On Wed, May 06, 2015 at 04:45:14PM +0000, Jie Liu <[email protected]> wrote:
> When I'm reading the code of libev, I find this definition of
> "array_needsize":
> #define array_needsize(type,base,cur,cnt,init) \
> if (expect_false ((cnt) > (cur))) \
> { \
> int ecb_unused ocur_ = (cur); \
> (base) = (type *)array_realloc \
> (sizeof (type), (base), &(cur), (cnt)); \
> init ((base) + (ocur_), (cur) - ocur_); \
> }
> According to the comments, memories are allocated in chunks of
> "MALLOC_ROUND". It is possible that the size needed is larger than
> "MALLOC_ROUND". In this case, the "array_needsize" may not allocate enough
> memories because it is using "if" instead of "while". I though there would be
> a "while" loop but I didn't find it. The library is proved by many projects,
> so I must miss something here. Could anyone point out how it works?
You missed that the macro does not call malloc but array_realloc, which
contains a while (via array_nextsize).
The if in array_needsize exists merely to decide whether an allocation
is needed at all, and MALLOC_ROUND is used to round allocations up to a
multiple of this size.
--
The choice of a Deliantra, the free code+content MORPG
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----==-- _ generation
---==---(_)__ __ ____ __ Marc Lehmann
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