[boost] boost::pool feature requests

From: Alberto Barbati (abarbati_at_[hidden])
Date: 2002-11-21 17:24:22

Hi Everybody,

I recently used library boost::pool, it's a very nice library and 
extremely useful. I would like to submit a few requests and ask one 
question about it.

1) purge_memory() does not reset the member next_size, but in my opinion 
it should. The rationale is that after a purge_memory() the pool should 
be in the exact state it was at the moment of construction. For example, 
in an application of mine, I have a long life pool object (in fact a 
singleton_pool) that is emptied with purge_memory() from time to time. 
The first allocation after purge_memory() allocates a block of size 
next_size, then multiplies next_size by 2. As the next_size is never 
reset, it grows exponentially. Imagine my face when I found that 
allocating a 12 byte object from an empty pool required more than 1Gb...

2) the name release_memory() confuses me. It makes me think that all 
memory is being released, a task accomplished by purge_memory(). I think 
a better name could be release_unused_memory(). This function also 
should reduce the value of next_size, for example by considering the 
size of the largest block left in the pool.

3) I would like to have a function to free the entire pool _without_ 
releasing the memory. The rationale for this is in the example above. 
Most probably, the number of objects allocated in each iteration of my 
application is almost the same. At the end of an iteration, I would like 
to free all allocated objects with one single call (as I have thousands 
of objects, it makes the difference) yet it's a waste of time to free 
the memory, because I will need the same amount again in the next 
iteration. Such function could be called free_all_chunks() or something 
similar.

4) what's the use of ordered_alloc/ordered_free? I made a few tests and 
they are indeed a bit slower than regular alloc/free, without any 
apparent advantage. Am I missing something?

Thanks in advance,

Alberto Barbati