学习内容
一共五百多行代码，其中包含了linux编程常用的API。可以通过学习源码，把不熟悉的API练习练习。
1 如何使用webbench
(1)查看参数帮助
(2)运行方法
即以上模拟30个客户端在30秒期间并发请求百度，结果如下：
每分钟平均有1532次请求连接，服务器每秒传输字节为4039230，在30秒期间请求连接成功为766次，失败0次。
2 源码常用函数练习
(1) 选项参数
int getopt_long(int argc, char * const argv[],const char *optstring, const struct option *longopts,int *longindex);
函数中的argc和argv通常直接从main()的两个参数传递而来。optsting是选项参数组成的字符串：
option结构数组，option结构称为长选项表，其声明如下：
struct option
{
const char *name;
int has_arg;
int *flag;
int val;
};
结构中的元素解释如下：
const char *name：选项名，前面没有短横线。譬如"help"、"verbose"之类。
int has_arg：描述长选项是否有选项参数，如果有，是哪种类型的参数，其值见下表: 符号常量 数值
含义
no_argument 0 选项没有参数
required_argument 1 选项需要参数
optional_argument 2 选项参数是可选的
int *flag：
如果该指针为NULL，那么getopt_long返回val字段的值；
如果该指针不为NULL，那么会使得它所指向的结构填入val字段的值，同时getopt_long返回0 int val：
如果flag是NULL，那么val通常是个字符常量，如果短选项和长选项一致，那么该字符就应该与optstring中
字符串optstring可以下列元素:
1.单个字符，表示选项，
2.单个字符后接一个冒号：表示该选项后必须跟一个参数。参数紧跟在选项后或者以空格隔开。该参数的指针赋给optarg。
3 单个字符后跟两个冒号，表示该选项后可以有参数也可以没有参数。如果有参数，参数必须紧跟在选项后不能以空格隔开。该参数的指针赋给optarg。（这个特性是GNU的扩张）。
optstring是一个字符串，表示可以接受的参数。例如，"a:b:cd"，表示可以接受的参数是a,b,c,d，其中，a和b参数后面跟有更多的参数值。(例如：-a host --b name)
最后一个参数：longindex参数一般赋为NULL即可；如果没有设置为NULL，那么它就指向一个变量，这个变量会被赋值为寻找到的长选项在longopts中的索引值，这可以用于错误诊断。
函数使用方法：
View Code
(3)信号相关API
案例https://www.cnblogs.com/yxk529188712/p/4983565.html
(4)IO相关
fwrite()
fread()
read()
(5)管道
int pipe(int fd[2]) 成功返回0，失败返回-1
管道和有名管道是进程间通信机制之一
管道是半双工，所以双方通信需要建立两个通道
FILE * fdopen(int fildes,const char * mode);
fdopen取一个现存的文件描述符（我 们可能从 o p e n , d u p , d u p 2 , f c n t l或p i p e函数得到此文件描述符） ，并使一个标准的I / O流与该描述符相结合。此函数常用于由创建管道和网络通信通道函数获得的描述符。因为这些特殊类型的文件不能用标准I/O fopen函数打开，首先必须先调用设备专用函数以获得一个文件描述符，然后用f d o p e n使一个标准I / O流与该描述符相结合。
fdopen()会将参数fildes 的文件描述符，转换为对应的文件指针后返回。参数mode 字符串 则代表着文件指针的流形态，此形态必须和原先文件描述词读写模式相同。
View Code
2 执行流程
3 源码注释
/*
* (C) Radim Kolar 1997-2004
* This is free software, see GNU Public License version 2 for
* details.
*
* Simple forking WWW Server benchmark:
*
* Usage:
* webbench --help
*
* Return codes:
* 0 - sucess
* 1 - benchmark failed (server is not on-line)
* 2 - bad param
* 3 - internal error, fork failed
*
*/
#include "socket.c"
#include <unistd.h>
#include <sys/param.h>
#include <rpc/types.h>
#include <getopt.h>
#include <strings.h>
#include <time.h>
#include <signal.h>
/* values */
volatile int timerexpired=0;
int speed=0;
int failed=0;
int bytes=0;
/* globals */
int http10=1; /* 0 - http/0.9, 1 - http/1.0, 2 - http/1.1 */
/* Allow: GET, HEAD, OPTIONS, TRACE */
#define METHOD_GET 0
#define METHOD_HEAD 1
#define METHOD_OPTIONS 2
#define METHOD_TRACE 3
#define PROGRAM_VERSION "1.5"
int method=METHOD_GET;
int clients=1;
int force=0;
int force_reload=0;
int proxyport=80;
char *proxyhost=NULL;
int benchtime=30;
/* internal */
int mypipe[2];
char host[MAXHOSTNAMELEN];
#define REQUEST_SIZE 2048
char request[REQUEST_SIZE];
static const struct option long_options[]=
{
{"force",no_argument,&force,1},
{"reload",no_argument,&force_reload,1},
{"time",required_argument,NULL,'t'},
{"help",no_argument,NULL,'?'},
{"http09",no_argument,NULL,'9'},
{"http10",no_argument,NULL,'1'},
{"http11",no_argument,NULL,'2'},
{"get",no_argument,&method,METHOD_GET},
{"head",no_argument,&method,METHOD_HEAD},
{"options",no_argument,&method,METHOD_OPTIONS},
{"trace",no_argument,&method,METHOD_TRACE},
{"version",no_argument,NULL,'V'},
{"proxy",required_argument,NULL,'p'},
{"clients",required_argument,NULL,'c'},
{NULL,0,NULL,0}
};
/* prototypes */
static void benchcore(const char* host,const int port, const char *request);
static int bench(void);
static void build_request(const char *url);
static void alarm_handler(int signal)
{
timerexpired=1;
}
static void usage(void)
{
fprintf(stderr,
"webbench [option]... URL\n"
" -f|--force Don't wait for reply from server.\n"
" -r|--reload Send reload request - Pragma: no-cache.\n"
" -t|--time <sec> Run benchmark for <sec> seconds. Default 30.\n"
" -p|--proxy <server:port> Use proxy server for request.\n"
" -c|--clients <n> Run <n> HTTP clients at once. Default one.\n"
" -9|--http09 Use HTTP/0.9 style requests.\n"
" -1|--http10 Use HTTP/1.0 protocol.\n"
" -2|--http11 Use HTTP/1.1 protocol.\n"
" --get Use GET request method.\n"
" --head Use HEAD request method.\n"
" --options Use OPTIONS request method.\n"
" --trace Use TRACE request method.\n"
" -?|-h|--help This information.\n"
" -V|--version Display program version.\n"
);
}
int main(int argc, char *argv[])
{
int opt=0;
int options_index=0;
char *tmp=NULL;
if(argc==1)
{
usage();
return 2;
}
//getopt_long 参数处理 根据不同的选项对应不同的操作
while((opt=getopt_long(argc,argv,"912Vfrt:p:c:?h",long_options,&options_index))!=EOF )
{
switch(opt)
{
case 0 : break;
case 'f': force=1;break;
case 'r': force_reload=1;break;
case '9': http10=0;break;
case '1': http10=1;break;
case '2': http10=2;break;
case 'V': printf(PROGRAM_VERSION"\n");exit(0);
case 't': benchtime=atoi(optarg);break;
case 'p':
/* proxy server parsing server:port */
tmp=strrchr(optarg,':');
proxyhost=optarg;
if(tmp==NULL)
{
break;
}
if(tmp==optarg)
{
fprintf(stderr,"Error in option --proxy %s: Missing hostname.\n",optarg);
return 2;
}
if(tmp==optarg+strlen(optarg)-1)
{
fprintf(stderr,"Error in option --proxy %s Port number is missing.\n",optarg);
return 2;
}
*tmp='\0';
proxyport=atoi(tmp+1);break;
case ':':
case 'h':
case '?': usage();return 2;break;
case 'c': clients=atoi(optarg);break;
}
}
if(optind==argc) {
fprintf(stderr,"webbench: Missing URL!\n");
usage();
return 2;
}
//默认clients用户为1
if(clients==0)
clients=1;
//默认压测30s
if(benchtime==0)
benchtime=30;
/* Copyright */
fprintf(stderr,"Webbench - Simple Web Benchmark "PROGRAM_VERSION"\n"
"Copyright (c) Radim Kolar 1997-2004, GPL Open Source Software.\n"
);
//构造请求
build_request(argv[optind]);
// print request info ,do it in function build_request
/*printf("Benchmarking: ");
switch(method)
{
case METHOD_GET:
default:
printf("GET");break;
case METHOD_OPTIONS:
printf("OPTIONS");break;
case METHOD_HEAD:
printf("HEAD");break;
case METHOD_TRACE:
printf("TRACE");break;
}
printf(" %s",argv[optind]);
switch(http10)
{
case 0: printf(" (using HTTP/0.9)");break;
case 2: printf(" (using HTTP/1.1)");break;
}
printf("\n");
*/
printf("Runing info: ");
if(clients==1)
printf("1 client");
else
printf("%d clients",clients);
printf(", running %d sec", benchtime);
if(force)
printf(", early socket close");
if(proxyhost!=NULL)
printf(", via proxy server %s:%d",proxyhost,proxyport);
if(force_reload)
printf(", forcing reload");
printf(".\n");
return bench();
}
//构造请求
void build_request(const char *url)
{
char tmp[10];
int i;
//bzero(host,MAXHOSTNAMELEN);
//bzero(request,REQUEST_SIZE);
memset(host,0,MAXHOSTNAMELEN);
memset(request,0,REQUEST_SIZE);
if(force_reload && proxyhost!=NULL && http10<1)
http10=1;
if(method==METHOD_HEAD && http10<1)
http10=1;
if(method==METHOD_OPTIONS && http10<2)
http10=2;
if(method==METHOD_TRACE && http10<2)
http10=2;
//不同的构造头方法
/*
http头部格式
请求方法 空格 URL 空格 协议版本 \r\n
头部字段名 值 \r\n
\r\n
*/
switch(method)
{
default:
case METHOD_GET: strcpy(request,"GET");break;
case METHOD_HEAD: strcpy(request,"HEAD");break;
case METHOD_OPTIONS: strcpy(request,"OPTIONS");break;
case METHOD_TRACE: strcpy(request,"TRACE");break;
}
strcat(request," ");
if(NULL==strstr(url,"://"))
{
fprintf(stderr, "\n%s: is not a valid URL.\n",url);
exit(2);
}
//url限制大小为1500
if(strlen(url)>1500)
{
fprintf(stderr,"URL is too long.\n");
exit(2);
}
if (0!=strncasecmp("http://",url,7))
{
fprintf(stderr,"\nOnly HTTP protocol is directly supported, set --proxy for others.\n");
exit(2);
}
/* protocol/host delimiter */
i=strstr(url,"://")-url+3;
if(strchr(url+i,'/')==NULL) {
fprintf(stderr,"\nInvalid URL syntax - hostname don't ends with '/'.\n");
exit(2);
}
if(proxyhost==NULL)
{
/* get port from hostname */
if(index(url+i,':')!=NULL && index(url+i,':')<index(url+i,'/'))
{
strncpy(host,url+i,strchr(url+i,':')-url-i);
//bzero(tmp,10);
memset(tmp,0,10);
strncpy(tmp,index(url+i,':')+1,strchr(url+i,'/')-index(url+i,':')-1);
/* printf("tmp=%s\n",tmp); */
proxyport=atoi(tmp);
if(proxyport==0) proxyport=80;
}
else
{
strncpy(host,url+i,strcspn(url+i,"/"));
}
// printf("Host=%s\n",host);
strcat(request+strlen(request),url+i+strcspn(url+i,"/"));
}
else
{
// printf("ProxyHost=%s\nProxyPort=%d\n",proxyhost,proxyport);
strcat(request,url);
}
if(http10==1)
strcat(request," HTTP/1.0");
else if (http10==2)
strcat(request," HTTP/1.1");
strcat(request,"\r\n");
//到这里头部构造完成
if(http10>0)
strcat(request,"User-Agent: WebBench "PROGRAM_VERSION"\r\n");
if(proxyhost==NULL && http10>0)
{
strcat(request,"Host: ");
strcat(request,host);
strcat(request,"\r\n");
}
if(force_reload && proxyhost!=NULL)
{
strcat(request,"Pragma: no-cache\r\n");
}
if(http10>1)
strcat(request,"Connection: close\r\n");
/* add empty line at end */
if(http10>0)
strcat(request,"\r\n");
printf("\nRequest:\n%s\n",request);
}
/* vraci system rc error kod */
static int bench(void)
{
int i,j,k;
pid_t pid=0;
FILE *f;
/* check avaibility of target server */
i=Socket(proxyhost==NULL?host:proxyhost,proxyport);
if(i<0) {
fprintf(stderr,"\nConnect to server failed. Aborting benchmark.\n");
return 1;
}
close(i);
/* 创建管道 */
if(pipe(mypipe))
{
perror("pipe failed.");
return 3;
}
/* not needed, since we have alarm() in childrens */
/* wait 4 next system clock tick */
/*
cas=time(NULL);
while(time(NULL)==cas)
sched_yield();
*/
/* fork childs */
//多少个用户多少个进程 fork一次返回两个
for(i=0;i<clients;i++)
{
pid=fork();
if(pid <= (pid_t) 0)
{
/* child process or error*/
sleep(1); /* make childs faster */
break;
}
}
if( pid < (pid_t) 0)
{
fprintf(stderr,"problems forking worker no. %d\n",i);
perror("fork failed.");
return 3;
}
//如果是子进程
if(pid == (pid_t) 0)
{
/* I am a child */
if(proxyhost==NULL)
benchcore(host,proxyport,request);
else
benchcore(proxyhost,proxyport,request);
/* write results to pipe */
//构造完请求得到结果写入管道
f=fdopen(mypipe[1],"w");
if(f==NULL)
{
perror("open pipe for writing failed.");
return 3;
}
/* fprintf(stderr,"Child - %d %d\n",speed,failed); */
fprintf(f,"%d %d %d\n",speed,failed,bytes);
fclose(f);
return 0;
}
else
{
//父进程从管道读数据
f=fdopen(mypipe[0],"r");
if(f==NULL)
{
perror("open pipe for reading failed.");
return 3;
}
setvbuf(f,NULL,_IONBF,0);//不使用缓冲。每个 I/O 操作都被即时写入。buffer 和 size 参数被忽略
speed=0;
failed=0;
bytes=0;
while(1)
{
pid=fscanf(f,"%d %d %d",&i,&j,&k);
if(pid<2)
{
fprintf(stderr,"Some of our childrens died.\n");
break;
}
speed+=i;
failed+=j;
bytes+=k;
/* fprintf(stderr,"*Knock* %d %d read=%d\n",speed,failed,pid); */
if(--clients==0)
break;
}
fclose(f);
printf("\nSpeed=%d pages/min, %d bytes/sec.\nRequests: %d susceed, %d failed.\n",
(int)((speed+failed)/(benchtime/60.0f)),
(int)(bytes/(float)benchtime),
speed,
failed);
}
return i;
}
void benchcore(const char *host,const int port,const char *req)
{
int rlen;
char buf[1500];
int s,i;
struct sigaction sa;
/* setup alarm signal handler */
sa.sa_handler=alarm_handler;
sa.sa_flags=0;
if(sigaction(SIGALRM,&sa,NULL))
exit(3);
alarm(benchtime); // after benchtime,then exit
rlen=strlen(req);
nexttry:while(1)
{
if(timerexpired)
{
if(failed>0)
{
/* fprintf(stderr,"Correcting failed by signal\n"); */
failed--;
}
return;
}
s=Socket(host,port); //尝试连接
//失败次数统计
if(s<0)
{
failed++;
continue;
}
if(rlen!=write(s,req,rlen))
{
failed++;
close(s);
continue;
}
if(http10==0)
if(shutdown(s,1))
{
failed++;
close(s);
continue;
}
if(force==0)
{
/* read all available data from socket */
while(1)
{
if(timerexpired) break;
i=read(s,buf,1500);
/* fprintf(stderr,"%d\n",i); */
if(i<0)
{
failed++;
close(s);
goto nexttry;
}
else
if(i==0)
break;
else
bytes+=i;//read返回的是字节数 所以在此可以统计字节数
}
}
if(close(s))
{
failed++;
continue;
}
speed++;
}
}