the design of inner function _S_oom_malloc in SGI-STL allocator -


the code follows:

template <int __inst> void* __malloc_alloc_template<__inst>::_s_oom_malloc(size_t __n) {     void (* __my_malloc_handler)();     void* __result;      (;;) {         __my_malloc_handler = __malloc_alloc_oom_handler;         if (0 == __my_malloc_handler) { __throw_bad_alloc; }         (*__my_malloc_handler)();         __result = malloc(__n);         if (__result) return(__result);     } }

i have 2 questions. 1. why _s_oom_malloc use infinite loop? 2. known, _s_oom_malloc called when malloc fails in __malloc_alloc_template::allocate function. , why use malloc allocate space?

anyone can me? lot.

first, loop not infinite. there 2 exits: throwing bad_alloc exception allocating requested amount of memory. exception thrown when current new-handler null pointer.

to understand how can happen, consult e.g. item 49 effective c++. new-handler can either

  • make more memory available
  • install different new-handler
  • deinstall new-handler (i.e. passing null pointer set_new_handler
  • throw exception
  • abort or exit

second, reason uses c library's malloc allocate space malloc on systems well-tested , efficiently implemented function. standard library's new functions "simply" exception-safe , type-safe wrappers around (which user can override, should want that).


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