并发Socket程序设计

1. 非阻塞并发模型

直接将socket设置为非阻塞, 轮询处理连接和接收。

缺点: 极大消耗CPU资源,不适合实际应用。

 

2. 信号驱动模型

当Socket文件描述符准备就绪后 内核会给进程发送一个 SIGIO 或 SIGPOLL信号,signal(SIGIO, fun);

实际中 并不只有套接字有输入时才会发出这些信号, 实际情况中并不能用。

 

3. 超时并发模型

A: 通过套接字选项设置超时

     通过套接字选项SO_SNDTIMEO 和 SO_RCVTIMEO设置读写超时,但是只能设置读写超时,不能设置connect 和 accept 等连接超时,并且有的系统不支持。

B: 通过信号SIGALRM 设置超时

#include <comlib.h>	
static int nTimeOut = 0;		
void OnTimeout(int nSignal)		
{
	signal(nSignal, SIG_IGN);	
	nTimeOut = 1;	
	return;
}

int main(int argc, char *argv[])
{
	int nSock = -1, ret;
	if (argc != 3) return 1;
	nTimeOut = 0; 
	signal(SIGALRM, OnTimeout);		
	alarm(10);				
	ret = ConnectSock(&nSock, atoi(argv[2]), argv[1]);	
	alarm(0);						
	signal(SIGALRM, SIG_IGN);	
	
	if (nTimeOut == 1) printf("Connect Timeout.\n"); 
	else if (ret == 0) printf("Connect Success.\n");	
	else printf("Connect Error!\n");
	if (nSock != -1) close(nSock);				
	return 0;
}

 

C: 通过信号SIGALRM 与 跳转设置超时

#include <comlib.h>	
#include  <setjmp.h>
static int nTimeOut = 0;		
jmp_buf env;				
void OnTimeout(int nSignal)
{
	signal(nSignal, SIG_IGN); 	
	nTimeOut = 1;			
	longjmp(env, 1);        		
	return;					
}

int main(int argc, char *argv[])
{
	int nSock = -1, ret;
	if (argc != 3) return 1;
	nTimeOut = 0; 
	setjmp(env);
	if (nTimeOut == 1) printf("Connect Timeout.\n"); 
	else
	{
		signal(SIGALRM, OnTimeout);		
		alarm(10);						
		ret = ConnectSock(&nSock, atoi(argv[2]), argv[1]);	
		alarm(0);						
		signal(SIGALRM, SIG_IGN);		
		if (ret == 0) printf("Connect Success.\n");	
		else printf("Connect Error!\n");
	}
	if (nSock != -1) close(nSock);					
	return 0;
}

 

 

4. 多路复用并发模型

 

 

5. 多进程并发模型

A: 不固定进程数的并发模型

比如父进程只执行函数accept等待并完成客户端连接申请,子进程执行函数recv等待客户端的信息发送。

缺陷: 客户端无限申请,服务器比爆。

 

B: 固定进程数的并发模型

服务器父进程在创建监听套接字(listen)后fork子进程, 由子进程等待客户端connect并 完成与客户端的通信交换等工作,父进程之后的功能只是维持子进程的数目不变。

 

 

#include<iostream>
#include<string.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<assert.h>
#include<errno.h>
#include<stdio.h>
#include<arpa/inet.h>
#include<stdio.h>
#include<wait.h>
#include<stdlib.h>
#include<semaphore.h>
#include<sys/ipc.h>

using namespace std;

int CreateSock( int *pSock, int nPort, int nMax )
{
    int ret, on;
    struct sockaddr_in addrin;
    struct sockaddr *paddr = (struct sockaddr *) &addrin;
    assert(pSock != NULL && nPort >0 && nMax > 0);
    memset(&addrin, 0, sizeof(addrin));

    addrin.sin_family = AF_INET;
    addrin.sin_addr.s_addr = htonl(INADDR_ANY);
    addrin.sin_port = htons(nPort);

    assert((*pSock = socket(AF_INET, SOCK_STREAM, 0)) > 0);
    on=1;
    ret = setsockopt( *pSock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on) );
    if( (bind(*pSock, paddr, sizeof(addrin)))< 0 )
    {
        perror("bind");
        //cout << "bind error" << endl;
        return 1;
    }
    if( (listen(*pSock, nMax)) < 0 )
    {
        cout << "listen error" << endl;
        return 1;
    }
    else
    {
        cout << "create cocket successfully" << endl;
        return 0;
    }

    return 1;
}

int AcceptSock(int *pSock, int nSock)
{
    struct sockaddr_in addrin;
    socklen_t lSize;
    assert( pSock!=NULL && nSock>0 );
    while(1)
    {
        lSize = sizeof(addrin);
        memset(&addrin, 0, sizeof(addrin));
        if( (*pSock = accept(nSock, (struct sockaddr *)&addrin, &lSize)) > 0 )
            return 0;
        else if( errno == EINTR ) continue;
        else assert(0);
    }
}

int ConnectSock(int *pSock, int nPort, char* pAddr)
{
    struct sockaddr_in addrin;
    long lAddr;
    int nSock;
    assert(pSock!=NULL && nPort>0 && pAddr!=NULL);
    assert( (nSock = socket(AF_INET, SOCK_STREAM, 0)) > 0 );
    memset(&addrin, 0, sizeof(addrin));
    addrin.sin_family = AF_INET;
    addrin.sin_addr.s_addr = inet_addr(pAddr);
    addrin.sin_port = htons(nPort);
    if( (connect(nSock, (struct sockaddr *)&addrin , sizeof(addrin))) == 0 )
    {
        *pSock = nSock;
        return 0;
    }
    close(nSock);
    return 1;
}

int LocateRemoteAddr(int nSock, char *pAddr)
{
    struct sockaddr_in addrin;
    socklen_t lSize;
    if( nSock<=0 && pAddr==NULL )
    {
        cout << "input error" << endl;
        return 1;
    }
    memset(&addrin, 0, sizeof(addrin));

    if( (getpeername(nSock, (struct sockaddr*)&addrin, &lSize)) == 0 )
    {
        strcpy(pAddr, inet_ntoa(addrin.sin_addr));
        return 0;
    }
    else
    {
        cout << "getpeername error " << endl;
        return 1;
    }
    return 1;
}


int main()
{
    cout << "tcp test!" << endl;

    int i, bShutdown = 0, MAXNUMBER = 3;
    int nSock, nSock1, nLisSock;
    char szAddr[30];
    char buf[1024];
    pid_t pid, nChild;
    sem_t sem;   //信号量

    sem_init(&sem, 0, 1); //初始化信号量

    CreateSock(&nLisSock, 8888, 9);

    for( i=0; i<MAXNUMBER; i++ )
    {
        nChild = fork();
        if(nChild == 0) break;
    }

    if( nChild > 0 )   //父进程
    {
        cout << "in parent process: " << getpid() << endl;
        while( !bShutdown )
        {
            pid = wait(NULL);   //父进程等待子进程结束,并补充子进程
            if( pid < 0 )
            {
                perror("wait");
                continue;
            }
            printf("catch a process %d end \n", pid);
            nChild = fork();
            if( nChild == 0 )   break;
        }
        exit(0);
    }
    else if( nChild == 0 )   //子进程
    {
        while(1)
        {
            //cout << "in Child process: " << getpid() << endl;
            sem_wait(&sem);   //信号量互斥
            if( (AcceptSock(&nSock, nLisSock)) == 0 )
                cout <<  "accept successfully" << endl;
            memset(buf, 0, sizeof(buf));
            recv(nSock, buf, sizeof(buf), 0);
            cout << "in process: " << getpid() << " receive: " << buf << endl;
            close(nSock);
            sem_post(&sem);
        }
    }

    return 0;
}



/*
int main()
{
    cout << "tcp test!" << endl;

    int nSock, nSock1;
    char szAddr[30];
    char buf[1024];

    CreateSock(&nSock, 8888, 9);

    if( (AcceptSock(&nSock1, nSock)) == 0 )
        cout <<  "accept successfully" << endl;

    memset(buf, 0, sizeof(buf));
    recv(nSock1, buf, sizeof(buf), 0);
    cout << "receive: " << buf << endl;

    cout << "input a key, send: " << endl;
    fgetc(stdin);
    send(nSock1, "world", strlen("world"), 0);
    cout << "send: " << "world" << endl;

    //LocateRemoteAddr(nSock1, szAddr);
    //cout << "IP--->" << szAddr << endl;

    close(nSock);
    close(nSock1);

    return 0;
}
*/

posted @ 2013-08-05 14:36  今晚打酱油_  阅读(264)  评论(0编辑  收藏  举报