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<h1>Module pqueue</h1>
<ul class="index"><li><a href="#description">Description</a></li><li><a href="#types">Data Types</a></li><li><a href="#index">Function Index</a></li><li><a href="#functions">Function Details</a></li></ul>
<h3><a name="Static_Priority_Queue.">Static Priority Queue.</a></h3>
This priority queue implementation depends on a static number of priorities
(-20 (high) to 20 (low)) so that tuple access times can be exploited for
quick in/out priority queue operations.
<p>Copyright © 2011-2017 Michael Truog</p>
<p><b>Version:</b> 1.7.1 May 31 2017 14:15:05
------------------------------------------------------------------------</p>
<p><b>Authors:</b> Michael Truog (<a href="mailto:mjtruog [at] gmail (dot) com"><tt>mjtruog [at] gmail (dot) com</tt></a>).</p>
<h2><a name="description">Description</a></h2>
<h3><a name="Static_Priority_Queue.">Static Priority Queue.</a></h3>
This priority queue implementation depends on a static number of priorities
(-20 (high) to 20 (low)) so that tuple access times can be exploited for
quick in/out priority queue operations. This implementation was created to
avoid the slowness within the priority queue used by both RabbitMQ and Riak
(https://github.com/basho/riak_core/blob/master/src/priority_queue.erl).
<h2><a name="types">Data Types</a></h2>
<h3 class="typedecl"><a name="type-pqueue">pqueue()</a></h3>
<p><tt>pqueue() = {integer(), {<a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>}, {<a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>}, {<a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>}, <a href="queue.html#type-queue">queue:queue()</a>, {<a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>}, {<a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>}, {<a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>}} | {empty, {<a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>}, {<a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>}, {<a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>}, <a href="queue.html#type-queue">queue:queue()</a>, {<a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>}, {<a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>}, {<a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>, <a href="queue.html#type-queue">queue:queue()</a>}}</tt></p>
<h2><a name="index">Function Index</a></h2>
<table width="100%" border="1" cellspacing="0" cellpadding="2" summary="function index"><tr><td valign="top"><a href="#in-2">in/2</a></td><td>
<h4><a name="Append_an_item_to_the_tail_of_the_0_priority_queue.">Append an item to the tail of the 0 priority queue.</a></h4>
O(1).</td></tr>
<tr><td valign="top"><a href="#in-3">in/3</a></td><td>
<h4><a name="Append_an_item_to_the_tail_of_a_specific_priority_queue.">Append an item to the tail of a specific priority queue.</a></h4>
O(1).</td></tr>
<tr><td valign="top"><a href="#is_empty-1">is_empty/1</a></td><td>
<h4><a name="Check_if_the_priority_queue_is_empty.">Check if the priority queue is empty.</a></h4>
O(1).</td></tr>
<tr><td valign="top"><a href="#is_queue-1">is_queue/1</a></td><td>
<h4><a name="Check_if_the_priority_queue_type_is_as_expected.">Check if the priority queue type is as expected.</a></h4>
O(1).</td></tr>
<tr><td valign="top"><a href="#join-2">join/2</a></td><td>
<h4><a name="Join_two_priority_queues.">Join two priority queues.</a></h4>
O(N).</td></tr>
<tr><td valign="top"><a href="#len-1">len/1</a></td><td>
<h4><a name="Determine_the_length_of_a_priority_queue.">Determine the length of a priority queue.</a></h4>
O(N).</td></tr>
<tr><td valign="top"><a href="#new-0">new/0</a></td><td>
<h4><a name="Create_a_new_priority_queue.">Create a new priority queue.</a></h4>
O(1).</td></tr>
<tr><td valign="top"><a href="#out-1">out/1</a></td><td>
<h4><a name="Take_an_item_from_the_head_of_the_priority_queue.">Take an item from the head of the priority queue.</a></h4>
O(1) amortized, O(N) worst case.</td></tr>
<tr><td valign="top"><a href="#out-2">out/2</a></td><td>
<h4><a name="Take_an_item_of_a_specific_priority_from_the_head_of_the_queue.">Take an item of a specific priority from the head of the queue.</a></h4>
O(1) amortized, O(N) worst case.</td></tr>
<tr><td valign="top"><a href="#pout-1">pout/1</a></td><td>
<h4><a name="Take_an_item_from_the_head_of_the_priority_queue.">Take an item from the head of the priority queue.</a></h4>
Includes the priority in the return value.</td></tr>
<tr><td valign="top"><a href="#test-0">test/0</a></td><td>
<h4><a name="Regression_test.">Regression test.</a></h4>.</td></tr>
<tr><td valign="top"><a href="#to_list-1">to_list/1</a></td><td>
<h4><a name="Convert_the_priority_queue_to_a_list.">Convert the priority queue to a list.</a></h4>
O(N).</td></tr>
</table>
<h2><a name="functions">Function Details</a></h2>
<h3 class="function"><a name="in-2">in/2</a></h3>
<div class="spec">
<p><tt>in(X::term(), Q::<a href="#type-pqueue">pqueue()</a>) -&gt; <a href="#type-pqueue">pqueue()</a></tt><br></p>
</div><p>
<h4><a name="Append_an_item_to_the_tail_of_the_0_priority_queue.">Append an item to the tail of the 0 priority queue.</a></h4>
O(1)</p>
<h3 class="function"><a name="in-3">in/3</a></h3>
<div class="spec">
<p><tt>in(X::term(), P::integer(), Q::<a href="#type-pqueue">pqueue()</a>) -&gt; <a href="#type-pqueue">pqueue()</a></tt><br></p>
</div><p>
<h4><a name="Append_an_item_to_the_tail_of_a_specific_priority_queue.">Append an item to the tail of a specific priority queue.</a></h4>
O(1)</p>
<h3 class="function"><a name="is_empty-1">is_empty/1</a></h3>
<div class="spec">
<p><tt>is_empty(X1::<a href="#type-pqueue">pqueue()</a>) -&gt; true | false</tt><br></p>
</div><p>
<h4><a name="Check_if_the_priority_queue_is_empty.">Check if the priority queue is empty.</a></h4>
O(1)</p>
<h3 class="function"><a name="is_queue-1">is_queue/1</a></h3>
<div class="spec">
<p><tt>is_queue(X1::<a href="#type-pqueue">pqueue()</a>) -&gt; true | false</tt><br></p>
</div><p>
<h4><a name="Check_if_the_priority_queue_type_is_as_expected.">Check if the priority queue type is as expected.</a></h4>
O(1)</p>
<h3 class="function"><a name="join-2">join/2</a></h3>
<div class="spec">
<p><tt>join(X1::<a href="#type-pqueue">pqueue()</a>, X2::<a href="#type-pqueue">pqueue()</a>) -&gt; <a href="#type-pqueue">pqueue()</a></tt><br></p>
</div><p>
<h4><a name="Join_two_priority_queues.">Join two priority queues.</a></h4>
O(N)</p>
<h3 class="function"><a name="len-1">len/1</a></h3>
<div class="spec">
<p><tt>len(X1::<a href="#type-pqueue">pqueue()</a>) -&gt; non_neg_integer()</tt><br></p>
</div><p>
<h4><a name="Determine_the_length_of_a_priority_queue.">Determine the length of a priority queue.</a></h4>
O(N)</p>
<h3 class="function"><a name="new-0">new/0</a></h3>
<div class="spec">
<p><tt>new() -&gt; <a href="#type-pqueue">pqueue()</a></tt><br></p>
</div><p>
<h4><a name="Create_a_new_priority_queue.">Create a new priority queue.</a></h4>
O(1)</p>
<h3 class="function"><a name="out-1">out/1</a></h3>
<div class="spec">
<p><tt>out(Q::<a href="#type-pqueue">pqueue()</a>) -&gt; {{value, term()}, <a href="#type-pqueue">pqueue()</a>} | {empty, <a href="#type-pqueue">pqueue()</a>}</tt><br></p>
</div><p>
<h4><a name="Take_an_item_from_the_head_of_the_priority_queue.">Take an item from the head of the priority queue.</a></h4>
O(1) amortized, O(N) worst case</p>
<h3 class="function"><a name="out-2">out/2</a></h3>
<div class="spec">
<p><tt>out(P::integer(), Q::<a href="#type-pqueue">pqueue()</a>) -&gt; {{value, term()}, <a href="#type-pqueue">pqueue()</a>} | {empty, <a href="#type-pqueue">pqueue()</a>}</tt><br></p>
</div><p>
<h4><a name="Take_an_item_of_a_specific_priority_from_the_head_of_the_queue.">Take an item of a specific priority from the head of the queue.</a></h4>
O(1) amortized, O(N) worst case</p>
<h3 class="function"><a name="pout-1">pout/1</a></h3>
<div class="spec">
<p><tt>pout(Q::<a href="#type-pqueue">pqueue()</a>) -&gt; {{value, term(), integer()}, <a href="#type-pqueue">pqueue()</a>} | {empty, <a href="#type-pqueue">pqueue()</a>}</tt><br></p>
</div><p>
<h4><a name="Take_an_item_from_the_head_of_the_priority_queue.">Take an item from the head of the priority queue.</a></h4>
Includes the priority in the return value.
O(1) amortized, O(N) worst case</p>
<h3 class="function"><a name="test-0">test/0</a></h3>
<div class="spec">
<p><tt>test() -&gt; any()</tt></p>
</div><p>
<h4><a name="Regression_test.">Regression test.</a></h4>
</p>
<h3 class="function"><a name="to_list-1">to_list/1</a></h3>
<div class="spec">
<p><tt>to_list(X1::<a href="#type-pqueue">pqueue()</a>) -&gt; [term()]</tt><br></p>
</div><p>
<h4><a name="Convert_the_priority_queue_to_a_list.">Convert the priority queue to a list.</a></h4>
O(N)</p>
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