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boost multi_index_container 多索引容器

来源：尚车旅游网

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hash
	CAmount 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 {};


	typedef
		boost::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 CompareTxMemPoolEntryByDescendantScore
            boost::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 {};


	typedef
		boost::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

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hash
	CAmount 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 {};


	typedef
		boost::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();
	t
	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;
}

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;

}

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