35ad531be3
Summary: Separate a new class InternalIterator from class Iterator, when the look-up is done internally, which also means they operate on key with sequence ID and type. This change will enable potential future optimizations but for now InternalIterator's functions are still the same as Iterator's. At the same time, separate the cleanup function to a separate class and let both of InternalIterator and Iterator inherit from it. Test Plan: Run all existing tests. Reviewers: igor, yhchiang, anthony, kradhakrishnan, IslamAbdelRahman, rven Reviewed By: rven Subscribers: leveldb, dhruba Differential Revision: https://reviews.facebook.net/D48549
76 lines
2.7 KiB
C++
76 lines
2.7 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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//
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#pragma once
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#include "rocksdb/iterator.h"
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#include "rocksdb/status.h"
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namespace rocksdb {
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class InternalIterator : public Cleanable {
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public:
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InternalIterator() {}
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virtual ~InternalIterator() {}
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// An iterator is either positioned at a key/value pair, or
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// not valid. This method returns true iff the iterator is valid.
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virtual bool Valid() const = 0;
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// Position at the first key in the source. The iterator is Valid()
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// after this call iff the source is not empty.
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virtual void SeekToFirst() = 0;
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// Position at the last key in the source. The iterator is
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// Valid() after this call iff the source is not empty.
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virtual void SeekToLast() = 0;
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// Position at the first key in the source that at or past target
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// The iterator is Valid() after this call iff the source contains
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// an entry that comes at or past target.
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virtual void Seek(const Slice& target) = 0;
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// Moves to the next entry in the source. After this call, Valid() is
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// true iff the iterator was not positioned at the last entry in the source.
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// REQUIRES: Valid()
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virtual void Next() = 0;
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// Moves to the previous entry in the source. After this call, Valid() is
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// true iff the iterator was not positioned at the first entry in source.
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// REQUIRES: Valid()
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virtual void Prev() = 0;
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// Return the key for the current entry. The underlying storage for
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// the returned slice is valid only until the next modification of
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// the iterator.
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// REQUIRES: Valid()
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virtual Slice key() const = 0;
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// Return the value for the current entry. The underlying storage for
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// the returned slice is valid only until the next modification of
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// the iterator.
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// REQUIRES: !AtEnd() && !AtStart()
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virtual Slice value() const = 0;
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// If an error has occurred, return it. Else return an ok status.
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// If non-blocking IO is requested and this operation cannot be
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// satisfied without doing some IO, then this returns Status::Incomplete().
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virtual Status status() const = 0;
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private:
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// No copying allowed
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InternalIterator(const InternalIterator&) = delete;
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InternalIterator& operator=(const InternalIterator&) = delete;
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};
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// Return an empty iterator (yields nothing).
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extern InternalIterator* NewEmptyInternalIterator();
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// Return an empty iterator with the specified status.
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extern InternalIterator* NewErrorInternalIterator(const Status& status);
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} // namespace rocksdb
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