boost multi_index_container 多索引容器的使用

多索引容器 multi_index_container

为什么要使用multi_index_container

相信想必大家在实际开发中一定多少会遇到一些的问题，我需要创建一个可以索引的容器，例如map,set 但是无论map还是set 都是单索引的，例如建立一个类，类里有多个成员变量我们都要对应的索引便于查找例如：

class Ticket
{
public:int ticketHeight;//块高uint256 ticketTxHash;//票hashCAmount ticketPrice;//当前票的票价CBitcoinAddress ticketAddress;//买票的地址Ticket();Ticket(const Ticket& ticket);Ticket(int ticketHeight, uint256 ticketTxHash, CAmount ticketPrice, CBitcoinAddress ticketAddress);void operator=(Ticket & ticket){this->ticketAddress = ticket.ticketAddress;this->ticketHeight = ticket.ticketHeight;this->ticketPrice = ticket.ticketPrice;this->ticketTxHash = ticket.ticketTxHash;}bool operator==(Ticket ticket){if (this->ticketAddress == ticket.ticketAddress &&this->ticketHeight == ticket.ticketHeight &&this->ticketTxHash == ticket.ticketTxHash &&this->ticketPrice == ticket.ticketPrice){return true;}return false;}std::string toString();~Ticket();
private:};

我需要对ticketHeight，ticketTxHash 经行排序索引，如果只是使用map,set构建索引的话，只能对应一种索引，ticketTxHash 或者ticketHeight，而我们需要使用两个map或者set才可以完成对应的需求，那么有没有一种结构可以对应两个排序索引——答案是有的就是我们要说的 boost库中的 multi_index_container

下面就来说一下 multi_index_container 的基本使用，以及我遇到的坑，希望大家不要踩到；

创建

multi_index_container可以看作加载在内存中的数据库，不多说直接上代码

 struct ticket_tx_hash {};//为排序索引后表建立的表明（）struct ticket_height {};typedefboost::multi_index_container<Ticket,   //此处为你要排序的成员类名indexed_by<    //indexed_by<...> 中填写索引规则ordered_unique< //ordered_unique 类比数据库中的主键为唯一索引，ordered默认升序，还有其他顺序下面会做具体描述//tag<...> 指定表名 需要声明即上面的结构体名//BOOST_MULTI_INDEX_MEMBER boost的宏，表示在目标中选取成员作为排序依据 //(Ticket, uint256, ticketTxHash) Ticket：容器成员  uint256：排序依据的类型  ticketTxHash ：排序依据tag<ticket_tx_hash>, BOOST_MULTI_INDEX_MEMBER(Ticket, uint256, ticketTxHash)>,ordered_non_unique<//非唯一索引——可与存在多个tag<ticket_height>, BOOST_MULTI_INDEX_MEMBER(Ticket, int, ticketHeight)>>> ticketpool_set;ticketpool_set ticket_pool;

这样就完成了一个多索引容器类型ticketpool_set的建立，接着实例化了一个ticketpool_set类型的ticket_pool

补充1 ：排序不止ordered_unique/ordered_non_unique一种，还有hashed_unique，下面是一段比特币mempool代码，以及指定排序规则

    typedef boost::multi_index_container<CTxMemPoolEntry,boost::multi_index::indexed_by<// hashed_unique 按照hash排序boost::multi_index::hashed_unique<mempoolentry_txid, SaltedTxidHasher>,//指定排序规则 CompareTxMemPoolEntryByDescendantScoreboost::multi_index::ordered_non_unique<boost::multi_index::tag<descendant_score>,boost::multi_index::identity<CTxMemPoolEntry>,CompareTxMemPoolEntryByDescendantScore>,。。。。//省略

不同索引的表以及迭代器

两种取迭代器的方法（固定格式）

 //index<ticket_tx_hash>指定tag 为 ticket_tx_hash的表的迭代器typedef ticketpool_set::index<ticket_tx_hash>::type::iterator Ticketiter;//index<0> 去上述排序规则中的第一条规则，实际效果和index<ticket_tx_hash>一样，// 规则序号自0 开始//typedef ticketpool_set::index<0>::type::iterator Ticketiter;

取表

//取出规则需要为0的表，
ticketpool_set::index<ticket_tx_hash>::type & ticket_tx_hash_pool = this->ticket_pool.get<0>();
//取出规则需要为ticket_tx_hash的表，
ticketpool_set::index<ticket_tx_hash>::type & ticket_tx_hash_pool = this->ticket_pool.get<ticket_tx_hash>();

补充2：在迭代的时候迭代器取出来的为const 类型的，需要注意，通过const_cast可以去除const

使用

ticketPool类完整版

class ticketPool
{
public:ticketPool();~ticketPool();struct ticket_tx_hash {};struct ticket_height {};typedefboost::multi_index_container<Ticket,indexed_by<ordered_unique<tag<ticket_tx_hash>, BOOST_MULTI_INDEX_MEMBER(Ticket, uint256, ticketTxHash)>,ordered_non_unique<tag<ticket_height>, BOOST_MULTI_INDEX_MEMBER(Ticket, int, ticketHeight)>>> ticketpool_set;ticketpool_set ticket_pool;typedef ticketpool_set::index<ticket_tx_hash>::type::iterator Ticketiter;//typedef ticketpool_set::index<0>::type::iterator Ticketiter;bool ticketPush(Ticket& ticket);bool ticketDel(Ticket ticket);bool ticketDelByHeight(int height);void print_ticket(){for (Ticketiter ticketiter = this->ticket_pool.get<ticket_tx_hash>().begin(); ticketiter != this->ticket_pool.get<ticket_tx_hash>().end(); ticketiter++){Ticket  ticket = *ticketiter;std::cout << ticket.toString() << std::endl;}std::cout << "------------------------------------------------------------------------" << std::endl;for (ticketpool_set::index<ticket_height>::type::iterator ticketiter = this->ticket_pool.get<ticket_height>().begin(); ticketiter != this->ticket_pool.get<ticket_height>().end(); ticketiter++){Ticket  ticket = *ticketiter;std::cout << ticket.toString() << std::endl;}}//Ticket ticketAt(unsigned int index);private:};

增加（insert）

bool ticketPool::ticketPush(Ticket& ticket)
{this->ticket_pool.insert(ticket);return true;
}

当然插入之后，表会自动按排序规则更新，完全不用担心

删除（erase）

ticket_tx_hash_pool.erase(ticketiter);

补充3：如果拿原有表直接删除是不行的，因为原表的为const,这里我是取出表之后在经行删除的。完整代码如下

bool ticketPool::ticketDel(Ticket  ticket)
{ticketpool_set::index<ticket_tx_hash>::type & ticket_tx_hash_pool = this->ticket_pool.get<ticket_tx_hash>();for (Ticketiter ticketiter = this->ticket_pool.get<ticket_tx_hash>().begin(); ticketiter != this->ticket_pool.get<ticket_tx_hash>().end(); ticketiter++){//上面说了迭代器取出的是有const属性的，所以(*ticketiter)==ticket，会导致boost编译时出错，也有一部分原因是我重载== 号的时候时没有const属性的原因if (ticket == (*ticketiter)){ticket_tx_hash_pool.erase(ticketiter);return true;}}return false;
}

补充4 : 删除当然也可以删除一段内容(需要排序后的表)，内容为两个迭代器之间的所有东西

bool ticketPool::ticketDelByHeight(int height)
{ticketpool_set::index<ticket_height>::type::iterator pend;ticketpool_set::index<ticket_height>::type::iterator pbegin = this->ticket_pool.get<1>().begin();while (pbegin   != this->ticket_pool.get<ticket_height>().end()){if (pbegin->ticketHeight == height){break;}pbegin++;} pend = pbegin;while (pend->ticketHeight ==height && pend!= this->ticket_pool.get<ticket_height>().end()){pend++;}this->ticket_pool.get<ticket_height>().erase(pbegin, pend);return true;
}

修改（replace和modify）

因为我时在写区块链底层代码，所以我的代码里没有修改这个方法，所以就简单介绍一下修改方法。
修改分为两种方法replace和modify（由ordered_index索引器提供）
可以自己去看boost文档boost中文文档链接

查看（find）

CBitcoinAddress a1("qfWkAzh1DqJTtNegiY7sEQteJUPNxKHEER");
icketpool_set::index<ticket_height>::type::iterator it = this->ticket_pool.get<1>().find(a1);

最后附上完整的代码及测试代码和测试结果，需要结合比特币代码看下，如果只是学习使用就够了

// ticketpool.h
#pragma once#include "uint256.h"
#include "base58.h"
#include "amount.h"#include <list>
#include <string>#include "boost/multi_index/identity.hpp"
#include "boost/multi_index/member.hpp"#include "boost/multi_index_container.hpp"
#include "boost/multi_index/ordered_index.hpp"
#include "boost/multi_index/hashed_index.hpp"
#include <boost/multi_index/sequenced_index.hpp>
using boost::multi_index_container;
using namespace boost::multi_index;class Ticket
{
public:int ticketHeight;//块高uint256 ticketTxHash;//票hashCAmount ticketPrice;//当前票的票价CBitcoinAddress ticketAddress;//买票的地址Ticket();Ticket(const Ticket& ticket);Ticket(int ticketHeight, uint256 ticketTxHash, CAmount ticketPrice, CBitcoinAddress ticketAddress);void operator=(Ticket & ticket){this->ticketAddress = ticket.ticketAddress;this->ticketHeight = ticket.ticketHeight;this->ticketPrice = ticket.ticketPrice;this->ticketTxHash = ticket.ticketTxHash;}bool operator==(Ticket ticket){if (this->ticketAddress == ticket.ticketAddress &&this->ticketHeight == ticket.ticketHeight &&this->ticketTxHash == ticket.ticketTxHash &&this->ticketPrice == ticket.ticketPrice){return true;}return false;}std::string toString();~Ticket();
private:};class ticketPool
{
public:ticketPool();~ticketPool();struct ticket_tx_hash {};struct ticket_height {};typedefboost::multi_index_container<Ticket,indexed_by<ordered_unique<tag<ticket_tx_hash>, BOOST_MULTI_INDEX_MEMBER(Ticket, uint256, ticketTxHash)>,ordered_non_unique<tag<ticket_height>, BOOST_MULTI_INDEX_MEMBER(Ticket, int, ticketHeight)>>> ticketpool_set;ticketpool_set ticket_pool;typedef ticketpool_set::index<ticket_tx_hash>::type::iterator Ticketiter;//typedef ticketpool_set::index<0>::type::iterator Ticketiter;bool ticketPush(Ticket& ticket);bool ticketDel(Ticket ticket);bool ticketDelByHeight(int height);void print_ticket(){for (Ticketiter ticketiter = this->ticket_pool.get<ticket_tx_hash>().begin(); ticketiter != this->ticket_pool.get<ticket_tx_hash>().end(); ticketiter++){Ticket  ticket = *ticketiter;std::cout << ticket.toString() << std::endl;}std::cout << "------------------------------------------------------------------------" << std::endl;for (ticketpool_set::index<ticket_height>::type::iterator ticketiter = this->ticket_pool.get<ticket_height>().begin(); ticketiter != this->ticket_pool.get<ticket_height>().end(); ticketiter++){Ticket  ticket = *ticketiter;std::cout << ticket.toString() << std::endl;}}//Ticket ticketAt(unsigned int index);private:};

//ticketpool.cpp#include "ticketpool.h"
#include "tinyformat.h"
Ticket::Ticket()
{
}Ticket::Ticket(const Ticket&  ticket)
{this->ticketAddress = ticket.ticketAddress;this->ticketHeight = ticket.ticketHeight;this->ticketPrice = ticket.ticketPrice;this->ticketTxHash = ticket.ticketTxHash;
}Ticket::Ticket(int ticketHeight, uint256 ticketTxHash, CAmount ticketPrice, CBitcoinAddress ticketAddress)
{this->ticketAddress =ticketAddress;this->ticketHeight = ticketHeight;this->ticketPrice = ticketPrice;this->ticketTxHash = ticketTxHash;}Ticket::~Ticket()
{
}std::string Ticket::toString()
{std::string ticketStr;ticketStr += strprintf("ticket info:\t ticketAddress = %s \t  ticketHeight = %d \t   ticketPrice = %d \t  ticketTxHash = %s \n",this->ticketAddress.ToString(),this->ticketHeight,this->ticketPrice,this->ticketTxHash.ToString());return ticketStr;
}ticketPool::ticketPool()
{
}ticketPool::~ticketPool()
{
}bool ticketPool::ticketPush(Ticket& ticket)
{this->ticket_pool.insert(ticket);return true;
}bool ticketPool::ticketDel(Ticket  ticket)
{ticketpool_set::index<ticket_tx_hash>::type & ticket_tx_hash_pool = this->ticket_pool.get<ticket_tx_hash>();for (Ticketiter ticketiter = this->ticket_pool.get<ticket_tx_hash>().begin(); ticketiter != this->ticket_pool.get<ticket_tx_hash>().end(); ticketiter++){if (ticket == (*ticketiter)){ticket_tx_hash_pool.erase(ticketiter);return true;}}return false;
}bool ticketPool::ticketDelByHeight(int height)
{ticketpool_set::index<ticket_height>::type::iterator pend;ticketpool_set::index<ticket_height>::type::iterator pbegin = this->ticket_pool.get<1>().begin();twhile (pbegin   != this->ticket_pool.get<ticket_height>().end()){if (pbegin->ticketHeight == height){break;}pbegin++;} pend = pbegin;while (pend->ticketHeight ==height && pend!= this->ticket_pool.get<ticket_height>().end()){pend++;}this->ticket_pool.get<ticket_height>().erase(pbegin, pend);return true;
}Ticket ticketPool::ticketAt(unsigned int index)
{Ticketiter  ticketiter = this->ticket_pool.get<ticket_tx_hash>().begin();if (index >= this->ticket_pool.size()  ){throw std::runtime_error("ticket index error");}for (unsigned int i = 0 ; i < index ; i++){ticketiter++;}return *ticketiter;}


#include <stdio.h>
#include <iostream>
#include <primitives/block.h>
#include "ticketpool.h"
#include "base58.h"
int main(int argc, char* argv[])
{printf("hello world!\n");CBitcoinAddress a1("qfWkAzh1DqJTtNegiY7sEQteJUPNxKHEER");CBitcoinAddress a2("qKyMFKqhTAUu6ka9t2nZ1bxYz1bAYfmuVN");CBitcoinAddress a3("qL3VbDUTbtm8MN9ii8Xm5DZe25LvYhxoe1");CBitcoinAddress a4("qMZupjWUQKFJpY63SvPrqz7R791CYUCsFn");CBitcoinAddress a5("qTLkcQALhxsqetNvkwdQ87XeVaeYoWcHx7");CBitcoinAddress a6("qRpj8gKWNHcYN3HjPpi5p8912fntEX6x5p");uint256 u1;u1.SetHex("0x1c2f3fb3ada4973384f3b1e84267fe7e80888a121b14480b74ed708329370deb");uint256 u2;u2.SetHex("0x2c2f3fb3ada4973384f3b1e84267fe7e80888a121b14480b74ed708329370deb"); uint256 u3;u3.SetHex("0x7c2f3fb3ada4973384f3b1e84267fe7e80888a121b14480b74ed708329370deb"); uint256 u4;u4.SetHex("0x4c2f3fb3ada4973384f3b1e84267fe7e80888a121b14480b74ed708329370deb");uint256 u5;u5.SetHex("0x5c2f3fb3ada4973384f3b1e84267fe7e80888a121b14480b74ed708329370deb");uint256 u6;u6.SetHex("0x6c2f3fb3ada4973384f3b1e84267fe7e80888a121b14480b74ed708329370deb");std::cout << "  a   "  << std::endl;Ticket t1(1,u1,1000, a1);std::cout << "  a  " << std::endl;Ticket t2(1, u2, 1000, a2);Ticket t3(2, u3, 1000, a3);Ticket t4(2, u4, 1000, a4);Ticket t5(3, u5, 1000, a5);Ticket t6(2, u6, 1000, a6);std::cout <<"    " <<t1.toString() << std::endl;ticketPool pool;pool.ticketPush(t1);pool.ticketPush(t2);pool.ticketPush(t3);pool.ticketPush(t4);pool.ticketPush(t5);pool.ticketPush(t6);pool.print_ticket();std::cout << " \n   " << pool.ticketAt(2).toString() << std::endl;std::cout << " \n   " << pool.ticketAt(1).toString() << std::endl;std::cout << " \n   " << pool.ticketAt(0).toString() << std::endl;//pool.ticketDel(t4);pool.ticketDelByHeight(2);std::cout << " -------------delete ---------------------  "  << std::endl;pool.print_ticket();return 0;}