Quota Resource

Implementing a quota resource for memory-limited allocations in C++

This is a medium-difficulty C++ coding problem that tests your ability to implement a polymorphic memory resource wrapper. It appears in interview loops at firms that care about resource control and server stability, where enforcing per-request or per-task memory budgets is a practical necessity.

The core challenge is implementing the std::pmr::memory_resource interface correctly: delegating allocations to an upstream resource while maintaining accurate bookkeeping of bytes in flight. You must handle the interaction between quota checks, upstream exceptions, and deallocation carefully to avoid leaks or budget corruption. The problem rewards clean separation between the quota logic (the guard) and the delegation logic (the pass-through).

• Polymorphic types and virtual method overrides in C++
• Exception safety and transactional semantics (all-or-nothing allocation)
• State management and invariant preservation across concurrent operations
• The std::pmr memory resource protocol