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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: How to get Ada to ?cross the chasm??
Date: Sun, 6 May 2018 18:32:28 +0300
Organization: Tidorum Ltd
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Xref: reader02.eternal-september.org comp.lang.ada:52040
Date: 2018-05-06T18:32:28+03:00
List-Id: <comp.lang.ada>

On 18-05-06 12:53 , Dmitry A. Kazakov wrote:
> On 2018-05-06 10:34, Niklas Holsti wrote:
   ...
>> Moving the focus back to Ada, efficient applicative data structures
>> are interesting for real-time systems because they could reduce
>> locking/blocking times: a "reader task" could quickly grab a (logical)
>> immutable copy of a large data structure and read the data at its own
>> speed, without interfering with "writer" tasks that transform their
>> own (logical) copies of the data structure.
>
> You need to merge incoherent copies at some point later.

In my applications, that would not be a big problem. In many cases the 
writers can be serialized, in other cases writers update separate parts 
of the data structure and merging would be easy. Other applications 
could have more problems, but applicative data structures do tend to 
provide high-level, merge-like operations.

> I have an intuitive feeling that in general lock-free approach does
> not work at large scale and is effective only at the low level and
> tight times.

If the data structure is applicative, it does not have to be lock-free. 
The applicative property should make lock holding durations very short 
because the structure looks immutable to pure readers.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .