August 2021

CppCon update: Near-record number of talk submissions

hallway_track-300x188.jpegA near-record number of talk submissions, with the large majority of speakers asking to deliver their talks in person, on-site in Aurora this October:

Big Update with Big Thanks for a Big Program

by Jon Kalb

From the announcement:

The deadline for Main Program submissions has passed with a near-record number of submissions! ... We are excited both by the quality of the submissions and by the fact that that the vast majority of submissions were for onsite presentations.

... Our Program Committee is currently hard at work reviewing and rating each submission and we know that we’ll have an amazing program for both onsite and online attendees in Aurora in October. As you know, we’ve announced that Bjarne Stroustrup will be our opening keynote onsite... Creating multiple, thoughtful evaluations on almost two-hundred submissions touching on virtually every topic of C++ and software design in less than a month is a mammoth task, but we know that the CppCon 2021 Program that you’ll be seeing in Aurora and/or online, will be something that we as organizers, the Program Committee, and the presenters, will be proud to present.

CppCon 2020 Calling Functions: A Tutorial--Klaus Iglberger

Registration is now open for CppCon 2021, which starts on October 24 and will be held both in person and online. To whet your appetite for this year’s conference, we’re posting videos of some of the top-rated talks from our most recent in-person conference in 2019 and our online conference in 2020. Here’s another CppCon talk video we hope you will enjoy – and why not register today for CppCon 2021 to attend in person, online, or both!

Calling Functions: A Tutorial

by Klaus Iglberger

Summary of the talk:

How is a function call resolved? How does the compiler find the right function and how does the compiler choose from a set of available functions? This talk will give an overview of the individual steps taken during the resolution of a function call. It will primarily focus on the different kinds of name lookup, argument deduction, and on overload resolution. Attendees will gain insight into the mechanics of (un-)qualified lookup, argument dependent lookup, two-phase lookup, name hiding, SFINAE, (viable) candiate functions, and ambiguous function calls. They will leave the talk with a much better understanding of the (sometimes surprising) details of function calls.

Asynchronous Stacks and Scopes--Eric Niebler

A revolution?

Asynchronous Stacks and Scopes

by Eric Niebler

From the article:

In Structured Concurrency, I talk about what structured concurrency is and why it’s a big deal for C++ especially. In this post I discuss some more interesting properties of asynchronous code that is structured: async stacks and async scopes...

The First Big Update of My C++20 Book--Rainer Grimm

Will you get it?

The First Big Update of My C++20 Book

by Rainer Grimm

From the article:

I'm happy to announce the first big update of my C++20 book. The update was mainly due to the improved C++ compiler support of C++20. The update includes concepts, the ranges library, modules, the three-way comparison operator, the format library, and the chrono library.

CppCon 2019 EDSL Infinity Wars: Mainstreaming Symbolic Computation--Joel Falcou, Vincent Reverdy

Registration is now open for CppCon 2021, which starts on October 24 and will be held both in person and online. To whet your appetite for this year’s conference, we’re posting videos of some of the top-rated talks from our most recent in-person conference in 2019 and our online conference in 2020. Here’s another CppCon talk video we hope you will enjoy – and why not register today for CppCon 2021 to attend in person, online, or both!

EDSL Infinity Wars: Mainstreaming Symbolic Computation

by Joel Falcou, Vincent Reverdy

Summary of the talk:

Scientists and Developers want the same thing: a simple code that does exactly what it should. For the former, it implies adhering to their knowledge base and domain idioms. For the latter, it means it compiles in a reasonable time frame and without bugs. for both, it better computes fast in the end. One way developers, especially in C++, provides scientists with usable libraries is to design them as Embedded Domain Specific Languages. Alas, in all honesty, if someone asked the Scientists, they will probably state that LaTex is *the* perfect DSLs they practice every day.

This is an old story and even if we only focus on matrix-based libraries, the current landscape of high-performance computing library -- Blaze, Blitz++, EIGEN, Armadillo, etc... -- is proof that those techniques have a decent public following. This is the point where the icky things start: stories of meta-programming, so-called expression templates and their uphill battle against new C++ features: interaction with auto, rvalue-references, move semantics and so on. The authors have spent quite a bit of their coding life trying to play with or around those techniques and this talk is about what they learned during this journey.

This talk will focus on what kind of mistakes, oversights and traps the old kind of scientific EDSLs fell into. We will investigate why the new C++ features didn't help them but pushed them further into a state of ever-growing complexity. We will present our vision of how a modern-C++ friendly EDSL for science can be built. By starting from scratch, this talk will cover the actual requirements of such a library including move-aware expression templates, symbolic formula building, type/value maps, named parameters and static visitors. As a conclusion, we will scheme over various immediate benefits of such an EDSL and new applications that old style libraries could not handle like symbolic simplification, automatic analytical derivation and more.

The Meeting C++ online job fair returns in September!

The next edition of the C++ online job fair organized by Meeting C++ will be on 21s/&22nd September!

The Meeting C++ online job fair returns!

by Jens Weller

From the article:

The first two online events in remo have been a great success. They've been very well received by the C++ community and this event will now be a part of regularly scheduled events for Meeting C++ online. As remo is not available anymore, the event will be hosted in the new online event platform for Meeting C++ 2021. The event will be again on two days: 21st/22nd September, with the first day being in the afternoon and the second day in the evening...

CppCon 2020 A Multi-threaded, Transaction-Based Locking Strategy for Containers--Bob Steagall

Registration is now open for CppCon 2021, which starts on October 24 and will be held both in person and online. To whet your appetite for this year’s conference, we’re posting videos of some of the top-rated talks from our most recent in-person conference in 2019 and our online conference in 2020. Here’s another CppCon talk video we hope you will enjoy – and why not register today for CppCon 2021 to attend in person, online, or both!

A Multi-threaded, Transaction-Based Locking Strategy for Containers

by Bob Steagall

Summary of the talk:

With the concurrency tools available in the modern C++ standard library, it is easier than ever to create multi-threaded programs. When we write such applications, there are sometimes cases in which a container simply must be shared among multiple threads. Of course, sharing is trivial if the only operations on the container are reads. In the case where reads greatly outnumber writes, acceptable performance is often attainable with a reader/writer mutex type, like std::shared_mutex. But suppose that the number of writes is similar to, or even greater than, the number of reads -- how does one then perform simultaneous reads and writes on a single container?

One common usage pattern is that, for a given operation, sets of related records are read and updated together. In order to prevent data races and inconsistent views of the data, such sets must be locked together as a unit before any of them can actually be read or updated. Further, it is very easy to accidentally create deadlocks by choosing a seemingly correct locking order. In order to avoid these problems, we would like a locking algorithm that provides three important properties: atomicity, consistency, and isolation.

This talk will describe an algorithm, implemented in C++, that performs such locking based on the concept of strict timestamp ordering. Using only facilities from the C++17 standard library, it employs a straightforward approach to multi-threaded, transactional record locking that requires minimal spatial overhead and yet fulfils the requirements of atomicity, consistency, and isolation. We'll discuss the pros, cons, and limitations of the algorithm, and provide some performance measurements.

Empty Base Class Optimisation, no_unique_address and unique_ptr--Bartlomiej Filipek

Life made easier.

Empty Base Class Optimisation, no_unique_address and unique_ptr

by Bartlomiej Filipek

From the article:

C++20 added a couple of new attributes in the form of [[attrib_name]]. One of them - [[no_unique_address]] - can have surprising effects on the code! In this blog post, you’ll learn how to optimize your classes' layout and make some data members “disappear”. In most cases, it will be just one line of C++20 code.

Let’s go...

CppCon 2019 Time Travel: Applying Gradual Typing to Time Types with Clang's LibTooling--Hyrum Wright

Registration is now open for CppCon 2021, which starts on October 24 and will be held both in person and online. To whet your appetite for this year’s conference, we’re posting videos of some of the top-rated talks from our most recent in-person conference in 2019 and our online conference in 2020. Here’s another CppCon talk video we hope you will enjoy – and why not register today for CppCon 2021 to attend in person, online, or both!

Time Travel: Applying Gradual Typing to Time Types with Clang's LibTooling

by Hyrum Wright

Summary of the talk:

Libraries for C++ are constantly evolving, with new APIs being added, old ones being deprecated and functionality continually changing. In past CppCon talks, I've described in abstract how Google manages this change by applying large-scale changes across our C++ codebase using clang's libTooling infrastructure.

In this talk, we'll put this previous work in practice by demonstrating how we use clang-tidy and clang's libTooling library to improve type safety of time types across Google's 250M lines of C++. Using tools currently open sourced as part of clang-tidy, we'll show how the underlying model of time types allow us to migrate from a collection of integers and floating point types to the much more strongly typed `absl::Time` and `absl::Duration` types representing time instants and intervals. Along the way, we'll discover how this process finds existing bugs and prevents new ones from creeping in.

This "gradual typing" technique is not limited to just Time types, and we'll explore how this can be used to improve pointer ownership deduction and other places where more constraining types eliminate classes of bugs.