Hi,

I have the following requirement,

Data shall be received at runtime from network, this data has an unique ID/Key
associated with it, say 100 or 103

Many such data can come over a period of time and it can come for the
for the same Key or different Keys. This data has to be displayed in
a GUI and capacity to store a maximum of 50 such data for a given Key
has to be provided.

Request to delete all the data associated with a Key, comes asynchronously
at runtime, which should clear all the data held for that Key.

To implement this i have used QHash

Qt Code: 
  1. QHash<int, QVector<TTrack> *> hash_for_track;
  2. class TTrack
  3. {
  4.   public:
  5.     TTrack();
  6.  
  7.     ~TTrack()
  8.     {
  9.  
  10.     }
  11.     int operator==(TTrack other);
  12.  
  13.     unsigned short track_number:12;
  14.     unsigned short reserved:4;
  15.  
  16.     unsigned char  track_status;
  17.     unsigned char track_status_ext;
  18.     signed short x_comp;
  19.     signed short y_comp;
  20.     signed short height;
  21.  
  22.     unsigned short calculated_ground_speed;
  23.     unsigned short calculated_heading;
  24.     UINT16 flight_level:14;
  25.     UINT16 flt_lvl_garbel:1;
  26.     UINT16 flt_lvl_validity:1;
  27.     unsigned short rho;
  28.     unsigned short theta;
  29.     UINT16 Mode1Code:5;
  30.     UINT16 Mode1CodeMatch:1;
  31.     UINT16 Mode1Garbel:1;
  32.     UINT16 Mode1Validity:1;
  33.     UINT16 Mode2Code:12;
  34.     UINT16 Mode2Confidencel:1;
  35.     UINT16 Mode2CodeMatch:1;
  36.     UINT16 Mode2Garbel:1;
  37.     UINT16 Mode2Validity:1;
  38.     UINT16 Mode3ACode:12;
  39.     UINT16 Mode3AConfidencel:1;
  40.     UINT16 Mode3ACodeMatch:1;
  41.     UINT16 Mode3AGarbel:1;
  42.     UINT16 Mode3AValidity:1;
  43. //Code match
  44. /*
  45.     This is to hold the Code match
  46.     Info for the New Track
  47. */
  48.     bool mode1_code_match;
  49.     bool mode2_code_match;
  50.     bool mode3_code_match;
  51.     bool code_match;
  52. };
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And the functions are
a. "track_dbase(TTrack local_track)"
One to store all the data related to New Key/ Old Key
b. "On_TrackDeleteSignal(const S_TRACK_DELETE_MSG &resp) "
Delete all the data associated with a Key


Function Implementation:
Qt Code: 
  1. void CircleWidget::track_dbase(TTrack local_track)
  2. {
  3. 	QHash<int, QVector<TTrack> *>::const_iterator iter_for_track_hash;
  4.  
  5. 	UINT16 key = 0;
  6. 	key = local_track.track_number;
  7.  
  8. 	/*
  9. 	 * 16-Oct-2009
  10. 	 * Track number is only 12 bits
  11. 	 * so bit wise AND with this value
  12. 	 */
  13. 	key = key & 0x0FFF;
  14.  
  15. 	if (hash_for_track.isEmpty() ==true)
  16. 	{
  17. 		/* no key exists in the hash so diretly insert the key and pointer to the track data
  18. 		 into the HASH
  19. 		 */
  20.  
  21. 		m_vtrack_ptr = new QVector<TTrack>;
  22. 		if (m_vtrack_ptr ==NULL)
  23. 		{
  24. 		}
  25. 		else
  26. 		{
  27. 			m_vtrack_ptr->append(local_track);
  28. 			hash_for_track.insert(key, m_vtrack_ptr);
  29. 		}
  30. 	}
  31. 	else
  32. 	{
  33.  
  34. 		if (trial_enabled == 0)
  35. 		{
  36. 			/*here we dont have store the trial details for all the tracks
  37. 			 only one element needs to be there in the vector of each
  38. 			 trackid
  39. 			 */
  40. 			number_of_points_in_vector = 1;
  41.  
  42. 		} //end of if trial enabled
  43. 		else
  44. 		{
  45. 			/* check to see if the key exists in the hash_for_track table
  46. 			 */
  47. 			number_of_points_in_vector = ELEMENTS_IN_TRACK_DBASE;
  48. 		}
  49.  
  50. 		if (hash_for_track.contains(key) == false)
  51. 		{
  52. 			/*
  53. 			 update the vector wtth the current track data
  54. 			 insert the (key,value) into the hash
  55. 			 */
  56.  
  57. 			m_vtrack_ptr = new QVector<TTrack>;
  58. 			if (m_vtrack_ptr ==NULL)
  59. 			{
  60. 			}
  61. 			else
  62. 			{
  63. 				m_vtrack_ptr->append(local_track);
  64. 				hash_for_track.insert(key, m_vtrack_ptr);
  65. 			}
  66.  
  67. 		} //end of if key is not present
  68. 		else
  69. 		{
  70.  
  71. 			/*hash table already has the key specified retreive the correcsponding value and then
  72. 			 update the vector
  73. 			 */
  74.  
  75. 			/*
  76. 			 here come and append into the vector
  77. 			 if the size is less than 50
  78.  
  79. 			 if the size is equal to 50 then remove the element at index 0 and then apend
  80. 			 because at any instant i need only 50 elements in the vector.
  81. 			 */
  82. 			iter_for_track_hash = hash_for_track.find(key);
  83. 			QVector<TTrack>* m_vtrack_ptr_alreadyinhash =
  84. 					iter_for_track_hash.value();
  85. 			if (m_vtrack_ptr_alreadyinhash == NULL)
  86. 			{
  87. 			}
  88. 			else
  89. 			{
  90. 				if (m_vtrack_ptr_alreadyinhash->size()
  91. 						< number_of_points_in_vector)
  92. 				{
  93. 					m_vtrack_ptr_alreadyinhash->append(local_track);
  94. 				}
  95. 				else
  96. 				{
  97. 					m_vtrack_ptr_alreadyinhash->remove(0);
  98. 					m_vtrack_ptr_alreadyinhash->append(local_track);
  99. 				}
  100. 			}
  101. 		}
  102. 	}
  103. }
  104.  
  105. void QCSurveillance::On_TrackDeleteSignal(const S_TRACK_DELETE_MSG &resp)
  106. {
  107. 	int number_trackdel = -1;
  108.  
  109. 	if (hm->m_gen.m_cwid->hash_for_track.isEmpty() == false)
  110. 	{
  111. 		//Find the key in the Hash Table if found then delete
  112. 		if (hm->m_gen.m_cwid->hash_for_track.contains(resp.track_id) == true)
  113. 		{
  114.  
  115. 			number_trackdel
  116. 					= hm->m_gen.m_cwid->hash_for_track.remove(resp.track_id);
  117. 			if (number_trackdel==0)
  118. 				if (RDSDEBUG)
  119. 					qWarning("Delete Failed %d", resp.track_id);
  120. 				else
  121. 					;
  122.  
  123. 		}
  124. 		else
  125. 		{
  126. 			;
  127. 		}
  128. 	}
  129. 	else
  130. 	{
  131. 		qDebug("Track Delete warning: No track in the database");
  132. 	}
  133. }
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Problem:
Application consumes memory continuosly, to debug the same i used Valgrind, which reported memory leak errors in the "new" operator used in the function "track_dbase".

I have removed the element in the hash using "remove" function for the given key in function "On_TrackDeleteSignal". Still i get memory leak error.

Query:
1. Is there any problem in the way i have used "new" operator in "track_dbase" function?
2.Does "remove" for a key in Hash remove all the memory explicitly used by value in the function "On_TrackDeleteSignal" ?
3. I have not defined the function "int operator==(TTrack other);" is it necessary to do it, and can this be a source of error?

I have limited time to solve this issue ... Kindly looking forward response from the community