1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>basic_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="basic_datagram_socket__rebind_executor/other.html" title="basic_datagram_socket::rebind_executor::other"> 10<link rel="next" href="basic_deadline_timer/async_wait.html" title="basic_deadline_timer::async_wait"> 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 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href="basic_deadline_timer.html" title="basic_deadline_timer">basic_deadline_timer</a> 28</h3></div></div></div> 29<p> 30 Provides waitable timer functionality. 31 </p> 32<pre class="programlisting">template< 33 typename Time, 34 typename <a class="link" href="TimeTraits.html" title="Time traits requirements">TimeTraits</a> = boost::asio::time_traits<Time>, 35 typename <a class="link" href="Executor1.html" title="Executor requirements">Executor</a> = any_io_executor> 36class basic_deadline_timer 37</pre> 38<h5> 39<a name="boost_asio.reference.basic_deadline_timer.h0"></a> 40 <span class="phrase"><a name="boost_asio.reference.basic_deadline_timer.types"></a></span><a class="link" href="basic_deadline_timer.html#boost_asio.reference.basic_deadline_timer.types">Types</a> 41 </h5> 42<div class="informaltable"><table class="table"> 43<colgroup> 44<col> 45<col> 46</colgroup> 47<thead><tr> 48<th> 49 <p> 50 Name 51 </p> 52 </th> 53<th> 54 <p> 55 Description 56 </p> 57 </th> 58</tr></thead> 59<tbody> 60<tr> 61<td> 62 <p> 63 <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> 64 </p> 65 </td> 66<td> 67 <p> 68 Rebinds the timer type to another executor. 69 </p> 70 </td> 71</tr> 72<tr> 73<td> 74 <p> 75 <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> 76 </p> 77 </td> 78<td> 79 <p> 80 The duration type. 81 </p> 82 </td> 83</tr> 84<tr> 85<td> 86 <p> 87 <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> 88 </p> 89 </td> 90<td> 91 <p> 92 The type of the executor associated with the object. 93 </p> 94 </td> 95</tr> 96<tr> 97<td> 98 <p> 99 <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> 100 </p> 101 </td> 102<td> 103 <p> 104 The time type. 105 </p> 106 </td> 107</tr> 108<tr> 109<td> 110 <p> 111 <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> 112 </p> 113 </td> 114<td> 115 <p> 116 The time traits type. 117 </p> 118 </td> 119</tr> 120</tbody> 121</table></div> 122<h5> 123<a name="boost_asio.reference.basic_deadline_timer.h1"></a> 124 <span class="phrase"><a name="boost_asio.reference.basic_deadline_timer.member_functions"></a></span><a class="link" href="basic_deadline_timer.html#boost_asio.reference.basic_deadline_timer.member_functions">Member 125 Functions</a> 126 </h5> 127<div class="informaltable"><table class="table"> 128<colgroup> 129<col> 130<col> 131</colgroup> 132<thead><tr> 133<th> 134 <p> 135 Name 136 </p> 137 </th> 138<th> 139 <p> 140 Description 141 </p> 142 </th> 143</tr></thead> 144<tbody> 145<tr> 146<td> 147 <p> 148 <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> 149 </p> 150 </td> 151<td> 152 <p> 153 Start an asynchronous wait on the timer. 154 </p> 155 </td> 156</tr> 157<tr> 158<td> 159 <p> 160 <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> 161 </p> 162 </td> 163<td> 164 <p> 165 Constructor. <br> <span class="silver"> —</span><br> Constructor to set a particular expiry 166 time as an absolute time. <br> <span class="silver"> —</span><br> Constructor to set a particular 167 expiry time relative to now. <br> <span class="silver"> —</span><br> Move-construct a basic_deadline_timer 168 from another. 169 </p> 170 </td> 171</tr> 172<tr> 173<td> 174 <p> 175 <a class="link" href="basic_deadline_timer/cancel.html" title="basic_deadline_timer::cancel"><span class="bold"><strong>cancel</strong></span></a> 176 </p> 177 </td> 178<td> 179 <p> 180 Cancel any asynchronous operations that are waiting on the timer. 181 </p> 182 </td> 183</tr> 184<tr> 185<td> 186 <p> 187 <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> 188 </p> 189 </td> 190<td> 191 <p> 192 Cancels one asynchronous operation that is waiting on the timer. 193 </p> 194 </td> 195</tr> 196<tr> 197<td> 198 <p> 199 <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> 200 </p> 201 </td> 202<td> 203 <p> 204 Get the timer's expiry time as an absolute time. <br> <span class="silver"> —</span><br> 205 Set the timer's expiry time as an absolute time. 206 </p> 207 </td> 208</tr> 209<tr> 210<td> 211 <p> 212 <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> 213 </p> 214 </td> 215<td> 216 <p> 217 Get the timer's expiry time relative to now. <br> <span class="silver"> —</span><br> Set 218 the timer's expiry time relative to now. 219 </p> 220 </td> 221</tr> 222<tr> 223<td> 224 <p> 225 <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> 226 </p> 227 </td> 228<td> 229 <p> 230 Get the executor associated with the object. 231 </p> 232 </td> 233</tr> 234<tr> 235<td> 236 <p> 237 <a class="link" href="basic_deadline_timer/operator_eq_.html" title="basic_deadline_timer::operator="><span class="bold"><strong>operator=</strong></span></a> 238 </p> 239 </td> 240<td> 241 <p> 242 Move-assign a basic_deadline_timer from another. 243 </p> 244 </td> 245</tr> 246<tr> 247<td> 248 <p> 249 <a class="link" href="basic_deadline_timer/wait.html" title="basic_deadline_timer::wait"><span class="bold"><strong>wait</strong></span></a> 250 </p> 251 </td> 252<td> 253 <p> 254 Perform a blocking wait on the timer. 255 </p> 256 </td> 257</tr> 258<tr> 259<td> 260 <p> 261 <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> 262 </p> 263 </td> 264<td> 265 <p> 266 Destroys the timer. 267 </p> 268 </td> 269</tr> 270</tbody> 271</table></div> 272<p> 273 The <a class="link" href="basic_deadline_timer.html" title="basic_deadline_timer"><code class="computeroutput">basic_deadline_timer</code></a> 274 class template provides the ability to perform a blocking or asynchronous 275 wait for a timer to expire. 276 </p> 277<p> 278 A deadline timer is always in one of two states: "expired" or "not 279 expired". If the <code class="computeroutput">wait()</code> or <code class="computeroutput">async_wait()</code> function 280 is called on an expired timer, the wait operation will complete immediately. 281 </p> 282<p> 283 Most applications will use the <a class="link" href="deadline_timer.html" title="deadline_timer"><code class="computeroutput">deadline_timer</code></a> 284 typedef. 285 </p> 286<h5> 287<a name="boost_asio.reference.basic_deadline_timer.h2"></a> 288 <span class="phrase"><a name="boost_asio.reference.basic_deadline_timer.thread_safety"></a></span><a class="link" href="basic_deadline_timer.html#boost_asio.reference.basic_deadline_timer.thread_safety">Thread 289 Safety</a> 290 </h5> 291<p> 292 <span class="emphasis"><em>Distinct</em></span> <span class="emphasis"><em>objects:</em></span> Safe. 293 </p> 294<p> 295 <span class="emphasis"><em>Shared</em></span> <span class="emphasis"><em>objects:</em></span> Unsafe. 296 </p> 297<h5> 298<a name="boost_asio.reference.basic_deadline_timer.h3"></a> 299 <span class="phrase"><a name="boost_asio.reference.basic_deadline_timer.examples"></a></span><a class="link" href="basic_deadline_timer.html#boost_asio.reference.basic_deadline_timer.examples">Examples</a> 300 </h5> 301<p> 302 Performing a blocking wait: 303 </p> 304<pre class="programlisting">// Construct a timer without setting an expiry time. 305boost::asio::deadline_timer timer(my_context); 306 307// Set an expiry time relative to now. 308timer.expires_from_now(boost::posix_time::seconds(5)); 309 310// Wait for the timer to expire. 311timer.wait(); 312</pre> 313<p> 314 Performing an asynchronous wait: 315 </p> 316<pre class="programlisting">void handler(const boost::system::error_code& error) 317{ 318 if (!error) 319 { 320 // Timer expired. 321 } 322} 323 324... 325 326// Construct a timer with an absolute expiry time. 327boost::asio::deadline_timer timer(my_context, 328 boost::posix_time::time_from_string("2005-12-07 23:59:59.000")); 329 330// Start an asynchronous wait. 331timer.async_wait(handler); 332</pre> 333<h5> 334<a name="boost_asio.reference.basic_deadline_timer.h4"></a> 335 <span class="phrase"><a name="boost_asio.reference.basic_deadline_timer.changing_an_active_deadline_timer_s_expiry_time"></a></span><a class="link" href="basic_deadline_timer.html#boost_asio.reference.basic_deadline_timer.changing_an_active_deadline_timer_s_expiry_time">Changing 336 an active deadline_timer's expiry time</a> 337 </h5> 338<p> 339 Changing the expiry time of a timer while there are pending asynchronous 340 waits causes those wait operations to be cancelled. To ensure that the action 341 associated with the timer is performed only once, use something like this: 342 used: 343 </p> 344<pre class="programlisting">void on_some_event() 345{ 346 if (my_timer.expires_from_now(seconds(5)) > 0) 347 { 348 // We managed to cancel the timer. Start new asynchronous wait. 349 my_timer.async_wait(on_timeout); 350 } 351 else 352 { 353 // Too late, timer has already expired! 354 } 355} 356 357void on_timeout(const boost::system::error_code& e) 358{ 359 if (e != boost::asio::error::operation_aborted) 360 { 361 // Timer was not cancelled, take necessary action. 362 } 363} 364</pre> 365<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 366<li class="listitem"> 367 The <code class="computeroutput">boost::asio::basic_deadline_timer::expires_from_now()</code> 368 function cancels any pending asynchronous waits, and returns the number 369 of asynchronous waits that were cancelled. If it returns 0 then you were 370 too late and the wait handler has already been executed, or will soon 371 be executed. If it returns 1 then the wait handler was successfully cancelled. 372 </li> 373<li class="listitem"> 374 If a wait handler is cancelled, the boost::system::error_code passed 375 to it contains the value <code class="computeroutput">boost::asio::error::operation_aborted</code>. 376 </li> 377</ul></div> 378<h5> 379<a name="boost_asio.reference.basic_deadline_timer.h5"></a> 380 <span class="phrase"><a name="boost_asio.reference.basic_deadline_timer.requirements"></a></span><a class="link" href="basic_deadline_timer.html#boost_asio.reference.basic_deadline_timer.requirements">Requirements</a> 381 </h5> 382<p> 383 <span class="emphasis"><em>Header: </em></span><code class="literal">boost/asio/basic_deadline_timer.hpp</code> 384 </p> 385<p> 386 <span class="emphasis"><em>Convenience header: </em></span><code class="literal">boost/asio.hpp</code> 387 </p> 388</div> 389<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 390<td align="left"></td> 391<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 392 Kohlhoff<p> 393 Distributed under the Boost Software License, Version 1.0. (See accompanying 394 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>) 395 </p> 396</div></td> 397</tr></table> 398<hr> 399<div class="spirit-nav"> 400<a accesskey="p" href="basic_datagram_socket__rebind_executor/other.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="basic_deadline_timer/async_wait.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 401</div> 402</body> 403</html> 404
