A crazy noob has just created a new but uncompleted tutorial and put it on the Wiki, it's your objective to clean it and refine it. So others members can use it and not get confused.

Objectives:

- Orthography
- Typos
- Expressions

START
OPTIONS
CREDITS
EXIT

Published by: UBISOFT™         A game by: AMCerasoli™

When the Wiki read your sign, said NO WAY BODY!

Oh, thanks gnolam, I didn't know anything about initialization list, well I think was obvious hohohoho.

Anyway I have changed it:

I think now it's fine.

and what for it's the {} at the end now?

@weapon_S I can't manage to explain better the example, how would you explain it? write it here, and I'll post it. Only that part that you said.

{"name":"604195","src":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/9\/9\/99e8f31cf663c1df6d02aa0e3ba52274.png","w":343,"h":623,"tn":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/9\/9\/99e8f31cf663c1df6d02aa0e3ba52274"}

Or have a separate init method that can return a failure.

Didn't I read somewhere or other today about the evils that beset video bitmaps and threads?

You shouldn't touch a GL/DX context from more than one thread at a time. Bad things can, and WILL happen.

I'll update the tut when I get the time. all this thing about threads it's incredible.

Edit:
I have uploaded the weapon_S tut.

Why are you using those // and _ _ like if you were writting on allegro.cc? On the Wiki that doesn't work.

ok we have some questions:

1 - A thread is like a program running separately. Separately means you have no idea how far it has run, and neither do they know about each others globals?.

2 -thread_1 is allocated. Don't forget to deallocate it afterwards. Shouldn't you check it's its value?

Neither al_start_thread and al_create_thread returns a value so how could I check it?

3 - The thread will be running the function Func_thread and getting the pointer *data as its argument when it starts. (Or only after it started it head hurts)

To be honest I don't understand the question.

4 - al_wait_cond takes a locked mutex as an argument???

On entering this function, mutex must be locked by the calling thread. The function will atomically release mutex and block on cond. That is what the manual says, I don't know if you was referring to another thing.

5 - In what order are you discussing the file? In what order was I discussing the file? I already discussed this???

When I said "Everything until here should be already clear" I was referring to the rest of the code the initialization of allegro, mouse etc, I guess I can remove it, though.

Here:

al_lock_mutex(data.mutex);
   while (!data.ready){
 
      al_wait_cond(data.cond, data.mutex);
 
   }
   al_unlock_mutex(data.mutex);

Instead of a while can't we use an if?

PS: the

<code></code>

tags shows the letters too small, can't be increased?

I thought // , ** and __ were called "wiki-markup"

1. Woops, my bad. I was confused for a second. It is a very bad idea to use globals to communicate between threads, it is however not impossible.

2. What he ^ said.

3. When it starts. (?) I can't remember asking that. Should be obvious. Or you could say that when it starts and after it starts are indistinguishable, because in neither cases any code has run.

4. Yes, I was referring to the manual. So, maybe expand that to "a mutex which is locked". I think it is very vital to understand such details.

5. Haven't looked yet at the new version. Removal sounds good.

I read somewhere that threads shouldn't be called "parents" or "child" I can't remember where, though. In the tutorial we're using those terms, should I keep it?.

Edit:

I have another question... why is useful a cond? if for example I have

al_lock_mutex(data.mutex);
while(!data.ready){}
al_unlock_mutex(data.mutex);

and that's it? that would wait until ready is... ready.

It would never release the mutex. It would sit in there forever blocking the other threads that want the mutex in order to change the variable.

When you wait on a condition variable, it essentially goes like:

1. lock mutex

2. check variable, if ready go to step 6

3. unlock mutex

4. wait on condition

5. repeat

6. unlock mutex

Ohhhh it's true... , know I think I understand it very well... al_wait_cond() unlock the mutex and block on the cond (the same that the manua says, I couldn't understand it the first time I read it ). I'm thinking in many threads using the same data, it's a good idea having just one cond and many flag to check if all the threads have done their job? something like:

al_lock_mutex(data.mutex);
while(!data.flag1 || !data.flag2 || !data.flag3){

al_wait_cond(cond, mutex);

}
al_unlock_mutex(data.mutex);

I don't need more conds right?

Edit: I have another question... What is the point of having multiple threads if I can't use them to load bitmaps, fonts since they're loaded as memory bitmaps? I guess I have no problem by loading sound on another thread right?

I have another question: If the object that I sent to the thread has a function, when I call the function from the main thread do I need to lock the mutex too?

data.cout_this("Hello Thread");

Yes it's possible, if someone wants more info read this: http://www.thinkingparallel.com/2006/10/15/a-short-guide-to-mastering-thread-safety/

BTW I didn't know that rand() wasn't thread-safe...

Yhea it's done... Someone has some ideas to create another simple one? I thought in one which multiple threads load a lot of images and make the comparison between using or not threads... But I don't want to load all those images to the wiki, I was thinking if there would be another idea like that, which shows the difference between multi-thread and just one thread very clear.