Boost Memory Management

SmartPtr

boost::shared_ptr, boost::weak_ptr, boost::scoped_ptr, boost::intrusive_ptr — these are the direct predecessors of the C++11 smart pointers.

intrusive_ptr

Unlike shared_ptr, intrusive_ptr requires the managed object itself to maintain the reference count:

struct MyObject {
    std::atomic<int> refcount{0};
    // ...
};

void intrusive_ptr_add_ref(MyObject* p) { p->refcount.fetch_add(1); }
void intrusive_ptr_release(MyObject* p) {
    if (p->refcount.fetch_sub(1) == 1) delete p;
}

boost::intrusive_ptr<MyObject> ptr(new MyObject);

Advantage: No separate control block allocation required (one fewer malloc compared to shared_ptr).

Pool: Memory Pool

Boost.Pool provides two pool allocators:

• pool<>: A memory pool of fixed-size blocks. O(1) allocation/deallocation, no fragmentation.
• object_pool<T>: An object pool that bulk-constructs and bulk-destroys objects of the same type.

boost::pool<> alloc(sizeof(int));  // pool of 4-byte blocks
int* p = static_cast<int*>(alloc.malloc());  // allocate from pool
alloc.free(p);  // return to pool

Align: Aligned Memory

boost::alignment::aligned_alloc provides aligned memory allocation — a cross-platform solution that predates C++17 std::aligned_alloc.