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. Fiber"> 8<link rel="up" href="../overview.html" title="Overview"> 9<link rel="prev" href="../overview.html" title="Overview"> 10<link rel="next" href="../fiber_mgmt.html" title="Fiber management"> 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="../overview.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../overview.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="../fiber_mgmt.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="fiber.overview.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<p> 31 <span class="bold"><strong>Boost.Fiber</strong></span> uses <a href="http://www.boost.org/doc/libs/release/libs/context/doc/html/context/cc.html" target="_top"><span class="emphasis"><em>call/cc</em></span></a> 32 from <a href="http://www.boost.org/doc/libs/release/libs/context/index.html" target="_top">Boost.Context</a> 33 as building-block. 34 </p> 35<h5> 36<a name="fiber.overview.implementations__fcontext_t__ucontext_t_and_winfiber.h0"></a> 37 <span class="phrase"><a name="fiber.overview.implementations__fcontext_t__ucontext_t_and_winfiber.fcontext_t"></a></span><a class="link" href="implementations__fcontext_t__ucontext_t_and_winfiber.html#fiber.overview.implementations__fcontext_t__ucontext_t_and_winfiber.fcontext_t">fcontext_t</a> 38 </h5> 39<p> 40 The implementation uses <code class="computeroutput"><span class="identifier">fcontext_t</span></code> 41 per default. fcontext_t is based on assembler and not available for all platforms. 42 It provides a much better performance than <code class="computeroutput"><span class="identifier">ucontext_t</span></code> 43 (the context switch takes two magnitudes of order less CPU cycles; see section 44 <a href="http://www.boost.org/doc/libs/release/libs/context/doc/html/context/performance.html" target="_top"><span class="emphasis"><em>performance</em></span></a>) 45 and <code class="computeroutput"><span class="identifier">WinFiber</span></code>. 46 </p> 47<h5> 48<a name="fiber.overview.implementations__fcontext_t__ucontext_t_and_winfiber.h1"></a> 49 <span class="phrase"><a name="fiber.overview.implementations__fcontext_t__ucontext_t_and_winfiber.ucontext_t"></a></span><a class="link" href="implementations__fcontext_t__ucontext_t_and_winfiber.html#fiber.overview.implementations__fcontext_t__ucontext_t_and_winfiber.ucontext_t">ucontext_t</a> 50 </h5> 51<p> 52 As an alternative, <a href="https://en.wikipedia.org/wiki/Setcontext" target="_top"><code class="computeroutput"><span class="identifier">ucontext_t</span></code></a> can be used by compiling 53 with <code class="computeroutput"><span class="identifier">BOOST_USE_UCONTEXT</span></code> and 54 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>. 55 <code class="computeroutput"><span class="identifier">ucontext_t</span></code> might be available 56 on a broader range of POSIX-platforms but has some <a href="http://www.boost.org/doc/libs/release/libs/context/doc/html/context/rational.html#ucontext" target="_top"><span class="emphasis"><em>disadvantages</em></span></a> 57 (for instance deprecated since POSIX.1-2003, not C99 conform). 58 </p> 59<div class="note"><table border="0" summary="Note"> 60<tr> 61<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td> 62<th align="left">Note</th> 63</tr> 64<tr><td align="left" valign="top"><p> 65 <a href="http://www.boost.org/doc/libs/release/libs/context/doc/html/context/cc.html" target="_top"><span class="emphasis"><em>call/cc</em></span></a> 66 supports <a class="link" href="../stack.html#segmented"><span class="emphasis"><em>Segmented stacks</em></span></a> 67 only with <code class="computeroutput"><span class="identifier">ucontext_t</span></code> as 68 its implementation. 69 </p></td></tr> 70</table></div> 71<h5> 72<a name="fiber.overview.implementations__fcontext_t__ucontext_t_and_winfiber.h2"></a> 73 <span class="phrase"><a name="fiber.overview.implementations__fcontext_t__ucontext_t_and_winfiber.winfiber"></a></span><a class="link" href="implementations__fcontext_t__ucontext_t_and_winfiber.html#fiber.overview.implementations__fcontext_t__ucontext_t_and_winfiber.winfiber">WinFiber</a> 74 </h5> 75<p> 76 With <code class="computeroutput"><span class="identifier">BOOST_USE_WINFIB</span></code> and 77 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> 78 Win32-Fibers are used as implementation for <a href="http://www.boost.org/doc/libs/release/libs/context/doc/html/context/cc.html" target="_top"><span class="emphasis"><em>call/cc</em></span></a>. 79 </p> 80<p> 81 Because the TIB (thread information block) is not fully described in the 82 MSDN, it might be possible that not all required TIB-parts are swapped. 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 href="http://www.boost.org/doc/libs/release/libs/context/doc/html/context/cc.html" target="_top"><span class="emphasis"><em>call/cc</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 © 2013 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="../overview.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../overview.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="../fiber_mgmt.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 107</div> 108</body> 109</html> 110
