C++负载均衡远程调用学习之负载均衡算法与实现

目录

01 lars 系统架构回顾

02 lars-lbAgentV0.4-route_lb处理report业务流程

03 lars-lbAgentV0.4-负责均衡判断参数配置

04 lars-lbAgentV0.4-负载均衡idle节点的失败率判断

05 lars-lbAgentV0.4-负载均衡overload节点的成功率判断

06 lars-lbAgentV0.4-负载均衡上报提交模块

07 lars-lbAgentV0.4-数据问题修改-上报业务测试

08 lars-lbAgentV0.4-模拟器测试工具

09 lars-lbAgentV0.5-idle连续成功-overload连续失败的定期窗口重置机制

10 lars-lbAgentV0.6-loadbalance主动更新主机信息功能

11 昨日回顾

12 Lars-LbAgentV0.7-GetRouteAPI实现

13 Lars-LbAgentV0.7-Udp-server-获取路由服务业务注册

14 Lars-LbAgentV0.7-Udp-server-API和udpserver的测试

---

01 lars 系统架构回顾

**启动 Lars Reporter**

```bash
$ ./run_lars reporter
 

        ▄▄                                               
        ██                                               
        ██         ▄█████▄   ██▄████  ▄▄█████▄           
        ██         ▀ ▄▄▄██   ██▀      ██▄▄▄▄ ▀           
        ██        ▄██▀▀▀██   ██        ▀▀▀▀██▄           
        ██▄▄▄▄▄▄  ██▄▄▄███   ██       █▄▄▄▄▄██           
        ▀▀▀▀▀▀▀▀   ▀▀▀▀ ▀▀   ▀▀        ▀▀▀▀▀▀            
    Load balance And Remote service schedule System 
                                                         
        _____                       _                       
       |  __ \                     | |
       | |__) |___ _ __   ___  _ __| |_ ___ _ __
       |  _  // _ \ '_ \ / _ \| '__| __/ _ \ '__|
       | | \ \  __/ |_) | (_) | |  | ||  __/ |
       |_|  \_\___| .__/ \___/|_|   \__\___|_|
                  | |
                  |_|

            ITCAST(https://www.itcast.cn)
         ------------------------------------ 

create 0 thread
create 1 thread
create 2 thread
create 3 thread
create 4 thread
add msg cb msgid = 3
```





**启动 Lars dns**

```bash
$ ./run_lars dns
 

        ▄▄                                               
        ██                                               
        ██         ▄█████▄   ██▄████  ▄▄█████▄           
        ██         ▀ ▄▄▄██   ██▀      ██▄▄▄▄ ▀           
        ██        ▄██▀▀▀██   ██        ▀▀▀▀██▄           
        ██▄▄▄▄▄▄  ██▄▄▄███   ██       █▄▄▄▄▄██           
        ▀▀▀▀▀▀▀▀   ▀▀▀▀ ▀▀   ▀▀        ▀▀▀▀▀▀            
    Load balance And Remote service schedule System 
                                                         
                _____ 
               |  __ \ 
               | |  | |_ __  ___ 
               | |  | | '_ \/ __|
               | |__| | | | \__ \ 
               |_____/|_| |_|___/ 

            ITCAST(https://www.itcast.cn)
         ------------------------------------ 

create 0 thread
create 1 thread
create 2 thread
create 3 thread
create 4 thread
add msg cb msgid = 1
lars dns service ....
now route version is 1574674421
```



**启动 Lars Lb Agent**

```c
$ ./run_lars lbagent

        ▄▄                                               
        ██                                               
        ██         ▄█████▄   ██▄████  ▄▄█████▄           
        ██         ▀ ▄▄▄██   ██▀      ██▄▄▄▄ ▀           
        ██        ▄██▀▀▀██   ██        ▀▀▀▀██▄           
        ██▄▄▄▄▄▄  ██▄▄▄███   ██       █▄▄▄▄▄██           
        ▀▀▀▀▀▀▀▀   ▀▀▀▀ ▀▀   ▀▀        ▀▀▀▀▀▀            
    Load balance And Remote service schedule System 
                                                         
      _      _                                _  
     | |    | |         /\                   | | 
     | |    | |__      /  \   __ _  ___ _ __ | |_ 
     | |    | '_ \    / /\ \ / _` |/ _ \ '_ \| __| 
     | |____| |_) |  / ____ \ (_| |  __/ | | | |_ 
     |______|_.__/  /_/    \_\__, |\___|_| |_|\__| 
                              __/ | 
                             |___/  

            ITCAST(https://www.itcast.cn)
         ------------------------------------ 

```

02 lars-lbAgentV0.4-route_lb处理report业务流程




LB Agent拥有5个线程，一个LB算法：

- UDP Server服务，并运行LB算法，对业务提供节点获取和节点调用结果上报服务；为了增大系统吞吐量，使用3个UDP Server服务互相独立运行LB算法：`modid+cmdid % 3 = i`的那些模块的服务与调度，由第`i+1`个UDP Server线程负责
- Dns Service Client：是dnsserver的客户端线程，负责根据需要，向dnsserver获取一个模块的节点集合（或称为获取路由）；UDP Server会按需向此线程的MQ写入获取路由请求，DSS Client将MQ到来的请求转发到dnsserver，之后将dnsserver返回的路由信息更新到对应的UDP Server线程维护的路由信息中
- Report Service Client：是reporter的客户端线程，负责将每个模块下所有节点在一段时间内的调用结果、过载情况上报到reporter Service端，便于观察情况、做报警；本身消费MQ数据，UDP Server会按需向MQ写入上报状态请求

03 lars-lbAgentV0.4-负责均衡判断参数配置

## 2) 构建Lars-Agent项目    

### 2.1 构建目录结构

依次创建如下目录：

> Lars/lars_loadbalance_agent



```bash
lars_loadbalance_agent/
├── bin/
├── conf/
│   └── lars_lb_agent.conf
├── include/
├── Makefile
└── src/
```



其中Makefile如下:

```makefile
TARGET= bin/lars_lb_agent
CXX=g++
CFLAGS=-g -O2 -Wall -Wno-deprecated

BASE=../base
BASE_H=$(BASE)/include

PROTO = $(BASE)/proto
PROTO_H = $(BASE)/proto

LARS_REACTOR=../lars_reactor
LARS_REACTOR_H =$(LARS_REACTOR)/include
LARS_REACTOR_LIB=$(LARS_REACTOR)/lib  -llreactor

MYSQL=$(BASE)/mysql-connector-c
MYSQL_H=$(MYSQL)/include
MYSQL_LIB=$(MYSQL)/lib/libmysqlclient.a

OTHER_LIB = -lpthread -ldl -lprotobuf
SRC= ./src
INC= -I./include -I$(BASE_H) -I$(LARS_REACTOR_H) -I$(MYSQL_H) -I$(PROTO_H)

LIB= $(MYSQL_LIB) -L$(LARS_REACTOR_LIB) $(OTHER_LIB) 


OBJS = $(addsuffix .o, $(basename $(wildcard $(SRC)/*.cpp)))
OBJS += $(PROTO)/lars.pb.o

$(TARGET): $(OBJS)
        mkdir -p bin
        $(CXX) $(CFLAGS) -o $(TARGET) $(OBJS) $(INC) $(LIB)

%.o: %.cpp
        $(CXX) $(CFLAGS) -c -o $@ $< $(INC) 

.PHONY: clean

clean:
        -rm -f src/*.o  $(PROTO)/lars.pb.o $(TARGET)
```

​        实际上reporter、dns相似。

> conf/lars_lb_agent.conf

```ini
[reporter]
ip = 127.0.0.1
port = 7779

[dnsserver]
ip = 127.0.0.1
port = 7778
```

​        目前的基本配置文件，因为loadbalance_agent是充当reporter和dnsserver的客户端，所以需要知道对应的reporter和dnsserver的ip和port信息。

04 lars-lbAgentV0.4-负载均衡idle节点的失败率判断

### 2.2 主模块业务搭建


​        首先我们要在主线程中，启动3个UDP Server线程，这个是提供业务层/API层的服务。然后分别启动report_client线程，用来和reporter Service进行通信，将请求上报信息发送给Reporter Service。 然后再启动dns_client线程，用来和dns service通信。

> lars_loadbalance_agent/include/main_server.h 

```c
#pragma once
#include "lars_reactor.h"
#include "lars.pb.h"


//与report_client通信的thread_queue消息队列
extern thread_queue<lars::ReportStatusRequest>* report_queue;
//与dns_client通信的thread_queue消息队列
extern thread_queue<lars::GetRouteRequest>* dns_queue;


// 启动udp server服务,用来接收业务层(调用者/使用者)的消息
void start_UDP_servers(void);

// 启动lars_reporter client 线程
void start_report_client(void);

// 启动lars_dns client 线程
void start_dns_client(void);
```

05 lars-lbAgentV0.4-负载均衡overload节点的成功率判断

> lars_loadbalance_agent/src/main_server.cpp 

```c
#include "main_server.h"
#include "lars.pb.h"

//与report_client通信的thread_queue消息队列
thread_queue<lars::ReportStatusRequest>* report_queue = NULL;
//与dns_client通信的thread_queue消息队列
thread_queue<lars::GetRouteRequest>* dns_queue = NULL;

int main(int argc, char **argv)
{
    //1 加载配置文件
    
    //2 启动udp server服务,用来接收业务层(调用者/使用者)的消息
    start_UDP_servers();
    
    //3 启动lars_reporter client 线程
    report_queue = new thread_queue<lars::ReportStatusRequest>();
    if (report_queue == NULL) {
        fprintf(stderr, "create report queue error!\n");
        exit(1);
    }
    start_report_client();
    
    //4 启动lars_dns client 线程
    dns_queue = new thread_queue<lars::GetRouteRequest>();
    if (dns_queue == NULL) {
        fprintf(stderr, "create dns queue error!\n");
        exit(1);
    }
    start_dns_client();
    

    std::cout <<"done!" <<std::endl;
    while (1) {
        sleep(10);
    }

    return 0;
}
```

06 lars-lbAgentV0.4-负载均衡上报提交模块

这里我们分别在main()中 ，开启以上线程。

​        其中`report_client`线程需要携带`thread_queue<lars::ReportStatusRequest>`消息队列通道。`agent`负责将上报请求消息`lars::ReportStatusRequest`通过thread_queue发送给reporter service。

​        其中`dns_client`线程需要携带`thread_queue<lars::GetRouteRequest>`。`agent`负责将请求modid/cmdid的route消息`lars::GetRouteRequest`通过thread_queue发送给dns service。



3个udp server的线程开辟实现如下：

> lars_loadbalance_agent/src/agent_udp_server.cpp

```c
#include "lars_reactor.h"
#include "main_server.h"


void * agent_server_main(void * args)
{
    int *index = (int*)args;
    short port = *index + 8888;
    event_loop loop;

    udp_server server(&loop, "0.0.0.0", port);

    //TODO 给server注册消息分发路由业务

    printf("agent UDP server :port %d is started...\n", port);
    loop.event_process();

    return NULL;
}

07 lars-lbAgentV0.4-数据问题修改-上报业务测试

void start_UDP_servers(void)
{
    for (int i = 0; i < 3; i ++) {
        pthread_t tid;
        
        int ret = pthread_create(&tid, NULL, agent_server_main, &i);
        if (ret == -1) {
            perror("pthread_create");
            exit(1);
        }

        pthread_detach(tid);

    }
}
```



reporter thread创建实现如下：

> lars_loadbalance_agent/src/reporter_client.cpp

```c
#include "lars_reactor.h"
#include "main_server.h"
#include <pthread.h>

void *report_client_thread(void* args)
{
    printf("report client thread start\n");
#if 0
    event_loop loop;

    //1 加载配置文件得到repoter ip + port
    std::string ip = config_file::instance()->GetString("reporter", "ip", "");
    short port = config_file::instance()->GetNumber("reporter", "port", 0);

    //2 创建客户端
    tcp_client client(&loop, ip.c_str(), port, "reporter client");

    //3 将 thread_queue消息回调事件，绑定到loop中
    report_queue->set_loop(&loop);
    report_queue->set_callback()

    //4 启动事件监听
    loop.event_process();
#endif

    return NULL;
}

08 lars-lbAgentV0.4-模拟器测试工具

void start_report_client()
{
    //开辟一个线程
    pthread_t tid;

    //启动线程业务函数
    int ret = pthread_create(&tid, NULL, report_client_thread, NULL);
    if (ret == -1) {
        perror("pthread_create");
        exit(1);
    }

    //设置分离模式
    pthread_detach(tid);
}
```



dns thread创建实现如下：

> lars_loadbalance_agent/src/dns_client.cpp

```c
#include "lars_reactor.h"
#include "main_server.h"
#include <pthread.h>

void *dns_client_thread(void* args)
{
    printf("dns client thread start\n");

    return NULL;
}

void start_dns_client()
{
    //开辟一个线程
    pthread_t tid;

    //启动线程业务函数
    int ret = pthread_create(&tid, NULL, dns_client_thread, NULL);
    if (ret == -1) {
        perror("pthread_create");
        exit(1);
    }

    //设置分离模式
    pthread_detach(tid);
}
```

09 lars-lbAgentV0.5-idle连续成功-overload连续失败的定期窗

口重置机制

### 2.3 测试lb_agentV0.1开发

编译，然后我们简单启动一下`./bin/lars_lb_agent`

```bash
$ ./bin/lars_lb_agent 
dns client thread start
report client thread start
done!
msg_router init...
server on 0.0.0.0:8888 is running...
agent UDP server :port 8888 is started...
msg_router init...
server on 0.0.0.0:8888 is running...
agent UDP server :port 8888 is started...
msg_router init...
server on 0.0.0.0:8888 is running...
agent UDP server :port 8888 is started...
...
```
 

10 lars-lbAgentV0.6-loadbalance主动更新主机信息功能

## 3) Report Client设计与实现

​        report client主要是实现thread_queue的回调业务，udp server会定期的上传上报数据到reporter，那么请求对于report client就是透传给reporter serivce即可。

> lars_loadbalance_agent/src/reporter_client.cpp

```c
#include "lars_reactor.h"
#include "main_server.h"
#include <string>
#include <pthread.h>

//typedef void io_callback(event_loop *loop, int fd, void *args);
//只要thread_queue有数据，loop就会触发此回调函数来处理业务
void new_report_request(event_loop *loop, int fd, void *args)
{
    tcp_client *client = (tcp_client*)args;

    //1. 将请求数据从thread_queue中取出，
    std::queue<lars::ReportStatusRequest>  msgs;

    //2. 将数据放在queue队列中
    report_queue->recv(msgs);
    
    //3. 遍历队列，通过client依次将每个msg发送给reporter service
    while (!msgs.empty()) {
        lars::ReportStatusRequest req = msgs.front();
        msgs.pop();

        std::string requestString;
        req.SerializeToString(&requestString);

        //client 发送数据
        client->send_message(requestString.c_str(), requestString.size(), lars::ID_ReportStatusRequest);
    }
}

11 昨日回顾

void *report_client_thread(void* args)
{
    printf("report client thread start\n");
    
    event_loop loop;

    //1 加载配置文件得到repoter ip + port
    std::string ip = config_file::instance()->GetString("reporter", "ip", "");
    short port = config_file::instance()->GetNumber("reporter", "port", 0);

    //2 创建客户端
    tcp_client client(&loop, ip.c_str(), port, "reporter client");

    //3 将 thread_queue消息回调事件，绑定到loop中
    report_queue->set_loop(&loop);
    report_queue->set_callback(new_report_request, &client);

    //4 启动事件监听
    loop.event_process();

    return NULL;
}

12 Lars-LbAgentV0.7-GetRouteAPI实现

void start_report_client()
{
    //开辟一个线程
    pthread_t tid;

    //启动线程业务函数
    int ret = pthread_create(&tid, NULL, report_client_thread, NULL);
    if (ret == -1) {
        perror("pthread_create");
        exit(1);
    }

    //设置分离模式
    pthread_detach(tid);
}
```



## 4) Dns Client设计与实现

​        dns client 和report client的业务十分相似，只是针对的协议不同了。dns client的thread_queue 回调业务主要是透传`lars::GetRouteRequest`数据包。

> lars_loadbalance_agent/src/dns_client.cpp

```c
#include "lars_reactor.h"
#include "main_server.h"
#include <pthread.h>


//typedef void io_callback(event_loop *loop, int fd, void *args);
//只要thread_queue有数据，loop就会触发此回调函数来处理业务
void new_dns_request(event_loop *loop, int fd, void *args)
{
    tcp_client *client = (tcp_client*)args;

    //1. 将请求数据从thread_queue中取出，
    std::queue<lars::GetRouteRequest>  msgs;

    //2. 将数据放在queue队列中
    dns_queue->recv(msgs);
    
    //3. 遍历队列，通过client依次将每个msg发送给reporter service
    while (!msgs.empty()) {
        lars::GetRouteRequest req = msgs.front();
        msgs.pop();

        std::string requestString;
        req.SerializeToString(&requestString);

        //client 发送数据
        client->send_message(requestString.c_str(), requestString.size(), lars::ID_GetRouteRequest);
    }

}

13 Lars-LbAgentV0.7-Udp-server-获取路由服务业务注册

void *dns_client_thread(void* args)
{
    printf("dns client thread start\n");
    event_loop loop;

    //1 加载配置文件得到dns service ip + port
    std::string ip = config_file::instance()->GetString("dnsserver", "ip", "");
    short port = config_file::instance()->GetNumber("dnsserver", "port", 0);

    //2 创建客户端
    tcp_client client(&loop, ip.c_str(), port, "dns client");

    //3 将thread_queue消息回调事件，绑定到loop中
    dns_queue->set_loop(&loop);
    dns_queue->set_callback(new_dns_request, &client);

    //4 启动事件监听
    loop.event_process(); 

    return NULL;
}


void start_dns_client()
{
    //开辟一个线程
    pthread_t tid;

    //启动线程业务函数
    int ret = pthread_create(&tid, NULL, dns_client_thread, NULL);
    if (ret == -1) {
        perror("pthread_create");
        exit(1);
    }

    //设置分离模式
    pthread_detach(tid);
}
```

14 Lars-LbAgentV0.7-Udp-server-API和udpserver的测试

## 5) 负载均衡模块基础设计(V0.2)



### 5.1 基础

​        每个模块`modid/cmdid`下有若干节点，节点的集合称为此模块的路由； 对于每个节点，有两种状态：

- `idle`：此节点可用，可作为API**(相当于Agent的客户端)**请求的节点使用；

- `overload`：此节点过载，暂时不可作为API请求的节点使用

  ​    在请求节点时，有几个关键属性：

- 虚拟成功次数`vsucc`，API汇报节点调用结果是成功时，该值+1
- 虚拟失败次数`verr`，API汇报节点调用结果是失败时，该值+1
- 连续成功次数`contin_succ`，连续请求成功的次数
- 连续失败次数`contin_err`，连续请求失败的次数

这4个字段，在节点状态改变时(idle<—>overload)，会被重置。