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From Sim IJskes - QCG <...@qcg.nl>
Subject Re: Progress, and a problem
Date Mon, 13 Dec 2010 15:58:25 GMT
On 13-12-10 16:27, Patricia Shanahan wrote:
> Sim IJskes - QCG wrote:
>> On 13-12-10 07:16, Patricia Shanahan wrote:
>>> On 12/12/2010 5:48 PM, Peter Firmstone wrote:
>>>> Patricia Shanahan wrote:
>>>>> On 12/3/2010 7:15 AM, Gregg Wonderly wrote:
>>>>> ...
>>>>> > The important issue in FastList is that it was written with the
>>>>> JDK1.4
>>>>> > memory model. After moving River to Java 1.5, we'd have the JSR166
>>>>> work
>>>>> > and the new, consistent memory model where volatile has a true
>>>>> meaning.
>>>>> > However, this code in particular is quite complex as you have
>>>>> noted, so
>>>>> > even adjusting to the new memory model could be problematic.
>>>>>
>>
>> I dont get it. What is the role of FastList. If it is only a very fast
>> concurrent single linked list, with an iterator, i can be implemented
>> much easier.
>
> As far as I can tell it is intended to be a concurrent linked list with
> add at tail, forwards iteration starting at head (not currently done as
> an Iterator, but I think it should be) and removal. I am not yet sure
> whether removal is always done in the context of an iteration or not.
>
>>
>> It i only has a iterator and add,remove operations, only the list
>> stitching needs to be guarded. As long as no garantuees are given in
>> timing relations.
>
> Having studied it closely for many hours, the code appears to me to be
> complicated out of all proportion to its function.

This scan is only meant to shorten the time to remove is it? Would a 
double-linked list, with the forward link used for iterator and the 
backward only to find the unstitch point not be a lot easier to build? 
Would a stitch of the 2 links back and forward separately guarded cost 
so much more time? I have to find some literature on this i think.

Gr. Sim

-- 
QCG, Software voor het MKB, 071-5890970, http://www.qcg.nl
Quality Consultancy Group b.v., Leiderdorp, Kvk Den Haag: 28088397

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