Atomics and concurrency patterns • How existing atomic are implemented (the split reference count technique) • Deferred reclamation, i.e., garbage collection in C++ Some assumed knowledge Atomics and concurrency patterns • How existing atomic are implemented (the split reference count technique) • Deferred reclamation, i.e., garbage collection in C++ Some assumed knowledge control_block pointer as a lock26 Daniel Anderson -- danielanderson.net Solution #2: The split reference count • Used by Folly (Facebook open-source library, used in production), • Used by JustThreads

“width”. Explicitly state/document/reference function conventions. • Defining a macro for calling conventions is a great start. For example, MYLIB_CCONV. • Reference: llvm - CallingConv.h • Don’t throw memory management”. - Reference counted - C++ – std::shared_ptr - Python - Objective-C (manual or automatic – see ARC) - Swift - COM – AddRef()/Release() - Non-Reference counted - .NET - JVM have been deleted here, if allocator was known.Memory model – Reference Counted Memory lifetime is tracked explicitly through reference counting. This typically means allocation locations are static

Edition (C++20) coming later this year  Co-author of C++ Standard Library Quick Reference& C++17 Standard Library Quick Reference  Founder of the Belgian C++ Users Group (BeCPP)3 C++20 C++20 is big! Lots C++11: remove "atomic_" and use special // functions every time you touch head public: class reference { shared_ptr p; }; auto find(T t) const { auto p = head.load(); atomic_load(&head) while (p && p->t != t) p = p->next; return reference(move(p)); } auto front() const { return reference(head); } void push_front(T t) { auto p = make_shared();

2nd, 3rd, 4th, and 5th Edition  Co-author of C++ Standard Library Quick Reference& C++17 Standard Library Quick Reference  Founder of the Belgian C++ Users Group (BeCPP) C++204 Agenda  C++23 a value, false otherwise  value(): returns reference to the contained value, or throws bad_expected_access if no value  error(): returns reference to the error91 Agenda  C++23 Core Language fails: std::cout << Process([p = std::make_unique(42)] { return *p; });  “Attempting to reference a deleted function”  The copy ctor of the std::function tries to copy the lambda, which is not

https://developers.arcgis.com/qt/ • ArcGIS Runtime Toolkit for Qt API reference - https://developers.arcgis.com/qt/toolkit/api-reference/ • ArcGIS Runtime Toolkit – Qt on GitHub - https://github.com/Es

2nd, 3rd, 4th, and 5th Edition  Co-author of C++ Standard Library Quick Reference& C++17 Standard Library Quick Reference  Founder of the Belgian C++ Users Group (BeCPP) C++203 Agenda  Compile-Time

*/ } Because of the nested scopes, it’s safe to pass locals by reference to callees... … no dynamic allocation or reference counting needed.64 SENDER/RECEIVER IS ALSO STRUCTURED CONCURRENCY

强引用胖指针： string • 刚刚说的 string 容器，是掌握着字符串生命周期（ lifespan ）的胖指针。 • 这种掌管了所指向对象生命周期的指针称为强引用（ strong reference ）。 • 这个强引用的强，体现在哪里？ • 当 string 容器被拷贝时，其指向的字符串也会被拷贝（深拷贝）。 • 当 string 容器被销毁时，其指向的字符串也会被销毁（内存释放）。 次拷贝，比较低效。人们常用 string const & 来避免不必要拷贝，但仍比较麻 烦。 • 因此 C++17 引入了弱引用胖指针 string_view ，这种弱引用（ weak reference ）不影响原对象的生命周期，原对象的销毁仍然由强引用控制。 • 这个弱引用的弱，体现在哪里？ • 当 string_view 被拷贝时，其指向的字符串仍然是同一个（浅拷贝）。 • 当 string_view

(or classes) of vertices and edges Labels 查询语言：基于 Cypher 贴合 ISO GQL Standard • Incorporate by reference specifications from SQL/Framework and SQL/Foundation • Capabilities needed by both SQL/PGQ (Property

question, please hold them until after the session is over. • When asking questions, please reference slide numbers5 About Me: • Miya Natsuhara • Software Engineer on the Visual C++ Libraries Team