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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
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<title>Priority Queue Text Join Timing Test</title>
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<body>
<div id="page">
<h1>Priority Queue Text <tt>join</tt> Timing Test</h1>
<h2><a name="description" id="description">Description</a></h2>
<p>This test inserts a number of values with keys from an
arbitrary text ([ <a href="references.html#wickland96thirty">wickland96thirty</a> ]) into
two containers, then merges the containers. It uses
<tt>join</tt> for <tt>pb_ds</tt>'s priority queues; for the
STL's priority queues, it successively pops values from one
container and pushes them into the other. The test measures the
average time as a function of the number of values.</p>
<p>(The test was executed with <a href="../../../../testsuite/performance/ext/pb_ds/priority_queue_text_join_timing.cc"><tt>priority_queue_text_join_timing_test</tt></a>
thirty_years_among_the_dead_preproc.txt 200 200 2100)</p>
<h2><a name="purpose" id="purpose">Purpose</a></h2>
<p>The test checks the effect of different underlying
data structures (see <a href="pq_design.html#pq_imp">Design::Priority
Queues::Implementations</a>).</p>
<h2><a name="results" id="results">Results</a></h2>
<p>Figures <a href="#NPG">NPG</a>, <a href="#NPM">NPM</a>, and
<a href="#NPL">NPL</a> show the results for the native priority
queues and <tt>pb_ds</tt> 's priority queues in <a href="pq_performance_tests.html#gcc"><u>g++</u></a>, <a href="pq_performance_tests.html#msvc"><u>msvc</u></a>, and <a href="pq_performance_tests.html#local"><u>local</u></a>,
respectively.</p>
<div id="NPG_res_div">
<div id="NPG_gcc">
<div id="NPG_priority_queue_text_join_timing_test">
<div id="NPG_pq">
<div id="NPG_Native_tree_and__tt_pb_ds_455tt__priority_queue__tt_push_455tt__timing_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NPG" id="NPG"><img src="priority_queue_text_join_timing_test_gcc.png" alt="no image" /></a></h6>NPG: Native tree and <tt>pb ds</tt> priority queue <tt>push</tt> timing test - <a href="pq_performance_tests.html#gcc">g++</a><p>In the above figure, the names in the legends have the following meaning:</p>
<ol>
<li>
n_pq_deque-
<tt>std::priority_queue</tt> adapting <tt>std::deque</tt></li>
<li>
n_pq_vector-
<tt>std::priority_queue</tt> adapting <tt>std::vector</tt></li>
<li>
binary_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="binary_heap_tag.html"><tt>binary_heap_tag</tt></a>
</li>
<li>
thin_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
</li>
<li>
rc_binomial_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="rc_binomial_heap_tag.html"><tt>rc_binomial_heap_tag</tt></a>
</li>
<li>
pairing_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
</li>
<li>
binomial_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="binomial_heap_tag.html"><tt>binomial_heap_tag</tt></a>
</li>
</ol>
</div><div style="width: 100%; height: 20px"></div></div>
</div>
</div>
</div>
</div>
<div id="NPM_res_div">
<div id="NPM_msvc">
<div id="NPM_priority_queue_text_join_timing_test">
<div id="NPM_pq">
<div id="NPM_Native_tree_and__tt_pb_ds_455tt__priority_queue__tt_push_455tt__timing_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NPM" id="NPM"><img src="priority_queue_text_join_timing_test_msvc.png" alt="no image" /></a></h6>NPM: Native tree and <tt>pb ds</tt> priority queue <tt>push</tt> timing test - <a href="pq_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in the legends have the following meaning:</p>
<ol>
<li>
n_pq_deque-
<tt>std::priority_queue</tt> adapting <tt>std::deque</tt></li>
<li>
n_pq_vector-
<tt>std::priority_queue</tt> adapting <tt>std::vector</tt></li>
<li>
binary_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="binary_heap_tag.html"><tt>binary_heap_tag</tt></a>
</li>
<li>
thin_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
</li>
<li>
rc_binomial_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="rc_binomial_heap_tag.html"><tt>rc_binomial_heap_tag</tt></a>
</li>
<li>
pairing_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
</li>
<li>
binomial_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="binomial_heap_tag.html"><tt>binomial_heap_tag</tt></a>
</li>
</ol>
</div><div style="width: 100%; height: 20px"></div></div>
</div>
</div>
</div>
</div>
<div id="NPL_res_div">
<div id="NPL_local">
<div id="NPL_priority_queue_text_join_timing_test">
<div id="NPL_pq">
<div id="NPL_Native_tree_and__tt_pb_ds_455tt__priority_queue__tt_push_455tt__timing_test"><div style = "border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NPL" id= "NPL"><img src="priority_queue_text_join_timing_test_local.png" alt="no image" /></a></h6>NPL: Native tree and <tt>pb ds</tt> priority queue <tt>push</tt> timing test - <a href = "pq_performance_tests.html#local">local</a></div><div style = "width: 100%; height: 20px"></div></div>
</div>
</div>
</div>
</div>
<h2><a name="observations" id="observations">Observations</a></h2>
<p>In this test the node-based heaps perform <tt>join</tt> in
either logarithmic or constant time. The binary heap requires
linear time, since the well-known heapify algorithm [<a href="references.html#clrs2001">clrs2001</a>] is linear.</p>
<p>It would be possible to apply the heapify algorithm to the
STL containers, if they would support iteration (which they
don't). Barring iterators, it is still somehow possible to
perform linear-time merge on a <tt>std::vector</tt>-based STL
priority queue, using <tt>top()</tt> and <tt>size()</tt> (since
they are enough to expose the underlying array), but this is
impossible for a <tt>std::deque</tt>-based STL priority queue.
Without heapify, the cost is super-linear.</p>
</div>
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