!= A HP Safe to delete A A 7 8 SAFE ACCESS If a hazard pointer points to an object before its removal, then the object will not be reclaimed as long objects that were • retired to the domain • and not protected by hazard pointers • before this call • will be reclaimed before this call returns Global cleanup Same Example Using Global Cleanup Synchronous TS2 – Maged Michael • Maintain an indicator of automatic dependent retirement. • Clear indicator before invoking global cleanup. • Repeat as needed if the indicator is set. • Problem: Where is user code

atomic> a Thread 1 auto s = a.load(); Thread 2 a.store(make_shared( …)); ++ -- If this happens first…23 The fundamental problem: The race to zero Thread 1 load(): Thread 2 store(shared_ptr store(shared_ptr desired): auto cb = ctrl.load(); Need a way to ensure that cb is not deleted before we increment the ref count Daniel Anderson -- danielanderson.net24 Solutions Daniel Anderson Disclaimer: Slide code omits some nullptr checks to save space. atomic> What happens when a concurrent operation changes the pointer to a different shared_ptr?29 Daniel Anderson

Ask any questions • Discuss the latest announcements Take our survey https://aka.ms/cppcon4 Before we begin... • Please use the Q&A tab for questions during the session (typed) • If you want Note that we don’t currently have a way to detect upcoming leap seconds on older Windows OSes (before the 2018 October update). • However, because leap seconds happen infrequently, we plan to update daylight saving time transition when an extra hour is inserted. When that happens, that one-hour block essentially happens twice. • If the local_time to be converted occurs in that period of time

ASYNC OPERATION SCHEDULER schedule SENDER Implementation details of algorithms. Magic happens here. then(sender, fn) -> sender21 BASIC LIFETIME OF AN ASYNC OPERATION SCHEDULER schedule “caught” by applying a sender adaptor that translates the done signal into a value or an error before awaiting the sender; e.g., with: • std::execution::done_as_optional() • std::execution::done_as_error() ... */ } What would happen if compute() could return after calling compute_helper() but before compute_helper() returned?68 CONCURRENCY MUST BE JOINED! schedul e schedul e then then then

single cache line is 64 bytes, enough to hold 16 single precision floating point values. But what happens when the data is not contiguous? • The Morton order is a mapping of multidimensional data to one

 Marking Unreachable Code  Assumptions  Named Universal Character Escapes  Trim Whitespace Before Line Splicing  C++23 Standard Library  String Formatting Improvements  Standard Library Modules  Marking Unreachable Code  Assumptions  Named Universal Character Escapes  Trim Whitespace Before Line Splicing  C++23 Standard Library  String Formatting Improvements  Standard Library Modules  Marking Unreachable Code  Assumptions  Named Universal Character Escapes  Trim Whitespace Before Line Splicing  C++23 Standard Library  String Formatting Improvements  Standard Library Modules

if 去判断是否已经初始化过， 非常方便！ 函数静态初始化和全局静态初始化的配合 • 如果在全局静态初始化（ before_main ）里 使用了函数静态初始化（ Helper ）会怎样？ • 会让函数静态初始化（ Helper ）执行得比全 局静态初始化（ before_main ）还早！ 用包装，避免因为链接的不确定性打乱了静态初始化的顺序 • 利用这个发现，我们意识到可以把

Library algorithms accepting ranges instead of iterator pairs  Projection: Transform elements before handing over to algorithm  Views: transform/filter range: lazily evaluated, non-owning, non- mutating Doumler Friday, September 18 • 12:00Lambda Expression Changes26 [=, this] as Lambda Capture  Before C++20, [=] captures ‘this’ implicitly  Since C++20, you need to be explicit, so: [=, this]27 Templated

unrelated to the original problemExample of Yak Shaving • “My client needed a simple wiki, but before I can help them I need…” • to Containerize the software, but to run that I need… • a Container Management

and message modification 模拟数据规则 例子包括握手，数据解析， 更改数据 new Websocket(“ws://localhost:3335") 模拟前 - before 模拟后 - after • Wasm builds a req buffer • If wasm does not have enough bytes, send /continue