithTimestamp:
case kTypeSingleDeletion:
case kTypeRangeDeletion: {
if (*(s->merge_in_progress)) {
if (s->value || s->columns) {
// `op_failure_scope` (an output parameter) is not provided (set to
// nullptr) since a failure must be propagated regardless of its
// value.
*(s->status) = MergeHelper::TimedFullMerge(
merge_operator, s->key->user_key(), MergeHelper::kNoBaseValue,
merge_context->GetOperands(), s->logger, s->statistics,
s->clock, /* update_num_ops_stats */ true,
/* op_failure_scope */ nullptr, s->value, s->columns);
} else {
// We have found a final value (a base deletion) and have newer
// merge operands that we do not intend to merge. Nothing remains
// to be done so assign status to OK.
*(s->status) = Status::OK();
}
} else {
*(s->status) = Status::NotFound();
}
*(s->found_final_value) = true;
return false;
}
case kTypeMerge: {
if (!merge_operator) {
*(s->status) = Status::InvalidArgument(
"merge_operator is not properly initialized.");
// Normally we continue the loop (return true) when we see a merge
// operand. But in case of an error, we should stop the loop
// immediately and pretend we have found the value to stop further
// seek. Otherwise, the later call will override this error status.
*(s->found_final_value) = true;
return false;
}
Slice v = GetLengthPrefixedSlice(key_ptr + key_length);
*(s->merge_in_progress) = true;
merge_context->PushOperand(
v, s->inplace_update_support == false /* operand_pinned */);
PERF_COUNTER_ADD(internal_merge_point_lookup_count, 1);
if (s->do_merge && merge_operator->ShouldMerge(
merge_context->GetOperandsDirectionBackward())) {
if (s->value || s->columns) {
// `op_failure_scope` (an output parameter) is not provided (set to
// nullptr) since a failure must be propagated regardless of its
// value.
*(s->status) = MergeHelper::TimedFullMerge(
merge_operator, s->key->user_key(), MergeHelper::kNoBaseValue,
merge_context->GetOperands(), s->logger, s->statistics,
s->clock, /* update_num_ops_stats */ true,
/* op_failure_scope */ nullptr, s->value, s->columns);
}
*(s->found_final_value) = true;
return false;
}
if (merge_context->get_merge_operands_options != nullptr &&
merge_context->get_merge_operands_options->continue_cb != nullptr &&
!merge_context->get_merge_operands_options->continue_cb(v)) {
// We were told not to continue.
*(s->found_final_value) = true;
return false;
}
return true;
}
default: {
std::string msg("Corrupted value not expected.");
if (s->allow_data_in_errors) {
msg.append("Unrecognized value type: " +
std::to_string(static_cast<int>(type)) + ". ");
msg.append("User key: " + user_key_slice.ToString(/*hex=*/true) +
". ");
msg.append("seq: " + std::to_string(seq) + ".");
}
*(s->found_final_value) = true;
*(s->status) = Status::Corruption(msg.c_str());
return false;
}
}
}
// s->state could be Corrupt, merge or notfound
return false;
}
bool MemTable::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,
bool immutable_memtable, ReadCallback* callback,
bool* is_blob_index, bool do_merge) {
// The sequence number is updated synchronously in version_set.h
if (IsEmpty()) {
// Avoiding recording stats for speed.
return false;
}
PERF_TIMER_GUARD(get_from_memtable_time);
std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter(
NewRangeTombstoneIterator(read_opts,
GetInternalKeySeqno(key.internal_key()),
immutable_memtable));
if (range_del_iter != nullptr) {
SequenceNumber covering_seq =
range_del_iter->MaxCoveringTombstoneSeqnum(key.user_key());
if (covering_seq > *max_covering_tombstone_seq) {
*max_covering_tombstone_seq = covering_seq;
if (timestamp) {
// Will be overwritten in SaveValue() if there is a point key with
// a higher seqno.
timestamp->assign(range_del_iter->timestamp().data(),
range_del_iter->timestamp().size());
}
}
}
bool found_final_value = false;
bool merge_in_progress = s->IsMergeInProgress();
bool may_contain = true;
Slice user_key_without_ts = StripTimestampFromUserKey(key.user_key(), ts_sz_);
bool bloom_checked = false;
if (bloom_filter_) {
// when both memtable_whole_key_filtering and prefix_extractor_ are set,
// only do whole key filtering for Get() to save CPU
if (moptions_.memtable_whole_key_filtering) {
may_contain = bloom_filter_->MayContain(user_key_without_ts);
bloom_checked = true;
} else {
assert(prefix_extractor_);
if (prefix_extractor_->InDomain(user_key_without_ts)) {
may_contain = bloom_filter_->MayContain(
prefix_extractor_->Transform(user_key_without_ts));
bloom_checked = true;
}
}
}
if (bloom_filter_ && !may_contain) {
// iter is null if prefix bloom says the key does not exist
PERF_COUNTER_ADD(bloom_memtable_miss_count, 1);
*seq = kMaxSequenceNumber;
} else {
if (bloom_checked) {
PERF_COUNTER_ADD(bloom_memtable_hit_count, 1);
}
GetFromTable(key, *max_covering_tombstone_seq, do_merge, callback,
is_blob_index, value, columns, timestamp, s, merge_context,
seq, &found_final_value, &merge_in_progress);
}
// No change to value, since we have not yet found a Put/Delete
// Propagate corruption error
if (!found_final_value && merge_in_progress) {
if (s->ok()) {
*s = Status::MergeInProgress();
} else {
assert(s->IsMergeInProgress());
}
}
PERF_COUNTER_ADD(get_from_memtable_count, 1);
return found_final_value;
}
void MemTable::GetFromTable(const LookupKey& key,
SequenceNumber max_covering_tombstone_seq,
bool do_merge, ReadCallback* callback,
bool* is_blob_index, std::string* value,
PinnableWideColumns* columns,
std::string* timestamp, Status* s,
MergeContext* merge_context, SequenceNumber* seq,
bool* found_final_value, bool* merge_in_progress) {
Saver saver;
saver.status = s;
saver.found_final_value = found_final_value;
saver.merge_in_progress = merge_in_progress;
saver.key = &key;
saver.value = value;
saver.columns = columns;
saver.timestamp = timestamp;
saver.seq = kMaxSequenceNumber;
saver.mem = this;
saver.merge_context = merge_context;
saver.max_covering_tombstone_seq = max_covering_tombstone_seq;
saver.merge_operator = moptions_.merge_operator;
saver.logger = moptions_.info_log;
saver.inplace_update_support = moptions_.inplace_update_support;
saver.statistics = moptions_.statistics;
saver.clock = clock_;
saver.callback_ = callback;
saver.is_blob_index = is_blob_index;
saver.do_merge = do_merge;
saver.allow_data_in_errors = moptions_.allow_data_in_errors;
saver.protection_bytes_per_key = moptions_.protection_bytes_per_key;
if (!moptions_.paranoid_memory_checks) {
table_->Get(key, &saver, SaveValue);
} else {
Status check_s = table_->GetAndValidate(key, &saver, SaveValue,
moptions_.allow_data_in_errors);
if (check_s.IsCorruption()) {
*(saver.status) = check_s;
// Should stop searching the LSM.
*(saver.found_final_value) = true;
}
}
assert(s->ok() || s->IsMergeInProgress() || *found_final_value);
*seq = saver.seq;
}
void MemTable::MultiGet(const ReadOptions& read_options, MultiGetRange* range,
ReadCallback* callback, bool immutable_memtable) {
// The sequence number is updated synchronously in version_set.h
if (IsEmpty()) {
// Avoiding recording stats for speed.
return;
}
PERF_TIMER_GUARD(get_from_memtable_time);
// For now, memtable Bloom filter is effectively disabled if there are any
// range tombstones. This is the simplest way to ensure range tombstones are
// handled. TODO: allow Bloom checks where max_covering_tombstone_seq==0
bool no_range_del = read_options.ignore_range_deletions ||
is_range_del_table_empty_.load(std::memory_order_relaxed);
MultiGetRange temp_range(*range, range->begin(), range->end());
if (bloom_filter_ && no_range_del) {
bool whole_key =
!prefix_extractor_ || moptions_.memtable_whole_key_filtering;
std::array<Slice, MultiGetContext::MAX_BATCH_SIZE> bloom_keys;
std::array<bool, MultiGetContext::MAX_BATCH_SIZE> may_match;
std::array<size_t, MultiGetContext::MAX_BATCH_SIZE> range_indexes;
int num_keys = 0;
for (auto iter = temp_range.begin(); iter != temp_range.end(); ++iter) {
if (whole_key) {
bloom_keys[num_keys] = iter->ukey_without_ts;
range_indexes[num_keys++] = iter.index();
} else if (prefix_extractor_->InDomain(iter->ukey_without_ts)) {
bloom_keys[num_keys] =
prefix_extractor_->Transform(iter->ukey_without_ts);
range_indexes[num_keys++] = iter.index();
}
}
bloom_filter_->MayContain(num_keys, bloom_keys.data(), may_match.data());
for (int i = 0; i < num_keys; ++i) {
if (!may_match[i]) {
temp_range.SkipIndex(range_indexes[i]);
PERF_COUNTER_ADD(bloom_memtable_miss_count, 1);
} else {
PERF_COUNTER_ADD(bloom_memtable_hit_count, 1);
}
}
}
for (auto iter = temp_range.begin(); iter != temp_range.end(); ++iter) {
bool found_final_value{false};
bool merge_in_progress = iter->s->IsMergeInProgress();
if (!no_range_del) {
std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter(
NewRangeTombstoneIteratorInternal(
read_options, GetInternalKeySeqno(iter->lkey->internal_key()),
immutable_memtable));
SequenceNumber covering_seq =
range_del_iter->MaxCoveringTombstoneSeqnum(iter->lkey->user_key());
if (covering_seq > iter->max_covering_tombstone_seq) {
iter->max_covering_tombstone_seq = covering_seq;
if (iter->timestamp) {
// Will be overwritten in SaveValue() if there is a point key with
// a higher seqno.
iter->timestamp->assign(range_del_iter->timestamp().data(),
range_del_iter->timestamp().size());
}
}
}
SequenceNumber dummy_seq;
GetFromTable(*(iter->lkey), iter->max_covering_tombstone_seq, true,
callback, &iter->is_blob_index,
iter->value ? iter->value->GetSelf() : nullptr, iter->columns,
iter->timestamp, iter->s, &(iter->merge_context), &dummy_seq,
&found_final_value, &merge_in_progress);
if (!found_final_value && merge_in_progress) {
if (iter->s->ok()) {
*(iter->s) = Status::MergeInProgress();
} else {
assert(iter->s->IsMergeInProgress());
}
}
if (found_final_value ||
(!iter->s->ok() && !iter->s->IsMergeInProgress())) {
// `found_final_value` should be set if an error/corruption occurs.
// The check on iter->s is just there in case GetFromTable() did not
// set `found_final_value` properly.
assert(found_final_value);
if (iter->value) {
iter->value->PinSelf();
range->AddValueSize(iter->value->size());
} else {
assert(iter->columns);
range->AddValueSize(iter->columns->serialized_size());
}
range->MarkKeyDone(iter);
RecordTick(moptions_.statistics, MEMTABLE_HIT);
if (range->GetValueSize() > read_options.value_size_soft_limit) {
// Set all remaining keys in range to Abort
for (auto range_iter = range->begin(); range_iter != range->end();
++range_iter) {
range->MarkKeyDone(range_iter);
*(range_iter->s) = Status::Aborted();
}
break;
}
}
}
PERF_COUNTER_ADD(get_from_memtable_count, 1);
}
Status MemTable::Update(SequenceNumber seq, ValueType value_type,
const Slice& key, const Slice& value,
const ProtectionInfoKVOS64* kv_prot_info) {
LookupKey lkey(key, seq);
Slice mem_key = lkey.memtable_key();
std::unique_ptr<MemTableRep::Iterator> iter(
table_->GetDynamicPrefixIterator());
iter->Seek(lkey.internal_key(), mem_key.data());
if (iter->Valid()) {
// Refer to comments under MemTable::Add() for entry format.
// Check that it belongs to same user key. We do not check the
// sequence number since the Seek() call above should have skipped
// all entries with overly large sequence numbers.
const char* entry = iter->key();
uint32_t key_length = 0;
const char* key_ptr = GetVarint32Ptr(entry, entry + 5, &key_length);
if (comparator_.comparator.user_comparator()->Equal(
Slice(key_ptr, key_length - 8), lkey.user_key())) {
// Correct user key
const uint64_t tag = DecodeFixed64(key_ptr + key_length - 8);
ValueType type;
SequenceNumber existing_seq;
UnPackSequenceAndType(tag, &existing_seq, &type);
assert(existing_seq != seq);
if (type == value_type) {
Slice prev_value = GetLengthPrefixedSlice(key_ptr + key_length);
uint32_t prev_size = static_cast<uint32_t>(prev_value.size());
uint32_t new_size = static_cast<uint32_t>(value.size());
// Update value, if new value size <= previous value size
if (new_size <= prev_size) {
WriteLock wl(GetLock(lkey.user_key()));
char* p =
EncodeVarint32(const_cast<char*>(key_ptr) + key_length, new_size);
memcpy(p, value.data(), value.size());
assert((unsigned)((p + value.size()) - entry) ==
(unsigned)(VarintLength(key_length) + key_length +
VarintLength(value.size()) + value.size()));
RecordTick(moptions_.statistics, NUMBER_KEYS_UPDATED);
if (kv_prot_info != nullptr) {
ProtectionInfoKVOS64 updated_kv_prot_info(*kv_prot_info);
// `seq` is swallowed and `existing_seq` prevails.
updated_kv_prot_info.UpdateS(seq, existing_seq);
UpdateEntryChecksum(&updated_kv_prot_info, key, value, type,
existing_seq, p + value.size());
Slice encoded(entry, p + value.size() - entry);
return VerifyEncodedEntry(encoded, updated_kv_prot_info);
} else {
UpdateEntryChecksum(nullptr, key, value, type, existing_seq,
p + value.size());
}
return Status::OK();
}
}
}
}
// The latest value is not value_type or key doesn't exist
return Add(seq, value_type, key, value, kv_prot_info);
}
Status MemTable::UpdateCallback(SequenceNumber seq, const Slice& key,
const Slice& delta,
const ProtectionInfoKVOS64* kv_prot_info) {
LookupKey lkey(key, seq);
Slice memkey = lkey.memtable_key();
std::unique_ptr<MemTableRep::Iterator> iter(
table_->GetDynamicPrefixIterator());
iter->Seek(lkey.internal_key(), memkey.data());
if (iter->Valid()) {
// Refer to comments under MemTable::Add() for entry format.
// Check that it belongs to same user key. We do not check the
// sequence number since the Seek() call above should have skipped
// all entries with overly large sequence numbers.
const char* entry = iter->key();
uint32_t key_length = 0;
const char* key_ptr = GetVarint32Ptr(entry, entry + 5, &key_length);
if (comparator_.comparator.user_comparator()->Equal(
Slice(key_ptr, key_length - 8), lkey.user_key())) {
// Correct user key
const uint64_t tag = DecodeFixed64(key_ptr + key_length - 8);
ValueType type;
uint64_t existing_seq;
UnPackSequenceAndType(tag, &existing_seq, &type);
if (type == kTypeValue) {
Slice prev_value = GetLengthPrefixedSlice(key_ptr + key_length);
uint32_t prev_size = static_cast<uint32_t>(prev_value.size());
char* prev_buffer = const_cast<char*>(prev_value.data());
uint32_t new_prev_size = prev_size;
std::string str_value;
WriteLock wl(GetLock(lkey.user_key()));
auto status = moptions_.inplace_callback(prev_buffer, &new_prev_size,
delta, &str_value);
if (status == UpdateStatus::UPDATED_INPLACE) {
// Value already updated by callback.
assert(new_prev_size <= prev_size);
if (new_prev_size < prev_size) {
// overwrite the new prev_size
char* p = EncodeVarint32(const_cast<char*>(key_ptr) + key_length,
new_prev_size);
if (VarintLength(new_prev_size) < VarintLength(prev_size)) {
// shift the value buffer as well.
memcpy(p, prev_buffer, new_prev_size);
prev_buffer = p;
}
}
RecordTick(moptions_.statistics, NUMBER_KEYS_UPDATED);
UpdateFlushState();
Slice new_value(prev_buffer, new_prev_size);
if (kv_prot_info != nullptr) {
ProtectionInfoKVOS64 updated_kv_prot_info(*kv_prot_info);
// `seq` is swallowed and `existing_seq` prevails.
updated_kv_prot_info.UpdateS(seq, existing_seq);
updated_kv_prot_info.UpdateV(delta, new_value);
Slice encoded(entry, prev_buffer + new_prev_size - entry);
UpdateEntryChecksum(&updated_kv_prot_info, key, new_value, type,
existing_seq, prev_buffer + new_prev_size);
return VerifyEncodedEntry(encoded, updated_kv_prot_info);
} else {
UpdateEntryChecksum(nullptr, key, new_value, type, existing_seq,
prev_buffer + new_prev_size);
}
return Status::OK();
} else if (status == UpdateStatus::UPDATED) {
Status s;
if (kv_prot_info != nullptr) {
ProtectionInfoKVOS64 updated_kv_prot_info(*kv_prot_info);
updated_kv_prot_info.UpdateV(delta, str_value);
s = Add(seq, kTypeValue, key, Slice(str_value),
&updated_kv_prot_info);
} else {
s = Add(seq, kTypeValue, key, Slice(str_value),
nullptr /* kv_prot_info */);
}
RecordTick(moptions_.statistics, NUMBER_KEYS_WRITTEN);
UpdateFlushState();
return s;
} else if (status == UpdateStatus::UPDATE_FAILED) {
// `UPDATE_FAILED` is named incorrectly. It indicates no update
// happened. It does not indicate a failure happened.
UpdateFlushState();
return Status::OK();
}
}
}
}
// The latest value is not `kTypeValue` or key doesn't exist
return Status::NotFound();
}
size_t MemTable::CountSuccessiveMergeEntries(const LookupKey& key,
size_t limit) {
Slice memkey = key.memtable_key();
// A total ordered iterator is costly for some memtablerep (prefix aware
// reps). By passing in the user key, we allow efficient iterator creation.
// The iterator only needs to be ordered within the same user key.
std::unique_ptr<MemTableRep::Iterator> iter(
table_->GetDynamicPrefixIterator());
iter->Seek(key.internal_key(), memkey.data());
size_t num_successive_merges = 0;
for (; iter->Valid() && num_successive_merges < limit; iter->Next()) {
const char* entry = iter->key();
uint32_t key_length = 0;
const char* iter_key_ptr = GetVarint32Ptr(entry, entry + 5, &key_length);
if (!comparator_.comparator.user_comparator()->Equal(
Slice(iter_key_ptr, key_length - 8), key.user_key())) {
break;
}
const uint64_t tag = DecodeFixed64(iter_key_ptr + key_length - 8);
ValueType type;
uint64_t unused;
UnPackSequenceAndType(tag, &unused, &type);
if (type != kTypeMerge) {
break;
}
++num_successive_merges;
}
return num_successive_merges;
}
void MemTableRep::Get(const LookupKey& k, void* callback_args,
bool (*callback_func)(void* arg, const char* entry)) {
auto iter = GetDynamicPrefixIterator();
for (iter->Seek(k.internal_key(), k.memtable_key().data());
iter->Valid() && callback_func(callback_args, iter->key());
iter->Next()) {
}
}
void MemTable::RefLogContainingPrepSection(uint64_t log) {
assert(log > 0);
auto cur = min_prep_log_referenced_.load();
while ((log < cur || cur == 0) &&
!min_prep_log_referenced_.compare_exchange_strong(cur, log)) {
cur = min_prep_log_referenced_.load();
}
}
uint64_t MemTable::GetMinLogContainingPrepSection() {
return min_prep_log_referenced_.load();
}
void MemTable::MaybeUpdateNewestUDT(const Slice& user_key) {
if (ts_sz_ == 0 || persist_user_defined_timestamps_) {
return;
}
const Comparator* ucmp = GetInternalKeyComparator().user_comparator();
Slice udt = ExtractTimestampFromUserKey(user_key, ts_sz_);
if (newest_udt_.empty() || ucmp->CompareTimestamp(udt, newest_udt_) > 0) {
newest_udt_ = udt;
}
}
const Slice& MemTable::GetNewestUDT() const {
// This path should not be invoked for MemTables that does not enable the UDT
// in Memtable only feature.
assert(ts_sz_ > 0 && !persist_user_defined_timestamps_);
return newest_udt_;
}
} // namespace ROCKSDB_NAMESPACE
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