libstdc++-v3/doc/html/manual/bk01pt03ch30s03.html

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  15     "><link rel="home" href="../index.html" title="The GNU C++ Library"><link rel="up" href="ext_concurrency.html" title="Chapter 30. Concurrency"><link rel="prev" href="bk01pt03ch30s02.html" title="Implementation"><link rel="next" href="bk01pt04.html" title="Part IV.  Appendices"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Use</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="bk01pt03ch30s02.html">Prev</a> </td><th width="60%" align="center">Chapter 30. Concurrency</th><td width="20%" align="right"> <a accesskey="n" href="bk01pt04.html">Next</a></td></tr></table><hr></div><div class="section" title="Use"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="manual.ext.concurrency.use"></a>Use</h2></div></div></div><p>Typical usage of the last two constructs is demonstrated as follows:
  16 </p><pre class="programlisting">
  17 #include &lt;ext/concurrence.h&gt;
  18
  19 namespace
  20 {
  21   __gnu_cxx::__mutex safe_base_mutex;
  22 } // anonymous namespace
  23
  24 namespace other
  25 {
  26   void
  27   foo()
  28   {
  29     __gnu_cxx::__scoped_lock sentry(safe_base_mutex);
  30     for (int i = 0; i &lt; max;  ++i)
  31       {
  32         _Safe_iterator_base* __old = __iter;
  33         __iter = __iter-&lt;_M_next;
  34         __old-&lt;_M_detach_single();
  35       }
  36 }
  37 </pre><p>In this sample code, an anonymous namespace is used to keep
  38 the <code class="code">__mutex</code> private to the compilation unit,
  39 and <code class="code">__scoped_lock</code> is used to guard access to the critical
  40 section within the for loop, locking the mutex on creation and freeing
  41 the mutex as control moves out of this block.
  42 </p><p>Several exception classes are used to keep track of
  43 concurrence-related errors. These classes
  44 are: <code class="code">__concurrence_lock_error</code>, <code class="code">__concurrence_unlock_error</code>, <code class="code">__concurrence_wait_error</code>,
  45 and <code class="code">__concurrence_broadcast_error</code>.
  46 </p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="bk01pt03ch30s02.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ext_concurrency.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="bk01pt04.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Implementation </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Part IV.
  47   Appendices
  48 </td></tr></table></div></body></html>