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rocksdb/db/skiplistrep.h

106 lines
2.7 KiB

#ifndef STORAGE_LEVELDB_DB_SKIPLISTREP_H_
#define STORAGE_LEVELDB_DB_SKIPLISTREP_H_
#include "leveldb/memtablerep.h"
#include "db/memtable.h"
#include "db/skiplist.h"
namespace leveldb {
class Arena;
class SkipListRep : public MemTableRep {
Arena arena_;
SkipList<const char*, MemTableRep::KeyComparator&> skip_list_;
public:
explicit SkipListRep(MemTableRep::KeyComparator& compare)
: 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) {
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 {
return skip_list_.Contains(key);
}
virtual size_t ApproximateMemoryUsage() {
return arena_.MemoryUsage();
}
virtual ~SkipListRep() { }
// 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() { }
// Returns true iff the iterator is positioned at a valid node.
virtual bool Valid() const {
return iter_.Valid();
}
// Returns the key at the current position.
// REQUIRES: Valid()
virtual const char* key() const {
return iter_.key();
}
// Advances to the next position.
// REQUIRES: Valid()
virtual void Next() {
iter_.Next();
}
// Advances to the previous position.
// REQUIRES: Valid()
virtual void Prev() {
iter_.Prev();
}
// Advance to the first entry with a key >= target
virtual void Seek(const char* target) {
iter_.Seek(target);
}
// Position at the first entry in list.
// Final state of iterator is Valid() iff list is not empty.
virtual void SeekToFirst() {
iter_.SeekToFirst();
}
// Position at the last entry in list.
// Final state of iterator is Valid() iff list is not empty.
virtual void SeekToLast() {
iter_.SeekToLast();
}
};
virtual std::shared_ptr<MemTableRep::Iterator> GetIterator() {
return std::shared_ptr<MemTableRep::Iterator>(
new SkipListRep::Iterator(&skip_list_)
);
}
};
class SkipListFactory : public MemTableRepFactory {
public:
virtual std::shared_ptr<MemTableRep> CreateMemTableRep (
MemTableRep::KeyComparator& compare) {
return std::shared_ptr<MemTableRep>(new SkipListRep(compare));
}
};
}
#endif // STORAGE_LEVELDB_DB_SKIPLISTREP_H_