How to make a function thread safe in mc++?

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BartMan - 15 Jul 2005 16:20 GMT

Greetings,

I was looking at the C#'s "lock()" statement, and I was wondering if there
was an equivalent or recommended way of doing this in MC++.

I have a thread which I am calling a function from mc++, and I was wondering
what
the recommended ways of making it thread safe within the mc++ world.

Thanks in advance for any suggestions.

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BartMan - 15 Jul 2005 16:31 GMT

Right after I made the post I stumbled accross something that I could use for
thread safety, so I thought I would post in case someone else needs it for a
solution.

Solution:
void Foo()
{
// At the beginning of your function.
System::Threading::Monitor::Enter(this);

... Do some code work

// Add the end of your function (this has to be called)
System::Threading::Monitor::Exit(this);
}

> Greetings,
>
[quoted text clipped - 6 lines]
>
> Thanks in advance for any suggestions.

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Carl Daniel [VC++ MVP] - 15 Jul 2005 16:37 GMT

> Right after I made the post I stumbled accross something that I could
> use for thread safety, so I thought I would post in case someone else
[quoted text clipped - 11 lines]
> System::Threading::Monitor::Exit(this);
> }

That's precisely what the C# 'lock' construct does.

-cd

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Jochen Kalmbach [MVP] - 15 Jul 2005 19:16 GMT

Hi Carl!

>>Right after I made the post I stumbled accross something that I could
>>use for thread safety, so I thought I would post in case someone else
[quoted text clipped - 13 lines]
>
> That's precisely what the C# 'lock' construct does.

Almost... the C# also does an try-finally construct..

System::Threading::Monitor::Enter(this);
__try
{
// Do some code work
}
__finally
{
System::Threading::Monitor::Exit(this);
}

Signature

Greetings
Jochen

My blog about Win32 and .NET
http://blog.kalmbachnet.de/

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Nemanja Trifunovic - 15 Jul 2005 16:52 GMT

I think it would be pretty easy to wrap this into a RAII __nogc class
with a little help from gcroot.

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BartMan - 15 Jul 2005 18:16 GMT

Hello Nemanja,

Thanks for the great idea, I didn't know about gcroot which is really
usefull. :)
Here is my attempt.

public __gc class lock
{
public:
lock(System::Object* obj)
{
threadObject = obj;
System::Threading::Monitor::Enter(threadObject);
}
~lock()
{
System::Threading::Monitor::Exit(threadObject);
}
protected:
gcroot<System::Object*> threadObject;
};

> I think it would be pretty easy to wrap this into a RAII __nogc class
> with a little help from gcroot.

Reply to this Message

Nemanja Trifunovic - 15 Jul 2005 18:30 GMT

I hope you mean __nogc lock.

__gc classes don't have deterministic destructors. Take a look at an
article I wrote a while ago on the topic:

http://www.codeproject.com/managedcpp/managedraii.asp

Reply to this Message

BartMan - 15 Jul 2005 18:55 GMT

Oops, you are right.
Very good article, thanks for the post!

> I hope you mean __nogc lock.
>
> __gc classes don't have deterministic destructors. Take a look at an
> article I wrote a while ago on the topic:
>
> http://www.codeproject.com/managedcpp/managedraii.asp

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How to make a function thread safe in mc++?

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