webbench 源码学习注解
Webbench是Radim Kolar在1997年写的一个在linux下使用的非常简单的网站压测工具。它使用fork()模拟多个客户端同时访问我们设定的URL,测试网站在压力下工作的性能,最多可以模拟3万个并发连接去测试网站的负载能力。
学习webbench的源代码,把代码注释记录下来,也算是一个典型小程序了。具体源码见https://github.com/EZLippi/WebBench:
#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 *///默认协议http1.0 /* 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;//设置一些默认请求选项,比如默认方法是GET int clients=1;//默认单请求,具体设置见帮助选项 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; } while((opt=getopt_long(argc,argv,"912Vfrt:p:c:?h",long_options,&options_index))!=EOF )//处理命令行选项,修改相应设置 { 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,':');//strrchr:char *strrchr(const char *s, int c);返回当前字符串中c最后出现的字符指针,若找不到返回NULL proxyhost=optarg; if(tmp==NULL)//出错,跳过 { break; } if(tmp==optarg)//缺少参数,直接终止程序 { fprintf(stderr,"Error in option --proxy %s: Missing hostname.\n",optarg); return 2; } if(tmp==optarg+strlen(optarg)-1)//同上 { fprintf(stderr,"Error in option --proxy %s Port number is missing.\n",optarg); return 2; } *tmp='\0'; proxyport=atoi(tmp+1);break;//proxy地址和端口号设置好 case ':': case 'h': case '?': usage();return 2;break; case 'c': clients=atoi(optarg);break; } } if(optind==argc) {//optind将会指向第一个非选项参数,如果optind==argc成立则表示这次执行没有非选项参数(所以optind指向末尾+1),即缺失URL。 fprintf(stderr,"webbench: Missing URL!\n"); usage(); return 2; } if(clients==0) clients=1; 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" ); build_request(argv[optind]);//第一个非选项参数argv[optind]视为URL地址,使用build_request对其进行解析 // 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: ");//运行信息打印 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(); } void build_request(const char *url)//该函数用于处理请求网址,这里假设整个网址为"http://www.cc98.org:80/index.html" { char tmp[10]; int i; //bzero(host,MAXHOSTNAMELEN); //bzero(request,REQUEST_SIZE); memset(host,0,MAXHOSTNAMELEN);//清空host和request memset(request,0,REQUEST_SIZE);//request用于产生具体的http request请求!!! if(force_reload && proxyhost!=NULL && http10<1) http10=1;//根据一些选项设置协议版本,可能和各版本的实现有关,这里暂不考虑 if(method==METHOD_HEAD && http10<1) http10=1; if(method==METHOD_OPTIONS && http10<2) http10=2; if(method==METHOD_TRACE && http10<2) http10=2; switch(method)//选择请求方式 { 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," ");//http请求头格式 if(NULL==strstr(url,"://"))//判断输入URL格式 { fprintf(stderr, "\n%s: is not a valid URL.\n",url); exit(2); } if(strlen(url)>1500) { fprintf(stderr,"URL is too long.\n"); exit(2); } if (0!=strncasecmp("http://",url,7)) //只支持http://开头的网址 { fprintf(stderr,"\nOnly HTTP protocol is directly supported, set --proxy for others.\n"); exit(2); } /* protocol/host delimiter */ i=strstr(url,"://")-url+3;//具体域名起始处位置,比如www.cc98.org:80/index.html中的w if(strchr(url+i,'/')==NULL) {//从网址开头开始查找,看能否找到目录标志'/',同时判断网址格式 fprintf(stderr,"\nInvalid URL syntax - hostname don't ends with '/'.\n"); exit(2); } if(proxyhost==NULL)//根据代理选项完善request { /* get port from hostname */ if(index(url+i,':')!=NULL && index(url+i,':')<index(url+i,'/'))//带端口号的网址 { strncpy(host,url+i,strchr(url+i,':')-url-i);//拷贝网址,作为host,"www.cc98.org" //bzero(tmp,10); memset(tmp,0,10); strncpy(tmp,index(url+i,':')+1,strchr(url+i,'/')-index(url+i,':')-1);//拷贝端口80 /* printf("tmp=%s\n",tmp); */ proxyport=atoi(tmp);//转换成数字 if(proxyport==0) proxyport=80;//默认80端口 } else { strncpy(host,url+i,strcspn(url+i,"/"));//相当于直接复制www.cc98.org主机名 } // printf("Host=%s\n",host); strcat(request+strlen(request),url+i+strcspn(url+i,"/"));//GET行中的资源定位 } else { // printf("ProxyHost=%s\nProxyPort=%d\n",proxyhost,proxyport); strcat(request,url);//若存在代理直接复制 } if(http10==1)//http版本选项 strcat(request," HTTP/1.0"); else if (http10==2) strcat(request," HTTP/1.1"); strcat(request,"\r\n");//拼接request if(http10>0) strcat(request,"User-Agent: WebBench "PROGRAM_VERSION"\r\n");//User-Agent if(proxyhost==NULL && http10>0) //Host { strcat(request,"Host: "); strcat(request,host); strcat(request,"\r\n"); } if(force_reload && proxyhost!=NULL) { strcat(request,"Pragma: no-cache\r\n"); //Pragma } if(http10>1) strcat(request,"Connection: close\r\n"); //Connection /* add empty line at end */ if(http10>0) strcat(request,"\r\n"); //结束request,末尾添加\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);//测试能否建立socket连接 if(i<0) { fprintf(stderr,"\nConnect to server failed. Aborting benchmark.\n"); return 1; } close(i); /* create pipe */ if(pipe(mypipe))//建立管道,仅亲属进程之间能够通信 { 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 */ for(i=0;i<clients;i++) { pid=fork(); if(pid <= (pid_t) 0) { /* child process or error*/ sleep(1); /* make childs faster */ break;//子进程不再fork } } if( pid < (pid_t) 0)//父进程创建子进程的时候失败,直接退出 { fprintf(stderr,"problems forking worker no. %d\n",i); perror("fork failed."); return 3; } if(pid == (pid_t) 0)//子进程代码 { /* I am a child */ if(proxyhost==NULL) benchcore(host,proxyport,request); else benchcore(proxyhost,proxyport,request); /* write results to pipe */ 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);//向管道写入总结反馈数据,多个进程同时向管道写入数据时不会穿插进行,具体可参见APUE2e P399 fclose(f); return 0; } else//父进程代码 { f=fdopen(mypipe[0],"r"); if(f==NULL) { perror("open pipe for reading failed."); return 3; } setvbuf(f,NULL,_IONBF,0);//将该标准IO流设置为不缓冲_IONBF speed=0; failed=0; bytes=0; while(1) { pid=fscanf(f,"%d %d %d",&i,&j,&k);//读入每个进程发送过来的统计数据 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;//clients读完了 } fclose(f); printf("\nSpeed=%d pages/min, %d bytes/sec.\nRequests: %d susceed, %d failed.\n",//输出总体统计数据 (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))//创建信号处理程序,设定程序运行时间 exit(3); alarm(benchtime); // after benchtime,then exit rlen=strlen(req); nexttry:while(1)//nexttry:c语言定位符,用于跳转...一般用的很少。 { if(timerexpired)//跳出条件,运行时间到了 { if(failed>0) { /* fprintf(stderr,"Correcting failed by signal\n"); */ failed--; } return; } s=Socket(host,port); if(s<0) { failed++;continue;} if(rlen!=write(s,req,rlen)) {failed++;close(s);continue;}//发送数据失败,直接关闭socket,重新连接 if(http10==0) if(shutdown(s,1)) { failed++;close(s);continue;}//关闭写端,SHUT_RD, SHUT_WR, SHUT_RDWR have the value 0, 1, 2,应该算是单方面关闭,服务器稍后就会关闭,TCP正常关闭 if(force==0) //强制读服务器数据 { /* 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; } } if(close(s)) {failed++;continue;}//关闭失败 speed++;//正常结束一次连接,完成数+1 } }
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