blocks|key|1590893|text|Boosts教程中的第二个示例解释了这一点。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1590894|你可以在here上找到它。|offset|length|1590895|之后，使用check+the+3rd+example查看如何使用周期性的时间间隔再次调用它|1590896|entityMap|0|LINK|mutability|MUTABLE|url|http://www.boost.org/doc/libs/release/doc/html/boost_asio/tutorial/tuttimer2.html|1|http://www.boost.org/doc/libs/release/doc/html/boost_asio/tutorial/tuttimer3.html^0|0|4|4|0|0|5|L|1|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|S|8|@]|9|@$D|T|E|U|1|V]]|A|$]]|$1|F|3|G|5|6|7|W|8|@]|9|@$D|X|E|Y|1|Z]]|A|$]]|$1|H|3|-4|5|6|7|10|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|O]]|P|$5|K|L|M|A|$N|Q]]]]

The second example on Boosts Asio tutorials explains it. 
You can find it <a href="http://www.boost.org/doc/libs/release/doc/html/boost_asio/tutorial/tuttimer2.html" rel="nofollow noreferrer">here</a>.

After that, <a href="http://www.boost.org/doc/libs/release/doc/html/boost_asio/tutorial/tuttimer3.html" rel="nofollow noreferrer">check the 3rd example</a> to see how you can call it again with a periodic time intervall

blocks|key|1590901|text|一个非常简单但功能齐全的示例：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1590902|#include+<iostream>
#include+<boost/asio.hpp>

boost::asio::io_service+io_service;
boost::posix_time::seconds+interval(1);++//+1+second
boost::asio::deadline_timer+timer(io_service,+interval);

void+tick(const+boost::system::error_code&+/*e*/)+{

++++std::cout+<<+"tick"+<<+std::endl;

++++//+Reschedule+the+timer+for+1+second+in+the+future:
++++timer.expires_at(timer.expires_at()+%2B+interval);
++++//+Posts+the+timer+event
++++timer.async_wait(tick);
}

int+main(void)+{

++++//+Schedule+the+timer+for+the+first+time:
++++timer.async_wait(tick);
++++//+Enter+IO+loop.+The+timer+will+fire+for+the+first+time+1+second+from+now:
++++io_service.run();
++++return+0;
}|code-block|syntax|javascript|1590903|注意，调用expires_at()来设置一个新的过期时间非常重要，否则计时器将立即触发，因为它的当前到期时间已经过期。|offset|length|style|CODE|1590904|entityMap^0|0|0|5|C|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

A very simple, but fully functional example:

<pre><code>#include &lt;iostream&gt;
#include &lt;boost/asio.hpp&gt;

boost::asio::io_service io_service;
boost::posix_time::seconds interval(1); // 1 second
boost::asio::deadline_timer timer(io_service, interval);

void tick(const boost::system::error_code&amp; /*e*/) {

 std::cout &lt;&lt; "tick" &lt;&lt; std::endl;

 // Reschedule the timer for 1 second in the future:
 timer.expires_at(timer.expires_at() + interval);
 // Posts the timer event
 timer.async_wait(tick);
}

int main(void) {

 // Schedule the timer for the first time:
 timer.async_wait(tick);
 // Enter IO loop. The timer will fire for the first time 1 second from now:
 io_service.run();
 return 0;
}
</code></pre>

Notice that it is very important to call <code>expires_at()</code> to set a new expiration time, otherwise the timer will fire immediately because it's current due time already expired.

blocks|key|1805526|text|来进一步扩展这个简单的例子。它会像注释中所说的那样阻塞执行，所以如果你想运行更多的io_services，你应该像这样在线程中运行它们。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1805527|boost::asio::io_service+io_service;
boost::asio::io_service+service2;
timer.async_wait(tick);
boost::thread_group+threads;
threads.create_thread(boost::bind(&boost::asio::io_service::run,+&io_service));
service2.run();
threads.join_all();|code-block|syntax|javascript|1805528|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

To further expand on this simple example. It will block the execution as was said in the comments, so if you want more io_services running, you should run them in a thread like so...

<pre><code>boost::asio::io_service io_service;
boost::asio::io_service service2;
timer.async_wait(tick);
boost::thread_group threads;
threads.create_thread(boost::bind(&amp;boost::asio::io_service::run, &amp;io_service));
service2.run();
threads.join_all();
</code></pre>

blocks|key|1805607|text|由于我对之前的答案有一些问题，下面是我的示例：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1805608|#include+<boost/asio.hpp>
#include+<boost/bind.hpp>
#include+<boost/date_time/posix_time/posix_time.hpp>
#include+<iostream>

void+print(const+boost::system::error_code&,+boost::asio::deadline_timer*+t,int*+count)
{
++++if+(*count+<+5)
++++{
++++++++std::cout+<<+*count+<<+std::endl;
++++++++%2B%2B(*count);
++++++++t->expires_from_now(boost::posix_time::seconds(1));
++++++++t->async_wait(boost::bind(print,+boost::asio::placeholders::error,+t,+count));
++++}
}

int+main()
{+
++++boost::asio::io_service+io;
++++int+count+=+0;
++++boost::asio::deadline_timer+t(io,+boost::posix_time::seconds(1));

++++t.async_wait(boost::bind(print,+boost::asio::placeholders::error,+&t,+&count));

++++io.run();
++++std::cout+<<+"Final+count+is+"+<<+count+<<+std::endl;

++++return+0;

}|code-block|syntax|javascript|1805609|它做了它应该做的事情:数到五。愿它能帮助某些人。|1805610|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

As I had some issues with prior answers, here is my example:

<pre><code>#include &lt;boost/asio.hpp&gt;
#include &lt;boost/bind.hpp&gt;
#include &lt;boost/date_time/posix_time/posix_time.hpp&gt;
#include &lt;iostream&gt;

void print(const boost::system::error_code&amp;, boost::asio::deadline_timer* t,int* count)
{
 if (*count &lt; 5)
 {
 std::cout &lt;&lt; *count &lt;&lt; std::endl;
 ++(*count);
 t-&gt;expires_from_now(boost::posix_time::seconds(1));
 t-&gt;async_wait(boost::bind(print, boost::asio::placeholders::error, t, count));
 }
}

int main()
{ 
 boost::asio::io_service io;
 int count = 0;
 boost::asio::deadline_timer t(io, boost::posix_time::seconds(1));

 t.async_wait(boost::bind(print, boost::asio::placeholders::error, &amp;t, &amp;count));

 io.run();
 std::cout &lt;&lt; "Final count is " &lt;&lt; count &lt;&lt; std::endl;

 return 0;

}
</code></pre>

it did what it supposed to do: counting to five. May it help someone.

blocks|key|1591139|text|封装此功能的Boost+Asio附加类(每N毫秒调用一次指定的函数)：https://github.com/mikehaben69/boost/tree/main/asio|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1591140|该存储库包括一个演示源文件和makefile。|1591141|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/mikehaben69/boost/tree/main/asio^0|Z|1F|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]]|C|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@]|C|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]]]

A Boost Asio add-on class that encapsulates this functionality (call a specfied function every N milliseconds): <a href="https://github.com/mikehaben69/boost/tree/main/asio" rel="nofollow noreferrer">https://github.com/mikehaben69/boost/tree/main/asio</a>
The repo includes a demo source file and makefile.

I want a very simple periodic timer to call my code every 50ms. I could make a thread that sleeps for 50ms all the time (but that's a pain)... I could start looking into Linux API's for making timers (but it's not portable)... 

I'd like to use boost.. I'm just not sure it's possible. Does boost provide this functionality?

C++ Boost ASIO simple periodic timer?

Linux

我想要一个非常简单的周期计时器来调用我的代码每50ms。我可以做一个一直睡眠50ms的线程(但这很痛苦)……我可以开始研究Linux API来制作定时器(但它不能移植)……我想使用boost..我只是不确定这有没有可能。boost是否提供此功能？

问C++ Boost ASIO简单周期定时器？
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