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<h1 align=center>QSemaphore Class Reference</h1><br clear="all">
<p>
The QSemaphore class provides a robust integer semaphore.
<a href="#details">More...</a>
<p>
<code>#include <<a href="qthread-h.html">qthread.h</a>></code>
<p>
Inherits <a href="qt.html">Qt</a>.
<p><a href="qsemaphore-members.html">List of all member functions.</a>
<h2>Public Members</h2>
<ul>
<li><div class="fn"><a href="#713da9"><b>QSemaphore</b></a>(int)</div>
<li><div class="fn">virtual<a href="#ef3e81"><b>~QSemaphore</b></a>()</div>
<li><div class="fn">int<a href="#6ad36b"><b>available</b></a>()const</div>
<li><div class="fn">int<a href="#82a09e"><b>total</b></a>()const</div>
<li><div class="fn">int<a href="#b67829"><b>operator++</b></a>(int)</div>
<li><div class="fn">int<a href="#d55d93"><b>operator--</b></a>(int)</div>
<li><div class="fn">int<a href="#a1e515"><b>operator+=</b></a>(int)</div>
<li><div class="fn">int<a href="#bc4995"><b>operator-=</b></a>(int)</div>
</ul>
<hr><h2><a name="details"></a>Detailed Description</h2>
The QSemaphore class provides a robust integer semaphore.
<p>
QSemaphore can be used to serialize thread execution, similar to a
<a href="qmutex.html">QMutex</a>. A semaphore differs from a mutex, in that a semaphore can be
accessed by more than one thread at a time.
<p>An example would be an application that stores data in a large tree
structure. The application creates 10 threads (commonly called a
thread pool) to do searches on the tree. When the application searches
the tree for some piece of data, it uses one thread per base node to
do the searching. A semaphore could be used to make sure that 2 threads
don't try to search the same branch of the tree.
<p>A real world example of a semaphore would be dining at a restuarant.
A semaphore initialized to have a maximum count equal to the number
of chairs in the restuarant. As people arrive, they want a seat. As
seats are filled, the semaphore is accessed, once per person. As people
leave, the access is released, allowing more people to enter. If a
party of 10 people want to be seated, but there are only 9 seats, those
10 people will wait, but a party of 4 people would be seated (taking
the available seats to 5, making the party of 10 people wait longer).
<hr><h2>Member Function Documentation</h2>
<h3 class="fn"><a name="713da9"></a>QSemaphore::QSemaphore(intmaxcount)</h3>
<p>Creates a new semaphore. The semaphore can be concurrently accessed at
most <em>maxcount</em> times.
<h3 class="fn"><a name="ef3e81"></a>QSemaphore::~QSemaphore() <code>[virtual]</code></h3>
<p>Destroys the semaphore.
<h3 class="fn">int<a name="6ad36b"></a>QSemaphore::available()const</h3>
<p>This function returns the number of accesses currently available to
the semaphore.
<h3 class="fn">int<a name="b67829"></a>QSemaphore::operator++(int)</h3>
<p>Postfix ++ operator.
<p>Try to get access to the semaphore. If <a href="#6ad36b">available()</a> is >= <a href="#82a09e">total()</a>,
this call will block until it can get access.
<h3 class="fn">int<a name="a1e515"></a>QSemaphore::operator+=(int<a href="n.html">n</a>)</h3>
<p>Try to get access to the semaphore. If <a href="#6ad36b">available()</a> is >= <a href="#82a09e">total()</a>,
the calling thread blocks until it can get access. The calling will
only get access from the semaphore if it can get all <em><a href="n.html">n</a></em> accesses
at once.
<h3 class="fn">int<a name="d55d93"></a>QSemaphore::operator--(int)</h3>
<p>Postfix -- operator.
<p>Release access of the semaphore. This wakes all threads waiting for
access to the semaphore.
<h3 class="fn">int<a name="bc4995"></a>QSemaphore::operator-=(int<a href="n.html">n</a>)</h3>
<p>Release <em><a href="n.html">n</a></em> accesses to the semaphore.
<h3 class="fn">int<a name="82a09e"></a>QSemaphore::total()const</h3>
<p>This function returns the total number of accesses to the semaphore.
<hr><p>
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