[cfe-dev] libclang cancellation of long running tasks

[Manuel Klimek]

I'll add my +1 to it being unfortunate that libclang operations cannot be
canceled (living in a code base where some TUs take > 30 seconds to parse).

On Tue Jan 13 2015 at 3:38:51 AM John Sully <john at csquare.ca> wrote:

> Hi Jonathan,
>
> I don't understand how std::future::wait_for would allow me to cancel a
> running libclang operation.
>
> I'm not asking how to do this asynchronously - I already have that
> working.  I need a way to stop performing work when the results become
> obsolete. I could always shutdown the thread its on but that would leave
> things in an undefined state.
>
>
> On Mon, Jan 12, 2015 at 6:04 PM, Jonathan Roelofs <
> jonathan at codesourcery.com> wrote:
>
>> John,
>>
>> It should be fairly straightforward for you to implement this behavior in
>> your application using std::future::wait_for.
>>
>>
>> Jon
>>
>> On 1/12/15 6:33 PM, John Sully wrote:
>>
>>> Yes it already runs on a separate thread; however when its known the
>>> result is no longer necessary (for example the user changed the cursor
>>> location - negating the need for autocomplete at the previous location)
>>> the separate thread still runs consuming resources.
>>>
>>> On slower devices like laptops these operations can take a long time.
>>> Even if we are willing to accept the waste of cycles (and battery
>>> life!), the processor has a limited number of cores and responsiveness
>>> will be poor if too many "zombie" jobs are still running.
>>>
>>> I'm willing to add this functionality and submit it upstream if
>>> necessary, but prior to doing so I wanted to reach out to current
>>> developers.  It would be unfortunate to invest significant effort only
>>> to find my patch can't be accepted for an avoidable reason.
>>>
>>>
>>> On Mon, Jan 12, 2015 at 4:09 PM, Sean Silva <chisophugis at gmail.com
>>> <mailto:chisophugis at gmail.com>> wrote:
>>>
>>>     Have you tried running libclang on a separate thread?
>>>
>>>     On Sun, Jan 11, 2015 at 7:59 PM, John Sully <john at csquare.ca
>>>     <mailto:john at csquare.ca>> wrote:
>>>
>>>         I'm in the process of writing an editor based upon libclang, and
>>>         a major issue I'm hitting is the inability to cancel long
>>>         running tasks.  The primary tasks are parsing and creation of
>>>         auto-complete results.
>>>
>>>         Is there already functionality to do this that I've missed?
>>>
>>>         If not, I would like to implement this as its a requirement to
>>>         get good responsiveness out of my editor.  Has there been any
>>>         prior discussions on how this should be implemented?
>>>
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>>>
>>>
>>>
>>>
>>>
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>>>
>> --
>> Jon Roelofs
>> jonathan at codesourcery.com
>> CodeSourcery / Mentor Embedded
>>
>
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