Pthreads and signals

[janaki]

i have a main thread which should have 3 different threads
receive thread - which receives data using sockets
process thread - process the receive data
display thread - display it on gui

thing is when some message is received then i shud send pthread_kill to my process thread then only it shud process the message

i don' t have an idea of pthreads and signals in c++
and i was told to use c++ calls only

i have written the program like this

and am getting segmentation fault
can any body suggest me how to solve and continue this

@
#include<iostream>
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include "structures.h"
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <arpa/inet.h>

#include <fcntl.h>
#include <signal.h>
#include <check.h>

#define MAX_DATA_SIZE 512

using namespace std;

pthread_t receive_thread,process_thread;

void sig_handler(int sig)
{
cout<<"caught signal"<<sig<<endl;
}
void *receive_data(void *)
{

cout<<"Receive thread is running"<<endl;
pthread_kill(process_thread,SIGUSR1);

return 0;
}
void process_data(void)
{

cout<<"process thread is running"<<endl;

struct sigaction sa;
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
sa.sa_handler = sig_handler;
sigaction(SIGUSR1,&sa,NULL);

pthread_exit(0);
return 0;
}
int main(void)
{
int receive_status,process_status;

receive_status=pthread_create(&receive_thread,NULL,receive_data,NULL); // Create Thread
pthread_join(receive_thread,NULL); // Parent waits for

process_status = pthread_create (&process_thread,NULL,process_data,NULL);
//pthread_join(process_thread,NULL);

return 0;
}

@

[Sanchir Kartiev]

Can you use std::thread?

[janaki]

thank u sir
actually am joining my first thread
so i got that error
my error is solved but when second time when a msg is received am not getting caught signal output
my original code is as follows:
@

#include<iostream>

#include <stdio.h>

#include <stdlib.h>
#include <pthread.h>
#include "structures.h"
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <signal.h>
#include <check.h>

#define MAX_DATA_SIZE 512
using namespace std;

struct Message
{
int message_id;
};

struct Message msg;

pthread_t p;

void * r_data(void *);
void * p_data(void *);

static void usr1_handler(int signo);

int main()
{
pthread_t r;
sigset_t sigmask;
struct sigaction action;
sigfillset(&sigmask);
pthread_sigmask(SIG_BLOCK, &sigmask,(sigset_t *)0);
action.sa_flags = 0;
action.sa_handler = usr1_handler;
sigaction(SIGUSR1, &action, (struct sigaction *)0);
pthread_create(&r,NULL,r_data,NULL);
//
pthread_create(&p,NULL,p_data,NULL);
struct sigaction action;
action.sa_flags = 0;
action.sa_handler = usr1_handler;
sigaction(SIGUSR1, &action, (struct sigaction *)0);
//pthread_join(r,NULL);
//pthread_join(p,NULL);

cout<<"main program"<<endl;
pthread_exit((void *)NULL);
return 0;
}

void *r_data(void *)
{
cout<<"first thread"<<endl;
printf("Hello\n");
int fd;
printf("Hello2\n");
struct sockaddr_in servaddr, cliaddr;
// void **status;
fd = socket(AF_INET,SOCK_DGRAM,0);
printf("Hello3\n");
if(fd <0)
cout<<"Socket creation Failed"<<endl;
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = inet_addr("10.66.48.11"); //server ip addr
// servaddr.sin_addr.s_addr = inet_addr("127.0.0.1"); //server ip addr
servaddr.sin_port = htons(12007); //server poet no.
printf("Hello4\n");
if(bind(fd,(const struct sockaddr *)&servaddr,sizeof(servaddr))<0)
cout<<"BIND FAILED"<<endl;

unsigned char buffer[MAX_DATA_SIZE];
socklen_t len=sizeof(cliaddr);
fcntl(fd,F_SETFL,O_NONBLOCK);
printf("Hello5\n");
for(;;)
{
sleep(3);
int n= recvfrom(fd,buffer,sizeof(buffer),0,(struct sockaddr *)&cliaddr,&len);
memcpy(&msg,buffer,sizeof(msg));
printf("Hello7\n");
cout<<"Received : bytes"<<n<<" "<<msg.message_id<<endl;
if(msg.message_id!=0)
{
pthread_kill(p, SIGUSR1);
}
}

pthread_exit((void *)NULL);
}

void p_data(void)
{
int sig;
sigset_t sigmask;
sigemptyset(&sigmask);
sigaddset(&sigmask, SIGUSR1);
pthread_sigmask(SIG_UNBLOCK, &sigmask, (sigset_t *)0);
sigwait(&sigmask, &sig);
switch(sig)
{
case SIGUSR1:
usr1_handler(sig);
break;
default:
break;
}
}

void usr1_handler(int sig)
{
cout<<"caught signal"<<endl;
}

pleas tell me how to resolve it