#include?
#include?“csapp.h“
#include?

//the?const?variable?below?are?requested?in?the?reference
static?const?char?*user_agent_hdr?=?“User-Agent:?Mozilla/5.0?（X11;?Linux?x86_64;?rv:10.0.3）?Gecko/20120305?Firefox/10.0.3\r\n“;
static?const?char?*connect_hdr?=?“Connection:?close\r\n“;
static?const?char?*proxy_hdr?=?“Proxy-Connection:?close\r\n“;

static?const?char?*connection_key?=?“Connection“;
static?const?char?*user_agent_key=?“User-Agent“;
static?const?char?*proxy_connection_key?=?“Proxy-Connection“;
static?const?char?*host_key?=?“Host“;

//the?micro?below?show?some?string?type?and?cache?size
#define?EOF_TYPE?1
#define?HOST_TYPE?2
#define?OTHER_TYPE?3
#define?MAX_CACHE_SIZE?1049000
#define?MAX_object_SIZE?102400
#define?CACHE_NUM?10

int?getType（char?*buf）;
void?doit（int?connfd）;
void?parseUri（char?uri[]char?hostname[]char?path[]char?port[]）;
void?build_http
（char?*server_httpchar?*hostnamechar*pathchar*?portrio_t?*clientrio）;
void*?thread（void?*vargp）;
void?initCache（）;
void?PreRead（int?index）;
void?afterRead（int?index）;
void?preWrite（int?index）;
void?afterWrite（int?index）;
int?findCache（char?*url）;
void?updateLRU（int?index）;
int?findSuitCache（）;
void?writeCacheContent（char?*urlchar*?buf）;

//the?struct?of?a?cacheLine?for?a?file
typedef?struct?
{
????char?content[MAX_object_SIZE];
????char?url[MAXLINE];
????int?time;
????int?isEmpty;
????int?readCount;
????int?writeCount;
????sem_t?mutex;
????sem_t?w;
}cacheunit;

//the?cache?struct?consist?of?ten?cacheLine
typedef?struct?
{
????cacheunit?cacheUnit[CACHE_NUM];
}Cache;

Cache?cache;
//record?the?overall?time?to?update?the?cacheline?time
int?allTime=0;
//the?flag?is?used?to?void?compete?of?“allTime“
sem_t?flag;
/*
the?main?function?to?connect?the?client??and?it?is?same?to?
the?code?in?the?page?672?of?textbook
*/

int?main（int?argcchar?**argv）
{
????int?listenfd*connfd;
????char?hostname[MAXLINE]port[MAXLINE];
????socklen_t?clientlen;
????struct??sockaddr_storage?clientaddr;
????pthread_t?tid;
????Signal（SIGPIPE?SIG_IGN）;
????Sem_init（&flag01）;
????//?the?cmd?parameters?fail
????if?（argc!=2）{
????????fprintf（stderr?“usage:?%s?\n“argv[0]）;
????????exit（1）;
????}
????initCache（）;
????listenfd=?open_listenfd（argv[1]）;
????while?（1）
????{
????????clientlen=sizeof（clientaddr）;
????????connfd=malloc（sizeof（int））;
????????*connfd=Accept（listenfd（SA*）&clientaddr&clientlen）;
????????Getnameinfo（（SA*）&clientaddrclientlenhostnameMAXLINE
????????????????????portMAXLINE0）;
????????printf（“Accepted?connection?from?（%s??%s）\n“hostnameport）;
????????Pthread_create（&tidNULLthread（void*）connfd）;
????}
}

//create?a?new?thread?to?run?for?servering?the?client
void?*thread（void?*vargo）
{
????int?connfd?=?*（（int?*）vargo）;
????Pthread_detach（pthread_self（））;
????free（vargo）;
????doit（connfd）;
????Close（connfd）;
????return?NULL;
}

//the?main?process?to?get?the?cmdparse?the?cmdfind?the?cache
//build?the?headerconnect?to?the?server?and?return?the?content?
//to?th