Programming with Rudiments using the listener class

The listener class provides methods for monitoring multiple file descriptors for activity.

Servers commonly need to listen on multiple sockets for client connections. They can listen on multiple inet sockets, multiple unix sockets, or a combination. Technically, they could listen on any set of file descriptors, whether they are all sockets or not. The listener class can be used to make this possible.

The following example creates both an inet socket server and a unix socket server, adds them to a listener, and waits for activity on either socket. When a socket becomes ready, the program checks which one it is and reports accordingly.

#include <rudiments/listener.h>
#include <rudiments/inetsocketserver.h>
#include <rudiments/unixsocketserver.h>
#include <rudiments/singlylinkedlist.h>
#include <rudiments/charstring.h>
#include <rudiments/stdio.h>

int main(int argc, const char **argv) {

	// create an inet socket server
	inetsocketserver	inetserver;
	if (!inetserver.listen(NULL,8002,15)) {
		stdoutput.write("failed to listen on port 8002\n");
		return 1;
	}
	stdoutput.write("listening on port 8002\n");


	// create a unix socket server
	unixsocketserver	unixserver;
	if (!unixserver.listen("/tmp/testlistener",0,15)) {
		stdoutput.write("failed to listen on /tmp/testlistener\n");
		return 1;
	}
	stdoutput.write("listening on /tmp/testlistener\n\n");


	// listen for connections on both sockets
	listener	lsnr;
	lsnr.addReadFileDescriptor(&inetserver);
	lsnr.addReadFileDescriptor(&unixserver);

	stdoutput.write("waiting for a connection "
			"on either socket...\n");

	// wait up to 10 seconds for activity
	int32_t	result=lsnr.listen(10,0);
	if (result>0) {

		// check which socket(s) are ready
		singlylinkedlist<filedescriptor *>	*readylist=
						lsnr.getReadReadyList();

		for (listnode<filedescriptor *>
				*node=readylist->getFirst();
				node; node=node->getNext()) {

			if (node->getValue()==
				(filedescriptor *)&inetserver) {
				stdoutput.write("inet socket is ready\n");
			}
			if (node->getValue()==
				(filedescriptor *)&unixserver) {
				stdoutput.write("unix socket is ready\n");
			}
		}

	} else if (result==RESULT_TIMEOUT) {
		stdoutput.write("timed out\n");
	} else {
		stdoutput.write("error\n");
	}


	// clean up
	inetserver.close();
	unixserver.close();
}