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// Copyright (c) 2013 The HyperLevelDB 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.
#ifndef STORAGE_LEVELDB_INCLUDE_REPLAY_ITERATOR_H_
#define STORAGE_LEVELDB_INCLUDE_REPLAY_ITERATOR_H_
#include "leveldb_wt_config.h"
#include "slice.h"
#include "status.h"
namespace leveldb {
class ReplayIterator {
public:
ReplayIterator();
// An iterator is either positioned at a deleted key, present key/value pair,
// or not valid. This method returns true iff the iterator is valid.
virtual bool Valid() = 0;
// Moves to the next entry in the source. After this call, Valid() is
// true iff the iterator was not positioned at the last entry in the source.
// REQUIRES: Valid()
virtual void Next() = 0;
// Position at the first key in the source that at or past target for this
// pass. Note that this is unlike the Seek call, as the ReplayIterator is
// unsorted.
// The iterator is Valid() after this call iff the source contains
// an entry that comes at or past target.
virtual void SkipTo(const Slice& target) = 0;
virtual void SkipToLast() = 0;
// Return true if the current entry points to a key-value pair. If this
// returns false, it means the current entry is a deleted entry.
virtual bool HasValue() = 0;
// Return the key for the current entry. The underlying storage for
// the returned slice is valid only until the next modification of
// the iterator.
// REQUIRES: Valid()
virtual Slice key() const = 0;
// Return the value for the current entry. The underlying storage for
// the returned slice is valid only until the next modification of
// the iterator.
// REQUIRES: !AtEnd() && !AtStart()
virtual Slice value() const = 0;
// If an error has occurred, return it. Else return an ok status.
virtual Status status() const = 0;
protected:
// must be released by giving it back to the DB
virtual ~ReplayIterator();
private:
// No copying allowed
ReplayIterator(const ReplayIterator&);
void operator=(const ReplayIterator&);
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_REPLAY_ITERATOR_H_
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