Re: atomic operations for shared_ptr ?

[Federico Terraneo <fede dot tft at hotmail dot it>]

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On 08/24/2013 08:58 PM, Bronek Kozicki wrote:
> On 24/08/2013 18:51, Jonathan Wakely wrote:
>> On 24 August 2013 18:45, Bronek Kozicki wrote:
>>> 
>>> what are the current plans for supporting atomic_* free
>>> functions for shared_ptr, as defined in C++11 (20.6.2 "Header
>>> <memory> synopsis")? These would be very useful for passing
>>> shared_ptr objects between threads, esp. if there are multiple
>>> readers and single writer.
>> 
>> I've been thinking about it recently and am probably just going
>> to implement it with a single global mutex used for all
>> shared_ptr instances.
> 
> 
> erm, but that would be even worse than using mutexes as in my
> example code ....

A while ago I was looking for a lock-free algorithm for reference
counted smart pointers, and found this:
http://www.drdobbs.com/atomic-reference-counting-pointers/184401888.
It depends on specific assembler instructions, but for machines that
have them it could really speed up concurrent access to shared_ptr,
which would be a good thing.
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