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std::pmr sandbox

PURPOSE: Provide a playing ground for std::pmr experimentation.

Description

This repository contains C++ source code that experiments with C++17's polymorphic memory resources (PMR) facilities. The code here accompanies a talk titled "C++17's std::pmr Comes With a Cost" by David Sankel that was delivered at C++Now 2018.

std::pmr shims

At the time of this writing neither libc++ nor libstd++ include an implementation of std::pmr in the std::pmr namespace. The header files memory_resource.hpp, string.hpp, and vector.hpp provide this functionality. They were pieced together by importing implementations of the library fundamentals TS into the std namespace. There is also an implementation of monotonic_buffer_resource in memory_resource.hpp which is based on Bloomberg's Open Source BDL library.

Contents

  • libcpp_bug.cpp. Demonstrate an allocator-related, exception-safety bug that is present in both libstdc++ and libc++.
  • simplicity.cpp. Provide various iterations of a class that is built up to allocator awareness. This is the main code used in the presentation.
  • before_after.cpp. Illustrate a simple class before and after getting allocator aware.

Building

To build, run make.

clang and gcc are used with with libc++ and libstdc++ respectively. Edit the Makefile to modify the build process; it is pretty simple. This was tested with gcc 8.1.0 with libstdc++ and clang 6.0.0 with libc++ 6.0.0.

If you'd like to experiment with the std::pmr::monotonic_buffer_resource that is built off of BDE, build https://github.com/bloomberg/bde.git and point the Makefile to its build artifacts.

Note that Boost also has an implementation of various memory resources in its container library.