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rocksdb/db/arena_wrapped_db_iter.h

127 lines
4.8 KiB

// 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.
#pragma once
#include <stdint.h>
#include <string>
#include "db/db_impl/db_impl.h"
#include "db/db_iter.h"
#include "db/range_del_aggregator.h"
#include "memory/arena.h"
#include "options/cf_options.h"
#include "rocksdb/db.h"
#include "rocksdb/iterator.h"
#include "util/autovector.h"
namespace ROCKSDB_NAMESPACE {
class Arena;
class Version;
// A wrapper iterator which wraps DB Iterator and the arena, with which the DB
// iterator is supposed to be allocated. This class is used as an entry point of
// a iterator hierarchy whose memory can be allocated inline. In that way,
// accessing the iterator tree can be more cache friendly. It is also faster
// to allocate.
// When using the class's Iterator interface, the behavior is exactly
// the same as the inner DBIter.
class ArenaWrappedDBIter : public Iterator {
public:
~ArenaWrappedDBIter() override {
if (db_iter_ != nullptr) {
db_iter_->~DBIter();
} else {
assert(false);
}
}
// Get the arena to be used to allocate memory for DBIter to be wrapped,
// as well as child iterators in it.
virtual Arena* GetArena() { return &arena_; }
const ReadOptions& GetReadOptions() { return read_options_; }
// Set the internal iterator wrapped inside the DB Iterator. Usually it is
// a merging iterator.
virtual void SetIterUnderDBIter(InternalIterator* iter) {
db_iter_->SetIter(iter);
}
void SetMemtableRangetombstoneIter(TruncatedRangeDelIterator** iter) {
memtable_range_tombstone_iter_ = iter;
}
bool Valid() const override { return db_iter_->Valid(); }
void SeekToFirst() override { db_iter_->SeekToFirst(); }
void SeekToLast() override { db_iter_->SeekToLast(); }
// 'target' does not contain timestamp, even if user timestamp feature is
// enabled.
void Seek(const Slice& target) override { db_iter_->Seek(target); }
void SeekForPrev(const Slice& target) override {
db_iter_->SeekForPrev(target);
}
void Next() override { db_iter_->Next(); }
void Prev() override { db_iter_->Prev(); }
Slice key() const override { return db_iter_->key(); }
Slice value() const override { return db_iter_->value(); }
const WideColumns& columns() const override { return db_iter_->columns(); }
Status status() const override { return db_iter_->status(); }
Slice timestamp() const override { return db_iter_->timestamp(); }
bool IsBlob() const { return db_iter_->IsBlob(); }
Status GetProperty(std::string prop_name, std::string* prop) override;
Status Refresh() override;
void Init(Env* env, const ReadOptions& read_options,
const ImmutableOptions& ioptions,
const MutableCFOptions& mutable_cf_options, const Version* version,
const SequenceNumber& sequence,
uint64_t max_sequential_skip_in_iterations, uint64_t version_number,
ReadCallback* read_callback, DBImpl* db_impl, ColumnFamilyData* cfd,
bool expose_blob_index, bool allow_refresh);
// Store some parameters so we can refresh the iterator at a later point
// with these same params
void StoreRefreshInfo(DBImpl* db_impl, ColumnFamilyData* cfd,
ReadCallback* read_callback, bool expose_blob_index) {
db_impl_ = db_impl;
cfd_ = cfd;
read_callback_ = read_callback;
expose_blob_index_ = expose_blob_index;
}
private:
DBIter* db_iter_ = nullptr;
Arena arena_;
uint64_t sv_number_;
ColumnFamilyData* cfd_ = nullptr;
DBImpl* db_impl_ = nullptr;
ReadOptions read_options_;
ReadCallback* read_callback_;
bool expose_blob_index_ = false;
bool allow_refresh_ = true;
// If this is nullptr, it means the mutable memtable does not contain range
// tombstone when added under this DBIter.
TruncatedRangeDelIterator** memtable_range_tombstone_iter_ = nullptr;
};
// Generate the arena wrapped iterator class.
// `db_impl` and `cfd` are used for reneweal. If left null, renewal will not
// be supported.
extern ArenaWrappedDBIter* NewArenaWrappedDbIterator(
Env* env, const ReadOptions& read_options, const ImmutableOptions& ioptions,
const MutableCFOptions& mutable_cf_options, const Version* version,
const SequenceNumber& sequence, uint64_t max_sequential_skip_in_iterations,
uint64_t version_number, ReadCallback* read_callback,
DBImpl* db_impl = nullptr, ColumnFamilyData* cfd = nullptr,
bool expose_blob_index = false, bool allow_refresh = true);
} // namespace ROCKSDB_NAMESPACE