Order pool

Headers: include/core/order_pool.hpp
Implementation: src/core/order_pool.cpp

Independent pool per side. Dense Order storage with O(1) allocate and deallocate.

Layout

Member	Purpose
orders_	Order array
free_	Stack of free indices
generations_	Per-slot counter; initial value 1

Construction fills free_ with indices capacity-1 .. 0.

Interface

PoolIndex allocate_index() noexcept;   // UINT32_MAX on exhaustion
void deallocate(PoolIndex index) noexcept;
Order &get_order(PoolIndex index) noexcept;
uint32_t generation(PoolIndex index) const noexcept;
size_t capacity() const noexcept;

deallocate increments generations_[index] and returns index to free_.

Generational refs

struct OrderRef {
    PoolIndex index;
    uint32_t generation;
};

Valid ref iff pool.generation(index) == ref.generation and pool.get_order(index).volume != 0.

Prevents stale FIFO entries from addressing a slot reused after cancel or fill.

Capacity

order_pool_capacity bounds resting orders per side. Pool index and order_id are independent; locators map order_id → { index, generation, side, active }.

Allocation

Construction validates capacity and allocates fixed-size vectors for orders, free indices, and generations.