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reference_counting.htm

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  1. <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/1999/REC-html401-19991224/strict.dtd">
    2. 

  2. <html><head>
    3. 

  3. <title>reference_counting</title>
    4. 

  4. </head><body>
    5. 

  5. <p>[<a href="mxdoc.htm">mainpage</a>]
    6. 

  6. [<a href="tags.htm">tags</a>]<br>
    7. 

  7. <h1>tag: reference_counting</h1><ul><li>
    8. 

  8. <a name="MX_ATOM"><code>MX_ATOM</code></a>
    9. 

  9. <p>
    10. 

  10. <p><b>Base class for reference counting and delete locking</b><p>
    11. 

  11. 

  12. MX_ATOM is an object intended to be used as a base class to
    13. 

  13. implement reference counting and delete locking in the derived class.
    14. 

  14. <p>
    15. 

  15. Properly constructed MX_ATOM objects are bit-copy-correct which means that
    16. 

  16. a binary copy retains proper functioning.  The copied object should not be
    17. 

  17. used after the binary copy.
    18. 

  18. <p>
    19. 

  19. Because MX_ATOM is bit-copy-correct it can safely be placed in a MX_VECTOR
    20. 

  20. or the memory realloc'd.  
    21. 

  21. (<a href="../include/deds/atom.h">../include/deds/atom.h</a>)<br>(library <a href="deds.htm">deds</a> : module <a href="deds_atom.htm">atom</a>)
    22. 

  22. <p></li>
    23. 

  23. <li>
    24. 

  24. <a name=" define mx_atom(a,d,s)"><code># define mx_atom(a,d,s)</code></a>
    25. 

  25. <p>
    26. 

  26. <p><b>Construct an MX_ATOM</b><p>
    27. 

  27. This macro constructs a MX_ATOM which is a base object for reference counting.  
    28. 

  28. (<a href="../include/deds/atom.h">../include/deds/atom.h</a>)<br>(library <a href="deds.htm">deds</a> : module <a href="deds_atom.htm">atom</a>)
    29. 

  29. <p></li>
    30. 

  30. <li>
    31. 

  31. <a name=" define mx_delete(a)"><code># define mx_delete(a)</code></a>
    32. 

  32. <p>
    33. 

  33. <p><b>Destroy an MX_ATOM</b><p>
    34. 

  34. This macro causes an object to be marked for destruction.  If no locks (MX_LOCK)
    35. 

  35. or references (MX_REF) exist for this object then the object is destroyed and
    36. 

  36. if appropitae the memory is released.  
    37. 

  37. (<a href="../include/deds/atom.h">../include/deds/atom.h</a>)<br>(library <a href="deds.htm">deds</a> : module <a href="deds_atom.htm">atom</a>)
    38. 

  38. <p></li>
    39. 

  39. <li>
    40. 

  40. <a name=" define mx_locked(a)"><code># define mx_locked(a)</code></a>
    41. 

  41. <p>
    42. 

  42. <p><b>Find out if an object is locked or not  </b><p>
    43. 

  43. (<a href="../include/deds/atom.h">../include/deds/atom.h</a>)<br>(library <a href="deds.htm">deds</a> : module <a href="deds_atom.htm">atom</a>)
    44. 

  44. <p></li>
    45. 

  45. <li>
    46. 

  46. <a name="MX_LOCK"><code>MX_LOCK</code></a>
    47. 

  47. <p>
    48. 

  48. <p><b>Stop MX_ATOMs from getting deleted</b><p>
    49. 

  49. This object implements a delete lock for an MX_ATOM.  While a valid 
    50. 

  50. MX_LOCK exists for an MX_ATOM object (or one derived from it) the
    51. 

  51. object is guaranteed not be deleted.  An object can have multiple locks
    52. 

  52. placed on it. <p>
    53. 

  53. MX_LOCK is NOT bit-copy-correct so it cannot safely be placed in a MX_VECTOR
    54. 

  54. or in memory that gets realloc'd.  
    55. 

  55. (<a href="../include/deds/atom.h">../include/deds/atom.h</a>)<br>(library <a href="deds.htm">deds</a> : module <a href="deds_atom.htm">atom</a>)
    56. 

  56. <p></li>
    57. 

  57. <li>
    58. 

  58. <a name=" define mx_lock(l,a)"><code># define mx_lock(l,a)</code></a>
    59. 

  59. <p>
    60. 

  60. <p><b>Construct a MX_LOCK</b><p>
    61. 

  61. This macro creates a lock for an object derived from MX_ATOM.  The locked 
    62. 

  62. MX_ATOM is guaranteed not to be deleted while a valid lock exists.  
    63. 

  63. (<a href="../include/deds/atom.h">../include/deds/atom.h</a>)<br>(library <a href="deds.htm">deds</a> : module <a href="deds_atom.htm">atom</a>)
    64. 

  64. <p></li>
    65. 

  65. <li>
    66. 

  66. <a name="unsigned mx_unlock(MX_LOCK* lock)"><code>unsigned mx_unlock(MX_LOCK* lock)</code></a>
    67. 

  67. <p>
    68. 

  68. <p><b>Destruct a MX_LOCK</b><p>
    69. 

  69. This function destroys a MX_LOCK and removes it from it's associated
    70. 

  70. MX_ATOM object.  If the object has been flagged for deletion (with the
    71. 

  71. mx_delete() macro) then removal of the last lock caused the MX_ATOM
    72. 

  72. destructor to be called and (if necessary) memory returned to the operating
    73. 

  73. system.
    74. 

  74. <p>
    75. 

  75. If the release of the lock triggered calling of the object destructor then
    76. 

  76. the function returns non-zero.  If this occurs then it is not safe to access
    77. 

  77. the object anymore.  If this function returns false then either:<ol>
    78. 

  78. <li>Other locks exist for the object.</li>
    79. 

  79. <li>The object hasn't been deleted yet.</li>
    80. 

  80. </ol>In either case you can still safely access the object after the unlock.  
    81. 

  81. (<a href="../include/deds/atom.h">../include/deds/atom.h</a>)<br>(library <a href="deds.htm">deds</a> : module <a href="deds_atom.htm">atom</a>)
    82. 

  82. <p></li>
    83. 

  83. <li>
    84. 

  84. <a name="unsigned mx_lastlock(const MX_LOCK* lock)"><code>unsigned mx_lastlock(const MX_LOCK* lock)</code></a>
    85. 

  85. <p>
    86. 

  86. <p><b>Find out if a lock is the last one of an object  </b><p>
    87. 

  87. (<a href="../include/deds/atom.h">../include/deds/atom.h</a>)<br>(library <a href="deds.htm">deds</a> : module <a href="deds_atom.htm">atom</a>)
    88. 

  88. <p></li>
    89. 

  89. <li>
    90. 

  90. <a name=" define MX_REF(type)"><code># define MX_REF(type)</code></a>
    91. 

  91. <p>
    92. 

  92. <p><b>A reference type, a typed MX_LOCK</b><p>
    93. 

  93. This macro defines a MX_LOCK where the target is of some defined type.
    94. 

  94. A reference functions the same way as a MX_LOCK except the locked (i.e. referenced)
    95. 

  95. object is available in a typesafe way.  A pointer to the reference target is
    96. 

  96. available with the MXREF macro.   
    97. 

  97. (<a href="../include/deds/atom.h">../include/deds/atom.h</a>)<br>(library <a href="deds.htm">deds</a> : module <a href="deds_atom.htm">atom</a>)
    98. 

  98. <p></li>
    99. 

  99. <li>
    100. 

  100. <a name=" define mx_ref(r,t)"><code># define mx_ref(r,t)</code></a>
    101. 

  101. <p>
    102. 

  102. <p><b>Construct a MX_REF</b><p>
    103. 

  103. The macro constructs a MX_REF to an object.  
    104. 

  104. (<a href="../include/deds/atom.h">../include/deds/atom.h</a>)<br>(library <a href="deds.htm">deds</a> : module <a href="deds_atom.htm">atom</a>)
    105. 

  105. <p></li>
    106. 

  106. <li>
    107. 

  107. <a name=" define mx_unref(r)"><code># define mx_unref(r)</code></a>
    108. 

  108. <p>
    109. 

  109. <p><b>Destruct a MX_REF</b><p>
    110. 

  110. The macro destroys a MX_REF to an object.  The object may
    111. 

  111. be deleted in the dereference, see the mx_unlock() macro.  
    112. 

  112. (<a href="../include/deds/atom.h">../include/deds/atom.h</a>)<br>(library <a href="deds.htm">deds</a> : module <a href="deds_atom.htm">atom</a>)
    113. 

  113. <p></li>
    114. 

  114. <li>
    115. 

  115. <a name=" define MXREF(r)"><code># define MXREF(r)</code></a>
    116. 

  116. <p>
    117. 

  117. <p><b>Return the object behind a MX_REF</b><p>
    118. 

  118. Return the object behind the MX_REF to an object.  
    119. 

  119. (<a href="../include/deds/atom.h">../include/deds/atom.h</a>)<br>(library <a href="deds.htm">deds</a> : module <a href="deds_atom.htm">atom</a>)
    120. 

  120. <p></li>
    121. 

  121. </ul><p>Generated by <a href="http://www.deleveld.dds.nl/mxdoc/index.htm">MXDOC</a> 2.2 on Sun Feb  4 15:16:26 2007
    122. 

  122. 

  123. 

  124. </body></html>
    125. 

  125.