Frictionless Allocators

This talk examines the complexity of supporting custom memory allocation in C++ libraries, including allocator traits, polymorphic memory resources, and allocator propagation. It discusses proposed language extensions intended to simplify allocator-aware designs.

Syllabus

Intro
Frictionless Allocators
Outline of Talk
What is an allocator?
Why Do We Want Allocators?
A Faster Allocator
Performance
Special Memory
Emery Berger
Initial empirical results
Early Results
Allocator Traits (since 2011)
How did we improve support in C++17
How does pmr work?
memory_resource
Standard Resources
Idiom and usage of pmr
Quick Example
Scoped Allocator Model
Limitations of pmr
Bloomberg Experience
Unsupported use cases
Allocator Propagation
Complexity of Propagation
Syntactic overhead is high
Copy Constructor Issue
Ideal Model
Allocator Awareness
Why Implicit from Members?
Allocator Aware Properties
Simplifying Construction
Worked Example