【RabbitMQ 项目】服务端：数据管理模块之绑定管理

一.编写思路

1. 定义绑定信息类
   1. 交换机名称
   2. 队列名称
   3. 绑定关键字：交换机的路由交换算法中会用到
      没有是否持久化的标志，因为绑定是否持久化取决于交换机和队列是否持久化，只有它们都持久化时绑定才需要持久化。绑定就好像一根绳子，两端连接着交换机和队列，当一方不存在，它就没有存在的必要了
2. 定义绑定持久化类
   1. 构造函数：如果数据库文件不存在则创建，打开数据库，创建 binding_table
   2. 插入交换机和队列的绑定
   3. 移除交换机和队列的绑定
   4. 移除与指定交换机相关的所有绑定
   5. 移除与指定队列相关的所有绑定
   6. 从数据库中恢复绑定到内存
   7. 删除绑定数据库表(仅调试)
3. 定义绑定管理类
   1. 构造函数：从数据库中恢复绑定
   2. 绑定交换机和队列
   3. 解绑交换机和队列
   4. 解绑与指定交换机相关的绑定：移除交换机时要用到
   5. 解绑与指定队列相关的绑定：移除队列时要用到
   6. 获取交换机相关的所有绑定信息：交换路由时要用到
   7. 销毁所有绑定(仅调试)

二.代码实践

Binding.hpp

#pragma once
#include "../common/Util.hpp"
#include 
#include 
#include 
/***************
 * 定义绑定信息类
 * **************/
namespace ns_data
{
    class Binding;
    using BindingPtr = std::shared_ptr<Binding>;
    using BindingMap = std::unordered_map<std::string, std::unordered_map<std::string, BindingPtr>>;
    struct Binding
    {
        std::string _exchangeName;
        std::string _msgQueueName;
        std::string _bindingKey;

        Binding(const std::string &exchangeName, const std::string &msgQueueName, const std::string &bindingKey)
            : _exchangeName(exchangeName),
              _msgQueueName(msgQueueName),
              _bindingKey(bindingKey)
        {
        }
    };

    class BindingMapper
    {
    private:
        ns_util::Sqlite3Util _sqlite;

    public:
        BindingMapper(const std::string &dbName)
            : _sqlite(dbName)
        {
            if (!ns_util::FileUtil::createFile(dbName))
            {
                LOG(FATAL) << "create database " << dbName << " fail" << endl;
                exit(1);
            }
            if (!_sqlite.open())
            {
                LOG(FATAL) << "open database " << dbName << " fail" << endl;
                exit(1);
            }
            createTable();
        }

        /****************
         * 插入绑定
         * *************/
        bool insertBinding(BindingPtr bindingPtr)
        {
            char insertSql[1024];
            sprintf(insertSql, "insert into binding_table values('%s', '%s', '%s');", bindingPtr->_exchangeName.c_str(),
                    bindingPtr->_msgQueueName.c_str(), bindingPtr->_bindingKey.c_str());
            if (!_sqlite.exec(insertSql, nullptr, nullptr))
            {
                LOG(WARNING) << "insert Binding fail: " << bindingPtr->_exchangeName << "->" << bindingPtr->_msgQueueName;
                return false;
            }
            return true;
        }

        /***********
         * 移除交换机和队列的绑定
         * ****************/
        void removeBinding(const std::string &exchangeName, const std::string &msgQueueName)
        {
            char deleteSql[1024];
            sprintf(deleteSql, "delete from binding_table where exchange_name='%s' and msg_queue_name='%s';",
                    exchangeName.c_str(), msgQueueName.c_str());
            if (!_sqlite.exec(deleteSql, nullptr, nullptr))
            {
                LOG(WARNING) << "remove Binding fail: " << exchangeName << "->" << msgQueueName << endl;
            }
        }

        /****************
         * 移除指定交换机相关的所有绑定
         * ************/
        void removeExchangeBindings(const std::string &exchangeName)
        {
            char deleteSql[1024];
            sprintf(deleteSql, "delete from binding_table where exchange_name='%s';", exchangeName.c_str());
            if (!_sqlite.exec(deleteSql, nullptr, nullptr))
            {
                LOG(WARNING) << "remove exchange Bindings fail, exchange: " << exchangeName << endl;
            }
        }

        /****************
         * 移除指定队列相关的所有的绑定
         * ************/
        void removeMsgQueueBindings(const std::string &msgQueueName)
        {
            char deleteSql[1024];
            sprintf(deleteSql, "delete from binding_table where msg_queue_name='%s';", msgQueueName.c_str());
            if (!_sqlite.exec(deleteSql, nullptr, nullptr))
            {
                LOG(WARNING) << "remove msg_queue Bindings fail, exchange: " << msgQueueName << endl;
            }
        }

        /******************
         * 恢复数据库中绑定到内存
         * BindingMap是一个二维数组，通过交换机名称和队列名称即可得到Binding的智能指针
         * **************/
        void recoverBindings(BindingMap* mapPtr)
        {
            const std::string selectSql = "select * from binding_table;";
            if (!_sqlite.exec(selectSql.c_str(), selectCallback, mapPtr))
            {
                LOG(FATAL) << "recover Bindings from binding_table fail" << endl;
                exit(1);
            }
        }

        /*********
         * 删除绑定数据库表(仅调试)
         * *************/
        void removeTable()
        {
            const std::string dropSql = "drop table if exists binding_table;";
            if (_sqlite.exec(dropSql.c_str(), nullptr, nullptr))
            {
                LOG(FATAL) << "drop binding_table fail" << endl;
            }
        }

    private:
        void createTable()
        {
            const std::string createSql = "create table if not exists binding_table(\
                exchange_name varchar(32),\
                msg_queue_name varchar(32),\
                binding_key varchar(32),\
                primary key(exchange_name, msg_queue_name)\
            );";

            if (!_sqlite.exec(createSql.c_str(), nullptr, nullptr))
            {
                LOG(FATAL) << "create table binding_table fail" << endl;
                exit(1);
            }
        }

        static int selectCallback(void* arg, int colNum, char** line, char** fields)
        {
            auto mapPtr = static_cast<BindingMap*>(arg);
            const std::string exchangeName = line[0];
            const std::string msgQueueName = line[1];
            const std::string bindingKey = line[2];

            auto bindingPtr = std::make_shared<Binding>(exchangeName, msgQueueName, bindingKey);
            (*mapPtr)[exchangeName][msgQueueName] = bindingPtr;
            return 0;
        }
    };

    class BindingManager
    {
    private:
        BindingMapper _mapper;
        BindingMap _bindings;
        std::mutex _mtx;
    public:
        BindingManager(const std::string& dbName)
            :_mapper(dbName)
        {
            _mapper.recoverBindings(&_bindings);
        }

        /**********
         * 绑定交换机和队列
         * 说明：让上层判断交换机和队列的持久性来告诉我Binding是否需要持久化，如果自己判断耦合度太高了
         * ***********/
        bool bind(const std::string &ename, const std::string &qname, const std::string& bindingKey, bool durable)
        {
            std::unique_lock<std::mutex> lck(_mtx);
            if (_bindings.count(ename) && _bindings[ename].count(qname))
            {
                return true;
            }
            auto bindingPtr = std::make_shared<Binding>(ename, qname, bindingKey);
            _bindings[ename][qname] = bindingPtr;

            if (durable)
            {
                return _mapper.insertBinding(bindingPtr);
            }
            return true;
        }

        /**********
         * 解绑交换机和队列
         * 说明：让上层判断交换机和队列的持久性来告诉我Binding是否需要持久化，如果自己判断耦合度太高了
         * 如果用户不说明，默认它是持久化的，执行一遍delete语句也不会出错
         * ***********/
        void unbind(const std::string &ename, const std::string &qname, bool durable = true)
        {
            std::unique_lock<std::mutex> lck(_mtx);
            if (_bindings.count(ename) == 0 || _bindings[ename].count(qname) == 0)
            {
                return;
            }
            if (durable)
            {
                _mapper.removeBinding(ename, qname);
            }
            _bindings[ename].erase(qname);
        }

        /**************
         * 解绑与指定交换机相关的绑定：删除交换机后要调用该接口
         * ******************/
        void removeExchangeBindings(const std::string &ename)
        {
            std::unique_lock<std::mutex> lck(_mtx);
            if (_bindings.count(ename) == 0)
            {
                return;
            }
            _mapper.removeExchangeBindings(ename);
            _bindings.erase(ename);
        }

        /**************
         * 解绑与指定交换机相关的绑定：删除队列后要调用该接口
         * ******************/
        void removeMsqQueueBindings(const std::string &qname)
        {
            std::unique_lock<std::mutex> lck(_mtx);
            _mapper.removeMsgQueueBindings(qname);
            for (auto it = _bindings.begin(); it != _bindings.end(); it++)
            {
                it->second.erase(qname);
            }
        }

        /***************
         * 获取指定的绑定
         * ***********/
        BindingPtr getBinding(const std::string& ename, const std::string& qname)
        {
            std::unique_lock<std::mutex> lck(_mtx);
            if (_bindings.count(ename) == 0 || _bindings[ename].count(qname) == 0)
            {
                return nullptr;
            }
            return _bindings[ename][qname];
        }

        /**************
         * 获取和指定交换机相关的绑定：路由交换时要用到该接口
         * ***************/
        bool getExchangeBindings(const std::string& ename, std::unordered_map<std::string, BindingPtr>* mapPtr)
        {
            std::unique_lock<std::mutex> lck(_mtx);
            if (_bindings.count(ename) == 0)
            {
                *mapPtr = std::unordered_map<std::string, BindingPtr>();
                return false;
            }
            *mapPtr = _bindings[ename];
            return true;
        }

        /**************
         * 清空绑定(仅调试)
         * ************/
        void clearBindings()
        {
            std::unique_lock<std::mutex> lck(_mtx);
            _bindings.clear();
            _mapper.removeTable();
        }
        
    };
}