Programming

#include <stdio.h>
#include <pthread.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <strings.h>
#include <stdlib.h>
#include <unistd.h>

#define BUFFERSIZE	512
#define NTHREADS	10
#define SERVER_PORT 6001
#define POOL_SIZE 5

void *main_client_thread(void *arg);

typedef struct mainthreadArg
{
	int csocketId;
	int threadCounter;
}mtArg;

int main(int argc, char** argv)
{
	int csock, ssock;
	socklen_t addr_len;
	pthread_t cthread[NTHREADS];
	
	struct sockaddr_in addr;
	bzero((void *)&addr, sizeof(addr));
	addr.sin_family = AF_INET;
	addr.sin_port = htons(SERVER_PORT);
	addr.sin_addr.s_addr = htonl(INADDR_ANY);
	addr_len = sizeof(addr);
	
	/* socket */
	if((ssock=socket(PF_INET, SOCK_STREAM, 0))==-1)
	{
		fprintf(stderr,"Unable to create server socket\n");
		exit(1);
	}
	
	/* bind */
	if(bind(ssock, (struct sockaddr *)&addr, sizeof(addr))==-1)
	{
		fprintf(stderr,"bind failed.\n");
		exit(1);
	}

	
	/* listen */
	if(listen(ssock, POOL_SIZE)==-1)
	{
		fprintf(stderr, "listen failed.\n");
		exit(1);
	}
	
	mtArg ta;
	ta.threadCounter = 0;   /* thread counter */
	
	/* main loop to manage clients */
	while(1)
	{
		if(ta.threadCounter > NTHREADS)
		{
			printf("No more threads can be created. Sorry\n");
			exit(1);
		}
		
		/* accept */
		if((csock=accept(ssock, (struct sockaddr *)&addr, &addr_len))==-1)
		{
			fprintf(stderr, "accept failed.\n");
			exit(1);
		}

		ta.csocketId = csock;
		if((pthread_create(&cthread[ta.threadCounter], NULL, main_client_thread, &ta)) != 0)
		{
			fprintf(stdout, "pthread was not created\n");
			exit(0);
		}
		ta.threadCounter++;
	}
	
	return 0;
}

void *main_client_thread(void *arg)
{
	mtArg t = *(mtArg *)arg;
	int cli,cnt;
	cli = t.csocketId;
	cnt = t.threadCounter;
	
	int stayConnected = 1;
	int nread;
	/* int nwrite; */
	char buffer[BUFFERSIZE];
	
	while(stayConnected == 1)
	{
		bzero(buffer, sizeof(buffer));
		if((nread=read(cli, buffer, BUFFERSIZE)) > 0)
		{
			printf("Thread %d read %d bytes from client.\n", t.threadCounter, nread);
			printf("Thread %d buffer=%s\n", t.threadCounter, buffer);
		}
		else  /* client disconnected */
		{
			printf("nread failed.\n");
			t.threadCounter--;
			/* report back to main thread so that thread counter is decremented */
                        /* use pipe or message queue for this */
			stayConnected = 0;
		}
	}
	return NULL;
}

sem_t sem;

void main_thread(void)
{
        sem_init(&sem, 0, 5); // Create sem with value of 5
        while(1)
        {
                sem_wait(&sem); // If sem goes below 5, main will wait until something else adds
                if(!running) break;
                launch_thread(threadfunc);
        }
}

void threadfunc(void)
{
        while(1)
        {
                do_stuff;
                if(!running) break;
        }

        sem_post(&sem); // add 1 to sem
}