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  6. <meta name="generator" content="HTML Tidy for Linux/x86 (vers 12 April 2005), see www.w3.org" />
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  7. <title>Tree Order Statistics Timing Test</title>
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  11. <div id="page">
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  12. <h1>Tree Order-Statistics Timing Test</h1>
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  13. <h2><a name="description" id="description">Description</a></h2>
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  14. <p>This test creates a container, inserts random integers into
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  15.     the the container, and then checks the order-statistics of the
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  16.     container's values. (If the container is one of <tt>pb_ds</tt>
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  17.     's trees, it does this with the <tt>order_of_key</tt> method of
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  18.     <a href="tree_order_statistics_node_update.html"><tt>tree_order_statistics_node_update</tt></a>
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  19.     ; otherwise, it uses the <tt>find</tt> method and
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  20.     <tt>std::distance</tt> .) It measures the average time for such
    21. 

  21.     queries as a function of the number of values inserted.</p>
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  22. <p>(The test was executed with <a href="http://gcc.gnu.org/viewcvs/*checkout*/trunk/libstdc%2B%2B-v3/testsuite/performance/ext/pb_ds/tree_order_statistics_timing.cc"><tt>tree_order_statistics_timing_test</tt></a>
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  23.     200 200 2100)</p>
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  24. <h2><a name="purpose" id="purpose">Purpose</a></h2>
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  25. <p>The test checks the performance difference of policies based
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  26.     on node-invariant as opposed to a external functions. (see
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  27.     <a href="tree_based_containers.html#invariants">Design::Associative
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  28.     Containers::Tree-Based Containers::Node Invariants</a> .)</p>
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  29. <h2><a name="results" id="results">Results</a></h2>
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  30. <p>Figures <a href="#NTG">NTG</a>, <a href="#NTM">NTM</a>, and
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  31.     <a href="#NTL">NTL</a> show the results for the native and
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  32.     tree-based containers in <a href="assoc_performance_tests.html#gcc"><u>g++</u></a>, <a href="assoc_performance_tests.html#msvc"><u>msvc++</u></a>, and
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  33.     <a href="assoc_performance_tests.html#local"><u>local</u></a>,
    34. 

  34.     respectively.</p>
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  35. <div id="NTG_res_div">
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  36. <div id="NTG_gcc">
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  37. <div id="NTG_tree_order_statistics_timing_test">
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  38. <div id="NTG_assoc">
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  39. <div id="NTG_Native_and_tree-based_container_order-statistics_queries"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NTG" id="NTG"><img src="tree_order_statistics_timing_test_gcc.png" alt="no image" /></a></h6>NTG: Native and tree-based container order-statistics queries - <a href="assoc_performance_tests.html#gcc">g++</a><p>In the above figure, the names in the legends have the following meaning:</p>
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  40. <ol>
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  41. <li>
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  42. n_set-
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  43. <tt>std::set</tt></li>
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  44. <li>
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  45. splay_tree_ost_set-
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  46. <a href="tree.html"><tt>tree</tt></a>
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  47.  with <tt>Tag</tt> = <a href="splay_tree_tag.html"><tt>splay_tree_tag</tt></a>
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  48. , and <tt>Node_Update</tt> = <a href="tree_order_statistics_node_update.html"><tt>tree_order_statistics_node_update</tt></a>
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  49. </li>
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  50. <li>
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  51. rb_tree_ost_set-
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  52. <a href="tree.html"><tt>tree</tt></a>
    53. 

  53.  with <tt>Tag</tt> = <a href="rb_tree_tag.html"><tt>rb_tree_tag</tt></a>
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  54. , and <tt>Node_Update</tt> = <a href="tree_order_statistics_node_update.html"><tt>tree_order_statistics_node_update</tt></a>
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  55. </li>
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  56. </ol>
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  57. </div><div style="width: 100%; height: 20px"></div></div>
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  58. </div>
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  59. </div>
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  60. </div>
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  61. </div>
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  62. <div id="NTM_res_div">
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  63. <div id="NTM_msvc">
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  64. <div id="NTM_tree_order_statistics_timing_test">
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  65. <div id="NTM_assoc">
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  66. <div id="NTM_Native_and_tree-based_container_order-statistics_queries"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NTM" id="NTM"><img src="tree_order_statistics_timing_test_msvc.png" alt="no image" /></a></h6>NTM: Native and tree-based container order-statistics queries - <a href="assoc_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in the legends have the following meaning:</p>
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  67. <ol>
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  68. <li>
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  69. n_set-
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  70. <tt>std::set</tt></li>
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  71. <li>
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  72. splay_tree_ost_set-
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  73. <a href="tree.html"><tt>tree</tt></a>
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  74.  with <tt>Tag</tt> = <a href="splay_tree_tag.html"><tt>splay_tree_tag</tt></a>
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  75. , and <tt>Node_Update</tt> = <a href="tree_order_statistics_node_update.html"><tt>tree_order_statistics_node_update</tt></a>
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  76. </li>
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  77. <li>
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  78. rb_tree_ost_set-
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  79. <a href="tree.html"><tt>tree</tt></a>
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  80.  with <tt>Tag</tt> = <a href="rb_tree_tag.html"><tt>rb_tree_tag</tt></a>
    81. 

  81. , and <tt>Node_Update</tt> = <a href="tree_order_statistics_node_update.html"><tt>tree_order_statistics_node_update</tt></a>
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  82. </li>
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  83. </ol>
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  84. </div><div style="width: 100%; height: 20px"></div></div>
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  85. </div>
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  86. </div>
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  87. </div>
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  88. </div>
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  89. <div id="NTL_res_div">
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  90. <div id="NTL_local">
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  91. <div id="NTL_tree_order_statistics_timing_test">
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  92. <div id="NTL_assoc">
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  93. <div id="NTL_Native_and_tree-based_container_order-statistics_queries"><div style = "border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NTL" id= "NTL"><img src="tree_order_statistics_timing_test_local.png" alt="no image" /></a></h6>NTL: Native and tree-based container order-statistics queries - <a href = "assoc_performance_tests.html#local">local</a></div><div style = "width: 100%; height: 20px"></div></div>
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  94. </div>
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  95. </div>
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  96. </div>
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  97. </div>
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  98. <h2><a name="observations" id="observations">Observations</a></h2>
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  99. <p>In this test, the native red-black tree can support
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  100.     order-statistics queries only externally, by performing a
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  101.     <tt>find</tt> (alternatively, <tt>lower_bound</tt> or
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  102.     <tt>upper_bound</tt> ) and then using <tt>std::distance</tt> .
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  103.     This is clearly linear, and it is not that surprising that the
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  104.     cost is high.</p>
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  105. <p><tt>pb_ds</tt> 's tree-based containers use in this test the
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  106.     <tt>order_of_key</tt> method of <a href="tree_order_statistics_node_update.html"><tt>tree_order_statistics_node_update</tt></a>.
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  107.     This method has only linear complexity in the length of the
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  108.     root-node path. Unfortunately, the average path of a splay tree
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  109.     (<a href="tree.html"><tt>tree</tt></a>
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  110.     with <tt>Tag =</tt> <a href="splay_tree_tag.html"><tt>splay_tree_tag</tt></a> ) can
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  111.     be higher than logarithmic; the longest path of a red-black
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  112.     tree (<a href="tree.html"><tt>tree</tt></a>
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  113.     with <tt>Tag =</tt> <a href="rb_tree_tag.html"><tt>rb_tree_tag</tt></a> ) is
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  114.     logarithmic in the number of elements. Consequently, the splay
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  115.     tree has worse performance than the red-black tree.</p>
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