ACE/ace/Managed_Object.h

   1 // -*- C++ -*-
   2
   3 //=============================================================================
   4 /**
   5  *  @file    Managed_Object.h
   6  *
   7  *  @author David L. Levine <levine@cs.wustl.edu>
   8  */
   9 //=============================================================================
  10
  11 #ifndef ACE_MANAGED_OBJECT_H
  12 #define ACE_MANAGED_OBJECT_H
  13
  14 #include /**/ "ace/pre.h"
  15
  16 #include /**/ "ace/config-all.h"
  17
  18 #if !defined (ACE_LACKS_PRAGMA_ONCE)
  19 # pragma once
  20 #endif /* ACE_LACKS_PRAGMA_ONCE */
  21
  22 #include "ace/Object_Manager.h"
  23 #include "ace/Global_Macros.h"
  24
  25 ACE_BEGIN_VERSIONED_NAMESPACE_DECL
  26
  27 /**
  28  * @class ACE_Cleanup_Adapter
  29  *
  30  * @brief Adapter for ACE_Cleanup objects that allows them to be readily
  31  * managed by the ACE_Object_Manager.
  32  *
  33  * This template class adapts an object of any type to be an
  34  * ACE_Cleanup object.  The object can then be destroyed
  35  * type-safely by the ACE_Object_Manager.  This class is
  36  * typically used to replace a cast; but, it's a bit cleaner and
  37  * allows insertion of, say, run-time type identification
  38  * internally if desired.
  39  */
  40 template <class TYPE>
  41 class ACE_Cleanup_Adapter : public ACE_Cleanup
  42 {
  43 public:
  44   /// Default constructor.
  45   ACE_Cleanup_Adapter ();
  46
  47   /// Virtual destructor, needed by some compilers for vtable placement.
  48   virtual ~ACE_Cleanup_Adapter ();
  49
  50   /// Accessor for contained object.
  51   TYPE &object ();
  52
  53 private:
  54   ACE_Cleanup_Adapter (const ACE_Cleanup_Adapter<TYPE> &) = delete;
  55   void operator= (const ACE_Cleanup_Adapter<TYPE> &) = delete;
  56
  57   /// Contained object.
  58   TYPE object_;
  59 };
  60
  61 /**
  62  * @class ACE_Managed_Object
  63  *
  64  * @brief Wrapper for interface to allocate an object managed by the
  65  * ACE_Object_Manager.
  66  *
  67  * This template class wraps an interface that is used to
  68  * allocate and access an object that is managed by the
  69  * ACE_Object_Manager.  Because static template member functions
  70  * are not supported by some compilers, it is a separate
  71  * (template) class.
  72  * This interface is typically used to replace a static object
  73  * with one that is dynamically allocated.  It helps to avoid
  74  * problems with order of static object
  75  * construction/destruction.  Managed objects won't be allocated
  76  * until needed, but should be allocated when first needed.  And
  77  * they are destroyed in the reverse order of construction.
  78  * <get_preallocated_object> accesses a "preallocated" object,
  79  * i.e., one that is identified by a value in the
  80  * ACE_Object_Manager:: Preallocated_Object enum.  These objects
  81  * are used internally by the ACE library.
  82  * Hooks are provided for the application to preallocate objects
  83  * via the same mechanism.
  84  * ACE_APPLICATION_PREALLOCATED_OBJECT_DECLARATIONS can be used
  85  * to define enum values;
  86  * ACE_APPLICATION_PREALLOCATED_OBJECT_DEFINITIONS can be used
  87  * to define the corresponding objects.  The format of the ACE
  88  * internal library definitions should be followed.  And
  89  * similarly, ACE_APPLICATION_PREALLOCATED_ARRAY_DECLARATIONS
  90  * and ACE_APPLICATION_PREALLOCATED_ARRAY_DEFINITIONS can be
  91  * used to preallocate arrays.
  92  * By default, preallocation uses dynamic allocation.  The
  93  * preallocated objects and arrays are allocated off the heap in
  94  * the ACE_Object_Manager constructor.  To statically place the
  95  * preallocated objects in program global data instead of on the
  96  * heap, #define ACE_HAS_STATIC_PREALLOCATION prior to building
  97  * the ACE library.
  98  */
  99 template <class TYPE>
 100 class ACE_Managed_Object
 101 {
 102 public:
 103   /// Get the preallocated object identified by "id".  Returns a
 104   /// pointer to the object.  Beware: no error indication is provided,
 105   /// because it can _only_ be used for accessing preallocated objects.
 106   static TYPE *get_preallocated_object (ACE_Object_Manager::Preallocated_Object identifier)
 107   {
 108     // The preallocated objects are in a separate, "read-only" array so
 109     // that this function doesn't need a lock.  Also, because it is
 110     // intended _only_ for use with hard-code values, it performs no
 111     // range checking on "id".
 112
 113     // Cast the return type of the the object pointer based
 114     // on the type of the function template parameter.
 115     return &((ACE_Cleanup_Adapter<TYPE> *)
 116              ACE_Object_Manager::preallocated_object[identifier])->object ();
 117   }
 118   /// Get the preallocated array identified by "id".  Returns a
 119   /// pointer to the array.  Beware: no error indication is provided,
 120   /// because it can _only_ be used for accessing preallocated arrays.
 121   static TYPE *get_preallocated_array (ACE_Object_Manager::Preallocated_Array identifier)
 122   {
 123     // The preallocated array are in a separate, "read-only" array so
 124     // that this function doesn't need a lock.  Also, because it is
 125     // intended _only_ for use with hard-code values, it performs no
 126     // range checking on "id".
 127
 128     // Cast the return type of the the object pointer based
 129     // on the type of the function template parameter.
 130     return &((ACE_Cleanup_Adapter<TYPE> *)
 131              ACE_Object_Manager::preallocated_array[identifier])->object ();
 132   }
 133
 134 protected:
 135   // Disallow instantiation of this class.
 136   ACE_Managed_Object () = delete;
 137
 138 private:
 139   ACE_Managed_Object (const ACE_Managed_Object<TYPE> &) = delete;
 140   void operator= (const ACE_Managed_Object<TYPE> &) = delete;
 141 };
 142
 143 ACE_END_VERSIONED_NAMESPACE_DECL
 144
 145 #if defined (__ACE_INLINE__)
 146 #include "ace/Managed_Object.inl"
 147 #endif /* __ACE_INLINE__ */
 148
 149 #include "ace/Managed_Object.cpp"
 150
 151 #include /**/ "ace/post.h"
 152
 153 #endif /* ACE_MANAGED_OBJECT_H */