Need way to shrink the freelist

[Stephenmax]

Hi,everybody~

I found nodes in freelist can never be shrinked, it can only grow larger(like "reserve_unsafe" and "reserve" do).
The only way to reduce the capacity of freelist is destruct queue,ringbuffer or stack. But that is not convenient. Sorry I must make the memory occupy not so high affter some request burst.
Is it possible to improve that?
If cann't, then "capacity_unsafe" function to tell current capacity is needed.
I understand data structure in freelist implementation should lock free as much as possible. But it can have a flexible way like limit the max freelist capacity. Such as when return node to freelist, examine the current capacity. It doesn't need to be accurate,so "capacity" doesn't need to be a atmoic variable.
Just some my silly ideas~

Thanks~

[Tim Blechmann]

not really:

• freeing memory is not lock-free
• freeing memory needs some safe memory reclamation algorithm like pass the buck or hazard pointers. both are patented.

one could add a method to have an 'unsafe' memory reclamation, which has undefined behavior when multiple threads access the queue, but i'm not a big fan of adding unsafe API as people won't be aware of the consequences.

[Stephenmax]

Thank you for your reply.
The "request burst" I talking about is not too often, but due to the mass amount lockfree.queue instances I used, I must take care of this.
I have appropriate timing window to shrink the queue (i.e. when I certain it will not accessed by other thread), and it only need to be shrinked after every long period per session, so "freeing memory is not lock-free" is not my problem.
Adding the shrinking API is too difficult for me, so I appreciate if it comes from the author.
Sorry for my poor english~