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rocksdb/util/skiplistrep.cc

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3.2 KiB

// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
#include "rocksdb/memtablerep.h"
#include "db/memtable.h"
#include "db/skiplist.h"
namespace rocksdb {
namespace {
class SkipListRep : public MemTableRep {
SkipList<const char*, MemTableRep::KeyComparator&> skip_list_;
public:
explicit SkipListRep(MemTableRep::KeyComparator& compare, Arena* arena)
: skip_list_(compare, arena) {
}
// Insert key into the list.
// REQUIRES: nothing that compares equal to key is currently in the list.
virtual void Insert(const char* key) override {
skip_list_.Insert(key);
}
// Returns true iff an entry that compares equal to key is in the list.
virtual bool Contains(const char* key) const override {
return skip_list_.Contains(key);
}
virtual size_t ApproximateMemoryUsage() override {
// All memory is allocated through arena; nothing to report here
return 0;
}
virtual ~SkipListRep() override { }
// Iteration over the contents of a skip list
class Iterator : public MemTableRep::Iterator {
SkipList<const char*, MemTableRep::KeyComparator&>::Iterator iter_;
public:
// Initialize an iterator over the specified list.
// The returned iterator is not valid.
explicit Iterator(
const SkipList<const char*, MemTableRep::KeyComparator&>* list
) : iter_(list) { }
virtual ~Iterator() override { }
// Returns true iff the iterator is positioned at a valid node.
virtual bool Valid() const override {
return iter_.Valid();
}
// Returns the key at the current position.
// REQUIRES: Valid()
virtual const char* key() const override {
return iter_.key();
}
// Advances to the next position.
// REQUIRES: Valid()
virtual void Next() override {
iter_.Next();
}
// Advances to the previous position.
// REQUIRES: Valid()
virtual void Prev() override {
iter_.Prev();
}
// Advance to the first entry with a key >= target
virtual void Seek(const Slice& user_key, const char* memtable_key)
override {
if (memtable_key != nullptr) {
iter_.Seek(memtable_key);
} else {
iter_.Seek(EncodeKey(&tmp_, user_key));
}
}
// Position at the first entry in list.
// Final state of iterator is Valid() iff list is not empty.
virtual void SeekToFirst() override {
iter_.SeekToFirst();
}
// Position at the last entry in list.
// Final state of iterator is Valid() iff list is not empty.
virtual void SeekToLast() override {
iter_.SeekToLast();
}
protected:
std::string tmp_; // For passing to EncodeKey
};
// Unhide default implementations of GetIterator
using MemTableRep::GetIterator;
virtual MemTableRep::Iterator* GetIterator() override {
return new SkipListRep::Iterator(&skip_list_);
}
};
}
MemTableRep* SkipListFactory::CreateMemTableRep(
MemTableRep::KeyComparator& compare, Arena* arena) {
return new SkipListRep(compare, arena);
}
} // namespace rocksdb