Main loop helper functions

[gamehack]

Hello all,

I've thought about having to implement 2 functions, say
enter_main_loop (func_name); and a function called quit_applicatio n();
which terminates the program. The enter_main_loop () can be defined as
something like:
int enter_main_loop (func_name)
{
while(1)
{
func_name();
}

return 0;
}

But then how am I going to implement the quit_applicatio n(); ? The only
way I thought it could be handled is changing enter_main_loop to
something like:
int terminate = 0;

int enter_main_loop (func_name)
{
if(!terminate)
func_name();

return 0;
}

and then quit_applicatio n(); can simply do
int quit_applicatio n()
{
return (terminate = 1);
}

What do you think about this approach? Any better ways of achieving the
same effect? I'm planning to use the quit_applicatio n() in a
multithreaded environment so I assume it should be thread-safe (but it
isn't now, is it)?

Thanks

[Vladimir S. Oka]

Re: Main loop helper functions

gamehack wrote:
[color=blue]
> Hello all,
>
> I've thought about having to implement 2 functions, say
> enter_main_loop (func_name); and a function called quit_applicatio n();
> which terminates the program. The enter_main_loop () can be defined as
> something like:
> int enter_main_loop (func_name)[/color]

This might as well be void enter_main_loop (...) as it never returns.
[color=blue]
> {
> while(1)
> {
> func_name();
> }
>[/color]

Making this redundant as well.
[color=blue]
> return 0;
> }
>
> But then how am I going to implement the quit_applicatio n(); ? The
> only way I thought it could be handled is changing enter_main_loop to
> something like:
> int terminate = 0;
>
> int enter_main_loop (func_name)
> {
> if(!terminate)
> func_name();
>
> return 0;
> }[/color]

This is not at all same as your first example, as it doesn't loop.
[color=blue]
>
> and then quit_applicatio n(); can simply do
> int quit_applicatio n()
> {
> return (terminate = 1);
> }[/color]

Where would you call this from (and why)?
[color=blue]
>
> What do you think about this approach? Any better ways of achieving
> the same effect? I'm planning to use the quit_applicatio n() in a
> multithreaded environment so I assume it should be thread-safe (but it
> isn't now, is it)?[/color]

I think you're on more-or-less right track. Could this be what you want:

#include <stdlib.h>

#define QUIT_LOOPIN (1)
#define KEEP_LOOPIN !(QUIT_LOOPIN)

int func_name(/* whatever */);
int quit_applicatio n(/* whatever */);
void enter_main_loop (/* whatever */);

int main(void)
{
enter_main_loop (/* whatever */);

return quit_applicatio n(/* whatever */);
}

void enter_main_loop (/* whatever */)
{
while (1)
{
if (QUIT_LOOPIN == func_name()) return;
}
}

int func_name(/* whatever */)
{
int time_to_quit = KEEP_LOOPIN;

/* do stuff possibly changing time_to_quit value */

return time_to_quit;
}

int quit_applicatio n(/* whatever */)
{
int success = EXIT_SUCCESS;

/* do cleanup stuff possibly setting success = EXIT_FAILURE */

return success;
}

Cheers

Vladimir

--
In Seattle, Washington, it is illegal to carry a concealed weapon that
is over six feet in length.

[gamehack]

Re: Main loop helper functions


Vladimir S. Oka wrote:[color=blue]
> gamehack wrote:
>[color=green]
> > Hello all,
> >
> > I've thought about having to implement 2 functions, say
> > enter_main_loop (func_name); and a function called quit_applicatio n();
> > which terminates the program. The enter_main_loop () can be defined as
> > something like:
> > int enter_main_loop (func_name)[/color]
>
> This might as well be void enter_main_loop (...) as it never returns.
>[color=green]
> > {
> > while(1)
> > {
> > func_name();
> > }
> >[/color]
>
> Making this redundant as well.
>[color=green]
> > return 0;
> > }
> >
> > But then how am I going to implement the quit_applicatio n(); ? The
> > only way I thought it could be handled is changing enter_main_loop to
> > something like:
> > int terminate = 0;
> >
> > int enter_main_loop (func_name)
> > {
> > if(!terminate)
> > func_name();
> >
> > return 0;
> > }[/color]
>
> This is not at all same as your first example, as it doesn't loop.
>[color=green]
> >
> > and then quit_applicatio n(); can simply do
> > int quit_applicatio n()
> > {
> > return (terminate = 1);
> > }[/color]
>
> Where would you call this from (and why)?
>[color=green]
> >
> > What do you think about this approach? Any better ways of achieving
> > the same effect? I'm planning to use the quit_applicatio n() in a
> > multithreaded environment so I assume it should be thread-safe (but it
> > isn't now, is it)?[/color]
>
> I think you're on more-or-less right track. Could this be what you want:
>
> #include <stdlib.h>
>
> #define QUIT_LOOPIN (1)
> #define KEEP_LOOPIN !(QUIT_LOOPIN)
>
> int func_name(/* whatever */);
> int quit_applicatio n(/* whatever */);
> void enter_main_loop (/* whatever */);
>
> int main(void)
> {
> enter_main_loop (/* whatever */);
>
> return quit_applicatio n(/* whatever */);
> }
>
> void enter_main_loop (/* whatever */)
> {
> while (1)
> {
> if (QUIT_LOOPIN == func_name()) return;
> }
> }
>
> int func_name(/* whatever */)
> {
> int time_to_quit = KEEP_LOOPIN;
>
> /* do stuff possibly changing time_to_quit value */
>
> return time_to_quit;
> }
>
> int quit_applicatio n(/* whatever */)
> {
> int success = EXIT_SUCCESS;
>
> /* do cleanup stuff possibly setting success = EXIT_FAILURE */
>
> return success;
> }
>
> Cheers
>
> Vladimir
>
> --
> In Seattle, Washington, it is illegal to carry a concealed weapon that
> is over six feet in length.[/color]

This is what I meant:

int func_name();
void enter_main_loop (func_name);
void quit_main_loop( void);

int terminate = 0;

void enter_main_loop (func_name)
{
while(1)
{
if(terminate != 0)
return;
else
{
func_name();
}
}
}


void quit_main_loop( void)
{
terminate = 1;
}

and then in main.c:

int main(int argc, char* argv[])
{
enter_main_loop (func_name);

return 0;
}

The only problem I can see is that func_name() can hold the termination
if it is synchronous. The func_name() function will be responsible for
making async calls(implement ed with threads) to other sync functions
which operate on a call queue so I can call quit_main_loop( ); from
anywhere and it will terminate the program without waiting for some
function to finish doing its work.

Thanks

[Vladimir S. Oka]

Re: Main loop helper functions

gamehack wrote:
[color=blue]
>
> Vladimir S. Oka wrote:[color=green]
>> gamehack wrote:
>>[color=darkred]
>> > Hello all,[/color][/color][/color]

<snip OP's first code snippet>
[color=blue][color=green][color=darkred]
>> >
>> > What do you think about this approach? Any better ways of achieving
>> > the same effect? I'm planning to use the quit_applicatio n() in a
>> > multithreaded environment so I assume it should be thread-safe (but
>> > it isn't now, is it)?[/color]
>>
>> I think you're on more-or-less right track. Could this be what you
>> want:
>>
>> #include <stdlib.h>
>>
>> #define QUIT_LOOPIN (1)
>> #define KEEP_LOOPIN !(QUIT_LOOPIN)
>>
>> int func_name(/* whatever */);
>> int quit_applicatio n(/* whatever */);
>> void enter_main_loop (/* whatever */);
>>
>> int main(void)
>> {
>> enter_main_loop (/* whatever */);
>>
>> return quit_applicatio n(/* whatever */);
>> }
>>
>> void enter_main_loop (/* whatever */)
>> {
>> while (1)
>> {
>> if (QUIT_LOOPIN == func_name()) return;
>> }
>> }
>>
>> int func_name(/* whatever */)
>> {
>> int time_to_quit = KEEP_LOOPIN;
>>
>> /* do stuff possibly changing time_to_quit value */
>>
>> return time_to_quit;
>> }
>>
>> int quit_applicatio n(/* whatever */)
>> {
>> int success = EXIT_SUCCESS;
>>
>> /* do cleanup stuff possibly setting success = EXIT_FAILURE */
>>
>> return success;
>> }
>>
>> Cheers
>>
>> Vladimir
>>
>> --
>> In Seattle, Washington, it is illegal to carry a concealed weapon
>> that is over six feet in length.[/color]
>
> This is what I meant:
>
> int func_name();
> void enter_main_loop (func_name);
> void quit_main_loop( void);
>
> int terminate = 0;
>
> void enter_main_loop (func_name)
> {
> while(1)
> {
> if(terminate != 0)
> return;
> else
> {
> func_name();
> }
> }
> }
>
>
> void quit_main_loop( void)
> {
> terminate = 1;
> }
>
> and then in main.c:
>
> int main(int argc, char* argv[])
> {
> enter_main_loop (func_name);
>
> return 0;
> }
>
> The only problem I can see is that func_name() can hold the
> termination if it is synchronous. The func_name() function will be
> responsible for making async calls(implement ed with threads) to other
> sync functions which operate on a call queue so I can call
> quit_main_loop( ); from anywhere and it will terminate the program
> without waiting for some function to finish doing its work.[/color]

You never call quit_main_loop( ) so your loop never ends.

If you're thinking of multi-threaded execution that is not supported by
Standard C, and is hence off topic here.

In my code above, you could call quit_main_loop( ) from func_name() to
determine whether it's time to quit. I misunderstood that
quit_applicatio n() does pre-exit clean-up.

Cheers

Vladimir

[Herbert Rosenau]

Re: Main loop helper functions

On Sat, 28 Jan 2006 16:09:16 UTC, "gamehack" <gamehack@gmail .com>
wrote:
[color=blue]
> This is what I meant:
>
> int func_name();
> void enter_main_loop (func_name);
> void quit_main_loop( void);[/color]

volatile int terminate = 0; /* thread save */[color=blue]
>
> void enter_main_loop (func_name)
> {
> while(!terminat e)
> {
> func_name();
> }
> }
>
>
> void quit_main_loop( void)
> {
> terminate = 1;
> }
>
> and then in main.c:
>
> int main(int argc, char* argv[])
> {
> enter_main_loop (func_name);
>
> return 0;
> }
>
> The only problem I can see is that func_name() can hold the termination
> if it is synchronous. The func_name() function will be responsible for
> making async calls(implement ed with threads) to other sync functions
> which operate on a call queue so I can call quit_main_loop( ); from
> anywhere and it will terminate the program without waiting for some
> function to finish doing its work.
>
> Thanks
>[/color]

For your problem the standard defines volatile - even C knows nothing
about threads.
So whenever a thread needs to quit the whole app it will change
terminate to not be 0 (it is on quit_main_loop to determine that all
threads are ready to let main (and themrself die.

--
Tschau/Bye
Herbert

Visit http://www.ecomstation.de the home of german eComStation
eComStation 1.2 Deutsch ist da!

[Malcolm]

Re: Main loop helper functions


"gamehack" <gamehack@gmail .com> wrote[color=blue]
> I've thought about having to implement 2 functions, say
> enter_main_loop (func_name); and a function called quit_applicatio n();
> which terminates the program. The enter_main_loop () can be defined as
> something like:
> int enter_main_loop (func_name)
> {
> while(1)
> {
> func_name();
> }
>
> return 0;
> }
>
> But then how am I going to implement the quit_applicatio n(); ? The only
> way I thought it could be handled is changing enter_main_loop to
> something like:
> int terminate = 0;
>
> int enter_main_loop (func_name)
> {
> if(!terminate)
> func_name();
>
> return 0;
> }
>
> and then quit_applicatio n(); can simply do
> int quit_applicatio n()
> {
> return (terminate = 1);
> }
>
> What do you think about this approach? Any better ways of achieving the
> same effect? I'm planning to use the quit_applicatio n() in a
> multithreaded environment so I assume it should be thread-safe (but it
> isn't now, is it)?
>[/color]
Use setjmp() and lngjmp().

Otherwise there is no option than to make every function in your program
return a "terminate" flag.

[Vladimir S. Oka]

Re: Main loop helper functions

Malcolm wrote:
[color=blue]
>
> "gamehack" <gamehack@gmail .com> wrote[color=green]
>> What do you think about this approach? Any better ways of achieving
>> the same effect? I'm planning to use the quit_applicatio n() in a
>> multithreaded environment so I assume it should be thread-safe (but
>> it isn't now, is it)?
>>[/color]
> Use setjmp() and lngjmp().
>
> Otherwise there is no option than to make every function in your
> program return a "terminate" flag.[/color]

<OT>
I don't think setjmp() and lngjmp() are thread safe either. I don't
think they're very safe/good practice either, threads or no threads.
</OT>

--
A classic is something that everybody wants to have read and nobody
wants to read.
-- Mark Twain