Linux--进程池

1.一个父进程生成五个子进程且分别建立与子进程管道

①用for循环，结束条件为<5 ②father父进程每次都要离开for循环，生成下一个子进程和管道

2.#include <cassert>和#include <assert.h>的区别

assert.h 是 C 标准库的头文件，cassert 是 C++ 标准库的头文件

3.子进程进行读取

那咱就关闭写端:close(pipefd[1])，保留读端

4.父进程进行写入

那咱就关闭读端:close(pipefd[0])，保留写端

5.让父进程实现：选择让哪个进程执行哪个命令

使用pair<pid_t,int>创建键值对，实现一一对应。

vector<pair<pid_t,int> > slots;创建各个进程与命令的对应表

slots.push_back(pair<pid_t,int>(id,pipefd[1]));将进程与命令建立连接

6.让子进程等待命令

waitCommand(pipefd[0]);//如果对方不发，我们就阻塞

int waitCommand(int waitFd)

{

    uint32_t command = 0;

    ssize_t s=read(waitFd,&command,sizeof(command));

    assert(s == sizeof(uint32_t));

    return command;

}

7.uint32_t对应几个字节

4个

8.typedef function<void()> func,以及它的等价写法

typedef function<void()> func表示定义函数对象，等价写法是using func=function<void()>

代码实现：

Makefile:

ProcessPool:ProcessPool.ccg++ -o $@ $^ -std=c++11 #-DDEBUG
.PHONY:clean
clean:rm -f ProcessPool

Task.hpp

#pragma once#include <iostream>
#include <string>
#include <unistd.h>
#include <functional>
#include <vector>
#include <unordered_map>using namespace std;
typedef function<void()> func;//等价于  using func=function<void()>vector<func> callbacks;
unordered_map<int,string> desc;
void readMySQL()
{cout<<"process["<<getpid()<<"]执行访问数据库的任务" <<endl;
}void execuleUrl()
{cout<<"process["<<getpid()<<"]执行url解析" <<endl;
}void cal()
{cout<<"process["<<getpid()<<"]执行加密任务" <<endl;
}void save()
{cout<<"process["<<getpid()<<"]执行数据持久化任务" <<endl;
}void load()
{desc.insert({callbacks.size(),"readMySQL:读取数据库"});callbacks.push_back(readMySQL);desc.insert({callbacks.size(),"execuleUrl:进行url解析"});callbacks.push_back(execuleUrl);desc.insert({callbacks.size(),"cal:进行加密计算"});callbacks.push_back(cal);desc.insert({callbacks.size(),"save:进行数据的文件保存"});callbacks.push_back(save);}void showHandler()
{for(const auto &iter:desc){cout<<iter.first<<"\t"<<iter.second<<endl;}
}int handlerSize()
{return callbacks.size();
}

processPool.cc

#include <iostream>
#include <unistd.h>
#include <stdio.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <cassert>
#include <vector>
#include "Task.hpp"
#include <cstdlib>
#include <ctime>#define PROCESS_NUM 5using namespace std;int waitCommand(int waitFd,bool &quit)
{uint32_t command = 0;ssize_t s = read(waitFd, &command, sizeof(command));if(s == 0){quit=true;return -1;}assert(s == sizeof(uint32_t));return command;
}void sendAndWakeup(pid_t who, int fd, uint32_t command)
{write(fd,&command,sizeof(command));cout<<"call process"<<who<<"execute"<<desc[command]<<"through"<<fd<<endl;
}int main()
{load();// vector内放置pid:pipefd键值对vector<pair<pid_t, int>> slots;// 先创建多个进程for (int i = 0; i < PROCESS_NUM; i++){// 创建管道int pipefd[2] = {0};int n = pipe(pipefd);assert(n > 0);(void)n;pid_t id = fork();assert(id != -1);// 子进程我们让它进行读取if (id == 0){// 关闭写端close(pipefd[1]);// childwhile (true){// pipefd[0]// 等命令bool quit=false;int command = waitCommand(pipefd[0],quit); // 如果对方不发，我们就阻塞if(quit) break;// 执行对应的命令if (command >= 0 && command < handlerSize()){callbacks[command]();}else{cout << "非法command:" << command << endl;}}exit(1);}// father,进行写入，关闭读端close(pipefd[0]);slots.push_back(pair<pid_t, int>(id, pipefd[1]));}// 父进程派发任务srand(unsigned long)time(nullptr)^getpid()^23323123123L);//让数据更随机while (true){int select;int command;cout << "##############################################" << endl;cout << "#    1.show functions    2.send command      #" << endl;cout << "##############################################" << endl;cout << "Please Select>";cin >> select;if (select == 1)showHandler();else if (select == 2){cout << "Enter Your Command>";// 选择任务cin >> command;// 选择进程int choice = rand() % slots.size();// 把任务给指定的进程sendAndWakeup(slots[choice].first, slots[choice].second, command);}}// 关闭fd,所有的子进程都会退出for(const auto& slot:slots){close(slot.second);}//回收所有的子进程信息for(const auto & slot:slots){waitpid(slot.first,nullptr,0);}}