Re: [boost] Re: Singleton

From: Jason Hise (chaos_at_[hidden])
Date: 2005-01-12 13:27:04

Alexander Terekhov wrote:

>Jason Hise wrote:
>[...]
>  
>
>>header.  The main thing that I would like to know is what this thread
>>safety *interface* should look like, if it should provide any features
>>other than locking, and/or how specifically it should be used within the
>>singleton itself (aka what operations need to be locked).
>>    
>>
>
>Nothing at all if the singleton itself is immutable or "atomic<>"-ized 
>internally (lock-free). In this case, for thread-safe lazy init and 
>static storage duration, the best "interface" is a synchronized static 
>local. Some compilers* turn all static locals into synchronized static 
>locals. (In MT mode. Same policy thing as with boost::shared_ptr. ;-) ) 
>
Please elaborate.  I have very little threading background.  What 
exactly is a synchronized static local?  Is this a class or object level 
mutex, or something entirely different?  The "some compilers" part 
worries me a bit, as I would like this library to be portable.  When you 
refer to atomic<>, I presume you are referring to operations that are 
indivisible at the processor level.  Are there such operations that can 
be assumed to be atomic on every processor, or would I be using a large 
boost library that defines common atomic operations based on the 
compiler, processor, and operating system?  Thanks in advance.

-Jason