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| <div class="titlepage"><div><div><h5 class="title"> |
| <a name="boost_asio.reference.basic_socket_streambuf.native_non_blocking.overload1"></a><a class="link" href="overload1.html" title="basic_socket_streambuf::native_non_blocking (1 of 3 overloads)">basic_socket_streambuf::native_non_blocking |
| (1 of 3 overloads)</a> |
| </h5></div></div></div> |
| <p> |
| <span class="emphasis"><em>Inherited from basic_socket.</em></span> |
| </p> |
| <p> |
| Gets the non-blocking mode of the native socket implementation. |
| </p> |
| <pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">native_non_blocking</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> |
| </pre> |
| <p> |
| This function is used to retrieve the non-blocking mode of the underlying |
| native socket. This mode has no effect on the behaviour of the socket |
| object's synchronous operations. |
| </p> |
| <a name="boost_asio.reference.basic_socket_streambuf.native_non_blocking.overload1.return_value"></a><h6> |
| <a name="boost_asio.reference.basic_socket_streambuf.native_non_blocking.overload1.return_value-heading"></a> |
| <a class="link" href="overload1.html#boost_asio.reference.basic_socket_streambuf.native_non_blocking.overload1.return_value">Return |
| Value</a> |
| </h6> |
| <p> |
| <code class="computeroutput"><span class="keyword">true</span></code> if the underlying socket |
| is in non-blocking mode and direct system calls may 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> (or the equivalent system |
| error). |
| </p> |
| <a name="boost_asio.reference.basic_socket_streambuf.native_non_blocking.overload1.remarks"></a><h6> |
| <a name="boost_asio.reference.basic_socket_streambuf.native_non_blocking.overload1.remarks-heading"></a> |
| <a class="link" href="overload1.html#boost_asio.reference.basic_socket_streambuf.native_non_blocking.overload1.remarks">Remarks</a> |
| </h6> |
| <p> |
| The current non-blocking mode is cached by the socket object. Consequently, |
| the return value may be incorrect if the non-blocking mode was set directly |
| on the native socket. |
| </p> |
| <a name="boost_asio.reference.basic_socket_streambuf.native_non_blocking.overload1.example"></a><h6> |
| <a name="boost_asio.reference.basic_socket_streambuf.native_non_blocking.overload1.example-heading"></a> |
| <a class="link" href="overload1.html#boost_asio.reference.basic_socket_streambuf.native_non_blocking.overload1.example">Example</a> |
| </h6> |
| <p> |
| This function is intended to allow the encapsulation of arbitrary non-blocking |
| system calls as asynchronous operations, in a way that is transparent |
| to the user of the socket object. The following example illustrates how |
| Linux's <code class="computeroutput"><span class="identifier">sendfile</span></code> system |
| call might be encapsulated: |
| </p> |
| <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Handler</span><span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">sendfile_op</span> |
| <span class="special">{</span> |
| <span class="identifier">tcp</span><span class="special">::</span><span class="identifier">socket</span><span class="special">&</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">handler_</span><span class="special">;</span> |
| <span class="identifier">off_t</span> <span class="identifier">offset_</span><span class="special">;</span> |
| <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> |
| |
| <span class="comment">// Function call operator meeting WriteHandler requirements.</span> |
| <span class="comment">// Used as the handler for the async_write_some operation.</span> |
| <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> |
| <span class="special">{</span> |
| <span class="comment">// Put the underlying socket into non-blocking mode.</span> |
| <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">ec</span><span class="special">)</span> |
| <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> |
| <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> |
| |
| <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">ec</span><span class="special">)</span> |
| <span class="special">{</span> |
| <span class="keyword">for</span> <span class="special">(;;)</span> |
| <span class="special">{</span> |
| <span class="comment">// Try the system call.</span> |
| <span class="identifier">errno</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> |
| <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">&</span><span class="identifier">offset_</span><span class="special">,</span> <span class="number">65536</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">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">(</span><span class="identifier">n</span> <span class="special"><</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> |
| <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> |
| <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> |
| |
| <span class="comment">// Retry operation immediately if interrupted by signal.</span> |
| <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> |
| <span class="keyword">continue</span><span class="special">;</span> |
| |
| <span class="comment">// Check if we need to run the operation again.</span> |
| <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> |
| <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> |
| <span class="special">{</span> |
| <span class="comment">// We have to wait for the socket to become ready again.</span> |
| <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> |
| <span class="keyword">return</span><span class="special">;</span> |
| <span class="special">}</span> |
| |
| <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> |
| <span class="special">{</span> |
| <span class="comment">// An error occurred, or we have reached the end of the file.</span> |
| <span class="comment">// Either way we must exit the loop so we can call the handler.</span> |
| <span class="keyword">break</span><span class="special">;</span> |
| <span class="special">}</span> |
| |
| <span class="comment">// Loop around to try calling sendfile again.</span> |
| <span class="special">}</span> |
| <span class="special">}</span> |
| |
| <span class="comment">// Pass result back to user's handler.</span> |
| <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> |
| <span class="special">}</span> |
| <span class="special">};</span> |
| |
| <span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Handler</span><span class="special">></span> |
| <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">&</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> |
| <span class="special">{</span> |
| <span class="identifier">sendfile_op</span><span class="special"><</span><span class="identifier">Handler</span><span class="special">></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> |
| <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> |
| <span class="special">}</span> |
| </pre> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2003-2011 Christopher |
| M. Kohlhoff<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 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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