Re: [boost] [thread] A few submissions

Subject: Re: [boost] [thread] A few submissions
From: Stefan Strasser (strasser_at_[hidden])
Date: 2010-07-04 16:58:17

Zitat von Andrey Semashev <andrey.semashev_at_[hidden]>:

>> a better implementation of the existing thread_specific_ptr interface
>> can be almost as efficient as static_thread_specific_ptr. there is one
>> additional indirection (two in the prototype implementation), but it is
>> just as efficient as thread_local otherwise.
>
> How do you work around the problem with delay loaded dlls?

I don't.
I suppose platforms that have that problem can be supported by hiding  
the TLS vector behind a function call, or if the platform doesn't  
support global TLS but supports TLS that is local to the DLL the  
pointer to the TLS vector could be obtained under a mutex lock for  
each module. note that this implementation only uses one TLS variable.
if it can't be supported you'd have to fall back to TlsAlloc etc.

I think this rather obscure use case should not punish most use cases.  
Vicente has performed some performance tests of Boost.Transact (that  
uses static_thread_specific_ptr) on different platforms, some  
supporting TLS, some don't.
IIRC it is pretty much unusable on platforms that don't.