From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of Boris Sent: Wednesday, October 22, 2008 1:27 PM
Are there any plans to make the pool's doubling algorithm configurable? It would be great if it was possible for example to set an upper limit or to use constant chunk sizes (thus no algorithm at all). If there are no plans may I propose then some patches? I ask as I need to configure the pool as it eats too much memory sometimes.
Parameterizing the growth algorithm for the pool is pretty high on my to-do list, as we have also found the default doubling algorithm to been overly-aggressive. My thinking is only half-baked, but it seemed natural to me to implement this via template-based policies. The two alternatives that came to mind were to either (1) integrate support for controlling growth into the existing UserAllocator concept; or (2) add an additional template parameter to boost::pool to allow the growth strategy to be configured independently of the UserAllocator. Solution (1) would result in the following additional required semantics for a UserAllocator implementation: Expression Return Type Pre-Condition/Notes --------------------------- ----------- --------------------------------- UserAllocator::nextSize( n, partition_sz) size_type Growth strategy support; given an existing allocation size of n elements each of partition_sz, return the suggested number of elements for the next allocation request. If n is zero, returns the suggested initial allocation size. --------------------------------------------------------------------------- Solution (2) introduces a new concept, GrowthStrategy, as an additional template argument for boost::pool (and the other related pool types): template <typename UserAllocator = default_user_allocator_new_delete, typename GrowthStrategy = default_growth_strategy> class pool; GrowthStrategy would have the following semantics: Expression Return Type Pre-Condition/Notes --------------------------- ----------- --------------------------------- GrowthStrategy::nextSize( n, partition_sz) size_type (same as above) -------------------------------------------------------------------------- I'd be interested in hearing your thoughts and ideas... -Chris