# 现代 C++ 入门：RAII 内存管 理 by 彭于斌 (github@archibate) 往期录播：https://space.bilibili.com/263032155 PPT 和代码：https://github.com/parallel101/course ## 高性能并行编程与优化 - 课程大纲 • 分为前半段和后半段，前半段主要介绍现代 C++，后半段主要介绍并行编程与优化。 C++，后半段主要介绍并行编程与优化。 1. 课程安排与开发环境搭建：cmake 与 git 入门 2. 现代 C++ 入门：常用 STL 容器，RAII 内存管理 3. 现代 C++ 进阶：模板元编程与函数式编程 4. 编译器如何自动优化：从汇编角度看 C++ 5. C++11 起的多线程编程：从 mutex 到无锁并行 6. 并行编程常用框架：OpenMP 与 Intel TBB 7. 被忽视的访存优化：内存带宽与 个文件时！  ## C++ 思想：RAII（Resource Acquisition Is Initialization） 资源获取视为初始化，反之，资源释放视为销毁 0.cpp #include #include

makers.f.dev@gmail.com ## Outline • Motivation • Overview • Patterns • Lifetime • Exceptions • RAII • Synchronization ## • Conclusions ## Motivation • 40 years of • Experience • Accumulated knowledge nts/e/2/0/8/e20839ae14710dcbb38ddda7e6a7f799/p14_1.jpg) ## Patterns • Lifetime • Exceptions • RAII • Synchronization ## Lifetime ## Lifetime • Lots of worries • Use Structured Concurrency $ ^{[1]} and members • Automatic variables ## RAII – Classes Async cleanup pattern • Define async cleanup method • Parents/owners call the method, recursively ## RAII – Classes class Foo { Task<>

Pointers ■ Allocate und deallocate their resource in the constructor and destructor according to the RAII idiom (Resource Acquisition Is Initialization) ■ Support automatic memory management with reference

• 分为前半段和后半段，前半段主要介绍现代 C++，后半段主要介绍并行编程与优化。 1. 课程安排与开发环境搭建：cmake 与 git 入门 2. 现代 C++ 入门：常用 STL 容器，RAII 内存管理 3. 现代 C++ 进阶：模板元编程与函数式编程 4. 编译器如何自动优化：从汇编角度看 C++ 5. C++11 起的多线程编程：从 mutex 到无锁并行 6. 并行编程常用框架：OpenMP 会用到第二讲（RAII 与智能指针）里的知识 2. 课件中一部分代码是基于 C++17 的  个人认为，C++11中很多特性，其实可以看做是为了支持多线程而顺带引入的……如 chrono、移动、lambda、RAII…… ## 第 0 bb4317bc7805d63cb/p18_1.jpg) ## std::thread 的解构函数会销毁线程 - 作为一个 C++ 类，std::thread 同样遵循 RAII 思想和三五法则：因为管理着资源，他自定义了解构函数，删除了拷贝构造 / 赋值函数，但是提供了移动构造 / 赋值函数。 - 因此，当 t1 所在的函数退出时，就会调用 std::thread 的解构函数，这会销毁

Resource Acquisition Is Initialization (RAII) RAII (Resource Acquisition Is Initialization) ## Resource Acquisition Is Initialization (RAII) ## Back to Basics: RAII and the Rule of Zero  "Keep your resources on a short operator=(Widget const& w) { if(this == &w) return *this; // RAII-based approach Widget tmp(w); return *this; } } // ... };

users of this (more on this later) • Non-intrusive rcu_retire() (now in Linux kernel...) ## RCU RAII Readers ## • As C++ developers might expect: void an_rcu_reader() { do_something_before_reader(); under the Creative Commons Attribution-ShareAlike license versions 3.0, 2.5, 2.0, and 1.0. ## RCU RAII Readers • As C++ developers might expect, but more succinctly: void an_rcu_reader() { do_so ; } - Except that not all the world can live within the confines of an RCU RAII reader... ## RCU Non-RAII Readers • And another fine example of diagnostic-driven development! • Function

{ return value < other; } private: const int value; } UnspeakableLambda l(value); 1(4); ## RAII with lambdas auto object = []() { struct S { S() { puts("constructor"); } ~S() return S(); }; int main() { auto obj = object(); } Program returned: 0 constructor destructor ## RAII with lambdas int main() { auto obj = []() { struct S { S() { puts("constructor"); destructor ## RAII with lambdas auto RAII = [ obj = []() { struct S { S() { puts("constructor"); } ~S() { puts("destructor"); } }; return S(); }()] ## RAII with lambdas

Resource Management C++’s most important idiom: RAII (Resource Acquisition Is Initialization) ▶ ▶ ▶ ▶ ## Resource Management ## Back to Basics: RAII and the Rule of Zero ### Cppcon | 2019 The C++ Conference Arthur O'Dwyer 2019-09-17 Back to Basics: RAII and the Rule of Zero Video Sponsorship Provided By: ## Back to Basics: Smart Pointers and RAII ## I NBAL LEVI Thursday, October 28th, 3:15pm MDT public: // ... Core Guideline R.1: Manage resources automatically using resource handles and RAII (Resource Acquisition Is Initialization) Guideline: Strive for the Rule of 0: Classes that don’t

(potential range error) ## • Historical factoid • My original design was for readonly and writeonly ## RAII (1979 and later) ## • From my 1979 lab book: • A “new function” creates the run-time environment // release }  ## RAII (Resource Acquisition Is Initialization) // use an object to represent a resource class File_handle Exceptions • Guaranteed error-handling – or termination • Proper interaction with resource management (RAII) ## • Containers • No need to fiddle with arrays (and pointers) • Enable range checking ## • Algorithms

string(data_.get(), cp); } std::unique_ptr data_; }; ## Simple String - Second RAII Copy Constructor struct SString { String(SString const & rhs) : data_(new char[string(rhs data_.get()); } std::unique_ptr data_; }; ## Simple String - Second RAII Copy Assignment struct SString { String & operator=(String const & rhs) { data_ String - Second RAII Move Constructor struct SString { String(SString && rhs) noexcept = default; std::unique_ptr data_; }; ## Simple String - Second RAII Move Assignment