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C++: Thread Safe Initialization Requirements

Seems like this has come up for me enough in discussing C++ with others, that it might help to put together the information in this gist.

Standard C++ has since C++11 required that block-scope variables with static or thread storage duration get initialized in a thread safe way. Besides there being a StackOverflow answer - to a related question - showing some example assembly for C++11 that includes thread safe guards, there's also the C++ standard documents themselves.

What follows is the specific requirement by versions of the standard.

C++03

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C++: Minimal Allocator

From item 11 of section 16.5.3.5 Cpp17Allocator requirements of n4861.pdf:

"The following is an allocator class template supporting the minimal interface...":

template<class Tp>
struct SimpleAllocator {
 typedef Tp value_type;

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C++: Stateless vs. Stateful Allocators

Categorizing Allocators

All standard C++ library conforming allocators have to support the minimal interface requirements. Beyond these requirements, some examples of fully defined allocators are LLVM's latest standard C++ library implementation of std::allocator, and a custom allocator I've written called ThreadLocalAllocator. These are both examples of what's been categorized as "stateless" allocators. Alternatively, allocators can be "stateful".

grantrostig

C++: Stateless vs. Stateful Allocators

Categorizing Allocators

All standard C++ library conforming allocators have to support the minimal interface requirements. Beyond these requirements, some examples of fully defined allocators are LLVM's latest standard C++ library implementation of std::allocator, and a custom allocator I've written called ThreadLocalAllocator. These are both examples of what's been categorized as "stateless" allocators. Alternatively, allocators can be "stateful".

grantrostig

/**
* Awesome website
* @author YOUR_NAME_HERE
* @version 0.1
*/

/* ============================ RESET ============================ */

/* ===== Eric Meyer Reset ===== */

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Introduction

Over time I come across lots of useful resources but then quickly forget about them. What a shame. So I have decided to put it all together in this page. Hopefully this page will come in handy one day. Will populate this page from time to time.

Dictionary type web / app

• ExplainShell.com - copy and paste a Linux command here and find out what it means!
• Bash Color Tips: wonder how to change terminal text color and styles? Use this guide plus this stackoverflow

AI / Machine Learning / Deep Learning