跳跃表C++实现

2018年12月21日 hu, zhigen Comments 0 Comment

仿Redis实现

#pragma once

#include "gntype.h"

#include <vector>

#include "utility.h"

static const uint32 MAX_LEVEL = 64;

static const double SKIPLIST_P = 0.25;

struct SkipListNode;

struct SkipListLevel

{

SkipListLevel(uint32 span, SkipListNode *forward) :nSpan(span), forwardNode(forward) {};

SkipListNode *forwardNode = nullptr;

uint32 nSpan = 0;

};

struct SkipListNode

{

uint64 nScore = 0;

uint64 nNodeId = 0;

SkipListNode *backwardNode = nullptr;

std::vector<SkipListLevel> level;

};

class SkipList

{

public:

SkipList();

~SkipList();

void InitSkipList();

bool IsExist(const uint64 key);

bool IsExist(const uint64& key, const uint64& value);

bool SearchNode(const uint64& key, std::vector<uint64>& vecRes);

bool DeleteNodeByKey(const uint64& key,const uint64 value);

void InsertNode(const uint64& key, const uint64& value);

SkipListNode* CreateNode(const uint32 level, const uint64& key, const uint64& value);

bool UpdateNode(const uint64& nNewkey, const uint64& nOldkey, const uint64& value);

void GetTopK(const uint32 nCount, std::vector<uint64>& vecRes);

uint32 GetRankByKey(const uint64& key, const uint64& value);

uint32 GetRandomLevel();

void Free();

private:

SkipListNode *headNode, *tailNode;

uint32 m_nLength;

uint32 m_nLevel;

void DeleteNode(SkipListNode * node, SkipListNode **update);

};

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#include "skip_list.h"

SkipList::SkipList()

{

}

SkipList::~SkipList()

{

}

SkipListNode* SkipList::CreateNode(const uint32 level, const uint64& key, const uint64& value)

{

SkipListNode* newNode = new SkipListNode;//factory

newNode->nScore = key;

newNode->nNodeId = value;

for (uint32 index = 0; index != level; ++index)

{

SkipListLevel newLevel(0, nullptr);

newNode->level.push_back(newLevel);

}

newNode->backwardNode = nullptr;

return newNode;

}

void SkipList::InitSkipList()

{

m_nLevel = 1;

m_nLength = 0;

headNode = CreateNode(MAX_LEVEL, 0, 0);

tailNode = nullptr;

}

void SkipList::InsertNode(const uint64& key, const uint64& value)

{

SkipListNode *update[MAX_LEVEL], *x;

unsigned int rank[MAX_LEVEL];

uint32 i, level;

x = headNode;

for (i = (m_nLevel - 1); i >= 0; i--) {

/* store rank that is crossed to reach the insert position */

rank[i] = (i == (m_nLevel - 1)) ? 0 : rank[i + 1];

while ((x->level.size() - 1) level[i].forwardNode &&

(x->level[i].forwardNode->nScore < key ||

(x->level[i].forwardNode->nScore == key &&

x->level[i].forwardNode->nNodeId < value)))

{

rank[i] += x->level[i].nSpan;

x = x->level[i].forwardNode;

}

update[i] = x;

}

level = GetRandomLevel();

if (level > m_nLevel) {

for (i = m_nLevel; i < level; i++) {

rank[i] = 0;

update[i] = headNode;

update[i]->level[i].nSpan = m_nLength;

}

m_nLevel = level;

}

x = CreateNode(level, key, value);

for (i = 0; i < level; i++) {

x->level[i].forwardNode = update[i]->level[i].forwardNode;

update[i]->level[i].forwardNode = x;

x->level[i].nSpan = update[i]->level[i].nSpan - (rank[0] - rank[i]);

update[i]->level[i].nSpan = (rank[0] - rank[i]) + 1;

}

for (i = level; i < m_nLevel; i++) {

update[i]->level[i].nSpan++;

}

x->backwardNode = (update[0] == headNode) ? nullptr : update[0];

if (x->level[0].forwardNode)

x->level[0].forwardNode->backwardNode = x;

else

tailNode = x;

m_nLength++;

}

bool SkipList::IsExist(const uint64 key)

{

return true;

}

bool SkipList::IsExist(const uint64& key, const uint64& value)

{

return true;

}

bool SkipList::SearchNode(const uint64& key, std::vector<uint64>& vecRes)

{

return true;

}

bool SkipList::DeleteNodeByKey(const uint64& key, const uint64 value)

{

SkipListNode *update[MAX_LEVEL], *x;

int i;

x = headNode;

for (i = m_nLevel - 1; i >= 0; i--) {

while ((x->level.size() - 1) level[i].forwardNode &&

(x->level[i].forwardNode->nScore < key ||

(x->level[i].forwardNode->nScore == key &&

x->level[i].forwardNode->nNodeId < value)))

{

x = x->level[i].forwardNode;

}

update[i] = x;

}

x = x->level[0].forwardNode;

if (x && key == x->nScore && value == x->nNodeId) {

DeleteNode(x, update);

delete x; //factory

return true;

}

return false;

}

bool SkipList::UpdateNode(const uint64& nNewkey, const uint64& nOldkey, const uint64& value)

{

SkipListNode *update[MAX_LEVEL], *x;

int i;

x = headNode;

for (i = m_nLevel - 1; i >= 0; i--) {

while ((x->level.size() - 1) level[i].forwardNode &&

(x->level[i].forwardNode->nScore < nOldkey ||

(x->level[i].forwardNode->nScore == nOldkey &&

x->level[i].forwardNode->nNodeId < value)))

{

x = x->level[i].forwardNode;

}

update[i] = x;

}

x = x->level[0].forwardNode;

bool bExist = x && nOldkey == x->nScore && value == x->nNodeId;

if (bExist = false)

{

return false;

}

if ((x->backwardNode == nullptr || x->backwardNode->nScore < nNewkey) &&

(x->level[0].forwardNode == nullptr || x->level[0].forwardNode->nScore > nNewkey))

{

x->nScore = nNewkey;

return true;

}

DeleteNode(x, update);

InsertNode(nNewkey, value);

delete x;//factory

return true;

}

void SkipList::GetTopK(const uint32 nCount, std::vector<uint64>& vecRes)

{

}

uint32 SkipList::GetRankByKey(const uint64& key, const uint64& value)

{

SkipListNode *x;

unsigned long rank = 0;

int i;

x = headNode;

for (i = m_nLevel - 1; i >= 0; i--) {

while ((x->level.size() - 1) level[i].forwardNode &&

(x->level[i].forwardNode->nScore < key ||

(x->level[i].forwardNode->nScore == key &&

x->level[i].forwardNode->nNodeId < value)))

{

rank += x->level[i].nSpan;

x = x->level[i].forwardNode;

}

if (x && x->nNodeId == value) {

return rank;

}

return INT_MAX;

}

void SkipList::Free()

{

}

void SkipList::DeleteNode(SkipListNode * node, SkipListNode **update)

{

int i;

for (i = 0; i < m_nLevel; i++) {

if (update[i]->level[i].forwardNode == node) {

update[i]->level[i].nSpan += node->level[i].nSpan - 1;

update[i]->level[i].forwardNode = node->level[i].forwardNode;

}

else {

update[i]->level[i].nSpan -= 1;

}

if (node->level[0].forwardNode) {

node->level[0].forwardNode->backwardNode = node->backwardNode;

}

else {

tailNode = node->backwardNode;

}

while (m_nLevel > 1 && headNode->level[m_nLevel - 1].forwardNode == nullptr)

m_nLevel--;

m_nLength--;

}

uint32 SkipList::GetRandomLevel()

{

uint32 level = 1;

while ((Storm::GetRand(1, 0xFFFF) & 0xFFFF) < (SKIPLIST_P * 0xFFFF))

level += 1;

return (level < MAX_LEVEL) ? level : MAX_LEVEL;

}

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菜鸡程序员成长日记

跳跃表C++实现

2018年12月21日 hu, zhigen Comments 0 Comment

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