高并发服务器学习笔记之一：客户端

写在前面：学习本系列需要具备网络基础、socket编程、多进程、多线程等前置知识，如果您对以上前置知识不怎么了解，请先去学习以上前置知识后再来阅读本文，废话不多说我们开始。

我们做一个服务简单一点的服务器，客户端先向服务端发送一个字符串，然后等待服务端返回的消息，循环十次后客户端断开连接；服务端等待客户端发来的消息，每收到一条消息，就向该客户端返回一条消息。

首先，我们先准备两个后面会用到的头文件，它们是日志相关的log.h和定义一些服务端和客户端都要用到的公共头文件public_head.h，代码如下

//log.h
#ifndef __LOG_H
#define __LOG_H

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>

typedef enum {
	SC_LOG_NONE = 0,
	SC_LOG_EMERGENCY,
	SC_LOG_ALERT,
	SC_LOG_CRITICAL,
	SC_LOG_ERROR,
	SC_LOG_WARNING,
	SC_LOG_NOTICE,
	SC_LOG_INFO,
	SC_LOG_DEBUG,

	SC_LOG_LEVEL_MAX,
} log_level;

inline FILE *open_logfile(const char *path)
{
	return fopen(path, "a+");
}

inline void write_logfile(log_level type, FILE *fp, const char *format, ...)
{
	char log[128];
	va_list arg_list;

	memset(log, 0, sizeof(log));

	switch (type)
	{
	case SC_LOG_EMERGENCY:
		sprintf(log, "[log type:%s] ", "emergency");
		break;
	case SC_LOG_ALERT:
		sprintf(log, "[log type:%s] ", "alert");
		break;
	case SC_LOG_CRITICAL:
		sprintf(log, "[log type:%s] ", "critical");
		break;
	case SC_LOG_ERROR:
		sprintf(log, "[log type:%s] ", "error");
		break;
	case SC_LOG_WARNING:
		sprintf(log, "[log type:%s] ", "warning");
		break;
	case SC_LOG_NOTICE:
		sprintf(log, "[log type:%s] ", "notice");
		break;
	case SC_LOG_INFO:
		sprintf(log, "[log type:%s] ", "info");
		break;
	case SC_LOG_DEBUG:
		sprintf(log, "[log type:%s] ", "debug");
		break;
	default:
		sprintf(log, "[log type is error] ");
		break;
	}

	fprintf(fp, log);

	va_start(arg_list, format);
	vfprintf(fp, format, arg_list);
	va_end(arg_list);

	fprintf(fp, "\n");
}

inline void close_logfile(FILE *fp)
{
	fclose(fp);
}

#define	writelog_emergency(fp, format, ...) \
	do { write_logfile(SC_LOG_EMERGENCY, fp, format, __VA_ARGS__); } while (0)

#define	writelog_alert(fp, format, ...) \
	do { write_logfile(SC_LOG_ALERT, fp, format, __VA_ARGS__); } while (0)

#define	writelog_critical(fp, format, ...) \
	do { write_logfile(SC_LOG_CRITICAL, fp, format, __VA_ARGS__); } while (0)

#define	writelog_error(fp, format, ...) \
	do { write_logfile(SC_LOG_ERROR, fp, format, __VA_ARGS__); } while (0)

#define	writelog_warning(fp, format, ...) \
	do { write_logfile(SC_LOG_WARNING, fp, format, __VA_ARGS__); } while (0)

#define	writelog_notice(fp, format, ...) \
	do { write_logfile(SC_LOG_NOTICE, fp, format, __VA_ARGS__); } while (0)

#define	writelog_info(fp, format, ...) \
	do { write_logfile(SC_LOG_INFO, fp, format, __VA_ARGS__); } while (0)

#define	writelog_debug(fp, format, ...) \
	do { write_logfile(SC_LOG_DEBUG, fp, format, __VA_ARGS__); } while (0)

#endif // !__LOG_H

//public_head.h
#ifndef __PUBLIC_HEAD_H
#define __PUBLIC_HEAD_H

#include "log.h"

#define handle_info(msg) \
        do { write_logfile(SC_LOG_INFO, stderr, \
            "file:%s line:%d errorno:%d message:%s", \
            __FILE__, __LINE__, errno, msg); \
            } while (0)

#define handle_warning(msg) \
        do { write_logfile(SC_LOG_WARNING, stderr, \
            "file:%s line:%d errorno:%d message:%s", \
            __FILE__, __LINE__, errno, msg); \
            } while (0)

#define handle_error(msg) \
        do { write_logfile(SC_LOG_ERROR, stderr, \
            "file:%s line:%d errorno:%d message:%s", \
            __FILE__, __LINE__, errno, msg); \
            exit(errno); } while (0)

#endif  //__PUBLIC_HEAD_H

客户端实现比较简单，不用多说，直接上代码，以后所有的服务器模型都用这个客户端进行演示

//client.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include <unistd.h>
#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h> /* superset of previous */
#include <arpa/inet.h>

#define LISTEN_BACKLOG 50
#define handle_error(msg) \
    do { perror(msg); exit(EXIT_FAILURE); } while (0)

int main(int argc, char ** argv)
{
    int i = 0;
    int sockfd = 0;
    ssize_t readret = 0;
    char read_buff[256] = { 0 };
    char write_buff[256] = { 0 };
    struct sockaddr_in server_addr;

    memset(&server_addr, 0, sizeof(server_addr));

    if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
        handle_error("socket");

    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(9527);
    inet_pton(sockfd, "127.0.0.1", &server_addr.sin_addr.s_addr);

    if(connect(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0)
    {
        close(sockfd);
        handle_error("connect");
    }

    for(i = 0; i < 10; ++i)
    {
        memset(write_buff, 0, sizeof(write_buff));
        sprintf(write_buff, "This is client send message:%d", i);
        write(sockfd, write_buff, strlen(write_buff) + 1);

        memset(read_buff, 0, sizeof(read_buff));
        readret = read(sockfd, read_buff, sizeof(read_buff));
        if(readret == 0)
            break;
        printf("%s\n", read_buff);   
		sleep(1);
    }

    close(sockfd);

    return 0;
}