1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Implementations: fcontext_t, ucontext_t and WinFiber</title> 5<link rel="stylesheet" href="../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../index.html" title="Chapter 1. Context"> 8<link rel="up" href="../ff.html" title="Context switching with fibers"> 9<link rel="prev" href="../ff.html" title="Context switching with fibers"> 10<link rel="next" href="class__fiber_.html" title="Class fiber"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="../ff.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../ff.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="class__fiber_.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h3 class="title"> 27<a name="context.ff.implementations__fcontext_t__ucontext_t_and_winfiber"></a><a name="implementation"></a><a class="link" href="implementations__fcontext_t__ucontext_t_and_winfiber.html" title="Implementations: fcontext_t, ucontext_t and WinFiber">Implementations: 28 fcontext_t, ucontext_t and WinFiber</a> 29</h3></div></div></div> 30<h5> 31<a name="context.ff.implementations__fcontext_t__ucontext_t_and_winfiber.h0"></a> 32 <span class="phrase"><a name="context.ff.implementations__fcontext_t__ucontext_t_and_winfiber.fcontext_t"></a></span><a class="link" href="implementations__fcontext_t__ucontext_t_and_winfiber.html#context.ff.implementations__fcontext_t__ucontext_t_and_winfiber.fcontext_t">fcontext_t</a> 33 </h5> 34<p> 35 The implementation uses <span class="emphasis"><em>fcontext_t</em></span> per default. fcontext_t 36 is based on assembler and not available for all platforms. It provides a 37 much better performance than <span class="emphasis"><em>ucontext_t</em></span> (the context 38 switch takes two magnitudes of order less CPU cycles; see section <a class="link" href="../performance.html#performance"><span class="emphasis"><em>performance</em></span></a>) 39 and <span class="emphasis"><em>WinFiber</em></span>. 40 </p> 41<div class="note"><table border="0" summary="Note"> 42<tr> 43<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td> 44<th align="left">Note</th> 45</tr> 46<tr><td align="left" valign="top"><p> 47 Because the TIB (thread information block on Windows) is not fully described 48 in the MSDN, it might be possible that not all required TIB-parts are swapped. 49 Using WinFiber implementation migh be an alternative. 50 </p></td></tr> 51</table></div> 52<h5> 53<a name="context.ff.implementations__fcontext_t__ucontext_t_and_winfiber.h1"></a> 54 <span class="phrase"><a name="context.ff.implementations__fcontext_t__ucontext_t_and_winfiber.ucontext_t"></a></span><a class="link" href="implementations__fcontext_t__ucontext_t_and_winfiber.html#context.ff.implementations__fcontext_t__ucontext_t_and_winfiber.ucontext_t">ucontext_t</a> 55 </h5> 56<p> 57 As an alternative, <a href="https://en.wikipedia.org/wiki/Setcontext" target="_top"><span class="emphasis"><em>ucontext_t</em></span></a> 58 can be used by compiling with <code class="computeroutput"><span class="identifier">BOOST_USE_UCONTEXT</span></code> 59 and b2 property <code class="computeroutput"><span class="identifier">context</span><span class="special">-</span><span class="identifier">impl</span><span class="special">=</span><span class="identifier">ucontext</span></code>. 60 <span class="emphasis"><em>ucontext_t</em></span> might be available on a broader range of 61 POSIX-platforms but has some <a class="link" href="../rationale/other_apis_.html#ucontext"><span class="emphasis"><em>disadvantages</em></span></a> 62 (for instance deprecated since POSIX.1-2003, not C99 conform). 63 </p> 64<div class="note"><table border="0" summary="Note"> 65<tr> 66<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td> 67<th align="left">Note</th> 68</tr> 69<tr><td align="left" valign="top"><p> 70 <a class="link" href="../ff.html#ff"><span class="emphasis"><em>fiber</em></span></a> supports <a class="link" href="../stack/segmented.html#segmented"><span class="emphasis"><em>Segmented 71 stacks</em></span></a> only with <span class="emphasis"><em>ucontext_t</em></span> as its 72 implementation. 73 </p></td></tr> 74</table></div> 75<h5> 76<a name="context.ff.implementations__fcontext_t__ucontext_t_and_winfiber.h2"></a> 77 <span class="phrase"><a name="context.ff.implementations__fcontext_t__ucontext_t_and_winfiber.winfiber"></a></span><a class="link" href="implementations__fcontext_t__ucontext_t_and_winfiber.html#context.ff.implementations__fcontext_t__ucontext_t_and_winfiber.winfiber">WinFiber</a> 78 </h5> 79<p> 80 With <code class="computeroutput"><span class="identifier">BOOST_USE_WINFIB</span></code> and 81 b2 property <code class="computeroutput"><span class="identifier">context</span><span class="special">-</span><span class="identifier">impl</span><span class="special">=</span><span class="identifier">winfib</span></code> 82 Win32-Fibers are used as implementation for <a class="link" href="../ff.html#ff"><span class="emphasis"><em>fiber</em></span></a>. 83 </p> 84<div class="note"><table border="0" summary="Note"> 85<tr> 86<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td> 87<th align="left">Note</th> 88</tr> 89<tr><td align="left" valign="top"><p> 90 The first call of <a class="link" href="../ff.html#ff"><span class="emphasis"><em>fiber</em></span></a> 91 converts the thread into a Windows fiber by invoking <code class="computeroutput"><span class="identifier">ConvertThreadToFiber</span><span class="special">()</span></code>. If desired, <code class="computeroutput"><span class="identifier">ConvertFiberToThread</span><span class="special">()</span></code> has to be called by the user explicitly 92 in order to release resources allocated by <code class="computeroutput"><span class="identifier">ConvertThreadToFiber</span><span class="special">()</span></code> (e.g. after using boost.context). 93 </p></td></tr> 94</table></div> 95</div> 96<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 97<td align="left"></td> 98<td align="right"><div class="copyright-footer">Copyright © 2014 Oliver Kowalke<p> 99 Distributed under the Boost Software License, Version 1.0. (See accompanying 100 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 101 </p> 102</div></td> 103</tr></table> 104<hr> 105<div class="spirit-nav"> 106<a accesskey="p" href="../ff.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../ff.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="class__fiber_.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 107</div> 108</body> 109</html> 110
