1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Future</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="../futures.html" title="Futures"> 9<link rel="prev" href="../futures.html" title="Futures"> 10<link rel="next" href="promise.html" title="Template promise<>"> 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="../futures.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../futures.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="promise.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h4 class="title"> 27<a name="fiber.synchronization.futures.future"></a><a class="link" href="future.html" title="Future">Future</a> 28</h4></div></div></div> 29<p> 30 A future provides a mechanism to access the result of an asynchronous operation. 31 </p> 32<a name="shared_state"></a><h6> 33<a name="fiber.synchronization.futures.future.h0"></a> 34 <span class="phrase"><a name="fiber.synchronization.futures.future.shared_state"></a></span><a class="link" href="future.html#fiber.synchronization.futures.future.shared_state">shared 35 state</a> 36 </h6> 37<p> 38 Behind a <a class="link" href="promise.html#class_promise"><code class="computeroutput">promise<></code></a> and its <a class="link" href="future.html#class_future"><code class="computeroutput">future<></code></a> lies 39 an unspecified object called their <span class="emphasis"><em>shared state</em></span>. The 40 shared state is what will actually hold the async result (or the exception). 41 </p> 42<p> 43 The shared state is instantiated along with the <a class="link" href="promise.html#class_promise"><code class="computeroutput">promise<></code></a>. 44 </p> 45<p> 46 Aside from its originating <code class="computeroutput"><span class="identifier">promise</span><span class="special"><></span></code>, a <a class="link" href="future.html#class_future"><code class="computeroutput">future<></code></a> holds 47 a unique reference to a particular shared state. However, multiple <a class="link" href="future.html#class_shared_future"><code class="computeroutput">shared_future<></code></a> instances 48 can reference the same underlying shared state. 49 </p> 50<p> 51 As <a class="link" href="packaged_task.html#class_packaged_task"><code class="computeroutput">packaged_task<></code></a> and <a class="link" href="future.html#fibers_async"><code class="computeroutput">fibers::async()</code></a> are 52 implemented using <a class="link" href="promise.html#class_promise"><code class="computeroutput">promise<></code></a>, discussions of shared state 53 apply to them as well. 54 </p> 55<a name="class_future_status"></a><h6> 56<a name="fiber.synchronization.futures.future.h1"></a> 57 <span class="phrase"><a name="fiber.synchronization.futures.future.enumeration__code__phrase_role__identifier__future_status__phrase___code_"></a></span><a class="link" href="future.html#fiber.synchronization.futures.future.enumeration__code__phrase_role__identifier__future_status__phrase___code_">Enumeration 58 <code class="computeroutput"><span class="identifier">future_status</span></code></a> 59 </h6> 60<p> 61 Timed wait-operations (<a class="link" href="future.html#future_wait_for"><code class="computeroutput">future::wait_for()</code></a> and <a class="link" href="future.html#future_wait_until"><code class="computeroutput">future::wait_until()</code></a>) 62 return the state of the future. 63 </p> 64<pre class="programlisting"><span class="keyword">enum</span> <span class="keyword">class</span> <span class="identifier">future_status</span> <span class="special">{</span> 65 <span class="identifier">ready</span><span class="special">,</span> 66 <span class="identifier">timeout</span><span class="special">,</span> 67 <span class="identifier">deferred</span> <span class="comment">// not supported yet</span> 68<span class="special">};</span> 69</pre> 70<h6> 71<a name="fiber.synchronization.futures.future.h2"></a> 72 <span class="phrase"><a name="fiber.synchronization.futures.future._code__phrase_role__identifier__ready__phrase___code_"></a></span><a class="link" href="future.html#fiber.synchronization.futures.future._code__phrase_role__identifier__ready__phrase___code_"><code class="computeroutput"><span class="identifier">ready</span></code></a> 73 </h6> 74<div class="variablelist"> 75<p class="title"><b></b></p> 76<dl class="variablelist"> 77<dt><span class="term">Effects:</span></dt> 78<dd><p> 79 The <a class="link" href="future.html#shared_state">shared state</a> is ready. 80 </p></dd> 81</dl> 82</div> 83<h6> 84<a name="fiber.synchronization.futures.future.h3"></a> 85 <span class="phrase"><a name="fiber.synchronization.futures.future._code__phrase_role__identifier__timeout__phrase___code_"></a></span><a class="link" href="future.html#fiber.synchronization.futures.future._code__phrase_role__identifier__timeout__phrase___code_"><code class="computeroutput"><span class="identifier">timeout</span></code></a> 86 </h6> 87<div class="variablelist"> 88<p class="title"><b></b></p> 89<dl class="variablelist"> 90<dt><span class="term">Effects:</span></dt> 91<dd><p> 92 The <a class="link" href="future.html#shared_state">shared state</a> did not become 93 ready before timeout has passed. 94 </p></dd> 95</dl> 96</div> 97<div class="note"><table border="0" summary="Note"> 98<tr> 99<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../../doc/src/images/note.png"></td> 100<th align="left">Note</th> 101</tr> 102<tr><td align="left" valign="top"><p> 103 Deferred futures are not supported. 104 </p></td></tr> 105</table></div> 106<p> 107 </p> 108<h5> 109<a name="class_future_bridgehead"></a> 110 <span class="phrase"><a name="class_future"></a></span> 111 <a class="link" href="future.html#class_future">Template <code class="computeroutput">future<></code></a> 112</h5> 113<p> 114 </p> 115<p> 116 A <a class="link" href="future.html#class_future"><code class="computeroutput">future<></code></a> contains a <a class="link" href="future.html#shared_state">shared 117 state</a> which is not shared with any other future. 118 </p> 119<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fiber</span><span class="special">/</span><span class="identifier">future</span><span class="special">/</span><span class="identifier">future</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 120 121<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> 122<span class="keyword">namespace</span> <span class="identifier">fibers</span> <span class="special">{</span> 123 124<span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">R</span> <span class="special">></span> 125<span class="keyword">class</span> <span class="identifier">future</span> <span class="special">{</span> 126<span class="keyword">public</span><span class="special">:</span> 127 <span class="identifier">future</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span> 128 129 <span class="identifier">future</span><span class="special">(</span> <span class="identifier">future</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">other</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span> 130 131 <span class="identifier">future</span> <span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">future</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">other</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span> 132 133 <span class="identifier">future</span><span class="special">(</span> <span class="identifier">future</span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 134 135 <span class="identifier">future</span> <span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">future</span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 136 137 <span class="special">~</span><span class="identifier">future</span><span class="special">();</span> 138 139 <span class="keyword">bool</span> <span class="identifier">valid</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span> 140 141 <span class="identifier">shared_future</span><span class="special"><</span> <span class="identifier">R</span> <span class="special">></span> <span class="identifier">share</span><span class="special">();</span> 142 143 <span class="identifier">R</span> <span class="identifier">get</span><span class="special">();</span> <span class="comment">// member only of generic future template</span> 144 <span class="identifier">R</span> <span class="special">&</span> <span class="identifier">get</span><span class="special">();</span> <span class="comment">// member only of future< R & > template specialization</span> 145 <span class="keyword">void</span> <span class="identifier">get</span><span class="special">();</span> <span class="comment">// member only of future< void > template specialization</span> 146 147 <span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span> <span class="identifier">get_exception_ptr</span><span class="special">();</span> 148 149 <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> 150 151 <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span> <span class="special">></span> 152 <span class="identifier">future_status</span> <span class="identifier">wait_for</span><span class="special">(</span> 153 <span class="identifier">std</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special"><</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span> <span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">timeout_duration</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 154 155 <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Duration</span> <span class="special">></span> 156 <span class="identifier">future_status</span> <span class="identifier">wait_until</span><span class="special">(</span> 157 <span class="identifier">std</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special"><</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span> <span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">timeout_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 158<span class="special">};</span> 159 160<span class="special">}}</span> 161</pre> 162<h6> 163<a name="fiber.synchronization.futures.future.h4"></a> 164 <span class="phrase"><a name="fiber.synchronization.futures.future.default_constructor"></a></span><a class="link" href="future.html#fiber.synchronization.futures.future.default_constructor">Default 165 constructor</a> 166 </h6> 167<pre class="programlisting"><span class="identifier">future</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span> 168</pre> 169<div class="variablelist"> 170<p class="title"><b></b></p> 171<dl class="variablelist"> 172<dt><span class="term">Effects:</span></dt> 173<dd><p> 174 Creates a future with no <a class="link" href="future.html#shared_state">shared state</a>. 175 After construction <code class="computeroutput"><span class="keyword">false</span> <span class="special">==</span> <span class="identifier">valid</span><span class="special">()</span></code>. 176 </p></dd> 177<dt><span class="term">Throws:</span></dt> 178<dd><p> 179 Nothing. 180 </p></dd> 181</dl> 182</div> 183<h6> 184<a name="fiber.synchronization.futures.future.h5"></a> 185 <span class="phrase"><a name="fiber.synchronization.futures.future.move_constructor"></a></span><a class="link" href="future.html#fiber.synchronization.futures.future.move_constructor">Move constructor</a> 186 </h6> 187<pre class="programlisting"><span class="identifier">future</span><span class="special">(</span> <span class="identifier">future</span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 188</pre> 189<div class="variablelist"> 190<p class="title"><b></b></p> 191<dl class="variablelist"> 192<dt><span class="term">Effects:</span></dt> 193<dd><p> 194 Constructs a future with the <a class="link" href="future.html#shared_state">shared 195 state</a> of other. After construction <code class="computeroutput"><span class="keyword">false</span> 196 <span class="special">==</span> <span class="identifier">other</span><span class="special">.</span><span class="identifier">valid</span><span class="special">()</span></code>. 197 </p></dd> 198<dt><span class="term">Throws:</span></dt> 199<dd><p> 200 Nothing. 201 </p></dd> 202</dl> 203</div> 204<h6> 205<a name="fiber.synchronization.futures.future.h6"></a> 206 <span class="phrase"><a name="fiber.synchronization.futures.future.destructor"></a></span><a class="link" href="future.html#fiber.synchronization.futures.future.destructor">Destructor</a> 207 </h6> 208<pre class="programlisting"><span class="special">~</span><span class="identifier">future</span><span class="special">();</span> 209</pre> 210<div class="variablelist"> 211<p class="title"><b></b></p> 212<dl class="variablelist"> 213<dt><span class="term">Effects:</span></dt> 214<dd><p> 215 Destroys the future; ownership is abandoned. 216 </p></dd> 217<dt><span class="term">Note:</span></dt> 218<dd><p> 219 <code class="computeroutput">~future()</code> does <span class="emphasis"><em>not</em></span> block the calling fiber. 220 </p></dd> 221</dl> 222</div> 223<p> 224 Consider a sequence such as: 225 </p> 226<div class="orderedlist"><ol class="orderedlist" type="1"> 227<li class="listitem"> 228 instantiate <a class="link" href="promise.html#class_promise"><code class="computeroutput">promise<></code></a> 229 </li> 230<li class="listitem"> 231 obtain its <code class="computeroutput"><span class="identifier">future</span><span class="special"><></span></code> 232 via <a class="link" href="promise.html#promise_get_future"><code class="computeroutput">promise::get_future()</code></a> 233 </li> 234<li class="listitem"> 235 launch <a class="link" href="../../fiber_mgmt/fiber.html#class_fiber"><code class="computeroutput">fiber</code></a>, capturing <code class="computeroutput"><span class="identifier">promise</span><span class="special"><></span></code> 236 </li> 237<li class="listitem"> 238 destroy <code class="computeroutput"><span class="identifier">future</span><span class="special"><></span></code> 239 </li> 240<li class="listitem"> 241 call <a class="link" href="promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> 242 </li> 243</ol></div> 244<p> 245 The final <code class="computeroutput"><span class="identifier">set_value</span><span class="special">()</span></code> 246 call succeeds, but the value is silently discarded: no additional <code class="computeroutput"><span class="identifier">future</span><span class="special"><></span></code> 247 can be obtained from that <code class="computeroutput"><span class="identifier">promise</span><span class="special"><></span></code>. 248 </p> 249<p> 250 </p> 251<h5> 252<a name="future_operator_assign_bridgehead"></a> 253 <span class="phrase"><a name="future_operator_assign"></a></span> 254 <a class="link" href="future.html#future_operator_assign">Member 255 function <code class="computeroutput">operator=</code>()</a> 256</h5> 257<p> 258 </p> 259<pre class="programlisting"><span class="identifier">future</span> <span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">future</span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 260</pre> 261<div class="variablelist"> 262<p class="title"><b></b></p> 263<dl class="variablelist"> 264<dt><span class="term">Effects:</span></dt> 265<dd><p> 266 Moves the <a class="link" href="future.html#shared_state">shared state</a> of other 267 to <code class="computeroutput"><span class="keyword">this</span></code>. After the assignment, 268 <code class="computeroutput"><span class="keyword">false</span> <span class="special">==</span> 269 <span class="identifier">other</span><span class="special">.</span><span class="identifier">valid</span><span class="special">()</span></code>. 270 </p></dd> 271<dt><span class="term">Throws:</span></dt> 272<dd><p> 273 Nothing. 274 </p></dd> 275</dl> 276</div> 277<p> 278 </p> 279<h5> 280<a name="future_valid_bridgehead"></a> 281 <span class="phrase"><a name="future_valid"></a></span> 282 <a class="link" href="future.html#future_valid">Member function <code class="computeroutput">valid</code>()</a> 283</h5> 284<p> 285 </p> 286<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">valid</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span> 287</pre> 288<div class="variablelist"> 289<p class="title"><b></b></p> 290<dl class="variablelist"> 291<dt><span class="term">Effects:</span></dt> 292<dd><p> 293 Returns <code class="computeroutput"><span class="keyword">true</span></code> if future 294 contains a <a class="link" href="future.html#shared_state">shared state</a>. 295 </p></dd> 296<dt><span class="term">Throws:</span></dt> 297<dd><p> 298 Nothing. 299 </p></dd> 300</dl> 301</div> 302<p> 303 </p> 304<h5> 305<a name="future_share_bridgehead"></a> 306 <span class="phrase"><a name="future_share"></a></span> 307 <a class="link" href="future.html#future_share">Member function <code class="computeroutput">share</code>()</a> 308</h5> 309<p> 310 </p> 311<pre class="programlisting"><span class="identifier">shared_future</span><span class="special"><</span> <span class="identifier">R</span> <span class="special">></span> <span class="identifier">share</span><span class="special">();</span> 312</pre> 313<div class="variablelist"> 314<p class="title"><b></b></p> 315<dl class="variablelist"> 316<dt><span class="term">Effects:</span></dt> 317<dd><p> 318 Move the state to a <a class="link" href="future.html#class_shared_future"><code class="computeroutput">shared_future<></code></a>. 319 </p></dd> 320<dt><span class="term">Returns:</span></dt> 321<dd><p> 322 a <a class="link" href="future.html#class_shared_future"><code class="computeroutput">shared_future<></code></a> containing the <a class="link" href="future.html#shared_state">shared 323 state</a> formerly belonging to <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>. 324 </p></dd> 325<dt><span class="term">Postcondition:</span></dt> 326<dd><p> 327 <code class="computeroutput"><span class="keyword">false</span> <span class="special">==</span> 328 <span class="identifier">valid</span><span class="special">()</span></code> 329 </p></dd> 330<dt><span class="term">Throws:</span></dt> 331<dd><p> 332 <code class="computeroutput"><span class="identifier">future_error</span></code> with 333 error condition <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code>. 334 </p></dd> 335</dl> 336</div> 337<p> 338 </p> 339<h5> 340<a name="future_get_bridgehead"></a> 341 <span class="phrase"><a name="future_get"></a></span> 342 <a class="link" href="future.html#future_get">Member function <code class="computeroutput">get</code>()</a> 343</h5> 344<p> 345 </p> 346<pre class="programlisting"><span class="identifier">R</span> <span class="identifier">get</span><span class="special">();</span> <span class="comment">// member only of generic future template</span> 347<span class="identifier">R</span> <span class="special">&</span> <span class="identifier">get</span><span class="special">();</span> <span class="comment">// member only of future< R & > template specialization</span> 348<span class="keyword">void</span> <span class="identifier">get</span><span class="special">();</span> <span class="comment">// member only of future< void > template specialization</span> 349</pre> 350<div class="variablelist"> 351<p class="title"><b></b></p> 352<dl class="variablelist"> 353<dt><span class="term">Precondition:</span></dt> 354<dd><p> 355 <code class="computeroutput"><span class="keyword">true</span> <span class="special">==</span> 356 <span class="identifier">valid</span><span class="special">()</span></code> 357 </p></dd> 358<dt><span class="term">Returns:</span></dt> 359<dd><p> 360 Waits until <a class="link" href="promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> or <a class="link" href="promise.html#promise_set_exception"><code class="computeroutput">promise::set_exception()</code></a> is 361 called. If <a class="link" href="promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> is called, returns 362 the value. If <a class="link" href="promise.html#promise_set_exception"><code class="computeroutput">promise::set_exception()</code></a> is called, 363 throws the indicated exception. 364 </p></dd> 365<dt><span class="term">Postcondition:</span></dt> 366<dd><p> 367 <code class="computeroutput"><span class="keyword">false</span> <span class="special">==</span> 368 <span class="identifier">valid</span><span class="special">()</span></code> 369 </p></dd> 370<dt><span class="term">Throws:</span></dt> 371<dd><p> 372 <code class="computeroutput"><span class="identifier">future_error</span></code> with 373 error condition <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code>, 374 <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">broken_promise</span></code>. Any exception passed 375 to <code class="computeroutput"><span class="identifier">promise</span><span class="special">::</span><span class="identifier">set_exception</span><span class="special">()</span></code>. 376 </p></dd> 377</dl> 378</div> 379<p> 380 </p> 381<h5> 382<a name="future_get_exception_ptr_bridgehead"></a> 383 <span class="phrase"><a name="future_get_exception_ptr"></a></span> 384 <a class="link" href="future.html#future_get_exception_ptr">Member 385 function <code class="computeroutput">get_exception_ptr</code>()</a> 386</h5> 387<p> 388 </p> 389<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span> <span class="identifier">get_exception_ptr</span><span class="special">();</span> 390</pre> 391<div class="variablelist"> 392<p class="title"><b></b></p> 393<dl class="variablelist"> 394<dt><span class="term">Precondition:</span></dt> 395<dd><p> 396 <code class="computeroutput"><span class="keyword">true</span> <span class="special">==</span> 397 <span class="identifier">valid</span><span class="special">()</span></code> 398 </p></dd> 399<dt><span class="term">Returns:</span></dt> 400<dd><p> 401 Waits until <a class="link" href="promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> or <a class="link" href="promise.html#promise_set_exception"><code class="computeroutput">promise::set_exception()</code></a> is 402 called. If <code class="computeroutput"><span class="identifier">set_value</span><span class="special">()</span></code> is called, returns a default-constructed 403 <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span></code>. If <code class="computeroutput"><span class="identifier">set_exception</span><span class="special">()</span></code> 404 is called, returns the passed <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span></code>. 405 </p></dd> 406<dt><span class="term">Throws:</span></dt> 407<dd><p> 408 <code class="computeroutput"><span class="identifier">future_error</span></code> with 409 error condition <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code>. 410 </p></dd> 411<dt><span class="term">Note:</span></dt> 412<dd><p> 413 <code class="computeroutput"><span class="identifier">get_exception_ptr</span><span class="special">()</span></code> does <span class="emphasis"><em>not</em></span> invalidate 414 the <code class="computeroutput">future</code>. After calling <code class="computeroutput"><span class="identifier">get_exception_ptr</span><span class="special">()</span></code>, you may still call <a class="link" href="future.html#future_get"><code class="computeroutput">future::get()</code></a>. 415 </p></dd> 416</dl> 417</div> 418<p> 419 </p> 420<h5> 421<a name="future_wait_bridgehead"></a> 422 <span class="phrase"><a name="future_wait"></a></span> 423 <a class="link" href="future.html#future_wait">Member function <code class="computeroutput">wait</code>()</a> 424</h5> 425<p> 426 </p> 427<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">wait</span><span class="special">();</span> 428</pre> 429<div class="variablelist"> 430<p class="title"><b></b></p> 431<dl class="variablelist"> 432<dt><span class="term">Effects:</span></dt> 433<dd><p> 434 Waits until <a class="link" href="promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> or <a class="link" href="promise.html#promise_set_exception"><code class="computeroutput">promise::set_exception()</code></a> is 435 called. 436 </p></dd> 437<dt><span class="term">Throws:</span></dt> 438<dd><p> 439 <code class="computeroutput"><span class="identifier">future_error</span></code> with 440 error condition <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code>. 441 </p></dd> 442</dl> 443</div> 444<p> 445 </p> 446<h5> 447<a name="future_wait_for_bridgehead"></a> 448 <span class="phrase"><a name="future_wait_for"></a></span> 449 <a class="link" href="future.html#future_wait_for">Templated member 450 function <code class="computeroutput">wait_for</code>()</a> 451</h5> 452<p> 453 </p> 454<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span> <span class="special">></span> 455<span class="identifier">future_status</span> <span class="identifier">wait_for</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special"><</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span> <span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">timeout_duration</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 456</pre> 457<div class="variablelist"> 458<p class="title"><b></b></p> 459<dl class="variablelist"> 460<dt><span class="term">Effects:</span></dt> 461<dd><p> 462 Waits until <a class="link" href="promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> or <a class="link" href="promise.html#promise_set_exception"><code class="computeroutput">promise::set_exception()</code></a> is 463 called, or <code class="computeroutput"><span class="identifier">timeout_duration</span></code> 464 has passed. 465 </p></dd> 466<dt><span class="term">Result:</span></dt> 467<dd><p> 468 A <code class="computeroutput"><span class="identifier">future_status</span></code> is 469 returned indicating the reason for returning. 470 </p></dd> 471<dt><span class="term">Throws:</span></dt> 472<dd><p> 473 <code class="computeroutput"><span class="identifier">future_error</span></code> with 474 error condition <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code> 475 or timeout-related exceptions. 476 </p></dd> 477</dl> 478</div> 479<p> 480 </p> 481<h5> 482<a name="future_wait_until_bridgehead"></a> 483 <span class="phrase"><a name="future_wait_until"></a></span> 484 <a class="link" href="future.html#future_wait_until">Templated 485 member function <code class="computeroutput">wait_until</code>()</a> 486</h5> 487<p> 488 </p> 489<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Duration</span> <span class="special">></span> 490<span class="identifier">future_status</span> <span class="identifier">wait_until</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special"><</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span> <span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">timeout_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 491</pre> 492<div class="variablelist"> 493<p class="title"><b></b></p> 494<dl class="variablelist"> 495<dt><span class="term">Effects:</span></dt> 496<dd><p> 497 Waits until <a class="link" href="promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> or <a class="link" href="promise.html#promise_set_exception"><code class="computeroutput">promise::set_exception()</code></a> is 498 called, or <code class="computeroutput"><span class="identifier">timeout_time</span></code> 499 has passed. 500 </p></dd> 501<dt><span class="term">Result:</span></dt> 502<dd><p> 503 A <code class="computeroutput"><span class="identifier">future_status</span></code> is 504 returned indicating the reason for returning. 505 </p></dd> 506<dt><span class="term">Throws:</span></dt> 507<dd><p> 508 <code class="computeroutput"><span class="identifier">future_error</span></code> with 509 error condition <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code> 510 or timeout-related exceptions. 511 </p></dd> 512</dl> 513</div> 514<p> 515 </p> 516<h5> 517<a name="class_shared_future_bridgehead"></a> 518 <span class="phrase"><a name="class_shared_future"></a></span> 519 <a class="link" href="future.html#class_shared_future">Template 520 <code class="computeroutput">shared_future<></code></a> 521</h5> 522<p> 523 </p> 524<p> 525 A <a class="link" href="future.html#class_shared_future"><code class="computeroutput">shared_future<></code></a> contains a <a class="link" href="future.html#shared_state">shared 526 state</a> which might be shared with other <a class="link" href="future.html#class_shared_future"><code class="computeroutput">shared_future<></code></a> instances. 527 </p> 528<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fiber</span><span class="special">/</span><span class="identifier">future</span><span class="special">/</span><span class="identifier">future</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 529 530<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> 531<span class="keyword">namespace</span> <span class="identifier">fibers</span> <span class="special">{</span> 532 533<span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">R</span> <span class="special">></span> 534<span class="keyword">class</span> <span class="identifier">shared_future</span> <span class="special">{</span> 535<span class="keyword">public</span><span class="special">:</span> 536 <span class="identifier">shared_future</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span> 537 538 <span class="special">~</span><span class="identifier">shared_future</span><span class="special">();</span> 539 540 <span class="identifier">shared_future</span><span class="special">(</span> <span class="identifier">shared_future</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">other</span><span class="special">);</span> 541 542 <span class="identifier">shared_future</span><span class="special">(</span> <span class="identifier">future</span><span class="special"><</span> <span class="identifier">R</span> <span class="special">></span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 543 544 <span class="identifier">shared_future</span><span class="special">(</span> <span class="identifier">shared_future</span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 545 546 <span class="identifier">shared_future</span> <span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">shared_future</span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 547 548 <span class="identifier">shared_future</span> <span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">future</span><span class="special"><</span> <span class="identifier">R</span> <span class="special">></span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 549 550 <span class="identifier">shared_future</span> <span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">shared_future</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 551 552 <span class="keyword">bool</span> <span class="identifier">valid</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span> 553 554 <span class="identifier">R</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">get</span><span class="special">();</span> <span class="comment">// member only of generic shared_future template</span> 555 <span class="identifier">R</span> <span class="special">&</span> <span class="identifier">get</span><span class="special">();</span> <span class="comment">// member only of shared_future< R & > template specialization</span> 556 <span class="keyword">void</span> <span class="identifier">get</span><span class="special">();</span> <span class="comment">// member only of shared_future< void > template specialization</span> 557 558 <span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span> <span class="identifier">get_exception_ptr</span><span class="special">();</span> 559 560 <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> 561 562 <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span> <span class="special">></span> 563 <span class="identifier">future_status</span> <span class="identifier">wait_for</span><span class="special">(</span> 564 <span class="identifier">std</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special"><</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span> <span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">timeout_duration</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 565 566 <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Duration</span> <span class="special">></span> 567 <span class="identifier">future_status</span> <span class="identifier">wait_until</span><span class="special">(</span> 568 <span class="identifier">std</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special"><</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span> <span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">timeout_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 569<span class="special">};</span> 570 571<span class="special">}}</span> 572</pre> 573<h6> 574<a name="fiber.synchronization.futures.future.h7"></a> 575 <span class="phrase"><a name="fiber.synchronization.futures.future.default_constructor0"></a></span><a class="link" href="future.html#fiber.synchronization.futures.future.default_constructor0">Default 576 constructor</a> 577 </h6> 578<pre class="programlisting"><span class="identifier">shared_future</span><span class="special">();</span> 579</pre> 580<div class="variablelist"> 581<p class="title"><b></b></p> 582<dl class="variablelist"> 583<dt><span class="term">Effects:</span></dt> 584<dd><p> 585 Creates a shared_future with no <a class="link" href="future.html#shared_state">shared 586 state</a>. After construction <code class="computeroutput"><span class="keyword">false</span> 587 <span class="special">==</span> <span class="identifier">valid</span><span class="special">()</span></code>. 588 </p></dd> 589<dt><span class="term">Throws:</span></dt> 590<dd><p> 591 Nothing. 592 </p></dd> 593</dl> 594</div> 595<h6> 596<a name="fiber.synchronization.futures.future.h8"></a> 597 <span class="phrase"><a name="fiber.synchronization.futures.future.move_constructor0"></a></span><a class="link" href="future.html#fiber.synchronization.futures.future.move_constructor0">Move constructor</a> 598 </h6> 599<pre class="programlisting"><span class="identifier">shared_future</span><span class="special">(</span> <span class="identifier">future</span><span class="special"><</span> <span class="identifier">R</span> <span class="special">></span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 600<span class="identifier">shared_future</span><span class="special">(</span> <span class="identifier">shared_future</span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 601</pre> 602<div class="variablelist"> 603<p class="title"><b></b></p> 604<dl class="variablelist"> 605<dt><span class="term">Effects:</span></dt> 606<dd><p> 607 Constructs a shared_future with the <a class="link" href="future.html#shared_state">shared 608 state</a> of other. After construction <code class="computeroutput"><span class="keyword">false</span> 609 <span class="special">==</span> <span class="identifier">other</span><span class="special">.</span><span class="identifier">valid</span><span class="special">()</span></code>. 610 </p></dd> 611<dt><span class="term">Throws:</span></dt> 612<dd><p> 613 Nothing. 614 </p></dd> 615</dl> 616</div> 617<h6> 618<a name="fiber.synchronization.futures.future.h9"></a> 619 <span class="phrase"><a name="fiber.synchronization.futures.future.copy_constructor"></a></span><a class="link" href="future.html#fiber.synchronization.futures.future.copy_constructor">Copy constructor</a> 620 </h6> 621<pre class="programlisting"><span class="identifier">shared_future</span><span class="special">(</span> <span class="identifier">shared_future</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 622</pre> 623<div class="variablelist"> 624<p class="title"><b></b></p> 625<dl class="variablelist"> 626<dt><span class="term">Effects:</span></dt> 627<dd><p> 628 Constructs a shared_future with the <a class="link" href="future.html#shared_state">shared 629 state</a> of other. After construction <code class="computeroutput"><span class="identifier">other</span><span class="special">.</span><span class="identifier">valid</span><span class="special">()</span></code> is unchanged. 630 </p></dd> 631<dt><span class="term">Throws:</span></dt> 632<dd><p> 633 Nothing. 634 </p></dd> 635</dl> 636</div> 637<h6> 638<a name="fiber.synchronization.futures.future.h10"></a> 639 <span class="phrase"><a name="fiber.synchronization.futures.future.destructor0"></a></span><a class="link" href="future.html#fiber.synchronization.futures.future.destructor0">Destructor</a> 640 </h6> 641<pre class="programlisting"><span class="special">~</span><span class="identifier">shared_future</span><span class="special">();</span> 642</pre> 643<div class="variablelist"> 644<p class="title"><b></b></p> 645<dl class="variablelist"> 646<dt><span class="term">Effects:</span></dt> 647<dd><p> 648 Destroys the shared_future; ownership is abandoned if not shared. 649 </p></dd> 650<dt><span class="term">Note:</span></dt> 651<dd><p> 652 <code class="computeroutput">~shared_future()</code> does <span class="emphasis"><em>not</em></span> block the calling fiber. 653 </p></dd> 654</dl> 655</div> 656<p> 657 </p> 658<h5> 659<a name="shared_future_operator_assign_bridgehead"></a> 660 <span class="phrase"><a name="shared_future_operator_assign"></a></span> 661 <a class="link" href="future.html#shared_future_operator_assign">Member 662 function <code class="computeroutput">operator=</code>()</a> 663</h5> 664<p> 665 </p> 666<pre class="programlisting"><span class="identifier">shared_future</span> <span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">future</span><span class="special"><</span> <span class="identifier">R</span> <span class="special">></span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 667<span class="identifier">shared_future</span> <span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">shared_future</span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 668<span class="identifier">shared_future</span> <span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">shared_future</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> 669</pre> 670<div class="variablelist"> 671<p class="title"><b></b></p> 672<dl class="variablelist"> 673<dt><span class="term">Effects:</span></dt> 674<dd><p> 675 Moves or copies the <a class="link" href="future.html#shared_state">shared state</a> 676 of other to <code class="computeroutput"><span class="keyword">this</span></code>. After 677 the assignment, the state of <code class="computeroutput"><span class="identifier">other</span><span class="special">.</span><span class="identifier">valid</span><span class="special">()</span></code> depends on which overload was invoked: 678 unchanged for the overload accepting <code class="computeroutput"><span class="identifier">shared_future</span> 679 <span class="keyword">const</span><span class="special">&</span></code>, 680 otherwise <code class="computeroutput"><span class="keyword">false</span></code>. 681 </p></dd> 682<dt><span class="term">Throws:</span></dt> 683<dd><p> 684 Nothing. 685 </p></dd> 686</dl> 687</div> 688<p> 689 </p> 690<h5> 691<a name="shared_future_valid_bridgehead"></a> 692 <span class="phrase"><a name="shared_future_valid"></a></span> 693 <a class="link" href="future.html#shared_future_valid">Member 694 function <code class="computeroutput">valid</code>()</a> 695</h5> 696<p> 697 </p> 698<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">valid</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span> 699</pre> 700<div class="variablelist"> 701<p class="title"><b></b></p> 702<dl class="variablelist"> 703<dt><span class="term">Effects:</span></dt> 704<dd><p> 705 Returns <code class="computeroutput"><span class="keyword">true</span></code> if shared_future 706 contains a <a class="link" href="future.html#shared_state">shared state</a>. 707 </p></dd> 708<dt><span class="term">Throws:</span></dt> 709<dd><p> 710 Nothing. 711 </p></dd> 712</dl> 713</div> 714<p> 715 </p> 716<h5> 717<a name="shared_future_get_bridgehead"></a> 718 <span class="phrase"><a name="shared_future_get"></a></span> 719 <a class="link" href="future.html#shared_future_get">Member function 720 <code class="computeroutput">get</code>()</a> 721</h5> 722<p> 723 </p> 724<pre class="programlisting"><span class="identifier">R</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">get</span><span class="special">();</span> <span class="comment">// member only of generic shared_future template</span> 725<span class="identifier">R</span> <span class="special">&</span> <span class="identifier">get</span><span class="special">();</span> <span class="comment">// member only of shared_future< R & > template specialization</span> 726<span class="keyword">void</span> <span class="identifier">get</span><span class="special">();</span> <span class="comment">// member only of shared_future< void > template specialization</span> 727</pre> 728<div class="variablelist"> 729<p class="title"><b></b></p> 730<dl class="variablelist"> 731<dt><span class="term">Precondition:</span></dt> 732<dd><p> 733 <code class="computeroutput"><span class="keyword">true</span> <span class="special">==</span> 734 <span class="identifier">valid</span><span class="special">()</span></code> 735 </p></dd> 736<dt><span class="term">Returns:</span></dt> 737<dd><p> 738 Waits until <a class="link" href="promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> or <a class="link" href="promise.html#promise_set_exception"><code class="computeroutput">promise::set_exception()</code></a> is 739 called. If <a class="link" href="promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> is called, returns 740 the value. If <a class="link" href="promise.html#promise_set_exception"><code class="computeroutput">promise::set_exception()</code></a> is called, 741 throws the indicated exception. 742 </p></dd> 743<dt><span class="term">Postcondition:</span></dt> 744<dd><p> 745 <code class="computeroutput"><span class="keyword">false</span> <span class="special">==</span> 746 <span class="identifier">valid</span><span class="special">()</span></code> 747 </p></dd> 748<dt><span class="term">Throws:</span></dt> 749<dd><p> 750 <code class="computeroutput"><span class="identifier">future_error</span></code> with 751 error condition <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code>, 752 <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">broken_promise</span></code>. Any exception passed 753 to <code class="computeroutput"><span class="identifier">promise</span><span class="special">::</span><span class="identifier">set_exception</span><span class="special">()</span></code>. 754 </p></dd> 755</dl> 756</div> 757<p> 758 </p> 759<h5> 760<a name="shared_future_get_exception_ptr_bridgehead"></a> 761 <span class="phrase"><a name="shared_future_get_exception_ptr"></a></span> 762 <a class="link" href="future.html#shared_future_get_exception_ptr">Member 763 function <code class="computeroutput">get_exception_ptr</code>()</a> 764</h5> 765<p> 766 </p> 767<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span> <span class="identifier">get_exception_ptr</span><span class="special">();</span> 768</pre> 769<div class="variablelist"> 770<p class="title"><b></b></p> 771<dl class="variablelist"> 772<dt><span class="term">Precondition:</span></dt> 773<dd><p> 774 <code class="computeroutput"><span class="keyword">true</span> <span class="special">==</span> 775 <span class="identifier">valid</span><span class="special">()</span></code> 776 </p></dd> 777<dt><span class="term">Returns:</span></dt> 778<dd><p> 779 Waits until <a class="link" href="promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> or <a class="link" href="promise.html#promise_set_exception"><code class="computeroutput">promise::set_exception()</code></a> is 780 called. If <code class="computeroutput"><span class="identifier">set_value</span><span class="special">()</span></code> is called, returns a default-constructed 781 <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span></code>. If <code class="computeroutput"><span class="identifier">set_exception</span><span class="special">()</span></code> 782 is called, returns the passed <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span></code>. 783 </p></dd> 784<dt><span class="term">Throws:</span></dt> 785<dd><p> 786 <code class="computeroutput"><span class="identifier">future_error</span></code> with 787 error condition <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code>. 788 </p></dd> 789<dt><span class="term">Note:</span></dt> 790<dd><p> 791 <code class="computeroutput"><span class="identifier">get_exception_ptr</span><span class="special">()</span></code> does <span class="emphasis"><em>not</em></span> invalidate 792 the <code class="computeroutput">shared_future</code>. After calling <code class="computeroutput"><span class="identifier">get_exception_ptr</span><span class="special">()</span></code>, you may still call <a class="link" href="future.html#shared_future_get"><code class="computeroutput">shared_future::get()</code></a>. 793 </p></dd> 794</dl> 795</div> 796<p> 797 </p> 798<h5> 799<a name="shared_future_wait_bridgehead"></a> 800 <span class="phrase"><a name="shared_future_wait"></a></span> 801 <a class="link" href="future.html#shared_future_wait">Member 802 function <code class="computeroutput">wait</code>()</a> 803</h5> 804<p> 805 </p> 806<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">wait</span><span class="special">();</span> 807</pre> 808<div class="variablelist"> 809<p class="title"><b></b></p> 810<dl class="variablelist"> 811<dt><span class="term">Effects:</span></dt> 812<dd><p> 813 Waits until <a class="link" href="promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> or <a class="link" href="promise.html#promise_set_exception"><code class="computeroutput">promise::set_exception()</code></a> is 814 called. 815 </p></dd> 816<dt><span class="term">Throws:</span></dt> 817<dd><p> 818 <code class="computeroutput"><span class="identifier">future_error</span></code> with 819 error condition <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code>. 820 </p></dd> 821</dl> 822</div> 823<p> 824 </p> 825<h5> 826<a name="shared_future_wait_for_bridgehead"></a> 827 <span class="phrase"><a name="shared_future_wait_for"></a></span> 828 <a class="link" href="future.html#shared_future_wait_for">Templated 829 member function <code class="computeroutput">wait_for</code>()</a> 830</h5> 831<p> 832 </p> 833<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span> <span class="special">></span> 834<span class="identifier">future_status</span> <span class="identifier">wait_for</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special"><</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span> <span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">timeout_duration</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 835</pre> 836<div class="variablelist"> 837<p class="title"><b></b></p> 838<dl class="variablelist"> 839<dt><span class="term">Effects:</span></dt> 840<dd><p> 841 Waits until <a class="link" href="promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> or <a class="link" href="promise.html#promise_set_exception"><code class="computeroutput">promise::set_exception()</code></a> is 842 called, or <code class="computeroutput"><span class="identifier">timeout_duration</span></code> 843 has passed. 844 </p></dd> 845<dt><span class="term">Result:</span></dt> 846<dd><p> 847 A <code class="computeroutput"><span class="identifier">future_status</span></code> is 848 returned indicating the reason for returning. 849 </p></dd> 850<dt><span class="term">Throws:</span></dt> 851<dd><p> 852 <code class="computeroutput"><span class="identifier">future_error</span></code> with 853 error condition <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code> 854 or timeout-related exceptions. 855 </p></dd> 856</dl> 857</div> 858<p> 859 </p> 860<h5> 861<a name="shared_future_wait_until_bridgehead"></a> 862 <span class="phrase"><a name="shared_future_wait_until"></a></span> 863 <a class="link" href="future.html#shared_future_wait_until">Templated 864 member function <code class="computeroutput">wait_until</code>()</a> 865</h5> 866<p> 867 </p> 868<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Duration</span> <span class="special">></span> 869<span class="identifier">future_status</span> <span class="identifier">wait_until</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special"><</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span> <span class="special">></span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">timeout_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 870</pre> 871<div class="variablelist"> 872<p class="title"><b></b></p> 873<dl class="variablelist"> 874<dt><span class="term">Effects:</span></dt> 875<dd><p> 876 Waits until <a class="link" href="promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> or <a class="link" href="promise.html#promise_set_exception"><code class="computeroutput">promise::set_exception()</code></a> is 877 called, or <code class="computeroutput"><span class="identifier">timeout_time</span></code> 878 has passed. 879 </p></dd> 880<dt><span class="term">Result:</span></dt> 881<dd><p> 882 A <code class="computeroutput"><span class="identifier">future_status</span></code> is 883 returned indicating the reason for returning. 884 </p></dd> 885<dt><span class="term">Throws:</span></dt> 886<dd><p> 887 <code class="computeroutput"><span class="identifier">future_error</span></code> with 888 error condition <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code> 889 or timeout-related exceptions. 890 </p></dd> 891</dl> 892</div> 893<p> 894 </p> 895<h5> 896<a name="fibers_async_bridgehead"></a> 897 <span class="phrase"><a name="fibers_async"></a></span> 898 <a class="link" href="future.html#fibers_async">Non-member function <code class="computeroutput">fibers::async()</code></a> 899</h5> 900<p> 901 </p> 902<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fiber</span><span class="special">/</span><span class="identifier">future</span><span class="special">/</span><span class="identifier">async</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 903 904<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> 905<span class="keyword">namespace</span> <span class="identifier">fibers</span> <span class="special">{</span> 906 907<span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">Function</span><span class="special">,</span> <span class="keyword">class</span> <span class="special">...</span> <span class="identifier">Args</span> <span class="special">></span> 908<span class="identifier">future</span><span class="special"><</span> 909 <span class="identifier">std</span><span class="special">::</span><span class="identifier">result_of_t</span><span class="special"><</span> 910 <span class="identifier">std</span><span class="special">::</span><span class="identifier">decay_t</span><span class="special"><</span> <span class="identifier">Function</span> <span class="special">>(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">decay_t</span><span class="special"><</span> <span class="identifier">Args</span> <span class="special">></span> <span class="special">...</span> <span class="special">)</span> 911 <span class="special">></span> 912<span class="special">></span> 913<span class="identifier">async</span><span class="special">(</span> <span class="identifier">Function</span> <span class="special">&&</span> <span class="identifier">fn</span><span class="special">,</span> <span class="identifier">Args</span> <span class="special">&&</span> <span class="special">...</span> <span class="identifier">args</span><span class="special">);</span> 914 915<span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">Function</span><span class="special">,</span> <span class="keyword">class</span> <span class="special">...</span> <span class="identifier">Args</span> <span class="special">></span> 916<span class="identifier">future</span><span class="special"><</span> 917 <span class="identifier">std</span><span class="special">::</span><span class="identifier">result_of_t</span><span class="special"><</span> 918 <span class="identifier">std</span><span class="special">::</span><span class="identifier">decay_t</span><span class="special"><</span> <span class="identifier">Function</span> <span class="special">>(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">decay_t</span><span class="special"><</span> <span class="identifier">Args</span> <span class="special">></span> <span class="special">...</span> <span class="special">)</span> 919 <span class="special">></span> 920<span class="special">></span> 921<span class="identifier">async</span><span class="special">(</span> <a class="link" href="../../fiber_mgmt.html#class_launch"><code class="computeroutput"><span class="identifier">launch</span></code></a> <span class="identifier">policy</span><span class="special">,</span> <span class="identifier">Function</span> <span class="special">&&</span> <span class="identifier">fn</span><span class="special">,</span> <span class="identifier">Args</span> <span class="special">&&</span> <span class="special">...</span> <span class="identifier">args</span><span class="special">);</span> 922 923<span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <a class="link" href="../../stack.html#stack_allocator_concept"><code class="computeroutput"><span class="identifier">StackAllocator</span></code></a><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Function</span><span class="special">,</span> <span class="keyword">class</span> <span class="special">...</span> <span class="identifier">Args</span> <span class="special">></span> 924<span class="identifier">future</span><span class="special"><</span> 925 <span class="identifier">std</span><span class="special">::</span><span class="identifier">result_of_t</span><span class="special"><</span> 926 <span class="identifier">std</span><span class="special">::</span><span class="identifier">decay_t</span><span class="special"><</span> <span class="identifier">Function</span> <span class="special">>(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">decay_t</span><span class="special"><</span> <span class="identifier">Args</span> <span class="special">></span> <span class="special">...</span> <span class="special">)</span> 927 <span class="special">></span> 928<span class="special">></span> 929<span class="identifier">async</span><span class="special">(</span> <a class="link" href="../../fiber_mgmt.html#class_launch"><code class="computeroutput"><span class="identifier">launch</span></code></a> <span class="identifier">policy</span><span class="special">,</span> <a href="http://en.cppreference.com/w/cpp/memory/allocator_arg_t" target="_top"><code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator_arg_t</span></code></a><span class="special">,</span> <a class="link" href="../../stack.html#stack_allocator_concept"><code class="computeroutput"><span class="identifier">StackAllocator</span></code></a> <span class="identifier">salloc</span><span class="special">,</span> 930 <span class="identifier">Function</span> <span class="special">&&</span> <span class="identifier">fn</span><span class="special">,</span> <span class="identifier">Args</span> <span class="special">&&</span> <span class="special">...</span> <span class="identifier">args</span><span class="special">);</span> 931 932<span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <a class="link" href="../../stack.html#stack_allocator_concept"><code class="computeroutput"><span class="identifier">StackAllocator</span></code></a><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Function</span><span class="special">,</span> <span class="keyword">class</span> <span class="special">...</span> <span class="identifier">Args</span> <span class="special">></span> 933<span class="identifier">future</span><span class="special"><</span> 934 <span class="identifier">std</span><span class="special">::</span><span class="identifier">result_of_t</span><span class="special"><</span> 935 <span class="identifier">std</span><span class="special">::</span><span class="identifier">decay_t</span><span class="special"><</span> <span class="identifier">Function</span> <span class="special">>(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">decay_t</span><span class="special"><</span> <span class="identifier">Args</span> <span class="special">></span> <span class="special">...</span> <span class="special">)</span> 936 <span class="special">></span> 937<span class="special">></span> 938<span class="identifier">async</span><span class="special">(</span> <a class="link" href="../../fiber_mgmt.html#class_launch"><code class="computeroutput"><span class="identifier">launch</span></code></a> <span class="identifier">policy</span><span class="special">,</span> <a href="http://en.cppreference.com/w/cpp/memory/allocator_arg_t" target="_top"><code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator_arg_t</span></code></a><span class="special">,</span> <a class="link" href="../../stack.html#stack_allocator_concept"><code class="computeroutput"><span class="identifier">StackAllocator</span></code></a> <span class="identifier">salloc</span><span class="special">,</span> 939 <span class="identifier">Allocator</span> <span class="identifier">alloc</span><span class="special">,</span> <span class="identifier">Function</span> <span class="special">&&</span> <span class="identifier">fn</span><span class="special">,</span> <span class="identifier">Args</span> <span class="special">&&</span> <span class="special">...</span> <span class="identifier">args</span><span class="special">);</span> 940 941<span class="special">}}</span> 942</pre> 943<div class="variablelist"> 944<p class="title"><b></b></p> 945<dl class="variablelist"> 946<dt><span class="term">Effects:</span></dt> 947<dd><p> 948 Executes <code class="computeroutput"><span class="identifier">fn</span></code> in a 949 <a class="link" href="../../fiber_mgmt/fiber.html#class_fiber"><code class="computeroutput">fiber</code></a> and returns an associated <a class="link" href="future.html#class_future"><code class="computeroutput">future<></code></a>. 950 </p></dd> 951<dt><span class="term">Result:</span></dt> 952<dd> 953<p> 954</p> 955<pre class="programlisting"><span class="identifier">future</span><span class="special"><</span> 956 <span class="identifier">std</span><span class="special">::</span><span class="identifier">result_of_t</span><span class="special"><</span> 957 <span class="identifier">std</span><span class="special">::</span><span class="identifier">decay_t</span><span class="special"><</span> <span class="identifier">Function</span> <span class="special">>(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">decay_t</span><span class="special"><</span> <span class="identifier">Args</span> <span class="special">></span> <span class="special">...</span> <span class="special">)</span> 958 <span class="special">></span> 959<span class="special">></span></pre> 960<p> 961 representing the <a class="link" href="future.html#shared_state">shared state</a> 962 associated with the asynchronous execution of <code class="computeroutput"><span class="identifier">fn</span></code>. 963 </p> 964</dd> 965<dt><span class="term">Throws:</span></dt> 966<dd><p> 967 <code class="computeroutput"><span class="identifier">fiber_error</span></code> or <code class="computeroutput"><span class="identifier">future_error</span></code> if an error occurs. 968 </p></dd> 969<dt><span class="term">Notes:</span></dt> 970<dd><p> 971 The overloads accepting <a href="http://en.cppreference.com/w/cpp/memory/allocator_arg_t" target="_top"><code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator_arg_t</span></code></a> use the 972 passed <a class="link" href="../../stack.html#stack_allocator_concept"><code class="computeroutput"><span class="identifier">StackAllocator</span></code></a> 973 when constructing the launched <code class="computeroutput"><span class="identifier">fiber</span></code>. 974 The overloads accepting <a class="link" href="../../fiber_mgmt.html#class_launch"><code class="computeroutput">launch</code></a> use the passed <code class="computeroutput"><span class="identifier">launch</span></code> when constructing the launched 975 <code class="computeroutput"><span class="identifier">fiber</span></code>. The default 976 <code class="computeroutput"><span class="identifier">launch</span></code> is <code class="computeroutput"><span class="identifier">post</span></code>, as for the <code class="computeroutput"><span class="identifier">fiber</span></code> constructor. 977 </p></dd> 978</dl> 979</div> 980<div class="note"><table border="0" summary="Note"> 981<tr> 982<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../../doc/src/images/note.png"></td> 983<th align="left">Note</th> 984</tr> 985<tr><td align="left" valign="top"><p> 986 Deferred futures are not supported. 987 </p></td></tr> 988</table></div> 989</div> 990<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 991<td align="left"></td> 992<td align="right"><div class="copyright-footer">Copyright © 2013 Oliver Kowalke<p> 993 Distributed under the Boost Software License, Version 1.0. (See accompanying 994 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>) 995 </p> 996</div></td> 997</tr></table> 998<hr> 999<div class="spirit-nav"> 1000<a accesskey="p" href="../futures.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../futures.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="promise.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 1001</div> 1002</body> 1003</html> 1004
