Re: [Boost-users] [thread] getting thread id number

Subject: Re: [Boost-users] [thread] getting thread id number
From: Hipatia (hipatia_370_at_[hidden])
Date: 2009-04-25 04:59:33

Actually I may have simplified my request too much. 
At first, I used to do what you propose me, that is, 
std::cout << "Thread id is: " << boost::this_thread::get_id();
But this command gives back the address of the 'thread_data' object rather
than the actual thread id number. Still, it is a good solution. 

But since I create several threads each one writing to the standard ouput, I
need a mutex-based function that centralizes all the writing: 
void writeout(std::string message);
(this function not only writes the thread's id number but also other
information)
So now I need the thread id converted into a string :(

Any suggestion?
Thanks,
Hipatia

Rush Manbert wrote:
> 
> 
> On Apr 24, 2009, at 11:47 AM, Hipatia wrote:
> 
>>
>> Hi!
>>
>> I'm trying to get the id number of a thread just to write it to the  
>> standard
>> output.
>>
>> Since I'm not an expert in c++ programming, let me explain what I do  
>> (even
>> if it's quite simple): a create an instance as follows,
>> boost::thread::id thread_id= boost::this_thread::get_id();
>> By debugging my code with Visual Studio, I see that 'thread_id' has an
>> 'unsigned int' object member called 'id', so I would like to display  
>> this
>> value.
>> Unfortunately, I cannot find in the boost documentation any function  
>> member
>> of boost::thread::id class that returns its value.
> 
> The id class defined operator<<, so just do this:
> 
> std::cout << "Thread id is: " << boost::this_thread::get_id();
> 
> I just did a replacement of a pthread implementation with a boost  
> thread implementation, and I needed to get the numeric value of the  
> data member, which I did like this (Thread::id_t is a typedef for  
> uint64_t):
> 
>    Thread::id_t getId() {
>      std::stringstream ios;
>      // This needs to be a pointer because on a *nix system,  
> this_thread::get_id()
>      // returns an object that defines operator<< to write the  
> pthread_t to the stream,
>      // and it's a pointer, so it gets formatted as hex and we can't  
> change that by
>      // inserting a dec manipulator. So when we read out of the  
> stream, we need to
>      // read into something for which a hex format makes sense.  
> Stupid. Just stupid.
>      void *numericId;
> 
>      ios << this_thread::get_id();
>      ios >> numericId;
>      // And, of course, static_cast can't be used to convert from  
> void* to the integer type.
>      return (Thread::id_t)numericId;
>   }
> 
> It's a hack, I know, but I couldn't think of anything else.
> 
> - Rush
> _______________________________________________
> Boost-users mailing list
> Boost-users_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/boost-users
> 
> 

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