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  26 <div class="titlepage"><div><div><h3 class="title">
  27 <a name="boost_asio.reference.deadline_timer"></a><a class="link" href="deadline_timer.html" title="deadline_timer">deadline_timer</a>
  28 </h3></div></div></div>
  29 <p>
  30         <a class="indexterm" name="boost_asio.indexterm.deadline_timer"></a>
  31 Typedef for the typical
  32         usage of timer. Uses a UTC clock.
  33       </p>
  34 <pre class="programlisting">typedef basic_deadline_timer&lt; boost::posix_time::ptime &gt; deadline_timer;
  35 </pre>
  36 <h5>
  37 <a name="boost_asio.reference.deadline_timer.h0"></a>
  38         <span class="phrase"><a name="boost_asio.reference.deadline_timer.types"></a></span><a class="link" href="deadline_timer.html#boost_asio.reference.deadline_timer.types">Types</a>
  39       </h5>
  40 <div class="informaltable"><table class="table">
  41 <colgroup>
  42 <col>
  43 <col>
  44 </colgroup>
  45 <thead><tr>
  46 <th>
  47                 <p>
  48                   Name
  49                 </p>
  50               </th>
  51 <th>
  52                 <p>
  53                   Description
  54                 </p>
  55               </th>
  56 </tr></thead>
  57 <tbody>
  58 <tr>
  59 <td>
  60                 <p>
  61                   <a class="link" href="basic_deadline_timer__rebind_executor.html" title="basic_deadline_timer::rebind_executor"><span class="bold"><strong>rebind_executor</strong></span></a>
  62                 </p>
  63               </td>
  64 <td>
  65                 <p>
  66                   Rebinds the timer type to another executor.
  67                 </p>
  68               </td>
  69 </tr>
  70 <tr>
  71 <td>
  72                 <p>
  73                   <a class="link" href="basic_deadline_timer/duration_type.html" title="basic_deadline_timer::duration_type"><span class="bold"><strong>duration_type</strong></span></a>
  74                 </p>
  75               </td>
  76 <td>
  77                 <p>
  78                   The duration type.
  79                 </p>
  80               </td>
  81 </tr>
  82 <tr>
  83 <td>
  84                 <p>
  85                   <a class="link" href="basic_deadline_timer/executor_type.html" title="basic_deadline_timer::executor_type"><span class="bold"><strong>executor_type</strong></span></a>
  86                 </p>
  87               </td>
  88 <td>
  89                 <p>
  90                   The type of the executor associated with the object.
  91                 </p>
  92               </td>
  93 </tr>
  94 <tr>
  95 <td>
  96                 <p>
  97                   <a class="link" href="basic_deadline_timer/time_type.html" title="basic_deadline_timer::time_type"><span class="bold"><strong>time_type</strong></span></a>
  98                 </p>
  99               </td>
 100 <td>
 101                 <p>
 102                   The time type.
 103                 </p>
 104               </td>
 105 </tr>
 106 <tr>
 107 <td>
 108                 <p>
 109                   <a class="link" href="basic_deadline_timer/traits_type.html" title="basic_deadline_timer::traits_type"><span class="bold"><strong>traits_type</strong></span></a>
 110                 </p>
 111               </td>
 112 <td>
 113                 <p>
 114                   The time traits type.
 115                 </p>
 116               </td>
 117 </tr>
 118 </tbody>
 119 </table></div>
 120 <h5>
 121 <a name="boost_asio.reference.deadline_timer.h1"></a>
 122         <span class="phrase"><a name="boost_asio.reference.deadline_timer.member_functions"></a></span><a class="link" href="deadline_timer.html#boost_asio.reference.deadline_timer.member_functions">Member Functions</a>
 123       </h5>
 124 <div class="informaltable"><table class="table">
 125 <colgroup>
 126 <col>
 127 <col>
 128 </colgroup>
 129 <thead><tr>
 130 <th>
 131                 <p>
 132                   Name
 133                 </p>
 134               </th>
 135 <th>
 136                 <p>
 137                   Description
 138                 </p>
 139               </th>
 140 </tr></thead>
 141 <tbody>
 142 <tr>
 143 <td>
 144                 <p>
 145                   <a class="link" href="basic_deadline_timer/async_wait.html" title="basic_deadline_timer::async_wait"><span class="bold"><strong>async_wait</strong></span></a>
 146                 </p>
 147               </td>
 148 <td>
 149                 <p>
 150                   Start an asynchronous wait on the timer.
 151                 </p>
 152               </td>
 153 </tr>
 154 <tr>
 155 <td>
 156                 <p>
 157                   <a class="link" href="basic_deadline_timer/basic_deadline_timer.html" title="basic_deadline_timer::basic_deadline_timer"><span class="bold"><strong>basic_deadline_timer</strong></span></a>
 158                 </p>
 159               </td>
 160 <td>
 161                 <p>
 162                   Constructor. <br> <span class="silver"> &#8212;</span><br> Constructor to set a particular expiry
 163                   time as an absolute time. <br> <span class="silver"> &#8212;</span><br> Constructor to set a particular
 164                   expiry time relative to now. <br> <span class="silver"> &#8212;</span><br> Move-construct a basic_deadline_timer
 165                   from another.
 166                 </p>
 167               </td>
 168 </tr>
 169 <tr>
 170 <td>
 171                 <p>
 172                   <a class="link" href="basic_deadline_timer/cancel.html" title="basic_deadline_timer::cancel"><span class="bold"><strong>cancel</strong></span></a>
 173                 </p>
 174               </td>
 175 <td>
 176                 <p>
 177                   Cancel any asynchronous operations that are waiting on the timer.
 178                 </p>
 179               </td>
 180 </tr>
 181 <tr>
 182 <td>
 183                 <p>
 184                   <a class="link" href="basic_deadline_timer/cancel_one.html" title="basic_deadline_timer::cancel_one"><span class="bold"><strong>cancel_one</strong></span></a>
 185                 </p>
 186               </td>
 187 <td>
 188                 <p>
 189                   Cancels one asynchronous operation that is waiting on the timer.
 190                 </p>
 191               </td>
 192 </tr>
 193 <tr>
 194 <td>
 195                 <p>
 196                   <a class="link" href="basic_deadline_timer/expires_at.html" title="basic_deadline_timer::expires_at"><span class="bold"><strong>expires_at</strong></span></a>
 197                 </p>
 198               </td>
 199 <td>
 200                 <p>
 201                   Get the timer's expiry time as an absolute time. <br> <span class="silver"> &#8212;</span><br>
 202                   Set the timer's expiry time as an absolute time.
 203                 </p>
 204               </td>
 205 </tr>
 206 <tr>
 207 <td>
 208                 <p>
 209                   <a class="link" href="basic_deadline_timer/expires_from_now.html" title="basic_deadline_timer::expires_from_now"><span class="bold"><strong>expires_from_now</strong></span></a>
 210                 </p>
 211               </td>
 212 <td>
 213                 <p>
 214                   Get the timer's expiry time relative to now. <br> <span class="silver"> &#8212;</span><br> Set
 215                   the timer's expiry time relative to now.
 216                 </p>
 217               </td>
 218 </tr>
 219 <tr>
 220 <td>
 221                 <p>
 222                   <a class="link" href="basic_deadline_timer/get_executor.html" title="basic_deadline_timer::get_executor"><span class="bold"><strong>get_executor</strong></span></a>
 223                 </p>
 224               </td>
 225 <td>
 226                 <p>
 227                   Get the executor associated with the object.
 228                 </p>
 229               </td>
 230 </tr>
 231 <tr>
 232 <td>
 233                 <p>
 234                   <a class="link" href="basic_deadline_timer/operator_eq_.html" title="basic_deadline_timer::operator="><span class="bold"><strong>operator=</strong></span></a>
 235                 </p>
 236               </td>
 237 <td>
 238                 <p>
 239                   Move-assign a basic_deadline_timer from another.
 240                 </p>
 241               </td>
 242 </tr>
 243 <tr>
 244 <td>
 245                 <p>
 246                   <a class="link" href="basic_deadline_timer/wait.html" title="basic_deadline_timer::wait"><span class="bold"><strong>wait</strong></span></a>
 247                 </p>
 248               </td>
 249 <td>
 250                 <p>
 251                   Perform a blocking wait on the timer.
 252                 </p>
 253               </td>
 254 </tr>
 255 <tr>
 256 <td>
 257                 <p>
 258                   <a class="link" href="basic_deadline_timer/_basic_deadline_timer.html" title="basic_deadline_timer::~basic_deadline_timer"><span class="bold"><strong>~basic_deadline_timer</strong></span></a>
 259                 </p>
 260               </td>
 261 <td>
 262                 <p>
 263                   Destroys the timer.
 264                 </p>
 265               </td>
 266 </tr>
 267 </tbody>
 268 </table></div>
 269 <p>
 270         The <a class="link" href="basic_deadline_timer.html" title="basic_deadline_timer"><code class="computeroutput">basic_deadline_timer</code></a>
 271         class template provides the ability to perform a blocking or asynchronous
 272         wait for a timer to expire.
 273       </p>
 274 <p>
 275         A deadline timer is always in one of two states: "expired" or "not
 276         expired". If the <code class="computeroutput">wait()</code> or <code class="computeroutput">async_wait()</code> function
 277         is called on an expired timer, the wait operation will complete immediately.
 278       </p>
 279 <p>
 280         Most applications will use the <a class="link" href="deadline_timer.html" title="deadline_timer"><code class="computeroutput">deadline_timer</code></a>
 281         typedef.
 282       </p>
 283 <h5>
 284 <a name="boost_asio.reference.deadline_timer.h2"></a>
 285         <span class="phrase"><a name="boost_asio.reference.deadline_timer.thread_safety"></a></span><a class="link" href="deadline_timer.html#boost_asio.reference.deadline_timer.thread_safety">Thread
 286         Safety</a>
 287       </h5>
 288 <p>
 289         <span class="emphasis"><em>Distinct</em></span> <span class="emphasis"><em>objects:</em></span> Safe.
 290       </p>
 291 <p>
 292         <span class="emphasis"><em>Shared</em></span> <span class="emphasis"><em>objects:</em></span> Unsafe.
 293       </p>
 294 <h5>
 295 <a name="boost_asio.reference.deadline_timer.h3"></a>
 296         <span class="phrase"><a name="boost_asio.reference.deadline_timer.examples"></a></span><a class="link" href="deadline_timer.html#boost_asio.reference.deadline_timer.examples">Examples</a>
 297       </h5>
 298 <p>
 299         Performing a blocking wait:
 300       </p>
 301 <pre class="programlisting">// Construct a timer without setting an expiry time.
 302 boost::asio::deadline_timer timer(my_context);
 303
 304 // Set an expiry time relative to now.
 305 timer.expires_from_now(boost::posix_time::seconds(5));
 306
 307 // Wait for the timer to expire.
 308 timer.wait();
 309 </pre>
 310 <p>
 311         Performing an asynchronous wait:
 312       </p>
 313 <pre class="programlisting">void handler(const boost::system::error_code&amp; error)
 314 {
 315   if (!error)
 316   {
 317     // Timer expired.
 318   }
 319 }
 320
 321 ...
 322
 323 // Construct a timer with an absolute expiry time.
 324 boost::asio::deadline_timer timer(my_context,
 325     boost::posix_time::time_from_string("2005-12-07 23:59:59.000"));
 326
 327 // Start an asynchronous wait.
 328 timer.async_wait(handler);
 329 </pre>
 330 <h5>
 331 <a name="boost_asio.reference.deadline_timer.h4"></a>
 332         <span class="phrase"><a name="boost_asio.reference.deadline_timer.changing_an_active_deadline_timer_s_expiry_time"></a></span><a class="link" href="deadline_timer.html#boost_asio.reference.deadline_timer.changing_an_active_deadline_timer_s_expiry_time">Changing
 333         an active deadline_timer's expiry time</a>
 334       </h5>
 335 <p>
 336         Changing the expiry time of a timer while there are pending asynchronous
 337         waits causes those wait operations to be cancelled. To ensure that the action
 338         associated with the timer is performed only once, use something like this:
 339         used:
 340       </p>
 341 <pre class="programlisting">void on_some_event()
 342 {
 343   if (my_timer.expires_from_now(seconds(5)) &gt; 0)
 344   {
 345     // We managed to cancel the timer. Start new asynchronous wait.
 346     my_timer.async_wait(on_timeout);
 347   }
 348   else
 349   {
 350     // Too late, timer has already expired!
 351   }
 352 }
 353
 354 void on_timeout(const boost::system::error_code&amp; e)
 355 {
 356   if (e != boost::asio::error::operation_aborted)
 357   {
 358     // Timer was not cancelled, take necessary action.
 359   }
 360 }
 361 </pre>
 362 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
 363 <li class="listitem">
 364             The <code class="computeroutput">boost::asio::basic_deadline_timer::expires_from_now()</code>
 365             function cancels any pending asynchronous waits, and returns the number
 366             of asynchronous waits that were cancelled. If it returns 0 then you were
 367             too late and the wait handler has already been executed, or will soon
 368             be executed. If it returns 1 then the wait handler was successfully cancelled.
 369           </li>
 370 <li class="listitem">
 371             If a wait handler is cancelled, the boost::system::error_code passed
 372             to it contains the value <code class="computeroutput">boost::asio::error::operation_aborted</code>.
 373           </li>
 374 </ul></div>
 375 <h5>
 376 <a name="boost_asio.reference.deadline_timer.h5"></a>
 377         <span class="phrase"><a name="boost_asio.reference.deadline_timer.requirements"></a></span><a class="link" href="deadline_timer.html#boost_asio.reference.deadline_timer.requirements">Requirements</a>
 378       </h5>
 379 <p>
 380         <span class="emphasis"><em>Header: </em></span><code class="literal">boost/asio/deadline_timer.hpp</code>
 381       </p>
 382 <p>
 383         <span class="emphasis"><em>Convenience header: </em></span><code class="literal">boost/asio.hpp</code>
 384       </p>
 385 </div>
 386 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 387 <td align="left"></td>
 388 <td align="right"><div class="copyright-footer">Copyright &#169; 2003-2019 Christopher M. Kohlhoff<p>
 389         Distributed under the Boost Software License, Version 1.0. (See accompanying
 390         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>)
 391       </p>
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