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rocksdb/utilities/write_batch_with_index/write_batch_with_index.cc

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// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#include "rocksdb/utilities/write_batch_with_index.h"
#include <memory>
#include "rocksdb/comparator.h"
#include "rocksdb/iterator.h"
#include "db/column_family.h"
#include "db/merge_context.h"
#include "db/merge_helper.h"
#include "db/skiplist.h"
#include "util/arena.h"
#include "utilities/write_batch_with_index/write_batch_with_index_internal.h"
namespace rocksdb {
// when direction == forward
// * current_at_base_ <=> base_iterator > delta_iterator
// when direction == backwards
// * current_at_base_ <=> base_iterator < delta_iterator
// always:
// * equal_keys_ <=> base_iterator == delta_iterator
class BaseDeltaIterator : public Iterator {
public:
BaseDeltaIterator(Iterator* base_iterator, WBWIIterator* delta_iterator,
const Comparator* comparator)
: forward_(true),
current_at_base_(true),
equal_keys_(false),
status_(Status::OK()),
base_iterator_(base_iterator),
delta_iterator_(delta_iterator),
comparator_(comparator) {}
virtual ~BaseDeltaIterator() {}
bool Valid() const override {
return current_at_base_ ? BaseValid() : DeltaValid();
}
void SeekToFirst() override {
forward_ = true;
base_iterator_->SeekToFirst();
delta_iterator_->SeekToFirst();
UpdateCurrent();
}
void SeekToLast() override {
forward_ = false;
base_iterator_->SeekToLast();
delta_iterator_->SeekToLast();
UpdateCurrent();
}
void Seek(const Slice& k) override {
forward_ = true;
base_iterator_->Seek(k);
delta_iterator_->Seek(k);
UpdateCurrent();
}
void Next() override {
if (!Valid()) {
status_ = Status::NotSupported("Next() on invalid iterator");
}
if (!forward_) {
// Need to change direction
// if our direction was backward and we're not equal, we have two states:
// * both iterators are valid: we're already in a good state (current
// shows to smaller)
// * only one iterator is valid: we need to advance that iterator
forward_ = true;
equal_keys_ = false;
if (!BaseValid()) {
assert(DeltaValid());
base_iterator_->SeekToFirst();
} else if (!DeltaValid()) {
delta_iterator_->SeekToFirst();
} else if (current_at_base_) {
// Change delta from larger than base to smaller
AdvanceDelta();
} else {
// Change base from larger than delta to smaller
AdvanceBase();
}
if (DeltaValid() && BaseValid()) {
if (comparator_->Compare(delta_iterator_->Entry().key,
base_iterator_->key()) == 0) {
equal_keys_ = true;
}
}
}
Advance();
}
void Prev() override {
if (!Valid()) {
status_ = Status::NotSupported("Prev() on invalid iterator");
}
if (forward_) {
// Need to change direction
// if our direction was backward and we're not equal, we have two states:
// * both iterators are valid: we're already in a good state (current
// shows to smaller)
// * only one iterator is valid: we need to advance that iterator
forward_ = false;
equal_keys_ = false;
if (!BaseValid()) {
assert(DeltaValid());
base_iterator_->SeekToLast();
} else if (!DeltaValid()) {
delta_iterator_->SeekToLast();
} else if (current_at_base_) {
// Change delta from less advanced than base to more advanced
AdvanceDelta();
} else {
// Change base from less advanced than delta to more advanced
AdvanceBase();
}
if (DeltaValid() && BaseValid()) {
if (comparator_->Compare(delta_iterator_->Entry().key,
base_iterator_->key()) == 0) {
equal_keys_ = true;
}
}
}
Advance();
}
Slice key() const override {
return current_at_base_ ? base_iterator_->key()
: delta_iterator_->Entry().key;
}
Slice value() const override {
return current_at_base_ ? base_iterator_->value()
: delta_iterator_->Entry().value;
}
Status status() const override {
if (!status_.ok()) {
return status_;
}
if (!base_iterator_->status().ok()) {
return base_iterator_->status();
}
return delta_iterator_->status();
}
private:
void AssertInvariants() {
#ifndef NDEBUG
if (!Valid()) {
return;
}
if (!BaseValid()) {
assert(!current_at_base_ && delta_iterator_->Valid());
return;
}
if (!DeltaValid()) {
assert(current_at_base_ && base_iterator_->Valid());
return;
}
// we don't support those yet
assert(delta_iterator_->Entry().type != kMergeRecord &&
delta_iterator_->Entry().type != kLogDataRecord);
int compare = comparator_->Compare(delta_iterator_->Entry().key,
base_iterator_->key());
if (forward_) {
// current_at_base -> compare < 0
assert(!current_at_base_ || compare < 0);
// !current_at_base -> compare <= 0
assert(current_at_base_ && compare >= 0);
} else {
// current_at_base -> compare > 0
assert(!current_at_base_ || compare > 0);
// !current_at_base -> compare <= 0
assert(current_at_base_ && compare <= 0);
}
// equal_keys_ <=> compare == 0
assert((equal_keys_ || compare != 0) && (!equal_keys_ || compare == 0));
#endif
}
void Advance() {
if (equal_keys_) {
assert(BaseValid() && DeltaValid());
AdvanceBase();
AdvanceDelta();
} else {
if (current_at_base_) {
assert(BaseValid());
AdvanceBase();
} else {
assert(DeltaValid());
AdvanceDelta();
}
}
UpdateCurrent();
}
void AdvanceDelta() {
if (forward_) {
delta_iterator_->Next();
} else {
delta_iterator_->Prev();
}
}
void AdvanceBase() {
if (forward_) {
base_iterator_->Next();
} else {
base_iterator_->Prev();
}
}
bool BaseValid() const { return base_iterator_->Valid(); }
bool DeltaValid() const { return delta_iterator_->Valid(); }
void UpdateCurrent() {
while (true) {
WriteEntry delta_entry;
if (DeltaValid()) {
delta_entry = delta_iterator_->Entry();
}
equal_keys_ = false;
if (!BaseValid()) {
// Base has finished.
if (!DeltaValid()) {
// Finished
return;
}
if (delta_entry.type == kDeleteRecord) {
AdvanceDelta();
} else {
current_at_base_ = false;
return;
}
} else if (!DeltaValid()) {
// Delta has finished.
current_at_base_ = true;
return;
} else {
int compare =
(forward_ ? 1 : -1) *
comparator_->Compare(delta_entry.key, base_iterator_->key());
if (compare <= 0) { // delta bigger or equal
if (compare == 0) {
equal_keys_ = true;
}
if (delta_entry.type != kDeleteRecord) {
current_at_base_ = false;
return;
}
// Delta is less advanced and is delete.
AdvanceDelta();
if (equal_keys_) {
AdvanceBase();
}
} else {
current_at_base_ = true;
return;
}
}
}
AssertInvariants();
}
bool forward_;
bool current_at_base_;
bool equal_keys_;
Status status_;
std::unique_ptr<Iterator> base_iterator_;
std::unique_ptr<WBWIIterator> delta_iterator_;
const Comparator* comparator_; // not owned
};
typedef SkipList<WriteBatchIndexEntry*, const WriteBatchEntryComparator&>
WriteBatchEntrySkipList;
class WBWIIteratorImpl : public WBWIIterator {
public:
WBWIIteratorImpl(uint32_t column_family_id,
WriteBatchEntrySkipList* skip_list,
const ReadableWriteBatch* write_batch)
: column_family_id_(column_family_id),
skip_list_iter_(skip_list),
write_batch_(write_batch) {}
virtual ~WBWIIteratorImpl() {}
virtual bool Valid() const override {
if (!skip_list_iter_.Valid()) {
return false;
}
const WriteBatchIndexEntry* iter_entry = skip_list_iter_.key();
return (iter_entry != nullptr &&
iter_entry->column_family == column_family_id_);
}
virtual void SeekToFirst() override {
WriteBatchIndexEntry search_entry(WriteBatchIndexEntry::kFlagMin,
column_family_id_);
skip_list_iter_.Seek(&search_entry);
}
virtual void SeekToLast() override {
WriteBatchIndexEntry search_entry(WriteBatchIndexEntry::kFlagMin,
column_family_id_ + 1);
skip_list_iter_.Seek(&search_entry);
if (!skip_list_iter_.Valid()) {
skip_list_iter_.SeekToLast();
} else {
skip_list_iter_.Prev();
}
}
virtual void Seek(const Slice& key) override {
WriteBatchIndexEntry search_entry(&key, column_family_id_);
skip_list_iter_.Seek(&search_entry);
}
virtual void Next() override { skip_list_iter_.Next(); }
virtual void Prev() override { skip_list_iter_.Prev(); }
virtual WriteEntry Entry() const override {
WriteEntry ret;
Slice blob;
const WriteBatchIndexEntry* iter_entry = skip_list_iter_.key();
// this is guaranteed with Valid()
assert(iter_entry != nullptr &&
iter_entry->column_family == column_family_id_);
auto s = write_batch_->GetEntryFromDataOffset(iter_entry->offset, &ret.type,
&ret.key, &ret.value, &blob);
assert(s.ok());
assert(ret.type == kPutRecord || ret.type == kDeleteRecord ||
ret.type == kMergeRecord);
return ret;
}
virtual Status status() const override {
// this is in-memory data structure, so the only way status can be non-ok is
// through memory corruption
return Status::OK();
}
const WriteBatchIndexEntry* GetRawEntry() const {
return skip_list_iter_.key();
}
private:
uint32_t column_family_id_;
WriteBatchEntrySkipList::Iterator skip_list_iter_;
const ReadableWriteBatch* write_batch_;
};
struct WriteBatchWithIndex::Rep {
Rep(const Comparator* index_comparator, size_t reserved_bytes = 0,
bool _overwrite_key = false)
: write_batch(reserved_bytes),
comparator(index_comparator, &write_batch),
skip_list(comparator, &arena),
overwrite_key(_overwrite_key),
last_entry_offset(0) {}
ReadableWriteBatch write_batch;
WriteBatchEntryComparator comparator;
Arena arena;
WriteBatchEntrySkipList skip_list;
bool overwrite_key;
size_t last_entry_offset;
// Remember current offset of internal write batch, which is used as
// the starting offset of the next record.
void SetLastEntryOffset() { last_entry_offset = write_batch.GetDataSize(); }
// In overwrite mode, find the existing entry for the same key and update it
// to point to the current entry.
// Return true if the key is found and updated.
bool UpdateExistingEntry(ColumnFamilyHandle* column_family, const Slice& key);
bool UpdateExistingEntryWithCfId(uint32_t column_family_id, const Slice& key);
// Add the recent entry to the update.
// In overwrite mode, if key already exists in the index, update it.
void AddOrUpdateIndex(ColumnFamilyHandle* column_family, const Slice& key);
void AddOrUpdateIndex(const Slice& key);
// Allocate an index entry pointing to the last entry in the write batch and
// put it to skip list.
void AddNewEntry(uint32_t column_family_id);
// Clear all updates buffered in this batch.
void Clear();
};
bool WriteBatchWithIndex::Rep::UpdateExistingEntry(
ColumnFamilyHandle* column_family, const Slice& key) {
uint32_t cf_id = GetColumnFamilyID(column_family);
return UpdateExistingEntryWithCfId(cf_id, key);
}
bool WriteBatchWithIndex::Rep::UpdateExistingEntryWithCfId(
uint32_t column_family_id, const Slice& key) {
if (!overwrite_key) {
return false;
}
WBWIIteratorImpl iter(column_family_id, &skip_list, &write_batch);
iter.Seek(key);
if (!iter.Valid()) {
return false;
}
if (comparator.CompareKey(column_family_id, key, iter.Entry().key) != 0) {
return false;
}
WriteBatchIndexEntry* non_const_entry =
const_cast<WriteBatchIndexEntry*>(iter.GetRawEntry());
non_const_entry->offset = last_entry_offset;
return true;
}
void WriteBatchWithIndex::Rep::AddOrUpdateIndex(
ColumnFamilyHandle* column_family, const Slice& key) {
if (!UpdateExistingEntry(column_family, key)) {
uint32_t cf_id = GetColumnFamilyID(column_family);
const auto* cf_cmp = GetColumnFamilyUserComparator(column_family);
if (cf_cmp != nullptr) {
comparator.SetComparatorForCF(cf_id, cf_cmp);
}
AddNewEntry(cf_id);
}
}
void WriteBatchWithIndex::Rep::AddOrUpdateIndex(const Slice& key) {
if (!UpdateExistingEntryWithCfId(0, key)) {
AddNewEntry(0);
}
}
void WriteBatchWithIndex::Rep::AddNewEntry(uint32_t column_family_id) {
auto* mem = arena.Allocate(sizeof(WriteBatchIndexEntry));
auto* index_entry =
new (mem) WriteBatchIndexEntry(last_entry_offset, column_family_id);
skip_list.Insert(index_entry);
}
void WriteBatchWithIndex::Rep::Clear() {
write_batch.Clear();
arena.~Arena();
new (&arena) Arena();
skip_list.~WriteBatchEntrySkipList();
new (&skip_list) WriteBatchEntrySkipList(comparator, &arena);
last_entry_offset = 0;
}
WriteBatchWithIndex::WriteBatchWithIndex(
const Comparator* default_index_comparator, size_t reserved_bytes,
bool overwrite_key)
: rep(new Rep(default_index_comparator, reserved_bytes, overwrite_key)) {}
WriteBatchWithIndex::~WriteBatchWithIndex() { delete rep; }
WriteBatch* WriteBatchWithIndex::GetWriteBatch() { return &rep->write_batch; }
WBWIIterator* WriteBatchWithIndex::NewIterator() {
return new WBWIIteratorImpl(0, &(rep->skip_list), &rep->write_batch);
}
WBWIIterator* WriteBatchWithIndex::NewIterator(
ColumnFamilyHandle* column_family) {
return new WBWIIteratorImpl(GetColumnFamilyID(column_family),
&(rep->skip_list), &rep->write_batch);
}
Iterator* WriteBatchWithIndex::NewIteratorWithBase(
ColumnFamilyHandle* column_family, Iterator* base_iterator) {
if (rep->overwrite_key == false) {
assert(false);
return nullptr;
}
return new BaseDeltaIterator(base_iterator, NewIterator(column_family),
GetColumnFamilyUserComparator(column_family));
}
Iterator* WriteBatchWithIndex::NewIteratorWithBase(Iterator* base_iterator) {
if (rep->overwrite_key == false) {
assert(false);
return nullptr;
}
// default column family's comparator
return new BaseDeltaIterator(base_iterator, NewIterator(),
rep->comparator.default_comparator());
}
void WriteBatchWithIndex::Put(ColumnFamilyHandle* column_family,
const Slice& key, const Slice& value) {
rep->SetLastEntryOffset();
rep->write_batch.Put(column_family, key, value);
rep->AddOrUpdateIndex(column_family, key);
}
void WriteBatchWithIndex::Put(const Slice& key, const Slice& value) {
rep->SetLastEntryOffset();
rep->write_batch.Put(key, value);
rep->AddOrUpdateIndex(key);
}
void WriteBatchWithIndex::Merge(ColumnFamilyHandle* column_family,
const Slice& key, const Slice& value) {
rep->SetLastEntryOffset();
rep->write_batch.Merge(column_family, key, value);
rep->AddOrUpdateIndex(column_family, key);
}
void WriteBatchWithIndex::Merge(const Slice& key, const Slice& value) {
rep->SetLastEntryOffset();
rep->write_batch.Merge(key, value);
rep->AddOrUpdateIndex(key);
}
void WriteBatchWithIndex::PutLogData(const Slice& blob) {
rep->write_batch.PutLogData(blob);
}
void WriteBatchWithIndex::Delete(ColumnFamilyHandle* column_family,
const Slice& key) {
rep->SetLastEntryOffset();
rep->write_batch.Delete(column_family, key);
rep->AddOrUpdateIndex(column_family, key);
}
void WriteBatchWithIndex::Delete(const Slice& key) {
rep->SetLastEntryOffset();
rep->write_batch.Delete(key);
rep->AddOrUpdateIndex(key);
}
void WriteBatchWithIndex::Clear() { rep->Clear(); }
Status WriteBatchWithIndex::GetFromBatch(ColumnFamilyHandle* column_family,
const DBOptions& options,
const Slice& key, std::string* value) {
Status s;
MergeContext merge_context;
WriteBatchWithIndexInternal::Result result =
WriteBatchWithIndexInternal::GetFromBatch(options, this, column_family,
key, &merge_context,
&rep->comparator, value, &s);
switch (result) {
case WriteBatchWithIndexInternal::Result::kFound:
case WriteBatchWithIndexInternal::Result::kError:
return s;
case WriteBatchWithIndexInternal::Result::kDeleted:
case WriteBatchWithIndexInternal::Result::kNotFound:
return Status::NotFound();
case WriteBatchWithIndexInternal::Result::kMergeInProgress:
return Status::MergeInProgress("");
default:
assert(false);
}
return s;
}
Status WriteBatchWithIndex::GetFromBatchAndDB(DB* db,
const ReadOptions& read_options,
const Slice& key,
std::string* value) {
return GetFromBatchAndDB(db, read_options, db->DefaultColumnFamily(), key,
value);
}
Status WriteBatchWithIndex::GetFromBatchAndDB(DB* db,
const ReadOptions& read_options,
ColumnFamilyHandle* column_family,
const Slice& key,
std::string* value) {
Status s;
MergeContext merge_context;
const DBOptions& options = db->GetDBOptions();
std::string batch_value;
WriteBatchWithIndexInternal::Result result =
WriteBatchWithIndexInternal::GetFromBatch(
options, this, column_family, key, &merge_context, &rep->comparator,
&batch_value, &s);
if (result == WriteBatchWithIndexInternal::Result::kFound) {
value->assign(batch_value.data(), batch_value.size());
return s;
}
if (result == WriteBatchWithIndexInternal::Result::kDeleted) {
return Status::NotFound();
}
if (result == WriteBatchWithIndexInternal::Result::kError) {
return s;
}
assert(result == WriteBatchWithIndexInternal::Result::kMergeInProgress ||
result == WriteBatchWithIndexInternal::Result::kNotFound);
// Did not find key in batch OR could not resolve Merges. Try DB.
s = db->Get(read_options, column_family, key, value);
if (s.ok() || s.IsNotFound()) { // DB Get Suceeded
if (result == WriteBatchWithIndexInternal::Result::kMergeInProgress) {
// Merge result from DB with merges in Batch
auto cfh = reinterpret_cast<ColumnFamilyHandleImpl*>(column_family);
const MergeOperator* merge_operator =
cfh->cfd()->ioptions()->merge_operator;
Statistics* statistics = options.statistics.get();
Env* env = options.env;
Logger* logger = options.info_log.get();
Slice db_slice(*value);
Slice* merge_data;
if (s.ok()) {
merge_data = &db_slice;
} else { // Key not present in db (s.IsNotFound())
merge_data = nullptr;
}
s = MergeHelper::TimedFullMerge(
key, merge_data, merge_context.GetOperands(), merge_operator,
statistics, env, logger, value);
}
}
return s;
}
} // namespace rocksdb