ceph/src/rocksdb/table/scoped_arena_iterator.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 // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
   6 // Use of this source code is governed by a BSD-style license that can be
   7 // found in the LICENSE file. See the AUTHORS file for names of contributors.
   8 #pragma once
   9
  10 #include "table/internal_iterator.h"
  11 #include "port/port.h"
  12
  13 namespace rocksdb {
  14 class ScopedArenaIterator {
  15
  16   void reset(InternalIterator* iter) ROCKSDB_NOEXCEPT {
  17     if (iter_ != nullptr) {
  18       iter_->~InternalIterator();
  19     }
  20     iter_ = iter;
  21   }
  22
  23  public:
  24
  25   explicit ScopedArenaIterator(InternalIterator* iter = nullptr)
  26       : iter_(iter) {}
  27
  28   ScopedArenaIterator(const ScopedArenaIterator&) = delete;
  29   ScopedArenaIterator& operator=(const ScopedArenaIterator&) = delete;
  30
  31   ScopedArenaIterator(ScopedArenaIterator&& o) ROCKSDB_NOEXCEPT {
  32     iter_ = o.iter_;
  33     o.iter_ = nullptr;
  34   }
  35
  36   ScopedArenaIterator& operator=(ScopedArenaIterator&& o) ROCKSDB_NOEXCEPT {
  37     reset(o.iter_);
  38     o.iter_ = nullptr;
  39     return *this;
  40   }
  41
  42   InternalIterator* operator->() { return iter_; }
  43   InternalIterator* get() { return iter_; }
  44
  45   void set(InternalIterator* iter) { reset(iter); }
  46
  47   InternalIterator* release() {
  48     assert(iter_ != nullptr);
  49     auto* res = iter_;
  50     iter_ = nullptr;
  51     return res;
  52   }
  53
  54   ~ScopedArenaIterator() {
  55     reset(nullptr);
  56   }
  57
  58  private:
  59   InternalIterator* iter_;
  60 };
  61 }  // namespace rocksdb