C++ multithreaded server

newdarkness · 06-21-2005, 12:31 AM

Hello, I just started C++ and I need a multitthreaded server which broadcasts all messages by clients to every other client.

The piece of crap I came up with looks like this - and shows lots of errors, so I'm pretty sure its totally wrong - i just dont know Whats wrong.

Code:

#include "ServerSocket.h"
#include "SocketException.h"
#include <string>
#include <iostream>

int main ( int argc, int argv[] )
{

  std::cout << "running....\n";

  try
    {
      while ( true )
	{

	  connection::open();

	  try
	    {
	      while ( true )
		{
		  std::string data;
		  new_sock >> data;
		  broadcast(data);
		}
	    }
	  catch ( SocketException& ) {}

	}
    }
  catch ( SocketException& e )
    {
    std::cout << "Exception was caught:" << e.description() << "\nExiting.\n";
    }

  return 0;
};

struct connection
{
ServerSocket server(3000);
ServerSocket socket[100];
bool i[100];


int reserve()
	{
	for(int iid=0;iid < 100;iid++)
		{
		if(!i[iid])
			{
			i[iid] = true;
			return iid;
			}
		}
	};

bool broadcast(std::string data)
	{
	for(bool iid=0;iid < 100;iid++)
		{
		if(i[iid])
			{
			socket[iid] << data;
			}
		}
	return true;
	};


bool open()
	{
	int iid=reserve();
	server.accept (socket[iid]);

	try
		{
		while ( true )
			{
			std::string data;
			socket[iid] >> data;
			broadcast(data);
			}
 	   	}
		catch ( SocketException& ) {}

	release(iid);
	return true;
	};

bool release(int iid)
	{
	i[iid] = false;
	return true;
	};
};

redhead · 06-21-2005, 01:23 AM

Code:

...
struct connection
{
    ServerSocket ...

Don't you mean

Code:

...
class connection
{
    ServerSocket ...

Code:

...
connection::open();
...

This is not the proper way of doing an open() call to a connection.

Code:

connection connect(3000);
// or
connection connect();
connect->open();
// or 
connect.open();

might be a better aproach, depending on, how you want to dereference your classes.
And in order to have it multithreaded, you need to use some sort of threadding.. One capturing the initial request, which spawns a child process, per clientrequest, doing all the communication with the caller and broadcasting to the clients.
So your codepart

Code:

...
while ( true )
{
    std::string data;
    new_sock >> data;
    spawn_child_broadcast(data);
...

And among others theres alot of syntactical errors, for instance

Code:

...
for(bool iid=0;iid < 100;iid++)

You can't store a value in a bool variabel, it either is true (1, 2, 3, 4, 5 ....) or false (0), it dosn't have a storage facility where you can do calculations on it, for that theres int, double, float, etc.

And why do you do an infinite loop in your open() function, when your main function want's to do one aswell..

Code:

...
ServerSocket server(3000);
...
server.accept (socket[iid]);
...

What does your ServerSocket class look like ??
What book are you learning this from ?
I see alot of loop through alot of sockets, but basicaly, your code isn't much of a multithreaddet solution.

DJMaze · 06-21-2005, 03:16 AM

For broadcasting i don't think a multitthreaded server is a good way.
For example 2 people broadcast a message and the server opens 2 threads to send to the clients. Then they could cought up by both sending a message to 1 person and the client will choke or shows 2 popups rapidly fast.

In my opinion the server should have a thread safe queue list for all recieved message.
(recieve message multithreaded, but don't send them at the same time)
And another process/timer sends the queued messages all at once or one at a time.
If it's used on high traffic networks you should send all messages at once to the client.

newdarkness · 06-22-2005, 01:28 AM

@redhead
I dont really have a book, what I tried to do is to have two loops, one for new connections and one for the connection state itself. - I probably screwed it all up anyways

...
@DJMaze:
I want a chat server, where everyone can send a message which is then broadcasted to every client.

DJMaze · 06-22-2005, 04:44 AM

If you want a chat server maybe check-out some ircd's their sources ?
http://directory.google.com/Top/Comp...vers/Chat/IRC/

newdarkness · 06-23-2005, 12:59 AM

I just want it really simple - client connects, each message ist broadcasted to all connected clients..

Valmont · 06-23-2005, 05:34 AM

Lots of errors newdarkness. I didn't bother to run it.

My proposal is to move up with your C++ skills without sockets first. For example you have to forward declare classes or structs before you can use them the way you do.

After practicing with C++ go to:
http://www.linuxgazette.com/issue74/tougher.html
For a decent intro.

newdarkness · 06-23-2005, 08:13 AM

Lol - for some reason the code there is exactly the one I started with- yeah, probably I gotta learn some more C++ before I get it to run multithreaded