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  26 <div class="titlepage"><div><div><h5 class="title">
  27 <a name="boost_asio.reference.basic_socket.native_non_blocking.overload3"></a><a class="link" href="overload3.html" title="basic_socket::native_non_blocking (3 of 3 overloads)">basic_socket::native_non_blocking
  28           (3 of 3 overloads)</a>
  29 </h5></div></div></div>
  30 <p>
  31             Sets the non-blocking mode of the native socket implementation.
  32           </p>
  33 <pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="identifier">native_non_blocking</span><span class="special">(</span>
  34     <span class="keyword">bool</span> <span class="identifier">mode</span><span class="special">,</span>
  35     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="special">&amp;</span> <span class="identifier">ec</span><span class="special">);</span>
  36 </pre>
  37 <p>
  38             This function is used to modify the non-blocking mode of the underlying
  39             native socket. It has no effect on the behaviour of the socket object's
  40             synchronous operations.
  41           </p>
  42 <h6>
  43 <a name="boost_asio.reference.basic_socket.native_non_blocking.overload3.h0"></a>
  44             <span><a name="boost_asio.reference.basic_socket.native_non_blocking.overload3.parameters"></a></span><a class="link" href="overload3.html#boost_asio.reference.basic_socket.native_non_blocking.overload3.parameters">Parameters</a>
  45           </h6>
  46 <div class="variablelist">
  47 <p class="title"><b></b></p>
  48 <dl>
  49 <dt><span class="term">mode</span></dt>
  50 <dd><p>
  51                   If <code class="computeroutput"><span class="keyword">true</span></code>, the underlying
  52                   socket is put into non-blocking mode and direct system calls may
  53                   fail with <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">error</span><span class="special">::</span><span class="identifier">would_block</span></code>
  54                   (or the equivalent system error).
  55                 </p></dd>
  56 <dt><span class="term">ec</span></dt>
  57 <dd><p>
  58                   Set to indicate what error occurred, if any. If the <code class="computeroutput"><span class="identifier">mode</span></code> is <code class="computeroutput"><span class="keyword">false</span></code>,
  59                   but the current value of <code class="computeroutput"><span class="identifier">non_blocking</span><span class="special">()</span></code> is <code class="computeroutput"><span class="keyword">true</span></code>,
  60                   this function fails with <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">error</span><span class="special">::</span><span class="identifier">invalid_argument</span></code>,
  61                   as the combination does not make sense.
  62                 </p></dd>
  63 </dl>
  64 </div>
  65 <h6>
  66 <a name="boost_asio.reference.basic_socket.native_non_blocking.overload3.h1"></a>
  67             <span><a name="boost_asio.reference.basic_socket.native_non_blocking.overload3.example"></a></span><a class="link" href="overload3.html#boost_asio.reference.basic_socket.native_non_blocking.overload3.example">Example</a>
  68           </h6>
  69 <p>
  70             This function is intended to allow the encapsulation of arbitrary non-blocking
  71             system calls as asynchronous operations, in a way that is transparent
  72             to the user of the socket object. The following example illustrates how
  73             Linux's <code class="computeroutput"><span class="identifier">sendfile</span></code> system
  74             call might be encapsulated:
  75           </p>
  76 <pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Handler</span><span class="special">&gt;</span>
  77 <span class="keyword">struct</span> <span class="identifier">sendfile_op</span>
  78 <span class="special">{</span>
  79   <span class="identifier">tcp</span><span class="special">::</span><span class="identifier">socket</span><span class="special">&amp;</span> <span class="identifier">sock_</span><span class="special">;</span>
  80   <span class="keyword">int</span> <span class="identifier">fd_</span><span class="special">;</span>
  81   <span class="identifier">Handler</span> <span class="identifier">handler_</span><span class="special">;</span>
  82   <span class="identifier">off_t</span> <span class="identifier">offset_</span><span class="special">;</span>
  83   <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">total_bytes_transferred_</span><span class="special">;</span>
  84
  85   <span class="comment">// Function call operator meeting WriteHandler requirements.</span>
  86   <span class="comment">// Used as the handler for the async_write_some operation.</span>
  87   <span class="keyword">void</span> <span class="keyword">operator</span><span class="special">()(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="identifier">ec</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">)</span>
  88   <span class="special">{</span>
  89     <span class="comment">// Put the underlying socket into non-blocking mode.</span>
  90     <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">ec</span><span class="special">)</span>
  91       <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">sock_</span><span class="special">.</span><span class="identifier">native_non_blocking</span><span class="special">())</span>
  92         <span class="identifier">sock_</span><span class="special">.</span><span class="identifier">native_non_blocking</span><span class="special">(</span><span class="keyword">true</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
  93
  94     <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">ec</span><span class="special">)</span>
  95     <span class="special">{</span>
  96       <span class="keyword">for</span> <span class="special">(;;)</span>
  97       <span class="special">{</span>
  98         <span class="comment">// Try the system call.</span>
  99         <span class="identifier">errno</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>
 100         <span class="keyword">int</span> <span class="identifier">n</span> <span class="special">=</span> <span class="special">::</span><span class="identifier">sendfile</span><span class="special">(</span><span class="identifier">sock_</span><span class="special">.</span><span class="identifier">native_handle</span><span class="special">(),</span> <span class="identifier">fd_</span><span class="special">,</span> <span class="special">&amp;</span><span class="identifier">offset_</span><span class="special">,</span> <span class="number">65536</span><span class="special">);</span>
 101         <span class="identifier">ec</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">(</span><span class="identifier">n</span> <span class="special">&lt;</span> <span class="number">0</span> <span class="special">?</span> <span class="identifier">errno</span> <span class="special">:</span> <span class="number">0</span><span class="special">,</span>
 102             <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">error</span><span class="special">::</span><span class="identifier">get_system_category</span><span class="special">());</span>
 103         <span class="identifier">total_bytes_transferred_</span> <span class="special">+=</span> <span class="identifier">ec</span> <span class="special">?</span> <span class="number">0</span> <span class="special">:</span> <span class="identifier">n</span><span class="special">;</span>
 104
 105         <span class="comment">// Retry operation immediately if interrupted by signal.</span>
 106         <span class="keyword">if</span> <span class="special">(</span><span class="identifier">ec</span> <span class="special">==</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">error</span><span class="special">::</span><span class="identifier">interrupted</span><span class="special">)</span>
 107           <span class="keyword">continue</span><span class="special">;</span>
 108
 109         <span class="comment">// Check if we need to run the operation again.</span>
 110         <span class="keyword">if</span> <span class="special">(</span><span class="identifier">ec</span> <span class="special">==</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">error</span><span class="special">::</span><span class="identifier">would_block</span>
 111             <span class="special">||</span> <span class="identifier">ec</span> <span class="special">==</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">error</span><span class="special">::</span><span class="identifier">try_again</span><span class="special">)</span>
 112         <span class="special">{</span>
 113           <span class="comment">// We have to wait for the socket to become ready again.</span>
 114           <span class="identifier">sock_</span><span class="special">.</span><span class="identifier">async_write_some</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">null_buffers</span><span class="special">(),</span> <span class="special">*</span><span class="keyword">this</span><span class="special">);</span>
 115           <span class="keyword">return</span><span class="special">;</span>
 116         <span class="special">}</span>
 117
 118         <span class="keyword">if</span> <span class="special">(</span><span class="identifier">ec</span> <span class="special">||</span> <span class="identifier">n</span> <span class="special">==</span> <span class="number">0</span><span class="special">)</span>
 119         <span class="special">{</span>
 120           <span class="comment">// An error occurred, or we have reached the end of the file.</span>
 121           <span class="comment">// Either way we must exit the loop so we can call the handler.</span>
 122           <span class="keyword">break</span><span class="special">;</span>
 123         <span class="special">}</span>
 124
 125         <span class="comment">// Loop around to try calling sendfile again.</span>
 126       <span class="special">}</span>
 127     <span class="special">}</span>
 128
 129     <span class="comment">// Pass result back to user's handler.</span>
 130     <span class="identifier">handler_</span><span class="special">(</span><span class="identifier">ec</span><span class="special">,</span> <span class="identifier">total_bytes_transferred_</span><span class="special">);</span>
 131   <span class="special">}</span>
 132 <span class="special">};</span>
 133
 134 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Handler</span><span class="special">&gt;</span>
 135 <span class="keyword">void</span> <span class="identifier">async_sendfile</span><span class="special">(</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">socket</span><span class="special">&amp;</span> <span class="identifier">sock</span><span class="special">,</span> <span class="keyword">int</span> <span class="identifier">fd</span><span class="special">,</span> <span class="identifier">Handler</span> <span class="identifier">h</span><span class="special">)</span>
 136 <span class="special">{</span>
 137   <span class="identifier">sendfile_op</span><span class="special">&lt;</span><span class="identifier">Handler</span><span class="special">&gt;</span> <span class="identifier">op</span> <span class="special">=</span> <span class="special">{</span> <span class="identifier">sock</span><span class="special">,</span> <span class="identifier">fd</span><span class="special">,</span> <span class="identifier">h</span><span class="special">,</span> <span class="number">0</span><span class="special">,</span> <span class="number">0</span> <span class="special">};</span>
 138   <span class="identifier">sock</span><span class="special">.</span><span class="identifier">async_write_some</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">null_buffers</span><span class="special">(),</span> <span class="identifier">op</span><span class="special">);</span>
 139 <span class="special">}</span>
 140 </pre>
 141 </div>
 142 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 143 <td align="left"></td>
 144 <td align="right"><div class="copyright-footer">Copyright &#169; 2003-2012 Christopher M. Kohlhoff<p>
 145         Distributed under the Boost Software License, Version 1.0. (See accompanying
 146         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>)
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