Re: [Qemu-devel] [RFC] introduce a dynamic library to expose qemu block API

[Paolo Bonzini]

Il 20/07/2012 13:38, Daniel P. Berrange ha scritto:
> There's two aspects to it. First we forbid use of malloc/free/realloc
> in favour of an alternative set of APIs designed such that we can get
> compile time errors when people don't check the result for NULL.
> 
>   
> http://berrange.com/posts/2008/05/23/better-living-through-api-design-low-level-memory-allocation/
> 
> This has been very successful in ensuring code checks for OOM correctly.
> Second there is a mode in our test suites where you can run under
> simulated OOM - it runs once to count the total set of mallocs in the
> test, and then re-run it 'n' times failing each malloc in turn and
> verifying that we correctly report the OOM error condition.

Does it fail each malloc in turn, or does it fail each malloc "above X
bytes" after the Y-th?  Because the latter is what you actually get in
practice, and it seriously hampers your recovery capabilities.

Right now, we always use g_malloc and abort on failure, but we could
replace it with g_try_malloc in specific large allocation cases, where
large could even be not that large, for example around 64K.

Paolo