73 lines
2.6 KiB
C
73 lines
2.6 KiB
C
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/**
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* PANDA 3D SOFTWARE
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* Copyright (c) Carnegie Mellon University. All rights reserved.
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*
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* All use of this software is subject to the terms of the revised BSD
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* license. You should have received a copy of this license along
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* with this source code in a file named "LICENSE."
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*
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* @file globalPointerRegistry.h
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* @author drose
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* @date 2000-02-03
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*/
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#ifndef GLOBALPOINTERREGISTRY_H
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#define GLOBALPOINTERREGISTRY_H
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#include "pandabase.h"
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#include "typedObject.h"
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#include "pmap.h"
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/**
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* This class maintains a one-to-one mapping from TypeHandle to a void *
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* pointer. Its purpose is to store a pointer to some class data for a given
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* class.
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*
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* Normally, one would simply use a static data member to store class data.
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* However, when the static data is associated with a template class, the
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* dynamic loader may have difficulty in properly resolving the statics.
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*
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* Consider: class foo<int> defines a static member, _a. There should be only
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* one instance of _a shared between all instances of foo<int>, and there will
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* be a different instance of _a shared between all instances of foo<float>.
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*
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* Now suppose that two different shared libraries instantiate foo<int>. In
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* each .so, there exists a different foo<int>::_a. It is the loader's job to
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* recognize this and collapse them together when both libraries are loaded.
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* This usually works, but sometimes it doesn't, and you end up with two
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* different instances of foo<int>::_a; some functions see one instance, while
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* others see the other. We have particularly seen this problem occur under
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* Linux with gcc.
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*
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* This class attempts to circumvent the problem by managing pointers to data
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* based on TypeHandle. Since the TypeHandle will already be unique based on
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* the string name supplied to the init_type() function, it can be used to
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* differentiate foo<int> from foo<float>, while allowing different instances
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* of foo<int> to guarantee that they share the same static data.
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*/
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class EXPCL_PANDA_PUTIL GlobalPointerRegistry {
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public:
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INLINE static void *get_pointer(TypeHandle type);
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INLINE static void store_pointer(TypeHandle type, void *ptr);
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INLINE static void clear_pointer(TypeHandle type);
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private:
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// Nonstatic implementations of the above functions.
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void *ns_get_pointer(TypeHandle type) const;
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void ns_store_pointer(TypeHandle type, void *ptr);
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void ns_clear_pointer(TypeHandle type);
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INLINE static GlobalPointerRegistry *get_global_ptr();
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static GlobalPointerRegistry *_global_ptr;
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private:
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typedef phash_map<TypeHandle, void *> Pointers;
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Pointers _pointers;
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};
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#include "globalPointerRegistry.I"
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#endif
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