Subj : Re: Challenge: Multithreading & Synchronization
To   : comp.programming.threads
From : Maciej Sobczak
Date : Sat May 21 2005 12:04 am

Uenal Mutlu wrote:

>>print("I'm doing something");
>>
>>Show me how you make it lockable. Forget about streams, cout, stdout or
>>any other object.
> 
> If you cannot assign a mutex to an object (funny imagination in MT app, btw)
> then use a wrapper + mutex for it. Like this one:
> mutex gm;
> void myprint(char* Apsz)
> {
>   Locker L(gm);
>   print(Apsz);
> }

Cool.

void f1()
{
     myprint("First name : Maciej");
     myprint("Family name: Sobczak");
     myprint("Profession : Programmer");
}

void f2()
{
     myprint("First name : Cody");
     myprint("Family name: Hacker");
     myprint("Profession : Programmer");
}

No luck, sorry. I run f1 and f2 in two threads and I got this:

First name : Cody
First name : Maciej
Family name: Sobczak
Profession : Programmer
Family name: Hacker
Profession : Programmer


>>>Time will prove you wrong.
>>
>>Time's already proved that I was wrong a few times in my life, so I'm ready.
> 
> Sorry to hear about this.

Don't worry about me. At least I learned how to recognize such 
situations and how to benefit from them.


>>>Using the "mutex per object" method gives you a simple and elegant solution:
>>
>>Except when there is no object? (see the print function above)
> 
> Everything is an object.

How do you achieve the "wait for something to be done"?

Example:
One thread moves some elements from one container to another. I want to 
know (in different thread) when it is done.


>>>Some people will argue that just 1 mutex would be sufficient. Let them think so.
>>>The above is the recommended method.
>>
>>Could you reference some books or articles recommending it?
> 
> I don't know if anybody else is recommending this method, but I for sure do it.
> Just do your own research --> google.

No need to google. It is enough to read one of your own previous posts 
to see the same code using only one mutex.

-- 
Maciej Sobczak : http://www.msobczak.com/
Programming    : http://www.msobczak.com/prog/

.