1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>deadline_timer</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="../../boost_asio.html" title="Boost.Asio"> 8<link rel="up" href="../reference.html" title="Reference"> 9<link rel="prev" href="coroutine/is_parent.html" title="coroutine::is_parent"> 10<link rel="next" href="default_completion_token.html" title="default_completion_token"> 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="coroutine/is_parent.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="default_completion_token.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 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> 31Typedef for the typical 32 usage of timer. Uses a UTC clock. 33 </p> 34<pre class="programlisting">typedef basic_deadline_timer< boost::posix_time::ptime > 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> <span class="silver">[constructor]</span> 158 </p> 159 </td> 160<td> 161 <p> 162 Constructor. <br> <span class="silver"> —</span><br> Constructor to set a particular expiry 163 time as an absolute time. <br> <span class="silver"> —</span><br> Constructor to set a particular 164 expiry time relative to now. <br> <span class="silver"> —</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"> —</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"> —</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> <span class="silver">[destructor]</span> 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. 302boost::asio::deadline_timer timer(my_context); 303 304// Set an expiry time relative to now. 305timer.expires_from_now(boost::posix_time::seconds(5)); 306 307// Wait for the timer to expire. 308timer.wait(); 309</pre> 310<p> 311 Performing an asynchronous wait: 312 </p> 313<pre class="programlisting">void handler(const boost::system::error_code& error) 314{ 315 if (!error) 316 { 317 // Timer expired. 318 } 319} 320 321... 322 323// Construct a timer with an absolute expiry time. 324boost::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. 328timer.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)) > 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 354void on_timeout(const boost::system::error_code& 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 © 2003-2020 Christopher M. 389 Kohlhoff<p> 390 Distributed under the Boost Software License, Version 1.0. (See accompanying 391 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>) 392 </p> 393</div></td> 394</tr></table> 395<hr> 396<div class="spirit-nav"> 397<a accesskey="p" href="coroutine/is_parent.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="default_completion_token.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 398</div> 399</body> 400</html> 401
