Book Image

Boost C++ Application Development Cookbook - Second Edition

By : Anton Polukhin Alekseevic
Book Image

Boost C++ Application Development Cookbook - Second Edition

By: Anton Polukhin Alekseevic

Overview of this book

If you want to take advantage of the real power of Boost and C++ and avoid the confusion about which library to use in which situation, then this book is for you. Beginning with the basics of Boost C++, you will move on to learn how the Boost libraries simplify application development. You will learn to convert data such as string to numbers, numbers to string, numbers to numbers and more. Managing resources will become a piece of cake. You’ll see what kind of work can be done at compile time and what Boost containers can do. You will learn everything for the development of high quality fast and portable applications. Write a program once and then you can use it on Linux, Windows, MacOS, Android operating systems. From manipulating images to graphs, directories, timers, files, networking – everyone will find an interesting topic. Be sure that knowledge from this book won’t get outdated, as more and more Boost libraries become part of the C++ Standard.
Table of Contents (19 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Initializing a shared variable safely


Imagine that we are designing a safety-critical class that is used from multiple threads, receives answers from a server, postprocesses them, and outputs the response:

struct postprocessor {
    typedef std::vector<std::string> answer_t;

    // Concurrent calls on the same variable are safe.
    answer_t act(const std::string& in) const {
        if (in.empty()) {
            // Extremely rare condition.
            return read_defaults();
        }

        // ...
    }
};

Note the return read_defaults(); line. There may be situations when server does not respond because of networking issues or some other problems. In those cases, we attempt to read defaults from file:

// Executes for a long time.
std::vector<std::string> read_defaults();

From the preceding code, we hit the problem: the server may be unreachable for some noticeable time, and for all that time we'll be rereading the file on each act call. This significantly affects performance...