Help with simple C chat + Kqueue

[James889]

Hello,

I'm writing a very simple server/client chat. At the moment i have no way of determining when data arrives in the receive buffer.

This is how the send/receive part of the chat currently looks like:

.
.
.
for(;;){

fgets(sendbuffer,sizeof sendbuf,stdin);

    send(acceptfd,sendbuffer,sizeof sendbuffer,0);

         recv(socketfd,recvbuff,sizeof recvbuff,0);
printf("%s",recvbuff);

}

This is very primitive, i would like to use kqueue() to decide when data is available on the listening socket. So i looked at a few examples of how to use kqueue but i didn't get it working properly. This is what i tried..

struct kevent events;
struct kevent changes;

int new_event;

EV_SET(&changes,sockfd,EVFILT_READ,EV_ADD | EV_ENABLE,0,0,0);

for(;;){

new_event = kevent(kq,&changes,1,&events,1,NULL);  

if(events.flags & EVFILT_READ){
// call recv..
}

else ...
//call fgets and send 
}

unfortunately this didn't work out very well, i still have to press return for reading and printing data from the buffer.

Any suggestions?

 

[nilesh_pat]

Thanks!</code>There are a few things that you need to do in order to get your kqueue code to work properly. First, you need to create the kqueue object with the kqueue() system call. Second, you need to register the socket descriptor with the kqueue() system call. This is done with the EV_SET macro, which is what you have done in your code. Third, you need to use the kevent() system call to wait for events to happen on the registered descriptors. This will return an array of events that have happened. Finally, you need to handle the events that have been triggered. You can do this by checking the flags field of the kevent structure. For example, if you are waiting for socket events, you can check the flags field for EVFILT_READ and EVFILT_WRITE. If the flag is set for EVFILT_READ, then you can read the data from the socket. Similarly, if the flag is set for EVFILT_WRITE, then you can write data to the socket. I hope this helps!