D's New GC and Object Allocation Pools

[Maxime Chevalier-Boisvert via Digitalmars-d]

I'll do that if I have to, but it's cleaner with an override of 
new as it makes it impossible to mistakenly allocate the object 
outside of the pool. It's also nicer if you can pass arguments to 
your constructor.

On Sunday, 26 October 2014 at 11:16:39 UTC, Damian wrote:
> On Sunday, 26 October 2014 at 03:37:47 UTC, Maxime 
> Chevalier-Boisvert wrote:
>> Hello,
>>
>> I was wondering if there have been updates regarding Andrei's 
>> announcement that he would rewrite the D garbage collector. Is 
>> there any kind of timeline for when a new version of the GC 
>> can be expected?
>>
>> I also wanted to ask if there was an implementation of an 
>> object pool in the standard library. If not, I'm wondering 
>> what the best way to implement this is. Is there any way to 
>> overload new and destroy?
>>
>> I was thinking of using the templated emplace operator from 
>> std.conv to allocate class objects into a large flat array, 
>> and to derive pool-allocated classes from a PoolObject base 
>> class. This base class would contain linked list pointers to 
>> implement a free list, as well as templated static methods to 
>> allocate and free the objects. Any advice welcome.
>
> For your object pool, why not just create functions, alloc and 
> free, instead of trying to override them - something like below
>
> version (USE_GC)
> {
>   import core.memory;
> }
> else
> {
>   import core.stdc.stdlib: malloc, free;
> }
>
> struct MemPool
> {
>   void* alloc(size_t size, bool usePool = true) nothrow
>   {
>     version (USE_GC) return GC.malloc(size);
>     else malloc(size);
>   }
>
>   void Free(void* p) nothrow
>   {
>     version (USE_GC) GC.free(p);
>     else free(p);
>   }
> }