my-chat_-server/common/channel.hpp

#pragma once
#include <brpc/channel.h>
#include <string>
#include <vector>
#include <unordered_map>
#include <mutex>
#include "logger.hpp"

namespace bite_im{
//1. 封装单个服务的信道管理类:
class ServiceChannel {
    public:
        using ptr = std::shared_ptr<ServiceChannel>;
        using ChannelPtr = std::shared_ptr<brpc::Channel>;
        ServiceChannel(const std::string &name):
            _service_name(name), _index(0){}
        //服务上线了一个节点，则调用append新增信道
        void append(const std::string &host) {
            auto channel = std::make_shared<brpc::Channel>();
            brpc::ChannelOptions options;
            options.connect_timeout_ms = -1;
            options.timeout_ms = -1;
            options.max_retry = 3;
            options.protocol = "baidu_std";
            int ret = channel->Init(host.c_str(), &options);
            if (ret == -1) {
                LOG_ERROR("初始化{}-{}信道失败!", _service_name, host);
                return;
            }
            std::unique_lock<std::mutex> lock(_mutex);
            _hosts.insert(std::make_pair(host, channel));
            _channels.push_back(channel);
        }
        //服务下线了一个节点，则调用remove释放信道
        void remove(const std::string &host) {
            std::unique_lock<std::mutex> lock(_mutex);
            auto it = _hosts.find(host);
            if (it == _hosts.end()) {
                LOG_WARN("{}-{}节点删除信道时，没有找到信道信息！", _service_name, host);
                return;
            }
            for (auto vit = _channels.begin(); vit != _channels.end(); ++vit) {
                if (*vit == it->second) {
                    _channels.erase(vit);
                    break;
                }
            }
            _hosts.erase(it);
        }
        //通过RR轮转策略，获取一个Channel用于发起对应服务的Rpc调用
        ChannelPtr choose() {
            std::unique_lock<std::mutex> lock(_mutex);
            if (_channels.size() == 0) {
                LOG_ERROR("当前没有能够提供 {} 服务的节点！", _service_name);
                return ChannelPtr();
            }
            int32_t idx = _index++ % _channels.size();
            return _channels[idx];
        }
    private:
        std::mutex _mutex;
        int32_t _index; //当前轮转下标计数器
        std::string _service_name;//服务名称
        std::vector<ChannelPtr> _channels; //当前服务对应的信道集合
        std::unordered_map<std::string, ChannelPtr> _hosts; //主机地址与信道映射关系
};

//总体的服务信道管理类
class ServiceManager {
    public:
        using ptr = std::shared_ptr<ServiceManager>;
        ServiceManager() {}
        //获取指定服务的节点信道
        ServiceChannel::ChannelPtr choose(const std::string &service_name) {
            std::unique_lock<std::mutex> lock(_mutex);
            auto sit = _services.find(service_name);
            if (sit == _services.end()) {
                LOG_ERROR("当前没有能够提供 {} 服务的节点！", service_name);
                return ServiceChannel::ChannelPtr();
            }
            return sit->second->choose();
        }

        //先声明，我关注哪些服务的上下线，不关心的就不需要管理了
        void declared(const std::string &service_name) {
            std::unique_lock<std::mutex> lock(_mutex);
            _follow_services.insert(service_name);
        }

        //服务上线时调用的回调接口，将服务节点管理起来
        void onServiceOnline(const std::string &service_instance, const std::string &host) {
            std::string service_name = getServiceName(service_instance);
            ServiceChannel::ptr service;
            {
                std::unique_lock<std::mutex> lock(_mutex);
                auto fit = _follow_services.find(service_name);
                if (fit == _follow_services.end()) {
                    LOG_DEBUG("{}-{} 服务上线了，但是当前并不关心！", service_name, host);
                    return;
                }
                //先获取管理对象，没有则创建，有则添加节点
                auto sit = _services.find(service_name);
                if (sit == _services.end()) {
                    service = std::make_shared<ServiceChannel>(service_name);
                    _services.insert(std::make_pair(service_name, service));
                }else {
                    service = sit->second;
                }
            }
            if (!service) {
                LOG_ERROR("新增 {} 服务管理节点失败！", service_name);
                return ;
            }
            service->append(host);
            LOG_DEBUG("{}-{} 服务上线新节点，进行添加管理！", service_name, host);
        }
        
        //服务下线时调用的回调接口，从服务信道管理中，删除指定节点信道
        void onServiceOffline(const std::string &service_instance, const std::string &host) {
            std::string service_name = getServiceName(service_instance);
            ServiceChannel::ptr service;
            {
                std::unique_lock<std::mutex> lock(_mutex);
                auto fit = _follow_services.find(service_name);
                if (fit == _follow_services.end()) {
                    LOG_DEBUG("{}-{} 服务下线了，但是当前并不关心！", service_name, host);
                    return;
                }
                //先获取管理对象，没有则创建，有则添加节点
                auto sit = _services.find(service_name);
                if (sit == _services.end()) {
                    LOG_WARN("删除{}服务节点时，没有找到管理对象", service_name);
                    return;
                }
                service = sit->second;
            }
            service->remove(host);
            LOG_DEBUG("{}-{} 服务下线节点，进行删除管理！", service_name, host);
        }
    private:
        std::string getServiceName(const std::string &service_instance) {
            auto pos = service_instance.find_last_of('/');
            if (pos == std::string::npos) return service_instance;
            return service_instance.substr(0, pos);
        }
    private:
        std::mutex _mutex;
        std::unordered_set<std::string> _follow_services;
        std::unordered_map<std::string, ServiceChannel::ptr> _services;
};
}