Intrusive Resource Management for Performance-Critical Systems

Snippet

Intrusive Resource Management for Performance-Critical Systems

Intrusive pointers store the reference count inside the object itself rather than in a separate control block (as std::shared_ptr does). This improves cache locality and reduces the number of dynamic allocations, which is critical in game engines and kernels.

snippet.cpp

cpp

struct IntrusiveBase {
    mutable int ref_count = 0;
    void retain() const { ++ref_count; }
    void release() const {
        if (--ref_count == 0) delete this;
    }
protected:
    virtual ~IntrusiveBase() = default;
};
 
class DataNode : public IntrusiveBase {
    // Node payload
};

Breakdown

mutable int ref_count = 0;

Stores the counter within the object; 'mutable' allows incrementing even if the object is accessed via a const pointer.

if (--ref_count == 0) delete this;

The object takes responsibility for its own destruction once all references are dropped.

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Intrusive Resource Management for Performance-Critical Systems

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