ceph/src/rocksdb/db/db_iter.h

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5 //
   6 // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
   7 // Use of this source code is governed by a BSD-style license that can be
   8 // found in the LICENSE file. See the AUTHORS file for names of contributors.
   9
  10 #pragma once
  11 #include <stdint.h>
  12 #include <string>
  13 #include "db/db_impl.h"
  14 #include "db/dbformat.h"
  15 #include "db/range_del_aggregator.h"
  16 #include "options/cf_options.h"
  17 #include "rocksdb/db.h"
  18 #include "rocksdb/iterator.h"
  19 #include "util/arena.h"
  20 #include "util/autovector.h"
  21
  22 namespace rocksdb {
  23
  24 class Arena;
  25 class DBIter;
  26
  27 // Return a new iterator that converts internal keys (yielded by
  28 // "*internal_iter") that were live at the specified "sequence" number
  29 // into appropriate user keys.
  30 extern Iterator* NewDBIterator(
  31     Env* env, const ReadOptions& read_options,
  32     const ImmutableCFOptions& cf_options,
  33     const MutableCFOptions& mutable_cf_options,
  34     const Comparator* user_key_comparator, InternalIterator* internal_iter,
  35     const SequenceNumber& sequence, uint64_t max_sequential_skip_in_iterations,
  36     ReadCallback* read_callback, DBImpl* db_impl = nullptr,
  37     ColumnFamilyData* cfd = nullptr, bool allow_blob = false);
  38
  39 // A wrapper iterator which wraps DB Iterator and the arena, with which the DB
  40 // iterator is supposed be allocated. This class is used as an entry point of
  41 // a iterator hierarchy whose memory can be allocated inline. In that way,
  42 // accessing the iterator tree can be more cache friendly. It is also faster
  43 // to allocate.
  44 class ArenaWrappedDBIter : public Iterator {
  45  public:
  46   virtual ~ArenaWrappedDBIter();
  47
  48   // Get the arena to be used to allocate memory for DBIter to be wrapped,
  49   // as well as child iterators in it.
  50   virtual Arena* GetArena() { return &arena_; }
  51   virtual RangeDelAggregator* GetRangeDelAggregator();
  52
  53   // Set the internal iterator wrapped inside the DB Iterator. Usually it is
  54   // a merging iterator.
  55   virtual void SetIterUnderDBIter(InternalIterator* iter);
  56   virtual bool Valid() const override;
  57   virtual void SeekToFirst() override;
  58   virtual void SeekToLast() override;
  59   virtual void Seek(const Slice& target) override;
  60   virtual void SeekForPrev(const Slice& target) override;
  61   virtual void Next() override;
  62   virtual void Prev() override;
  63   virtual Slice key() const override;
  64   virtual Slice value() const override;
  65   virtual Status status() const override;
  66   virtual Status Refresh() override;
  67   bool IsBlob() const;
  68
  69   virtual Status GetProperty(std::string prop_name, std::string* prop) override;
  70
  71   void Init(Env* env, const ReadOptions& read_options,
  72             const ImmutableCFOptions& cf_options,
  73             const MutableCFOptions& mutable_cf_options,
  74             const SequenceNumber& sequence,
  75             uint64_t max_sequential_skip_in_iterations, uint64_t version_number,
  76             ReadCallback* read_callback, DBImpl* db_impl, ColumnFamilyData* cfd,
  77             bool allow_blob, bool allow_refresh);
  78
  79   void StoreRefreshInfo(const ReadOptions& read_options, DBImpl* db_impl,
  80                         ColumnFamilyData* cfd, ReadCallback* read_callback,
  81                         bool allow_blob) {
  82     read_options_ = read_options;
  83     db_impl_ = db_impl;
  84     cfd_ = cfd;
  85     read_callback_ = read_callback;
  86     allow_blob_ = allow_blob;
  87   }
  88
  89  private:
  90   DBIter* db_iter_;
  91   Arena arena_;
  92   uint64_t sv_number_;
  93   ColumnFamilyData* cfd_ = nullptr;
  94   DBImpl* db_impl_ = nullptr;
  95   ReadOptions read_options_;
  96   ReadCallback* read_callback_;
  97   bool allow_blob_ = false;
  98   bool allow_refresh_ = true;
  99 };
 100
 101 // Generate the arena wrapped iterator class.
 102 // `db_impl` and `cfd` are used for reneweal. If left null, renewal will not
 103 // be supported.
 104 extern ArenaWrappedDBIter* NewArenaWrappedDbIterator(
 105     Env* env, const ReadOptions& read_options,
 106     const ImmutableCFOptions& cf_options,
 107     const MutableCFOptions& mutable_cf_options, const SequenceNumber& sequence,
 108     uint64_t max_sequential_skip_in_iterations, uint64_t version_number,
 109     ReadCallback* read_callback, DBImpl* db_impl = nullptr,
 110     ColumnFamilyData* cfd = nullptr, bool allow_blob = false,
 111     bool allow_refresh = true);
 112 }  // namespace rocksdb