Diff mt_allocator.h part 1 of item 3

[Stefan Olsson <stefan at xapa dot se>]

Hi,

here's the first part of the patch that addresses item 3 in the rfc - 
the one that will reuse thread id's as soon as possible by changing the 
behaviour of thread_freelist to do "push_front" when threads die instead 
of "push_back". I know that it seems like a lot of patches, but I really 
want to make sure that everyone sees what is being altered.

At the same time - after some reading up - we have added keyword 
volatile to the global vars affected by this patch and if no-one has an 
other opinion, we will do this where it makes sense on other global vars 
(such as the freelists etc) as well.

Brgds

/Stefan

125c125
<       static bool _S_initialized;
---
>       static bool volatile _S_initialized;
154c154
<        * is called, we return the thread id to the back of this list.
---
>        * is called, we return the thread id to the front of this list.
162c162
<         thread_record* next;
---
>         thread_record* volatile next;
170,171c170
<       static thread_record* _S_thread_freelist_first;
<       static thread_record* _S_thread_freelist_last;
---
>       static thread_record* volatile _S_thread_freelist_first;
415c414
<            }
---
>           }
602c601
<            * Set last record and pointer to this
---
>            * Set last record
606d604
<           _S_thread_freelist_last = &_S_thread_freelist_first[i - 1];
711c709
<        * Return this thread id record to thread_freelist
---
>        * Return this thread id record to front of thread_freelist
714,716c712,713
<       _S_thread_freelist_last->next = (thread_record*)freelist_pos;
<       _S_thread_freelist_last = (thread_record*)freelist_pos;
<       _S_thread_freelist_last->next = NULL;
---
>       ((thread_record*)freelist_pos)->next = _S_thread_freelist_first;
>       _S_thread_freelist_first = (thread_record*)freelist_pos;
733c730
<           thread_record* freelist_pos;
---
>           thread_record* volatile freelist_pos;
781c778
<   __mt_alloc<_Tp>::_S_initialized = false;
---
>   volatile __mt_alloc<_Tp>::_S_initialized = false;
832,835c829
<   __mt_alloc<_Tp>::_S_thread_freelist_first = NULL;
< 
<   template<typename _Tp> typename __mt_alloc<_Tp>::thread_record*
<   __mt_alloc<_Tp>::_S_thread_freelist_last = NULL;
---
>   volatile __mt_alloc<_Tp>::_S_thread_freelist_first = NULL;