From: ZaCk <ladacez@...>
Date: 2011-07-03T10:17:32+09:00
Subject: Re: Ruby C API:How to prevent a VALUE being collected by the garbage collecter?

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Thanks.
Finally I use rb_gc_mark to do this. I am embedding ruby, but the program
collapsed when calling rb_funcall. I debugged it and found out that if GC
occurs during the calling, the arguments would be collected, and the program
throwed a segment fault. I tried rb_gc_mark and rb_gc_force_recycle to
protect the arguments. It worked. Maybe ruby is not suitable for embedding.
Hah...

2011/7/3 ZaCk <ladacez@gmail.com>

> Thanks.
> Finally I use rb_gc_mark to do this. I am embedding ruby, but the program
> collapsed when calling rb_funcall. I debugged it and found out that if GC
> occurs during the calling, the arguments would be collected, and the program
> throwed a segment fault. I tried rb_gc_mark and rb_gc_force_recycle to
> protect the arguments. It worked. Maybe ruby is not suitable for embedding.
> Hah...
>
>
> 2011/7/3 Joel VanderWerf <joelvanderwerf@gmail.com>
>
>> On 07/02/2011 11:35 AM, Kim Burgestrand wrote:
>>
>>>
>>> On Saturday, 2 July 2011 at 18:35, Quintus wrote:
>>>
>>>  Ruby C API:How to prevent a VALUE being collected by the garbage
>>>>> collecter? Is there any function to call?
>>>>>
>>>> If you want it to never be collected, make it a global variable.
>>> rb_gc_mark will
>>> only do what you want until the next GC cycle.
>>>
>>
>> That's right. Take a look at README.EXT in ruby source, which says:
>>
>>  GC should know about global variables which refer to Ruby's objects, but
>>> are not exported to the Ruby world.  You need to protect them by
>>>
>>>  void rb_global_variable(VALUE *var)
>>>
>>
>> So if you do this:
>>
>> VALUE my_global;
>> ...
>>  rb_global_variable(&my_global)**;
>>
>> Then whatever object is referenced by my_global when GC runs will not be
>> collected.
>>
>> If you just want to protect some VALUEs that are not necessarily pointed
>> to by C variables, you could just keep them in a (ruby) array or other data
>> structure, as long as that array is reachable from some variable known to
>> ruby.
>>
>>
>

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