[libvirt] PATCH: 1/4: Add OOM hooks to the memory allocator

[Daniel Veillard]

On Thu, May 22, 2008 at 06:17:27PM +0100, Daniel P. Berrange wrote:
> This patch adds extra code to src/memory.c which allows us to force an OOM
> condition on specific allocations. This is not code you *ever* want to use
> in a production build, so its all conditional on TEST_OOM, which is enabled
> by passing  --enable-test-oom to the configure script.
> 
> The hooks work as follows...
> 
>  - The test suite first calls  virAllocTestInit() to initialize the hooks.
>    This causes it to start counting allocations.
> 
>  ....then run the code you want to check for OOM...
> 
>  - Next call virAllocTestCount() to find out how many allocations were 
>    made.
> 
>  - Given a number of allocations 'n', we need to repeat 'n' times...
> 
>        - Call virAllocTestOOM(n, m) to tell it to fail the n'th allocation
>          upto the (n + m -1)'th allocation. eg,  virAllocTestOOM(3, 2)
>          will cause allocations 3 and 4 to fail.
> 
>         ... run the code you want to check and verify it reports OOM
>         in the way you expect.
> 
> 
> It can be quite hard to find out just where allocation failure bugs are
> hiding. So there is also a virAllocTestHook() function which lets you
> register a callback to be invoked at the time an allocation is artificially
> failed. Obvious use for this is to capture a stack trace.

  Fine by me. +1

Daniel

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