Re: [Boost-build] question(s) about bjam code

Subject: Re: [Boost-build] question(s) about bjam code
From: Stefan Seefeld (stefan_at_[hidden])
Date: 2017-10-13 14:45:06

On 05.10.2017 22:31, Steven Watanabe via Boost-build wrote:
> AMDG
>
> On 10/05/2017 08:12 PM, Stefan Seefeld via Boost-build wrote:
>> <snip>
>> I'm looking at 
>> https://github.com/boostorg/build/blob/develop/src/engine/make1.c#L326, and 
>> wonder why, despite the inline comment above the referenced line, this is not 
>> the first statement to be executed in the make1a function. I understand that the 
>> make1a function may be called multiple times from different locations, but 
>> should be ignored (i.e., should be a noop) in all but one case.
>>
>> However, each time the function is called, its parent's async counter is 
>> incremented (as long as this target 's progress is not yet RUNNING).
>>
> Example:
>
> A depends on C
> B depends on C
>
> We enter make1a for C twice, once with each parent,
> A and B.  A and B both need to wait for C to complete,
> hence we increment the async counter both times.
>
> We only skip this if C has already completed, and
> no waiting is required.

Fair enough. However, if the parent counter is incremented, shouldn't
there also (directly or indirectly) be a MAKE1B state that is pushed
onto the stack for that parent ?
This happens if the child target hasn't started processing, but it
doesn't if it's already on the stack.
In my modified code I'm observing a bug caused by the state machine
running out of states without completing all tasks, and I wonder whether
that isn't caused by this asymmetry.

Thanks,

Stefan

-- 
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