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24</div>
25<div class="section">
26<div class="titlepage"><div><div><h2 class="title" style="clear: both">
27<a name="fiber.fls"></a><a class="link" href="fls.html" title="Fiber local storage">Fiber local storage</a>
28</h2></div></div></div>
29<h4>
30<a name="fiber.fls.h0"></a>
31 <span><a name="fiber.fls.synopsis"></a></span><a class="link" href="fls.html#fiber.fls.synopsis">Synopsis</a>
32 </h4>
33<p>
34 Fiber local storage allows a separate instance of a given data item for each
35 fiber.
36 </p>
37<h4>
38<a name="fiber.fls.h1"></a>
39 <span><a name="fiber.fls.cleanup_at_fiber_exit"></a></span><a class="link" href="fls.html#fiber.fls.cleanup_at_fiber_exit">Cleanup
40 at fiber exit</a>
41 </h4>
42<p>
43 When a fiber exits, the objects associated with each <a class="link" href="fls.html#class_fiber_specific_ptr"><code class="computeroutput">fiber_specific_ptr</code></a> instance
44 are destroyed. By default, the object pointed to by a pointer <code class="computeroutput"><span class="identifier">p</span></code> is destroyed by invoking <code class="computeroutput"><span class="keyword">delete</span> <span class="identifier">p</span></code>,
45 but this can be overridden for a specific instance of <a class="link" href="fls.html#class_fiber_specific_ptr"><code class="computeroutput">fiber_specific_ptr</code></a> by
46 providing a cleanup routine <code class="computeroutput"><span class="identifier">func</span></code>
47 to the constructor. In this case, the object is destroyed by invoking <code class="computeroutput"><span class="identifier">func</span><span class="special">(</span><span class="identifier">p</span><span class="special">)</span></code>. The cleanup functions are called in an unspecified
48 order.
49 </p>
50<p>
51 </p>
52<h5>
53<a name="class_fiber_specific_ptr_bridgehead"></a>
54 <span><a name="class_fiber_specific_ptr"></a></span>
55 <a class="link" href="fls.html#class_fiber_specific_ptr">Class
56 <code class="computeroutput">fiber_specific_ptr</code></a>
57</h5>
58<p>
59 </p>
60<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">fiber</span><span class="special">/</span><span class="identifier">fss</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
61
62<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
63<span class="keyword">namespace</span> <span class="identifier">fibers</span> <span class="special">{</span>
64
65<span class="keyword">template</span><span class="special">&lt;</span> <span class="keyword">typename</span> <span class="identifier">T</span> <span class="special">&gt;</span>
66<span class="keyword">class</span> <span class="identifier">fiber_specific_ptr</span> <span class="special">{</span>
67<span class="keyword">public</span><span class="special">:</span>
68 <span class="keyword">typedef</span> <span class="identifier">T</span> <span class="identifier">element_type</span><span class="special">;</span>
69
70 <span class="identifier">fiber_specific_ptr</span><span class="special">();</span>
71
72 <span class="keyword">explicit</span> <span class="identifier">fiber_specific_ptr</span><span class="special">(</span> <span class="keyword">void</span><span class="special">(*</span><span class="identifier">fn</span><span class="special">)(</span><span class="identifier">T</span><span class="special">*)</span> <span class="special">);</span>
73
74 <span class="special">~</span><span class="identifier">fiber_specific_ptr</span><span class="special">();</span>
75
76 <span class="identifier">fiber_specific_ptr</span><span class="special">(</span> <span class="identifier">fiber_specific_ptr</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
77 <span class="identifier">fiber_specific_ptr</span> <span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">fiber_specific_ptr</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
78
79 <span class="identifier">T</span> <span class="special">*</span> <span class="identifier">get</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
80
81 <span class="identifier">T</span> <span class="special">*</span> <span class="keyword">operator</span><span class="special">-&gt;()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
82
83 <span class="identifier">T</span> <span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">*()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
84
85 <span class="identifier">T</span> <span class="special">*</span> <span class="identifier">release</span><span class="special">();</span>
86
87 <span class="keyword">void</span> <span class="identifier">reset</span><span class="special">(</span> <span class="identifier">T</span> <span class="special">*);</span>
88<span class="special">};</span>
89
90<span class="special">}}</span>
91</pre>
92<h4>
93<a name="fiber.fls.h2"></a>
94 <span><a name="fiber.fls.constructor"></a></span><a class="link" href="fls.html#fiber.fls.constructor">Constructor</a>
95 </h4>
96<pre class="programlisting"><span class="identifier">fiber_specific_ptr</span><span class="special">();</span>
97<span class="keyword">explicit</span> <span class="identifier">fiber_specific_ptr</span><span class="special">(</span> <span class="keyword">void</span><span class="special">(*</span><span class="identifier">fn</span><span class="special">)(</span><span class="identifier">T</span><span class="special">*)</span> <span class="special">);</span>
98</pre>
99<div class="variablelist">
100<p class="title"><b></b></p>
101<dl>
102<dt><span class="term">Requires:</span></dt>
103<dd><p>
104 <code class="computeroutput"><span class="keyword">delete</span> <span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">()</span></code> is well-formed; <code class="computeroutput"><span class="identifier">fn</span><span class="special">(</span><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">())</span></code> does not throw
105 </p></dd>
106<dt><span class="term">Effects:</span></dt>
107<dd><p>
108 Construct a <a class="link" href="fls.html#class_fiber_specific_ptr"><code class="computeroutput">fiber_specific_ptr</code></a> object for storing
109 a pointer to an object of type <code class="computeroutput"><span class="identifier">T</span></code>
110 specific to each fiber. When <code class="computeroutput"><span class="identifier">reset</span><span class="special">()</span></code> is called, or the fiber exits, <a class="link" href="fls.html#class_fiber_specific_ptr"><code class="computeroutput">fiber_specific_ptr</code></a> calls
111 <code class="computeroutput"><span class="identifier">fn</span><span class="special">(</span><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">())</span></code>.
112 If the no-arguments constructor is used, the default <code class="computeroutput"><span class="keyword">delete</span></code>-based
113 cleanup function will be used to destroy the fiber-local objects.
114 </p></dd>
115<dt><span class="term">Throws:</span></dt>
116<dd><p>
117 <code class="computeroutput"><span class="identifier">fiber_error</span></code> if an error
118 occurs.
119 </p></dd>
120</dl>
121</div>
122<h4>
123<a name="fiber.fls.h3"></a>
124 <span><a name="fiber.fls.destructor"></a></span><a class="link" href="fls.html#fiber.fls.destructor">Destructor</a>
125 </h4>
126<pre class="programlisting"><span class="special">~</span><span class="identifier">fiber_specific_ptr</span><span class="special">();</span>
127</pre>
128<div class="variablelist">
129<p class="title"><b></b></p>
130<dl>
131<dt><span class="term">Requires:</span></dt>
132<dd><p>
133 All the fiber specific instances associated to this <a class="link" href="fls.html#class_fiber_specific_ptr"><code class="computeroutput">fiber_specific_ptr</code></a>
134(except
135 maybe the one associated to this fiber) must be nullptr.
136 </p></dd>
137<dt><span class="term">Effects:</span></dt>
138<dd><p>
139 Calls <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">reset</span><span class="special">()</span></code>
140 to clean up the associated value for the current fiber, and destroys
141 <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
142 </p></dd>
143<dt><span class="term">Remarks:</span></dt>
144<dd><p>
145 The requirement is an implementation restriction. If the destructor promised
146 to delete instances for all fibers, the implementation would be forced
147 to maintain a list of all the fibers having an associated specific ptr,
148 which is against the goal of fiber specific data. In general, a <a class="link" href="fls.html#class_fiber_specific_ptr"><code class="computeroutput">fiber_specific_ptr</code></a> should
149 outlive the fibers that use it.
150 </p></dd>
151</dl>
152</div>
153<div class="note"><table border="0" summary="Note">
154<tr>
155<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../doc/src/images/note.png"></td>
156<th align="left">Note</th>
157</tr>
158<tr><td align="left" valign="top"><p>
159 Care needs to be taken to ensure that any fibers still running after an instance
160 of <a class="link" href="fls.html#class_fiber_specific_ptr"><code class="computeroutput">fiber_specific_ptr</code></a> has been destroyed do not call
161 any member functions on that instance.
162 </p></td></tr>
163</table></div>
164<p>
165 </p>
166<h5>
167<a name="fiber_specific_ptr_get_bridgehead"></a>
168 <span><a name="fiber_specific_ptr_get"></a></span>
169 <a class="link" href="fls.html#fiber_specific_ptr_get">Member
170 function <code class="computeroutput">get</code>()</a>
171</h5>
172<p>
173 </p>
174<pre class="programlisting"><span class="identifier">T</span> <span class="special">*</span> <span class="identifier">get</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
175</pre>
176<div class="variablelist">
177<p class="title"><b></b></p>
178<dl>
179<dt><span class="term">Returns:</span></dt>
180<dd><p>
181 The pointer associated with the current fiber.
182 </p></dd>
183<dt><span class="term">Throws:</span></dt>
184<dd><p>
185 Nothing.
186 </p></dd>
187</dl>
188</div>
189<div class="note"><table border="0" summary="Note">
190<tr>
191<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../doc/src/images/note.png"></td>
192<th align="left">Note</th>
193</tr>
194<tr><td align="left" valign="top"><p>
195 The initial value associated with an instance of <a class="link" href="fls.html#class_fiber_specific_ptr"><code class="computeroutput">fiber_specific_ptr</code></a> is
196 <code class="computeroutput"><span class="keyword">nullptr</span></code> for each fiber.
197 </p></td></tr>
198</table></div>
199<p>
200 </p>
201<h5>
202<a name="fiber_specific_ptr_operator_arrow_bridgehead"></a>
203 <span><a name="fiber_specific_ptr_operator_arrow"></a></span>
204 <a class="link" href="fls.html#fiber_specific_ptr_operator_arrow">Member
205 function <code class="computeroutput">operator-&gt;</code>()</a>
206</h5>
207<p>
208 </p>
209<pre class="programlisting"><span class="identifier">T</span> <span class="special">*</span> <span class="keyword">operator</span><span class="special">-&gt;()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
210</pre>
211<div class="variablelist">
212<p class="title"><b></b></p>
213<dl>
214<dt><span class="term">Requires:</span></dt>
215<dd><p>
216 <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">()</span></code>
217 is not <code class="computeroutput"><span class="keyword">nullptr</span></code>.
218 </p></dd>
219<dt><span class="term">Returns:</span></dt>
220<dd><p>
221 <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">()</span></code>
222 </p></dd>
223<dt><span class="term">Throws:</span></dt>
224<dd><p>
225 Nothing.
226 </p></dd>
227</dl>
228</div>
229<p>
230 </p>
231<h5>
232<a name="fiber_specific_ptr_operator_star_bridgehead"></a>
233 <span><a name="fiber_specific_ptr_operator_star"></a></span>
234 <a class="link" href="fls.html#fiber_specific_ptr_operator_star">Member
235 function <code class="computeroutput">operator*</code>()</a>
236</h5>
237<p>
238 </p>
239<pre class="programlisting"><span class="identifier">T</span> <span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">*()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
240</pre>
241<div class="variablelist">
242<p class="title"><b></b></p>
243<dl>
244<dt><span class="term">Requires:</span></dt>
245<dd><p>
246 <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">()</span></code>
247 is not <code class="computeroutput"><span class="keyword">nullptr</span></code>.
248 </p></dd>
249<dt><span class="term">Returns:</span></dt>
250<dd><p>
251 <code class="computeroutput"><span class="special">*(</span><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">())</span></code>
252 </p></dd>
253<dt><span class="term">Throws:</span></dt>
254<dd><p>
255 Nothing.
256 </p></dd>
257</dl>
258</div>
259<p>
260 </p>
261<h5>
262<a name="fiber_specific_ptr_release_bridgehead"></a>
263 <span><a name="fiber_specific_ptr_release"></a></span>
264 <a class="link" href="fls.html#fiber_specific_ptr_release">Member
265 function <code class="computeroutput">release</code>()</a>
266</h5>
267<p>
268 </p>
269<pre class="programlisting"><span class="identifier">T</span> <span class="special">*</span> <span class="identifier">release</span><span class="special">();</span>
270</pre>
271<div class="variablelist">
272<p class="title"><b></b></p>
273<dl>
274<dt><span class="term">Effects:</span></dt>
275<dd><p>
276 Return <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">()</span></code>
277 and store <code class="computeroutput"><span class="keyword">nullptr</span></code> as the
278 pointer associated with the current fiber without invoking the cleanup
279 function.
280 </p></dd>
281<dt><span class="term">Postcondition:</span></dt>
282<dd><p>
283 <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">()==</span><span class="keyword">nullptr</span></code>
284 </p></dd>
285<dt><span class="term">Throws:</span></dt>
286<dd><p>
287 Nothing.
288 </p></dd>
289</dl>
290</div>
291<p>
292 </p>
293<h5>
294<a name="fiber_specific_ptr_reset_bridgehead"></a>
295 <span><a name="fiber_specific_ptr_reset"></a></span>
296 <a class="link" href="fls.html#fiber_specific_ptr_reset">Member
297 function <code class="computeroutput">reset</code>()</a>
298</h5>
299<p>
300 </p>
301<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">reset</span><span class="special">(</span> <span class="identifier">T</span> <span class="special">*</span> <span class="identifier">new_value</span><span class="special">);</span>
302</pre>
303<div class="variablelist">
304<p class="title"><b></b></p>
305<dl>
306<dt><span class="term">Effects:</span></dt>
307<dd><p>
308 If <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">()!=</span><span class="identifier">new_value</span></code> and <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">()</span></code> is not <code class="computeroutput"><span class="keyword">nullptr</span></code>,
309 invoke <code class="computeroutput"><span class="keyword">delete</span> <span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">fn</span><span class="special">(</span><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">())</span></code> as appropriate. Store <code class="computeroutput"><span class="identifier">new_value</span></code> as the pointer associated
310 with the current fiber.
311 </p></dd>
312<dt><span class="term">Postcondition:</span></dt>
313<dd><p>
314 <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get</span><span class="special">()==</span><span class="identifier">new_value</span></code>
315 </p></dd>
316<dt><span class="term">Throws:</span></dt>
317<dd><p>
318 Exception raised during cleanup of previous value.
319 </p></dd>
320</dl>
321</div>
322</div>
323<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
324<td align="left"></td>
325<td align="right"><div class="copyright-footer">Copyright &#169; 2013 Oliver Kowalke<p>
326 Distributed under the Boost Software License, Version 1.0. (See accompanying
327 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>)
328 </p>
329</div></td>
330</tr></table>
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