l4/pkg/libstdc++-v3/contrib/libstdc++-v3-4.3.3/doc/html/ext/pb_ds/hash_random_int_erase_mem_usage_test.html

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  12 <h1>Hash-Based Erase Memory-Use Test</h1>
  13 <h2><a name="description" id="description">Description</a></h2>
  14 <p>This test inserts a number of uniform i.i.d. integer keys
  15     into a container, then erases all keys except one. It measures
  16     the final size of the container.</p>
  17 <p>(The test was executed with <a href="../../../../testsuite/performance/ext/pb_ds/hash_random_int_erase_mem_usage.cc"><tt>hash_random_int_erase_mem_usage.cc</tt></a>
  18     2000 2000 2100)</p>
  19 <h2><a name="purpose" id="purpose">Purpose</a></h2>
  20 <p>The test checks how containers adjust internally as their
  21     logical size decreases (see <a href="motivation.html#assoc_ers_methods">Motivation::Associative
  22     Containers::Slightly Different Methods::Methods Related to
  23     Erase</a>).</p>
  24 <h2><a name="results" id="results">Results</a></h2>
  25 <p>Figures <a href="#NHG">NHG</a>, <a href="#NHM">NHM</a> and
  26     <a href="#NHL">NHL</a> show the results for the native and
  27     collision-chaining types in <a href="assoc_performance_tests.html#gcc"><u>g++</u></a>, <a href="assoc_performance_tests.html#msvc"><u>msvc++</u></a> and
  28     <a href="assoc_performance_tests.html#local"><u>local</u></a>,
  29     respectively.</p>
  30 <div id="NHG_res_div">
  31 <div id="NHG_gcc">
  32 <div id="NHG_hash_random_int_erase_mem_usage_test">
  33 <div id="NHG_assoc">
  34 <div id="NHG_Native_456_collision-chaing_456_and_probing_456_hash_random_int_erase_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NHG" id="NHG"><img src="hash_random_int_erase_mem_usage_test_gcc.png" alt="no image" /></a></h6>NHG: Native, collision-chaing, and probing, hash random int erase test - <a href="assoc_performance_tests.html#gcc">g++</a><p>In the above figure, the names in the legends have the following meaning:</p>
  35 <ol>
  36 <li>
  37 n_hash_set_ncah-
  38 <tt>std::tr1::unordered_set</tt> with <tt>cache_hash_code</tt> = <tt><b>false</b></tt></li>
  39 <li>
  40 gp_hash_mask_linp_exp_nea_lc_1div8_1div2_nsth_set-
  41 <a href="gp_hash_table.html"><tt>gp_hash_table</tt></a>
  42  with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
  43 , <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
  44  with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
  45 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
  46  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/2</i>, and <tt>Probe_Fn</tt> = <a href="linear_probe_fn.html"><tt>linear_probe_fn</tt></a>
  47 </li>
  48 <li>
  49 cc_hash_mod_prime_nea_lc_1div8_1div1_nsth_set-
  50 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
  51 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mod_range_hashing.html"><tt>direct_mod_range_hashing</tt></a>
  52 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
  53  with <tt>Size_Policy</tt> = <a href="hash_prime_size_policy.html"><tt>hash_prime_size_policy</tt></a>
  54 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
  55  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/1</i></li>
  56 <li>
  57 cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_set-
  58 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
  59 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
  60 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
  61  with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
  62 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
  63  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/2</i></li>
  64 </ol>
  65 </div><div style="width: 100%; height: 20px"></div></div>
  66 </div>
  67 </div>
  68 </div>
  69 </div>
  70 <div id="NHM_res_div">
  71 <div id="NHM_msvc">
  72 <div id="NHM_hash_random_int_erase_mem_usage_test">
  73 <div id="NHM_assoc">
  74 <div id="NHM_Native_456_collision-chaing_456_and_probing_456_hash_random_int_erase_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NHM" id="NHM"><img src="hash_random_int_erase_mem_usage_test_msvc.png" alt="no image" /></a></h6>NHM: Native, collision-chaing, and probing, hash random int erase test - <a href="assoc_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in the legends have the following meaning:</p>
  75 <ol>
  76 <li>
  77 n_hash_set_ncah-
  78 <tt>stdext::hash_set</tt></li>
  79 <li>
  80 gp_hash_mask_linp_exp_nea_lc_1div8_1div2_nsth_set-
  81 <a href="gp_hash_table.html"><tt>gp_hash_table</tt></a>
  82  with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
  83 , <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
  84  with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
  85 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
  86  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/2</i>, and <tt>Probe_Fn</tt> = <a href="linear_probe_fn.html"><tt>linear_probe_fn</tt></a>
  87 </li>
  88 <li>
  89 cc_hash_mod_prime_nea_lc_1div8_1div1_nsth_set-
  90 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
  91 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mod_range_hashing.html"><tt>direct_mod_range_hashing</tt></a>
  92 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
  93  with <tt>Size_Policy</tt> = <a href="hash_prime_size_policy.html"><tt>hash_prime_size_policy</tt></a>
  94 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
  95  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/1</i></li>
  96 <li>
  97 cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_set-
  98 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
  99 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
 100 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
 101  with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
 102 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
 103  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/2</i></li>
 104 </ol>
 105 </div><div style="width: 100%; height: 20px"></div></div>
 106 </div>
 107 </div>
 108 </div>
 109 </div>
 110 <div id="NHM_res_div">
 111 <div id="NHM_msvc">
 112 <div id="NHM_hash_random_int_erase_mem_usage_test">
 113 <div id="NHM_assoc">
 114 <div id="NHM_Native_456_collision-chaing_456_and_probing_456_hash_random_int_erase_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NHM" id="NHM"><img src="hash_random_int_erase_mem_usage_test_msvc.png" alt="no image" /></a></h6>NHM: Native, collision-chaing, and probing, hash random int erase test - <a href="assoc_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in the legends have the following meaning:</p>
 115 <ol>
 116 <li>
 117 n_hash_set_ncah-
 118 <tt>stdext::hash_set</tt></li>
 119 <li>
 120 gp_hash_mask_linp_exp_nea_lc_1div8_1div2_nsth_set-
 121 <a href="gp_hash_table.html"><tt>gp_hash_table</tt></a>
 122  with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
 123 , <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
 124  with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
 125 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
 126  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/2</i>, and <tt>Probe_Fn</tt> = <a href="linear_probe_fn.html"><tt>linear_probe_fn</tt></a>
 127 </li>
 128 <li>
 129 cc_hash_mod_prime_nea_lc_1div8_1div1_nsth_set-
 130 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
 131 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mod_range_hashing.html"><tt>direct_mod_range_hashing</tt></a>
 132 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
 133  with <tt>Size_Policy</tt> = <a href="hash_prime_size_policy.html"><tt>hash_prime_size_policy</tt></a>
 134 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
 135  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/1</i></li>
 136 <li>
 137 cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_set-
 138 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
 139 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
 140 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
 141  with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
 142 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
 143  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/2</i></li>
 144 </ol>
 145 </div><div style="width: 100%; height: 20px"></div></div>
 146 </div>
 147 </div>
 148 </div>
 149 </div>
 150 <div id="NHL_res_div">
 151 <div id="NHL_local">
 152 <div id="NHL_hash_random_int_erase_mem_usage_test">
 153 <div id="NHL_assoc">
 154 <div id="NHL_Native_456_collision-chaing_456_and_probing_456_hash_random_int_erase_test"><div style = "border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NHL" id= "NHL"><img src="hash_random_int_erase_mem_usage_test_local.png" alt="no image" /></a></h6>NHL: Native, collision-chaing, and probing, hash random int erase test - <a href = "assoc_performance_tests.html#local">local</a></div><div style = "width: 100%; height: 20px"></div></div>
 155 </div>
 156 </div>
 157 </div>
 158 </div>
 159 <h2><a name="observations" id="observations">Observations</a></h2>
 160 <p>STL hash-based containers act very differently than trees in
 161     this respect. When erasing numerous keys from an STL
 162     associative-container, the resulting memory user varies greatly
 163     depending on whether the container is tree-based or hash-based.
 164     As noted in <a href="motivation.html#assoc_methods">Motivation::Choice of
 165     Methods</a> , this is a fundamental consequence of the STL's
 166     associative containers' interface, it is not due to a specific
 167     implementation.</p>
 168 <p>(See <a href="priority_queue_text_pop_mem_usage_test.html">Priority Queue
 169     Text <tt>pop</tt> Memory Use Test</a> for a similar phenomenon
 170     regarding priority queues.)</p>
 171 </div>
 172 </body>
 173 </html>