Ichthyostega
d6167c1845
This is borderline yet acceptable; A service might indeed depend on itself circularly The concrete example is the Advice-System, which needs to push the clean-up of AdviceProvicions into a static context. From there the deleters need to call back into the AdviceSystem, since they have no wey to find out, if this is an individual Advice being retracted, or a mass-cleanup due to system shutdown. Thus the DependencyFactory now invokes the actual deleter prior to setting the instance-Ptr to NULL. This sidesteps the whole issue with the ClassLock, which actually must be already destroyed at that point, according to the C++ standard. (since it was created on-demand, on first actual usage, *after* the DependencyFactory was statically initialised). A workaround would be to have the ctor of DependencyFactory actively pull and allocate the Monitor for the ClassLock; however this seems a bit overingeneered to deal with such a borderline issue
87 lines
3.1 KiB
C++
87 lines
3.1 KiB
C++
/*
|
|
SYNC-CLASSLOCK.hpp - special case of object based locking tied directly to a type
|
|
|
|
Copyright (C) Lumiera.org
|
|
2008, Christian Thaeter <ct@pipapo.org>
|
|
Hermann Vosseler <Ichthyostega@web.de>
|
|
|
|
This program is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU General Public License as
|
|
published by the Free Software Foundation; either version 2 of
|
|
the License, or (at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; if not, write to the Free Software
|
|
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
|
|
|
*/
|
|
|
|
/** @file sync-classlock.hpp
|
|
** A special implementation of lib::Sync, where the storage of the object monitor
|
|
** is associated directly to a type rather then to a single object instance. While
|
|
** being problematic in conjunction with static startup/shutdown, doing so is sometimes
|
|
** necessary to setup type based dispatcher tables, managing singleton creation etc.
|
|
**
|
|
** @note simply using the ClassLock may cause a Monitor object (with a mutex) to be
|
|
** created at static initialisation and destroyed on application shutdown.
|
|
** @see depend.hpp usage example
|
|
** @see SyncClasslock_test
|
|
*/
|
|
|
|
|
|
#ifndef LIB_SYNC_CLASSLOCK_H
|
|
#define LIB_SYNC_CLASSLOCK_H
|
|
|
|
#include "lib/nobug-init.hpp"
|
|
#include "lib/zombie-check.hpp"
|
|
#include "lib/sync.hpp"
|
|
|
|
|
|
namespace lib {
|
|
|
|
|
|
/**
|
|
* A synchronisation protection guard employing a lock scoped
|
|
* to the parameter type as a whole, not an individual instance.
|
|
* After creating an instance, every other access specifying the same
|
|
* type is blocked.
|
|
* @note the Lock is recursive, because several instances within the same
|
|
* thread may want to acquire it at the same time without deadlock.
|
|
* @note there is a design sloppiness, as two instantiations of the
|
|
* ClassLock template with differing CONF count as different type.
|
|
* Actually using two different configurations within for a single
|
|
* class X should be detected and flagged as error, but actually
|
|
* just two non-shared lock instances get created silently. Beware!
|
|
* @see Sync::Lock the usual simple instance-bound variant
|
|
*/
|
|
template<class X, class CONF = RecursiveLock_NoWait>
|
|
class ClassLock
|
|
: public Sync<CONF>::Lock
|
|
{
|
|
typedef typename Sync<CONF>::Lock Lock;
|
|
typedef typename sync::Monitor<CONF> Monitor;
|
|
|
|
struct PerClassMonitor : Monitor {};
|
|
|
|
Monitor&
|
|
getPerClassMonitor()
|
|
{
|
|
static PerClassMonitor classMonitor;
|
|
static ZombieCheck zombieCheck;
|
|
|
|
zombieCheck();
|
|
return classMonitor;
|
|
}
|
|
|
|
public:
|
|
ClassLock() : Lock (getPerClassMonitor()) { }
|
|
};
|
|
|
|
|
|
} // namespace lib
|
|
#endif /*LIB_SYNC_CLASSLOCK_H*/
|