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Subject: Re: [boost] [thread] terminating destructor
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2012-10-23 12:16:15

Le 23/10/12 17:56, Daniela Engert a écrit :
> Am 23.10.2012 11:44, schrieb Andrzej Krzemienski:
>> 2012/10/23 Rob Stewart <robertstewart_at_[hidden]>
>>> On Oct 21, 2012, at 2:28 AM, "Vicente J. Botet Escriba" <
>>> vicente.botet_at_[hidden]> wrote:
>>>> Le 20/10/12 20:41, Andrzej Krzemienski a écrit :
>>>>> 2012/10/20 Vicente J. Botet Escriba <vicente.botet_at_[hidden]>
>>>>> What do you think of adding a thread_guard class that could interrupt
>>> and
>>>>>> join on the destructor?
>>>>> By "adding", do you mean adding it to Boost? I suggested this
>>> interruption
>>>>> because I believed (apparently incorrectly) that class thread
>>> represents a
>>>>> tool ready to be used by "end-user" programmers. After this
>>>>> discussion I
>>>>> realize that thread is a low-level primitive that you use for
>>>>> building
>>>>> high-level concurrency constructs, but would rather not use it
>>>>> directly.
>>>>> Following this view, anyone can build their own abstraction atop
>>>>> boost::thread. I do not think the above thread_guard should be added
>>> into
>>>>> Boost. If I need it I can write it myself (and I would probably
>>>>> write it
>>>>> differently; e.g. using variadic forwarding constructor).
>>>> I agree that these classes are easy to write by the user. Maybe adding
>>> them as examples of use in the documentation could help the user.
>>> I don't agree with the it's-easy-to-write-so-don't-add-it-to-Boost
>>> philosophy. By adding such a class to Boost, you highlight the idea to
>>> those that otherwise hadn't thought of it, and you standardize the
>>> I/F and
>>> semantics.
>> I understand your reasoning, but the situation with boost::thread (and
>> std::thread) is very particular: 'end-user' programmers will not use
>> naked
>> threads; they will also not use "thread guards" (as described above)
>> because they are still too low-level, aren't they?
> Even Bjarne Stroustup doesn't pretend to know what 'end-users' do.
> Most likely, nobody does.
> Looking at the code base in our company (VC10 or VC11 only) I can say
> that none of my colleagues ever used something higher-level than
> boost::thread - mostly for historical reasons and an 'it ain't broke
> so leave it alone' attitude. If a tool like 'thread_guard' or the like
> came pre-packaged with Boost, they'd happily swallow it rather than
> rolling their own.

I have created two tickets to track this possible additions: Add a helper class that
interrupts a thread and join it on destruction Add a thread wrapper class
that interrupts and join on destruction

While the scoped_thread class defined in C++ Concurrency in Action is a
strict scoped class that doesn't allows any change in the wrapped
thread, I think that making the interface thread compatible is also a
good option. This doesn't means that a strict scoped thread has no use.


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