Home » Blog » Categories »

New paper: N3696, Proposal to extend atomic with priority update functions -- Bronek Kozicki

By Blog Staff | Jun 29, 2013 07:14 AM | Tags: experimental

Note: This paper explores potential future standardization directions and alternatives. It does not discuss or propose to amend the C++14 Committee Draft paper whose ballot is currently in progress.

 

A new WG21 paper is available. A copy is linked below, and the paper will also appear in the next normal WG21 mailing. If you are not a committee member, please use the comments section below or the std-proposals forum for public discussion.

Document number: N3696

Date: 2013-06-26

Proposal to extend atomic with priority update functions

by Bronek Kozicki

Excerpt:

Paper [1] identifies a range of concurrent algorithms which, when implemented using the above described primitive, exhibit very good performance characteristics. If such algorithms were to become more popular in C++ , it would be useful to provide the primitive in <atomic>, rather than rely on the user to "Bring Your Own". This would serve the purpose of establishing a primitive which can be used for reasoning about, writing and reading of such concurrent algorithms, as well as allow users to automatically benefit from the hardware support for certain specializations of these operations, where it is available [2].

Quick Q: What type does auto use for containers? -- StackOverflow

By Blog Staff | Jun 28, 2013 10:43 AM | Tags: None

Quick A: std::initalizer_list. And did you know you can even do for(auto i: {1,2,3,4,5}) ?

What type does auto use for containers?

I can achieve identical output by using different containers in C++. For example . .

    std::array<int, 5> v = {1,2,3,4,5};
    for(auto i : v)
        std::cout << i << ", ";

or

    std::vector<int> v = {1,2,3,4,5};

or

    int v[] = {1,2,3,4,5};

etc.

So what container does auto use here?

    auto v = {1,2,3,4,5};
    for(auto i : v)
        std::cout << i << ", ";

Quick Q: Why does draft C++14 have both runtime-sized arrays and std::dynarray? -- StackOverflow

By Blog Staff | Jun 27, 2013 09:56 PM | Tags: c++14

Several people have asked:

Why both runtime-sized arrays and std::dynarray in C++14?

Draft C++14 includes both runtime-sized arrays and the std::dynarray container. From what I can tell, the only real difference between the two is that std::dynarray has an STL interface (e.g., begin, end, size, etc.), while runtime-sized arrays do not. So why does C++14 need them both?

Scott Meyers speaking at NWC++UG -- July 17, Redmond, WA, USA

By Blog Staff | Jun 27, 2013 10:02 AM | Tags: intermediate

In three weeks, Scott Meyers will be giving a free talk at the Northwest C++ Users' Group:

The Universal Reference/Overloading Collision Conundrum

by Scott Meyers

July 17, 2013 at 7:00pm (pizza at 6:45)
Microsoft Campus, Building 40
Redmond, WA, USA

Abstract

To help address the confusion that arises when rvalue references become lvalue references through reference collapsing, Scott Meyers introduced the notion of “universal references.” In this presentation, he builds on this foundation by explaining that overloading functions on rvalue references is sensible and useful, while seemingly similar overloading on universal references yields confusing, unhelpful behavior. But what do you do when you want to write a perfect forwarding function (which requires universal references), yet you want to customize its behavior for certain types? If overloading is off the table, what’s on? In this talk, Scott surveys a variety of options.

Though Scott will give a one-slide overview of the idea behind universal references at the beginning of the presentation, attendees are encouraged to familiarize themselves with the notion in more detail prior to the talk. Links to written and video introductions to universal references are available here.

Bio

Scott Meyers is one of the world’s foremost authorities on C++. He wrote the best-selling Effective C++ series (Effective C++, More Effective C++, and Effective STL); published and maintains the annotated training materials Overview of the New C++ (C++11) and Effective C++ in an Embedded Environment; is Consulting Editor for Addison Wesley’s Effective Software Development Series, and, with Herb Sutter and Andrei Alexandrescu, is a principal in C++ and Beyond. He has a Ph.D in Computer Science from Brown University. He’s currently working on a new book, Effective C++11/14, which he hopes to publish in early 2014.

C++11 Regular Expression Library -- Brian Overland

By Blog Staff | Jun 26, 2013 09:37 AM | Tags: intermediate

New at InformIT:

C++11 Regular-Expression Library

by Brian Overland

From the article:

Regular expressions are of practical value in many programs, as they can aid with the task of lexical analysis—intelligently breaking up pieces of an input string—as well as tasks such as converting from one text-file format (such as HTML) to another.

I’ve found that when the C++11 regular expression library is explained in a straightforward, simple manner, it’s easy to use. This chapter doesn’t describe all the endless variations on the regex function-call syntax, but it does explain all the basic functionality: how to do just about anything you’d want to do.

New paper: N3697, WG21 Business Plan and Convener's Report -- Herb Sutter

By Blog Staff | Jun 25, 2013 02:07 PM | Tags: None

A new WG21 paper is available. A copy is linked below, and the paper will also appear in the next normal WG21 mailing. If you are not a committee member, please use the comments section below or the std-proposals forum for public discussion.

Document number: N3697

Date: 2013-06-25

WG21 Business Plan and Convener's Report

by Herb Sutter

Excerpt:

2.1. MARKET REQUIREMENTS

ISO C++ remains a widely-used foundation technology, well-received in the marketplace.

Although C++ has long been a consistently popular language, since 2011 in particular it has enjoyed a renewed cycle of growth and investment in tools and platform support across the industry. This was driven primarily by the C++11 standard's completion at the same time as the industry saw a resurgence of interest in performance-efficient, hardware-efficient, and especially power-efficient systems programming capability for mobile devices, cloud data centers, high-performance financial systems, vector and GPGPU computing (via nonstandard extensions to C++ that we are now investigating standardizing), and other major growth sectors and environments.

This new cycle of industry investment in C++ includes, but is not limited to, investment in:
  • tools, such as the advent of a new major C++ implementation in the Clang compiler and other major new products actively competing to fully implement the latest ISO C++ standard;
  • organization, with the establishment of the Standard C++ Foundation trade association in 2012 (see isocpp.org/about);
  • standardization participation, so that at our most recent meeting WG21 attendance reached 107 experts organized into 16 active subgroups -- this includes 12 domain-specific subgroups (e.g., networking, transactional memory) that were established since 2012 and have drawn domain experts who did not previously participate in C++ standardization; and
  • faster and more predictable standardization output, for example that WG21 is on track to produce in 2014 a "C++14 wave" of one revised International Standard and three Technical Specifications (File System library, Networking library, and Concepts template constraints language extensions).

Efficient Programming with Components -- Alexander Stepanov

By Mantosh Kumar | Jun 23, 2013 01:56 PM | Tags: stepanov performance intermediate efficiency components advanced

stepanov-components.PNGA wonderful video series by the inventor of the Standard Template Library (STL).

Video Series: Efficient Programming with Components

by Alexander Stepanov

Performance is essential for infrastructure software. Modern infrastructure software depends heavily on components. Therefore, writing performant code in this environment requires deep understanding of the characteristics of such components. The course will help programmers to improve performance of their code by learning how to use these existing generic components effectively. In addition, it will teach them to extend the library with new high-performance components. Along the way, participants will learn how to use C++ as a high-performance language.The course will be taught interactively with the class discussing, discovering, and developing components together.

Code is available here.

 

 

 

Scaling with C++11 -- Edouard Alligand

By Blog Staff | Jun 23, 2013 10:04 AM | Tags: scalability parallel intermediate cores advanced

cppnow13-alligand.PNGFrom the recent BoostCon/C++Now event. If you missed it there, check it out online. An updated version of this talk is also slated for the upcoming Meeting C++ this fall if you want to catch it in person.

Scaling with C++11

Edouard Alligand

As the number of cores per processor increases, software needs to be able to execute multiple tasks in parallel in order to benefit from Moore's law. This is not only a question of writing parallel algorithms, but also a matter of designing the application properly to reduce inter-thread dependencies. These dependencies may be very hard to find and are the results of decades of serial programming. Thus, writing truly scalable software is less a question of technical expertise than adopting the appropriate state of mind.

This presentation is about the design, techniques and tools used by the team who wrote the hyperscalable database "quasardb." Building upon concrete scalability challenges, the presenter will expose typical multithreading anti-patterns and how to avoid them. The topics covered include: atomics, micro locks, lock-free and wait-free containers, memory management strategies (copy on write, smart pointers, perfect forwarding...), thread local storage, asynchronous I/O, and much more!