rocksdb/util/skiplistrep.cc
kailiu eae1804f29 Remove the unnecessary use of shared_ptr
Summary:
shared_ptr is slower than unique_ptr (which literally comes with no performance cost compare with raw pointers).
In memtable and memtable rep, we use shared_ptr when we'd actually should use unique_ptr.

According to igor's previous work, we are likely to make quite some performance gain from this diff.

Test Plan: make check

Reviewers: dhruba, igor, sdong, haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D15213
2014-01-15 18:22:01 -08:00

105 lines
3.0 KiB
C++

// 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 char* target) override {
iter_.Seek(target);
}
// 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();
}
};
// 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