Book Image

Extreme C

By : Kamran Amini
5 (1)
Book Image

Extreme C

5 (1)
By: Kamran Amini

Overview of this book

There’s a lot more to C than knowing the language syntax. The industry looks for developers with a rigorous, scientific understanding of the principles and practices. Extreme C will teach you to use C’s advanced low-level power to write effective, efficient systems. This intensive, practical guide will help you become an expert C programmer. Building on your existing C knowledge, you will master preprocessor directives, macros, conditional compilation, pointers, and much more. You will gain new insight into algorithm design, functions, and structures. You will discover how C helps you squeeze maximum performance out of critical, resource-constrained applications. C still plays a critical role in 21st-century programming, remaining the core language for precision engineering, aviations, space research, and more. This book shows how C works with Unix, how to implement OO principles in C, and fully covers multi-processing. In Extreme C, Amini encourages you to think, question, apply, and experiment for yourself. The book is essential for anybody who wants to take their C to the next level.
Table of Contents (23 chapters)

Named POSIX semaphores

As you saw in Chapter 16, Thread Synchronization, semaphores are the main tool to synchronize a number of concurrent tasks. We saw them in multi-threaded programs and saw how they help to overcome the concurrency issues.

In this section, we are going to show how they can be used among some processes. Example 18.1 shows how to use a POSIX semaphore to solve the data races we encountered in examples 17.6 and 17.7 given in the previous chapter, Process Execution. The example is remarkably similar to example 17.6, and it again uses a shared memory region for storing the shared counter variable. But it uses named semaphores to synchronize the access to the shared counter.

The following code boxes show the way that we use a named semaphore to synchronize two processes while accessing a shared variable. The following code box shows the global declarations of example 18.1:

#include <stdio.h>
...
#include <semaphore.h>  // For using semaphores
#define...