/*

* A thread-safe version of echo that counts the total number

* of bytes received from clients.

*/

/* $begin echo_cnt */

#include "csapp.h"

static int byte_cnt; /* Byte counter */

static sem_t mutex; /* and the mutex that protects it */

static void init_echo_cnt(void)

{

Sem_init(&mutex, 0, 1);

byte_cnt = 0;

}

void echo_cnt(int connfd)

{

int n;

char buf[MAXLINE];

rio_t rio;

static pthread_once_t once = PTHREAD_ONCE_INIT;

Pthread_once(&once, init_echo_cnt); //line:conc:pre:pthreadonce

Rio_readinitb(&rio, connfd); //line:conc:pre:rioinitb

while((n = Rio_readlineb(&rio, buf, MAXLINE)) != 0) {

P(&mutex);

byte_cnt += n; //line:conc:pre:cntaccess1

printf("server received %d (%d total) bytes on fd %d\n",

n, byte_cnt, connfd); //line:conc:pre:cntaccess2

V(&mutex);

Rio_writen(connfd, buf, n);

}

}

/* $end echo_cnt */