Estimate the memory needed for pmr pool resource - c++

Question

I am learning about the std::pmr::unsynchronized_pool_resource and tried using it in a simple example.
In my example, I'm using a buffer l_Buffer with an arbitrarily determined size.
Is it possible to estimate the size (k_BufferSize) needed at build time?
The code snippet:
#include <iostream>
#include <array>
#include <memory_resource>
#include <string>
#include <cassert>
#include <list>
class NoisyAllocator : public std::pmr::memory_resource {
public:
NoisyAllocator(std::string name, std::pmr::memory_resource* upstream) :
m_name {name}, m_upstream {upstream}
{
assert(upstream);
}
private:
std::string m_name;
std::pmr::memory_resource* m_upstream;
void* do_allocate(std::size_t bytes, std::size_t alignment) override {
printf("[%s (alloc)] Size: %zu Alignment: %zu ...\n", m_name.c_str(), bytes, alignment);
auto result = m_upstream->allocate(bytes, alignment);
printf("[%s (alloc)] ... Address: %p\n", m_name.c_str(), result);
return result;
}
void do_deallocate(void* p, std::size_t bytes, std::size_t alignment) override {
printf("[%s (dealloc)] Address: %p Dealloc Size: %zu Alignment: %zu\n", m_name.c_str(), p, bytes, alignment);
m_upstream->deallocate(p, bytes, alignment);
}
bool do_is_equal(const std::pmr::memory_resource& other) const noexcept override {
return this == &other;
}
};
int main(int, char**) {
static constexpr std::size_t k_BufferSize {10000};
static constexpr std::size_t k_NbElems {10};
static constexpr std::size_t k_ValueSize {1};
std::cout << "---- Default allocator ----" << std::endl;
NoisyAllocator l_DefaultAlloc {"Default allocator", std::pmr::null_memory_resource()};
std::pmr::set_default_resource(&l_DefaultAlloc);
std::cout << "---- Buffer resource ----" << std::endl;
NoisyAllocator l_OomAlloc {"Out of memory allocator", std::pmr::null_memory_resource()};
std::array<uint8_t, k_BufferSize> l_Buffer {};
std::pmr::monotonic_buffer_resource l_BufferResource(l_Buffer.data(), l_Buffer.size(), &l_OomAlloc);
std::cout << "---- Monotonic allocator ----" << std::endl;
NoisyAllocator l_MonotonicAlloc {"Monotonic allocator", &l_BufferResource};
std::cout << "---- Pool allocator ----" << std::endl;
std::pmr::unsynchronized_pool_resource l_UnsyncPool(&l_MonotonicAlloc);
NoisyAllocator l_PoolAlloc {"Pool allocator", &l_UnsyncPool};
std::cout << "---- Create list ----" << std::endl;
using value_type_t = std::array<uint8_t, k_ValueSize>;
std::pmr::list<value_type_t> l_Lst {&l_PoolAlloc};
for (std::size_t i {0}; i < k_NbElems; i++)
{
std::cout << "---- Emplace element n°" << i << " ----" << std::endl;
l_Lst.emplace_back();
}
std::cout << "---- End ----" << std::endl;
return 0;
}
Output:
---- Default allocator ----
---- Buffer resource ----
---- Monotonic allocator ----
---- Pool allocator ----
[Monotonic allocator (alloc)] Size: 528 Alignment: 8 ...
[Monotonic allocator (alloc)] ... Address: 0x7fffdcf0ef90
---- Create list ----
---- Emplace element n°0 ----
[Pool allocator (alloc)] Size: 24 Alignment: 8 ...
[Monotonic allocator (alloc)] Size: 992 Alignment: 32 ...
[Monotonic allocator (alloc)] ... Address: 0x7fffdcf0f1a0
[Monotonic allocator (alloc)] Size: 192 Alignment: 8 ...
[Monotonic allocator (alloc)] ... Address: 0x7fffdcf0f580
[Pool allocator (alloc)] ... Address: 0x7fffdcf0f1a0
---- Emplace element n°1 ----
[Pool allocator (alloc)] Size: 24 Alignment: 8 ...
[Pool allocator (alloc)] ... Address: 0x7fffdcf0f1b8
---- Emplace element n°2 ----
[Pool allocator (alloc)] Size: 24 Alignment: 8 ...
[Pool allocator (alloc)] ... Address: 0x7fffdcf0f1d0
---- Emplace element n°3 ----
[Pool allocator (alloc)] Size: 24 Alignment: 8 ...
[Pool allocator (alloc)] ... Address: 0x7fffdcf0f1e8
---- Emplace element n°4 ----
[Pool allocator (alloc)] Size: 24 Alignment: 8 ...
[Pool allocator (alloc)] ... Address: 0x7fffdcf0f200
---- Emplace element n°5 ----
[Pool allocator (alloc)] Size: 24 Alignment: 8 ...
[Pool allocator (alloc)] ... Address: 0x7fffdcf0f218
---- Emplace element n°6 ----
[Pool allocator (alloc)] Size: 24 Alignment: 8 ...
[Pool allocator (alloc)] ... Address: 0x7fffdcf0f230
---- Emplace element n°7 ----
[Pool allocator (alloc)] Size: 24 Alignment: 8 ...
[Pool allocator (alloc)] ... Address: 0x7fffdcf0f248
---- Emplace element n°8 ----
[Pool allocator (alloc)] Size: 24 Alignment: 8 ...
[Pool allocator (alloc)] ... Address: 0x7fffdcf0f260
---- Emplace element n°9 ----
[Pool allocator (alloc)] Size: 24 Alignment: 8 ...
[Pool allocator (alloc)] ... Address: 0x7fffdcf0f278
---- End ----
[Pool allocator (dealloc)] Address: 0x7fffdcf0f1a0 Dealloc Size: 24 Alignment: 8
[Pool allocator (dealloc)] Address: 0x7fffdcf0f1b8 Dealloc Size: 24 Alignment: 8
[Pool allocator (dealloc)] Address: 0x7fffdcf0f1d0 Dealloc Size: 24 Alignment: 8
[Pool allocator (dealloc)] Address: 0x7fffdcf0f1e8 Dealloc Size: 24 Alignment: 8
[Pool allocator (dealloc)] Address: 0x7fffdcf0f200 Dealloc Size: 24 Alignment: 8
[Pool allocator (dealloc)] Address: 0x7fffdcf0f218 Dealloc Size: 24 Alignment: 8
[Pool allocator (dealloc)] Address: 0x7fffdcf0f230 Dealloc Size: 24 Alignment: 8
[Pool allocator (dealloc)] Address: 0x7fffdcf0f248 Dealloc Size: 24 Alignment: 8
[Pool allocator (dealloc)] Address: 0x7fffdcf0f260 Dealloc Size: 24 Alignment: 8
[Pool allocator (dealloc)] Address: 0x7fffdcf0f278 Dealloc Size: 24 Alignment: 8
[Monotonic allocator (dealloc)] Address: 0x7fffdcf0f1a0 Dealloc Size: 992 Alignment: 32
[Monotonic allocator (dealloc)] Address: 0x7fffdcf0f580 Dealloc Size: 192 Alignment: 8
[Monotonic allocator (dealloc)] Address: 0x7fffdcf0ef90 Dealloc Size: 528 Alignment: 8
Online compiler: https://godbolt.org/z/EhTE1zr4Y