AF_UNIX和127.0.0.1(AF_INET)回环地址写数据速度对比

在linux下，存在着这样的情况，本地的进程间通信，并且其中一个是服务端，另外的都是客户端。
服务端通过绑定端口，客户端往127.0.0.1的对应端口发送，即可办到，不过这样会浪费一个端口，同时也容易造成安全隐患。

今天发现linux服务端创建socket的时候，协议族用AF_UNIX即可，AF_LOCAL和AF_UNIX的值是一样的。

而AF_UNIX和127.0.0.1回环地址相比，具有哪些好处呢。本人读了下面博客：
Unix domain socket 简介

其中里面讲到UNIX domain socket 用于 IPC 更有效率：不需要经过网络协议栈，不需要打包拆包、计算校验和、维护序号和应答等。本人想当然认为AF_UNIX速度比127.0.0.1更快，为此鄙人进行了实验。

找一个比较大的文件，超过1G大小，然后
1。用AF_UNIX写客户端和服务端，由客户端读取文件，发送给AF_UNIX服务端，然后服务端写文件，看看用AF_UNIX传递一个文件需要多久。
2. 用127.0.0.1写客户端和服务端，由客户端读取文件，发送给127.0.0.1服务端，然后服务端写文件，看看用127.0.0.1传递一个文件需要多久。

废话不多说，直接上代码，先上AF_UNIX的：
AF_UNIX服务端(unixsocketserver.c)：

#include   
#include   
#include   
#include   
#include   
#include   
#include   
#include   
#include    
 
#define MAXLINE 80  
 
char *socket_path = "/tmp/server.socket";  

#define RECV_LEN 1000
 
int main(void)  
{  
	fd_set readmask, exceptmask;
	struct timeval tv;
	int maxfd = FD_SETSIZE;
	int nready = 0;
	FILE *fp = fopen("/tmp/pull_desktop234_copy.flv", "w");
    if(fp == NULL)
    {
        perror("fopen pull_desktop234_copy.flv failed");
        goto end;
    } 
	char buf[RECV_LEN + 1];
	int readbyte, writebyte;
	
    struct sockaddr_un serun, cliun;  
    socklen_t cliun_len;  
    int listenfd, connfd, size;  
 
    if ((listenfd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {  
        perror("socket error");  
        exit(1);  
    }  
 
    memset(&serun, 0, sizeof(serun));  
    serun.sun_family = AF_UNIX;  
    strcpy(serun.sun_path, socket_path);  
    size = offsetof(struct sockaddr_un, sun_path) + strlen(serun.sun_path);  
    unlink(socket_path);  
    if (bind(listenfd, (struct sockaddr *)&serun, size) < 0) {  
        perror("bind error");  
        exit(1);  
    }  
    printf("UNIX domain socket bound\n");  
      
    if (listen(listenfd, 20) < 0) {  
        perror("listen error");  
        exit(1);          
    }  
    printf("Accepting connections ...\n");  
 
    cliun_len = sizeof(cliun);         
    if ((connfd = accept(listenfd, (struct sockaddr *)&cliun, &cliun_len)) < 0){  
        perror("accept error");  
        goto end;  
    }
	
	time_t now, endtime;
	now = time(NULL);
    while(1)
	{
		FD_ZERO(&readmask);
		FD_ZERO(&exceptmask);
		FD_SET(connfd, &readmask);
		FD_SET(connfd, &exceptmask);
		tv.tv_sec = 3;
		tv.tv_usec = 0;
		nready = select(maxfd, &readmask, NULL, &exceptmask, &tv);
		if(nready < 0)
		{
			goto end;
		}

		if(nready == 0)
		{
			printf("nready == 0\n");
			continue;
		}
		
		if(FD_ISSET(connfd, &readmask))
		{
			readbyte = recv(connfd, buf, RECV_LEN, 0);
			if(readbyte < 0)
			{
				perror("readbyte < 0");
				goto end;
			}
			if(readbyte == 0)
			{
				perror("readbyte == 0");
				goto end;
			}
			if(readbyte > 0)
			{
				buf[readbyte] = 0;
				writebyte = fwrite(buf, 1, readbyte, fp);
				if(writebyte != readbyte)
				{
					printf("writebyte(%d) != readbyte(%d)\n", writebyte, readbyte);
					goto end;
				}
			}
		}
		
		if(FD_ISSET(connfd, &exceptmask))
		{
			printf("select, exceptmask\n");
			goto end;
		}
	}  
end:
	endtime = time(NULL);
	printf("costs %d seconds\n", endtime - now);
	if(fp != NULL)
	{
		fclose(fp);
		fp = NULL;
	}	
	close(connfd);
    close(listenfd);  
    return 0;  
}

AF_UNIX客户端(unixsocketclient.c)：

#include   
#include   
#include   
#include   
#include   
#include   
#include   
#include   


#define SEND_LEN 1000
 
char *client_path = "/tmp/client.socket";  
char *server_path = "/tmp/server.socket";  
 
int main() {  
    struct  sockaddr_un cliun, serun;  
    int len;   
    int sockfd, n;  
	
	FILE *fp = fopen("/tmp/pull_desktop234.flv", "r");
    if(fp == NULL)
	{
		perror("fopen pull_desktop234.flv failed");
		goto end;
	}   
 
    if ((sockfd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0){  
        perror("client socket error");  
        exit(1);  
    }  
      
    // 一般显式调用bind函数，以便服务器区分不同客户端  
    memset(&cliun, 0, sizeof(cliun));  
    cliun.sun_family = AF_UNIX;  
    strcpy(cliun.sun_path, client_path);  
    len = offsetof(struct sockaddr_un, sun_path) + strlen(cliun.sun_path);  
    unlink(cliun.sun_path);  
    if (bind(sockfd, (struct sockaddr *)&cliun, len) < 0) {  
        perror("bind error");  
        exit(1);  
    }  
 
    memset(&serun, 0, sizeof(serun));  
    serun.sun_family = AF_UNIX;  
    strcpy(serun.sun_path, server_path);  
    len = offsetof(struct sockaddr_un, sun_path) + strlen(serun.sun_path);  
    if (connect(sockfd, (struct sockaddr *)&serun, len) < 0){  
        perror("connect error");  
        exit(1);  
    }  
 
    int sendbyte = 0;
    int alreadysendbyte = 0;
    char buf[SEND_LEN + 1];
    while((n = fread(buf, 1, SEND_LEN, fp)) > 0)
	{
		sendbyte = send(sockfd, buf, n, 0);
		if(sendbyte == -1)
		{
			perror("send error");
			goto end;
		}
        alreadysendbyte += sendbyte;
        while(alreadysendbyte < n)
        {
			sendbyte = send(sockfd, buf + alreadysendbyte, n - alreadysendbyte, 0);
			if(sendbyte == -1)
            {
				perror("send error");
				goto end;
			}
			alreadysendbyte += sendbyte;
		}
	}
end:
	if(fp != NULL)
	{
		fclose(fp);
		fp = NULL;
	}
	close(sockfd);
    return 0;  
}

接着上127.0.0.1的：
127.0.0.1服务端(loopsocketserver.c)：

#include 
#include 
#include 
#include 
#include 

#define RECV_LEN 1000

int main(){
	fd_set readmask, exceptmask;
	struct timeval tv;
	int maxfd = FD_SETSIZE;
	int nready = 0;
	FILE *fp = fopen("/tmp/pull_desktop234_copy.flv", "w");
    if(fp == NULL)
    {
        perror("fopen pull_desktop234_copy.flv failed");
        goto end;
    } 
	char buf[RECV_LEN + 1];
	int readbyte, writebyte;
    int serv_sock=socket(AF_INET,SOCK_STREAM,0);
 
    struct sockaddr_in serv_addr;
    memset(&serv_addr,0,sizeof(serv_addr));
    serv_addr.sin_family=AF_INET;
    serv_addr.sin_addr.s_addr=htonl(INADDR_ANY);
    serv_addr.sin_port=htons(9990);
 
    bind(serv_sock,(struct sockaddr*)&serv_addr,sizeof(serv_addr));
 
    listen(serv_sock,5);
 
    struct sockaddr_in clnt_addr;
    socklen_t clnt_addr_size=sizeof(clnt_addr);
    int clnt_sock=accept(serv_sock,(struct sockaddr*)&clnt_addr,&clnt_addr_size);
	time_t now, endtime;
	now = time(NULL);
    while(1)
	{
		FD_ZERO(&readmask);
		FD_ZERO(&exceptmask);
		FD_SET(clnt_sock, &readmask);
		FD_SET(clnt_sock, &exceptmask);
		tv.tv_sec = 3;
		tv.tv_usec = 0;
		nready = select(maxfd, &readmask, NULL, &exceptmask, &tv);
		if(nready < 0)
		{
			goto end;
		}

		if(nready == 0)
		{
			printf("nready == 0\n");
			continue;
		}
		
		if(FD_ISSET(clnt_sock, &readmask))
		{
			readbyte = recv(clnt_sock, buf, RECV_LEN, 0);
			if(readbyte < 0)
			{
				perror("readbyte < 0");
				goto end;
			}
			if(readbyte == 0)
			{
				perror("readbyte == 0");
				goto end;
			}
			if(readbyte > 0)
			{
				buf[readbyte] = 0;
				writebyte = fwrite(buf, 1, readbyte, fp);
				if(writebyte != readbyte)
				{
					printf("writebyte(%d) != readbyte(%d)\n", writebyte, readbyte);
					goto end;
				}
			}
		}
		
		if(FD_ISSET(clnt_sock, &exceptmask))
		{
			printf("select, exceptmask\n");
			goto end;
		}
	}
end: 
	endtime = time(NULL);
	printf("costs %d seconds\n", endtime - now);
	if(fp != NULL)
	{
		fclose(fp);
		fp = NULL;
	}
    close(clnt_sock);
    close(serv_sock);
    return 0;
}

127.0.0.1客户端(loopsocketclient.c)：

#include
#include
#include
#include
#include 
#include 

#define SEND_LEN 1000

int main(){

    int sock=socket(AF_INET,SOCK_STREAM,0);
    FILE *fp = fopen("/tmp/pull_desktop234.flv", "r");
    if(fp == NULL)
	{
		perror("fopen pull_desktop234.flv failed");
		goto end;
	}   

	int n = 0;
    struct sockaddr_in serv_addr;
    memset(&serv_addr,0,sizeof(serv_addr));
    serv_addr.sin_family=AF_INET;
    serv_addr.sin_addr.s_addr=inet_addr("127.0.0.1");
    serv_addr.sin_port=htons(9990);

    if(connect(sock,(struct sockaddr*)&serv_addr,sizeof(serv_addr)) < 0)
	{
		perror("connect failed");
		goto end;
	}
    int sendbyte = 0;
    int alreadysendbyte = 0;
    char buf[SEND_LEN + 1];
    while((n = fread(buf, 1, SEND_LEN, fp)) > 0)
	{
		sendbyte = send(sock, buf, n, 0);
		if(sendbyte == -1)
		{
			perror("send error");
			goto end;
		}
        alreadysendbyte += sendbyte;
        while(alreadysendbyte < n)
        {
			sendbyte = send(sock, buf + alreadysendbyte, n - alreadysendbyte, 0);
			if(sendbyte == -1)
            {
				perror("send error");
				goto end;
			}
			alreadysendbyte += sendbyte;
		}
	}
end:
	if(fp != NULL)
	{
		fclose(fp);
		fp = NULL;
	}
    close(sock);
    return 0;
}

本人的缓冲区大小分为3种情况(文件大小为1.15G)，上图代码片段缓冲区大小为1000字节：
缓冲区大小100字节：AF_UNIX传递完文件费时25秒，127.0.0.1传递完文件费时33秒
缓冲区大小1000字节：AF_UNIX传递完文件费时8秒，127.0.0.1传递完文件费时7秒
缓冲区大小10000字节：AF_UNIX传递完文件费时5秒，127.0.0.1传递完文件费时4秒