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Diffstat (limited to 'ACE/ace/Dynamic_Service_Dependency.h')
-rw-r--r-- | ACE/ace/Dynamic_Service_Dependency.h | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/ACE/ace/Dynamic_Service_Dependency.h b/ACE/ace/Dynamic_Service_Dependency.h new file mode 100644 index 00000000000..3eb4e0df7c7 --- /dev/null +++ b/ACE/ace/Dynamic_Service_Dependency.h @@ -0,0 +1,70 @@ +// -*- C++ -*- + +//============================================================================= +/** + * @file Dynamic_Service_Dependency.h + * + * $Id$ + * + * @author Iliyan Jeliazkov <iliyan@ociweb.com> + */ +//============================================================================= + +#ifndef ACE_DYNAMIC_SERVICE_DEPENDENCY_H +#define ACE_DYNAMIC_SERVICE_DEPENDENCY_H + +#include /**/ "ace/pre.h" + + +#if !defined (ACE_LACKS_PRAGMA_ONCE) +# pragma once +#endif /* ACE_LACKS_PRAGMA_ONCE */ + +#include "ace/Dynamic_Service_Base.h" +#include "ace/Service_Object.h" +#include "ace/DLL.h" + +ACE_BEGIN_VERSIONED_NAMESPACE_DECL + +/** + * @class ACE_Dynamic_Service_Dependency + * + * @brief Provides a way to declare dependency on specific service, + * thus helping to avoid order of initialization issues with instances + * of an objects whose implementation code resides in dynamically loaded + * services. + * + * It is disastrous to have dynamically loadable services create and give away + * ownership of objects and then ending up being unloaded before all those + * instances have been deleted. Normally the code for such objects classes + * resides within the TEXT segment of the DLL, which implements the service. + * If a service gets removed, its DLL may be unmapped from memory and then + * any attempt to invoke a method on the said objects will cause SEGV. + * + * Such instances must contain a member of ACE_Dynamic_Service_Dependency + * initialized with the service they depend on. + * ACE_Dynamic_Service_Dependency's constructor and destructor are + * "magical" - they work by maintaining the underlying dynamic service's + * DLL reference count. + */ +class ACE_Export ACE_Dynamic_Service_Dependency +{ +public: + ACE_Dynamic_Service_Dependency (const ACE_Service_Gestalt *cfg, + const ACE_TCHAR *principal); + ACE_Dynamic_Service_Dependency (const ACE_TCHAR *principal); + ~ACE_Dynamic_Service_Dependency (void); + +private: + void init (const ACE_Service_Gestalt *cfg, const ACE_TCHAR *principal); + +private: + ACE_DLL tracker_; +}; + +ACE_END_VERSIONED_NAMESPACE_DECL + + +#include /**/ "ace/post.h" + +#endif /* ACE_DYNAMIC_SERVICE_DEPENDENCY_H */ |