Lifetime Safety Profile • Herb plans to revise the Lifetime Safety Profile as part of Cpp2Future of C++?Future of C++? C++ Core Guidelines’ Lifetime Safety ProfileFuture of C++? C++ Core Guidelines’ Simplified borrowing Hylo (formerly Val): Mutable Value SemanticsSwift’s Law of Exclusivity Future of C++? C++ Core Guidelines’ Lifetime Safety Profile Crubit: Adopting Rust’s Type System Simplified borrowing Hylo (formerly Val): Mutable Value SemanticsSwift’s Law of Exclusivity Future of C++? C++ Core Guidelines’ Lifetime Safety Profile Crubit: Adopting Rust’s Type System

FILE I/O: PAST, PRESENT AND FUTURE CPPCON OCTOBER 3RD 2023 GUY DAVIDSON @HATCAT01INTRODUCTIONS • Head of Engineering Practice at Creative Assembly • 1980 – Acorn Atom • ISO/IEC JTC1/SC22/WG21 • BSI buffered file IO? • How do we optimise unbuffered file IO? • How might the standard help us in future?AGENDA • Sub-megabyte days • More RAM, more disk capacity • Moving data into and out of RAM • buffered file IO? • How do we optimise unbuffered file IO? • How might the standard help us in future?SUMMARY • https://wg21.link/p1040 • https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3017.htm

thread yfutures/promises: “buffered channel” Promise promise; Future future = promise.Future(); reader.Read(); // Blocks! Channel::Writer writer = channel.Writer(); thread yfutures/promises: “buffered channel” Promise promise; Future future = promise.Future(); reader.Read(); // Blocks! Channel::Writer writer = channel.Writer(); thread yfutures/promises: “buffered channel” Promise promise; Future future = promise.Future(); future.Get(); // Blocks! Channel::Writer writer = channel.Writer();

IT WORKS* HOW IT WORKS* EXAMPLES: C++20 AND BEYOND EXAMPLES: C++20 AND BEYOND SUMMARY / FUTURE? SUMMARY / FUTURE? * BASED ON * BASED ON P1609R1 P1609R1 2MOTIVATION MOTIVATION 3 . 1WHAT IS JITTING? using meta = std::string; // [Future] Abstract Syntax Tree (AST) node 5 . 10READ–EVAL–PRINT LOOP (REPL) READ–EVAL–PRINT LOOP (REPL) using meta = std::string; // [Future] Abstract Syntax Tree (AST) node C++ 5 . 10READ–EVAL–PRINT LOOP (REPL) READ–EVAL–PRINT LOOP (REPL) using meta = std::string; // [Future] Abstract Syntax Tree (AST) node P1717: COMPILE TIME METAPROGRAMMING IN C++ P1717: COMPILE TIME

solvers, and related algorithms. • Modern C++: • : Pseudo-random number generation • <future>: Task-Based Concurrency • : Parallel versions of certain STL algorithms 2Cancer and early 2)Task-based concurrency 13 • Each tumor is a parallel task: std::vectorfuture> • For each future object, call get() to obtain a 2d array. two different tumorsEigen::ArrayXXd initial_population, const Eigen::ArrayXXd& transition_rates); int main(){ //... std::vectorfuture> sample_tumor_par; for (auto k : seeds) sample_tumor_par.emplace_back(std::as

Patterns Synchronization Patterns Dealing with Sharing ▪ Copied Value ▪ Thread-Specific Storage ▪ Future Dealing with Mutation ▪ Scoped Locking ▪ Strategized Locking ▪ Thread-Safe Interface ▪ Guarded Patterns Synchronization Patterns Dealing with Sharing ▪ Copied Value ▪ Thread-Specific Storage ▪ Future Dealing with Mutation ▪ Scoped Locking ▪ Strategized Locking ▪ Thread-Safe Interface ▪ Guarded threadLocalSummation.cppFuture A future is a non-mutable placeholder for a value, which is set by a promise. auto future = std::async([]{ return "LazyOrEager"; }); future.get(); Future: receiver get Promise:

Bloomberg Finance L.P. All rights reserved. std::future 63© 2018 Bloomberg Finance L.P. All rights reserved. std::future 01: // sender/producer 02: std::future async_algo() { 03: std::promise std::promise p; 04: auto f = p.get_future(); 05: std::thread t { [p = std::move(p)] () mutable { 06: int answer = // compute! 07: p.set_value(answer); 08: }}; 09: t.detach(); Bloomberg Finance L.P. All rights reserved. std::future std::future f1 = ...; T2 continuationA(T1); auto f2 = f1.then(continuationA); std::future continuationB(T1); auto f2 = f1.then(continuationB);

bin_checker_async_t { using element_type = tl::expected; using reference = std::future; using data_handle_type = position_t*; using size_type = std::size_t; explicit function signature*/>; std::future operator()(position_t goal) { task_type task(is_bin_occupied); std::future result = task.get_future(); queue_.push(std::make_ arbiter}; auto bins = bin_view_async_t(bin_positions.data(), {}, bin_checker); std::vectorfuture futures; for (auto i = 0u; i != bins.extent(0); ++i) { for (auto j = 0u;

for initial entry 24 • CG+tools: 12 • Tools+CG: 5 • Modifies CG: 4 • Same as CG: 3 • Deferred for future: 26 • Rejected: 18 • Shared drive of Status from Phase 1: • https://docs.google.com/sp readsheets/d/1f-NX2z6axIy if (handles.empty()) { return; } RadarServiceProxy service(handles.front()); ara::core::Future fut = service.UpdateRate.Get(); // ... }); // ... RadarServiceProxy::StopFindSer RadarServiceProxy service(handles.front()); ara::core::Future fut = service.UpdateRate.Get(); auto fut2 = fut.then([](ara::core::Future f) -> auto { uint32_t update_rate = f

Critical Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 7.3 Future . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 Deprecation is not completely unusable, it is only intended to imply that features will disappear from future standards and should be avoided. But, the deprecated features are still part of the standard library static std::mutex mtx; std::unique_lock lock(mtx); // do contention operations 72 7.3 Future CHAPTER 07 PARALLELISM AND CONCURRENCY v = change_v; std::cout << v << std::endl; // release the