Re: [boost] boost.lockfree update

Subject: Re: [boost] boost.lockfree update
From: Tim Blechmann (tim_at_[hidden])
Date: 2010-07-24 16:07:44

>>> 3. For the empty() method, it says "Not thread-safe, use for debugging
>>> purposes only". Does this mean calling it might destroy the data
>>> structure's invariants? Or is it always safe in that regard? In which
>>> scenarios can it be used, specifically?
>>>     
>> calling it may return a wrong result. the data structure is not
>> corrupted.
>>   
> Am I right in assuming that the result it produces is correct when it is
> produced, and the only problem is that something could get added to the
> queue before the caller gets a chance to examine the result?

for empty(), the following steps need to be done:
1. atomically load the head pointer
2. atomically load the tail pointer
3. compare the pointers.

if the state of the fifo is changed between steps 1 and 2, the result 
doesn't reflect the state of the fifo anymore ...

tim

-- 
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