While I was programming a file receiver/sender , I was recommended not to use the select() function for reading active sockets, I was told to use event libraries such as libevent. I've read the documentation about those libraries and they use an event loop, what would you recomment to read and process active connections while gtkmm is in an idle status? Gtkmm also has a socket monitoring library, but I really don't like it. What do you recommend me to use?
Thanks in advance
Did you ask why you should not use a select? It's my understanding that select is one of the more standard approaches to monitoring streams in general (sockets included).
I was told that select has a poor performance on windows applications. I want to make the app for both linux and windows
> I was told that select has a poor performance on windows applications
Rather than being told everything, why not actually try some things and find out for yourself.
Instead of worrying how "efficiently" a function that waits for things to happen (like select) actually is.
You haven't written anything yet, but already you're premature optimising. It might be "poor" in relative terms (to other windows specific approaches), but in absolute terms for your actual program, it might not make a bean of difference.
> I want to make the app for both linux and windows
You've already sacrificed some performance by deciding to go for portability.
> What do you recommend me to use?
The thing between your ears.
Look at the options you have, make some choices, do some experiments.
So long as you have a half-decent design, then refactoring areas with poor performance (when you've got something to benchmark) will be relatively easy.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
If you're going for a multi-platform solution... I'd recommend wxWidgets to my own mother. It has the socket and event functionality you're looking for. And don't be fooled, wxWidgets applications may be console or GUI based. And yes, Windows' select is a poor hack-job that barely mimics the functionality of linux's, but it'll do, pig. It'll do.
Side note: it's not tough to make a simple program (such as a file sender/receiver) portable. You probably won't have to change more than a few socket calls and includes.
Bonus note!: If you're feeling adventurous and this program is more of a toy learning tool than a major project, you can always use #ifdefs and compiler options to make your program portable.
Code:#include <string.h> #include <stdlib.h> #include <unistd.h> #ifdef __WIN32__ #include <winsock.h> #else #include <sys/socket.h> #include <sys/types.h> #endif int foobar() { #ifdef __WIN32__ // LOL WSAStartup crap #endif }
I'll take a look at wxWidgets, but gtrkmm also works multi platform. My main doubt was how to imitate the select function in the main loop of gtkmm, but I think I know how.
How can I know when data is ready to be readen in a socket?
Thanks for everything
I'm not sure how it's done in gtrkmm, but wxWidgets works with a callback, rather than select, kind of like:Originally Posted by lautarox
Code:void MyClass::MyCallback(wxSocketEvent& e) { switch e.EventType() { case SOME_DEFINE_CONNECT: // Do connect stuff case SOME_DEFINE_DISCONNECT: // Do disconnect stuff case SOME_DEFINE_RECV // Do recv stuff default: } }
You may also want to look at glib, which I think is necessary for gtk, so you are already using it anyway:
IO Channels
That tish is perfect for use in event loops, it also uses callbacks -- eg, with g_io_add_watch(), you just set a function to fire when the socket has data waiting to read. It has additional functionality too, such as detecting when an error has occurred on the socket because the other end disappeared.
I replaced a good hundred or so lines of code involving multiple sockets, a forked server, and a polling function in a gtk+ app when I found that gio_add_watch() thing.
Last edited by MK27; 03-01-2010 at 08:22 PM.
C programming resources:
GNU C Function and Macro Index -- glibc reference manual
The C Book -- nice online learner guide
Current ISO draft standard
CCAN -- new CPAN like open source library repository
3 (different) GNU debugger tutorials: #1 -- #2 -- #3
cpwiki -- our wiki on sourceforge
Also the glib is portable. Do you recommend me to use the glib? I was worried about windows performance..
Gtk requires glib everywhere, inc. windows:
GTK+ - Download for Windows
Pretty sure that the event loop used in gtk is from glib, which has a ton of functionality if you start looking (inc the high level io stuff). I believe gtk and glib were both developed together years ago for GIMP.
C programming resources:
GNU C Function and Macro Index -- glibc reference manual
The C Book -- nice online learner guide
Current ISO draft standard
CCAN -- new CPAN like open source library repository
3 (different) GNU debugger tutorials: #1 -- #2 -- #3
cpwiki -- our wiki on sourceforge
Yeah, that's right, I've taken a look to the i/o monitoring functions Monitoring I/O I really don't know if it could handle much connections, but with 10 or 20 I think it will be ok. I think I'll use the monitoring function to receive the incoming data and the idle functions to send when there's nothing to do Idle Functions
