ChorusOS 4.0 Introduction

GNU 2.7.1 C++ API

The C++ library os/lib/CC/libC.a provides support for C++ applications with a complete and thread-safe library package. Every service offered by libC.a ensures that shared data is only accessed after signaling the relevant synchronization objects.

To allow atomic manipulation of any stream class (iostream or fstream for example), the API of libC.a has been extended with the following two services:

The ios::lock()service is used to lock any stream class object. The ios::unlock() service is used to unlock any stream class object. All services called upon a given stream object StrObj which are preceded by StrObj.lock() and followed by StrObj.unlock() are executed in an atomic way. It is guaranteed that no other thread can access StrObj as long as the lock is on.

An I/O stream object can be locked in two ways. For example, if cout is an I/O stream object:

cout << "atomic " << "output";  
... (any other operation on cout)  
In this case the member function ios::lock() is called.

The following syntax could also be used:

cout << lock << "atomic " << "output" << unlock;

Embedded C++ actors can be linked with os/lib/CC/libC.a if they do not make use of the iostream and fstream packages.