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 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
 <a name="intrusive.using_smart_pointers"></a><a class="link" href="using_smart_pointers.html" title="Using smart pointers with Boost.Intrusive containers">Using smart pointers with
     Boost.Intrusive containers</a>
 </h2></div></div></div>
 <div class="toc"><dl><dt><span class="section"><a href="using_smart_pointers.html#intrusive.using_smart_pointers.smart_pointers_requirements">Requirements
       for smart pointers compatible with Boost.Intrusive</a></span></dt></dl></div>
 <p>
       <span class="bold"><strong>Boost.Intrusive</strong></span> hooks can be configured to
       use other pointers than raw pointers. When a <span class="bold"><strong>Boost.Intrusive</strong></span>
       hook is configured with a smart pointer as an argument, this pointer configuration
       is passed to the containers. For example, if the following hook is configured
       with a smart pointer (for example, an offset pointer from <span class="bold"><strong>Boost.Interprocess</strong></span>):
     </p>
 <p>

 </p>
 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">intrusive</span><span class="special">/</span><span class="identifier">list</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">interprocess</span><span class="special">/</span><span class="identifier">offset_ptr</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

 <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">intrusive</span><span class="special">;</span>
 <span class="keyword">namespace</span> <span class="identifier">ip</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">interprocess</span><span class="special">;</span>

 <span class="keyword">class</span> <span class="identifier">shared_memory_data</span>
    <span class="comment">//Declare the hook with an offset_ptr from Boost.Interprocess
 </span>   <span class="comment">//to make this class compatible with shared memory
 </span>   <span class="special">:</span>  <span class="keyword">public</span> <span class="identifier">list_base_hook</span><span class="special">&lt;</span> <span class="identifier">void_pointer</span><span class="special">&lt;</span> <span class="identifier">ip</span><span class="special">::</span><span class="identifier">offset_ptr</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">&gt;</span>
 <span class="special">{</span>
    <span class="keyword">int</span> <span class="identifier">data_id_</span><span class="special">;</span>
    <span class="keyword">public</span><span class="special">:</span>

    <span class="keyword">int</span> <span class="identifier">get</span><span class="special">()</span> <span class="keyword">const</span>   <span class="special">{</span>  <span class="keyword">return</span> <span class="identifier">data_id_</span><span class="special">;</span>  <span class="special">}</span>
    <span class="keyword">void</span> <span class="identifier">set</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">id</span><span class="special">)</span>  <span class="special">{</span>  <span class="identifier">data_id_</span> <span class="special">=</span> <span class="identifier">id</span><span class="special">;</span>    <span class="special">}</span>
 <span class="special">};</span>
 </pre>
 <p>
     </p>
 <p>
       Any intrusive list constructed using this hook will be ready for shared memory,
       because the intrusive list will also use offset pointers internally. For example,
       we can create an intrusive list in shared memory combining <span class="bold"><strong>Boost.Interprocess</strong></span>
       and <span class="bold"><strong>Boost.Intrusive</strong></span>:
     </p>
 <p>

 </p>
 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">interprocess</span><span class="special">/</span><span class="identifier">managed_shared_memory</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">interprocess</span><span class="special">/</span><span class="identifier">containers</span><span class="special">/</span><span class="identifier">vector</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">interprocess</span><span class="special">/</span><span class="identifier">containers</span><span class="special">/</span><span class="identifier">list</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">interprocess</span><span class="special">/</span><span class="identifier">allocators</span><span class="special">/</span><span class="identifier">allocator</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

 <span class="comment">//Definition of the shared memory friendly intrusive list
 </span><span class="keyword">typedef</span> <span class="identifier">ip</span><span class="special">::</span><span class="identifier">list</span><span class="special">&lt;</span><span class="identifier">shared_memory_data</span><span class="special">&gt;</span> <span class="identifier">shm_list_t</span><span class="special">;</span>

 <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
 <span class="special">{</span>
    <span class="comment">//Now create an intrusive list in shared memory:
 </span>   <span class="comment">//nodes and the container itself must be created in shared memory
 </span>   <span class="keyword">const</span> <span class="keyword">int</span> <span class="identifier">MaxElem</span>    <span class="special">=</span> <span class="number">100</span><span class="special">;</span>
    <span class="keyword">const</span> <span class="keyword">int</span> <span class="identifier">ShmSize</span>    <span class="special">=</span> <span class="number">50000</span><span class="special">;</span>
    <span class="keyword">const</span> <span class="keyword">char</span> <span class="special">*</span><span class="identifier">ShmName</span>  <span class="special">=</span> <span class="identifier">get_shared_memory_name</span><span class="special">();</span>
    <span class="special">{</span>
       <span class="comment">//Erase all old shared memory
 </span>      <span class="identifier">ip</span><span class="special">::</span><span class="identifier">shared_memory_object</span><span class="special">::</span><span class="identifier">remove</span><span class="special">(</span><span class="identifier">ShmName</span><span class="special">);</span>
       <span class="identifier">ip</span><span class="special">::</span><span class="identifier">managed_shared_memory</span> <span class="identifier">shm</span><span class="special">(</span><span class="identifier">ip</span><span class="special">::</span><span class="identifier">create_only</span><span class="special">,</span> <span class="identifier">ShmName</span><span class="special">,</span> <span class="identifier">ShmSize</span><span class="special">);</span>

       <span class="comment">//Create all nodes in shared memory using a shared memory vector
 </span>      <span class="comment">//See Boost.Interprocess documentation for more information on this
 </span>      <span class="keyword">typedef</span> <span class="identifier">ip</span><span class="special">::</span><span class="identifier">allocator</span>
          <span class="special">&lt;</span> <span class="identifier">shared_memory_data</span><span class="special">,</span> <span class="identifier">ip</span><span class="special">::</span><span class="identifier">managed_shared_memory</span><span class="special">::</span><span class="identifier">segment_manager</span><span class="special">&gt;</span>
             <span class="identifier">shm_allocator_t</span><span class="special">;</span>
       <span class="keyword">typedef</span> <span class="identifier">ip</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">shared_memory_data</span><span class="special">,</span> <span class="identifier">shm_allocator_t</span><span class="special">&gt;</span> <span class="identifier">shm_vector_t</span><span class="special">;</span>
       <span class="identifier">shm_allocator_t</span> <span class="identifier">shm_alloc</span><span class="special">(</span><span class="identifier">shm</span><span class="special">.</span><span class="identifier">get_segment_manager</span><span class="special">());</span>
       <span class="identifier">shm_vector_t</span> <span class="special">*</span><span class="identifier">pshm_vect</span> <span class="special">=</span>
          <span class="identifier">shm</span><span class="special">.</span><span class="identifier">construct</span><span class="special">&lt;</span><span class="identifier">shm_vector_t</span><span class="special">&gt;(</span><span class="identifier">ip</span><span class="special">::</span><span class="identifier">anonymous_instance</span><span class="special">)(</span><span class="identifier">shm_alloc</span><span class="special">);</span>
       <span class="identifier">pshm_vect</span><span class="special">-&gt;</span><span class="identifier">resize</span><span class="special">(</span><span class="identifier">MaxElem</span><span class="special">);</span>

       <span class="comment">//Initialize all the nodes
 </span>      <span class="keyword">for</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="identifier">MaxElem</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span>    <span class="special">(*</span><span class="identifier">pshm_vect</span><span class="special">)[</span><span class="identifier">i</span><span class="special">].</span><span class="identifier">set</span><span class="special">(</span><span class="identifier">i</span><span class="special">);</span>

       <span class="comment">//Now create the shared memory intrusive list
 </span>      <span class="identifier">shm_list_t</span> <span class="special">*</span><span class="identifier">plist</span> <span class="special">=</span> <span class="identifier">shm</span><span class="special">.</span><span class="identifier">construct</span><span class="special">&lt;</span><span class="identifier">shm_list_t</span><span class="special">&gt;(</span><span class="identifier">ip</span><span class="special">::</span><span class="identifier">anonymous_instance</span><span class="special">)();</span>
       <span class="identifier">plist</span><span class="special">-&gt;</span><span class="identifier">insert</span><span class="special">(</span><span class="identifier">plist</span><span class="special">-&gt;</span><span class="identifier">end</span><span class="special">(),</span> <span class="identifier">pshm_vect</span><span class="special">-&gt;</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">pshm_vect</span><span class="special">-&gt;</span><span class="identifier">end</span><span class="special">());</span>

       <span class="comment">//Check all the inserted nodes
 </span>      <span class="keyword">int</span> <span class="identifier">checker</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>
       <span class="keyword">for</span><span class="special">(</span> <span class="identifier">shm_list_t</span><span class="special">::</span><span class="identifier">const_iterator</span> <span class="identifier">it</span> <span class="special">=</span> <span class="identifier">plist</span><span class="special">-&gt;</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">itend</span><span class="special">(</span><span class="identifier">plist</span><span class="special">-&gt;</span><span class="identifier">end</span><span class="special">())</span>
          <span class="special">;</span> <span class="identifier">it</span> <span class="special">!=</span> <span class="identifier">itend</span><span class="special">;</span> <span class="special">++</span><span class="identifier">it</span><span class="special">,</span> <span class="special">++</span><span class="identifier">checker</span><span class="special">){</span>
          <span class="keyword">if</span><span class="special">(</span><span class="identifier">it</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">()</span> <span class="special">!=</span> <span class="identifier">checker</span><span class="special">)</span>   <span class="keyword">return</span> <span class="keyword">false</span><span class="special">;</span>
       <span class="special">}</span>

       <span class="comment">//Now delete the list and after that, the nodes
 </span>      <span class="identifier">shm</span><span class="special">.</span><span class="identifier">destroy_ptr</span><span class="special">(</span><span class="identifier">plist</span><span class="special">);</span>
       <span class="identifier">shm</span><span class="special">.</span><span class="identifier">destroy_ptr</span><span class="special">(</span><span class="identifier">pshm_vect</span><span class="special">);</span>
    <span class="special">}</span>
    <span class="identifier">ip</span><span class="special">::</span><span class="identifier">shared_memory_object</span><span class="special">::</span><span class="identifier">remove</span><span class="special">(</span><span class="identifier">ShmName</span><span class="special">);</span>
    <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
 <span class="special">}</span>
 </pre>
 <p>
     </p>
 <div class="section">
 <div class="titlepage"><div><div><h3 class="title">
 <a name="intrusive.using_smart_pointers.smart_pointers_requirements"></a><a class="link" href="using_smart_pointers.html#intrusive.using_smart_pointers.smart_pointers_requirements" title="Requirements for smart pointers compatible with Boost.Intrusive">Requirements
       for smart pointers compatible with Boost.Intrusive</a>
 </h3></div></div></div>
 <p>
         Not every smart pointer is compatible with <span class="bold"><strong>Boost.Intrusive</strong></span>;
         the smart pointer must have the following features:
       </p>
 <div class="itemizedlist"><ul class="itemizedlist" type="disc">
 <li class="listitem">
             It must support the same operations as a raw pointer, except casting.
           </li>
 <li class="listitem">
             It must be convertible to a raw pointer and constructible from a raw
             pointer.
           </li>
 <li class="listitem">
             It must have the same ownership semantics as a raw pointer. This means
             that resource management smart pointers (like <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_ptr</span></code>)
             can't be used.
           </li>
 </ul></div>
 <p>
         The conversion from the smart pointer to a raw pointer must be implemented
         following Boost smart pointer <code class="computeroutput"><span class="identifier">detail</span><span class="special">::</span><span class="identifier">get_pointer</span><span class="special">()</span></code> function. This function will be found using
         ADL. For example, for <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">interprocess</span><span class="special">::</span><span class="identifier">offset_ptr</span></code>,
         <code class="computeroutput"><span class="identifier">detail</span><span class="special">::</span><span class="identifier">get_pointer</span></code> is defined as follows:
       </p>
 <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
 <span class="identifier">T</span> <span class="special">*</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">get_pointer</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">interprocess</span><span class="special">::</span><span class="identifier">offset_ptr</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">p</span><span class="special">)</span>
 <span class="special">{</span>  <span class="keyword">return</span> <span class="identifier">p</span><span class="special">.</span><span class="identifier">get</span><span class="special">();</span>   <span class="special">}</span>
 </pre>
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 <td align="right"><div class="copyright-footer">Copyright &#169; 2005 Olaf Krzikalla, 2006-2010 Ion Gaztanaga<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>)
       </p>
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