[asterisk-dev] [Code Review] 4108: Weak Proxy Objects

[rmudgett]

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/trunk/main/astobj2.c
<https://reviewboard.asterisk.org/r/4108/#comment25845>

    Only if the code actually follows the rules. :)



/trunk/main/astobj2.c
<https://reviewboard.asterisk.org/r/4108/#comment25844>

    Rather than play games with the real object's ref count.  How about replacing the indicated code with this:
    ----------
    /* Unlink the obj from the weak proxy */
    internal_weakproxy->priv_data.weakptr = NULL;
    obj->priv_data.weakptr = NULL;
    
    /* Notify the subscribers that obj is about to die. */
    weakproxy_run_callbacks(weakproxy);
    
    /*
     * Weak is already unlinked from obj so this won't recurse.
     * This will destroy obj.
     */
    ao2_ref(user_data, -1);
    ----------
    
    The test to release the weakproxy ref below needs to be adjusted to:
    if (current_value == 1)
    and that code moved to just after the unlock of weakproxy.



/trunk/main/astobj2.c
<https://reviewboard.asterisk.org/r/4108/#comment25843>

    The comment doesn't make sense.  How is destructor_fn supposed to access values in the weak proxy?  The real object is no longer linked with the weakproxy.



/trunk/tests/test_astobj2_weaken.c
<https://reviewboard.asterisk.org/r/4108/#comment25846>

    Heh.  Interesting ability to reuse weakproxy objects.  Not sure how useful it will be.


- rmudgett


On April 3, 2015, 11:58 a.m., Corey Farrell wrote:
> 
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> This is an automatically generated e-mail. To reply, visit:
> https://reviewboard.asterisk.org/r/4108/
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> 
> (Updated April 3, 2015, 11:58 a.m.)
> 
> 
> Review request for Asterisk Developers, George Joseph and rmudgett.
> 
> 
> Bugs: ASTERISK-24936
>     https://issues.asterisk.org/jira/browse/ASTERISK-24936
> 
> 
> Repository: Asterisk
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> Description
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> This implements "weak" references.  The weakproxy object is a real ao2 with normal reference counting of its own.  When a weakproxy is pointed to a normal object they hold references to each other.  The normal object is automatically freed when a single reference remains (the weakproxy).  The weakproxy also supports subscriptions that will notify callbacks when it does not point to any real object.
> 
> 
> Diffs
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> 
>   /trunk/tests/test_astobj2_weaken.c PRE-CREATION 
>   /trunk/main/astobj2.c 433964 
>   /trunk/include/asterisk/astobj2.h 433964 
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> Diff: https://reviewboard.asterisk.org/r/4108/diff/
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> 
> Testing
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> Ran the included test with REF_DEBUG enabled under valgrind.  No reference leaks or improper memory access.  Though this does not test for races, I don't know of an automated way to do that.
> 
> 
> Thanks,
> 
> Corey Farrell
> 
>

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