l4/pkg/libstdc++-v3/contrib/libstdc++-v3-4.7/doc/html/manual/bk01pt03ch30s03.html

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   3 <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Use</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.76.1"/><meta name="keywords" content="&#10;      ISO C++&#10;    , &#10;      library&#10;    "/><meta name="keywords" content="&#10;      ISO C++&#10;    , &#10;      library&#10;    "/><meta name="keywords" content="&#10;      ISO C++&#10;    , &#10;      runtime&#10;    , &#10;      library&#10;    "/><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><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Use</th></tr><tr><td align="left"><a accesskey="p" href="bk01pt03ch30s02.html">Prev</a> </td><th width="60%" align="center">Chapter 30. Concurrency</th><td 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"><a id="manual.ext.concurrency.use"/>Use</h2></div></div></div><p>Typical usage of the last two constructs is demonstrated as follows:
   4 </p><pre class="programlisting">
   5 #include &lt;ext/concurrence.h&gt;
   6
   7 namespace
   8 {
   9   __gnu_cxx::__mutex safe_base_mutex;
  10 } // anonymous namespace
  11
  12 namespace other
  13 {
  14   void
  15   foo()
  16   {
  17     __gnu_cxx::__scoped_lock sentry(safe_base_mutex);
  18     for (int i = 0; i &lt; max;  ++i)
  19       {
  20         _Safe_iterator_base* __old = __iter;
  21         __iter = __iter-&lt;_M_next;
  22         __old-&lt;_M_detach_single();
  23       }
  24 }
  25 </pre><p>In this sample code, an anonymous namespace is used to keep
  26 the <code class="code">__mutex</code> private to the compilation unit,
  27 and <code class="code">__scoped_lock</code> is used to guard access to the critical
  28 section within the for loop, locking the mutex on creation and freeing
  29 the mutex as control moves out of this block.
  30 </p><p>Several exception classes are used to keep track of
  31 concurrence-related errors. These classes
  32 are: <code class="code">__concurrence_lock_error</code>, <code class="code">__concurrence_unlock_error</code>, <code class="code">__concurrence_wait_error</code>,
  33 and <code class="code">__concurrence_broadcast_error</code>.
  34 </p></div><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td align="left"><a accesskey="p" href="bk01pt03ch30s02.html">Prev</a> </td><td align="center"><a accesskey="u" href="ext_concurrency.html">Up</a></td><td align="right"> <a accesskey="n" href="bk01pt04.html">Next</a></td></tr><tr><td align="left" valign="top">Implementation </td><td align="center"><a accesskey="h" href="../index.html">Home</a></td><td align="right" valign="top"> Part IV.
  35   Appendices
  36 </td></tr></table></div></body></html>