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diff --git a/3rdparty/asio/src/examples/cpp03/tutorial/timer_dox.txt b/3rdparty/asio/src/examples/cpp03/tutorial/timer_dox.txt deleted file mode 100644 index 7c5a0a099a6..00000000000 --- a/3rdparty/asio/src/examples/cpp03/tutorial/timer_dox.txt +++ /dev/null @@ -1,383 +0,0 @@ -// -// Copyright (c) 2003-2016 Christopher M. Kohlhoff (chris at kohlhoff dot com) -// -// Distributed under the Boost Software License, Version 1.0. (See accompanying -// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) -// - -/** -\page tuttimer1 Timer.1 - Using a timer synchronously - -This tutorial program introduces asio by showing how to perform a blocking -wait on a timer. - -\dontinclude timer1/timer.cpp -\skip #include - -We start by including the necessary header files. - -All of the asio classes can be used by simply including the <tt>"asio.hpp"</tt> -header file. - -\until asio.hpp - -Since this example uses timers, we need to include the appropriate -Boost.Date_Time header file for manipulating times. - -\until posix_time.hpp - -All programs that use asio need to have at least one asio::io_service object. -This class provides access to I/O functionality. We declare an object of this -type first thing in the main function. - -\until asio::io_service - -Next we declare an object of type asio::deadline_timer. The core asio classes -that provide I/O functionality (or as in this case timer functionality) always -take a reference to an io_service as their first constructor argument. The -second argument to the constructor sets the timer to expire 5 seconds from now. - -\until asio::deadline_timer - -In this simple example we perform a blocking wait on the timer. -That is, the call to asio::deadline_timer::wait() will not return until the -timer has expired, 5 seconds after it was created (i.e. <b>not</b> from when the -wait starts). - -A deadline timer is always in one of two states: "expired" or "not expired". If -the asio::deadline_timer::wait() function is called on an expired timer, it -will return immediately. - -\until wait - -Finally we print the obligatory <tt>"Hello, world!"</tt> -message to show when the timer has expired. - -\until } - -See the \ref tuttimer1src "full source listing" \n -Return to the \ref index "tutorial index" \n -Next: \ref tuttimer2 - -*/ - -/** -\page tuttimer1src Source listing for Timer.1 -\include timer1/timer.cpp -Return to \ref tuttimer1 -*/ - -/** -\page tuttimer2 Timer.2 - Using a timer asynchronously - -This tutorial program demonstrates how to use asio's asynchronous callback -functionality by modifying the program from tutorial Timer.1 to perform an -asynchronous wait on the timer. - -\dontinclude timer2/timer.cpp -\skip #include - -\until posix_time.hpp - -Using asio's asynchronous functionality means having a callback -function that will be called when an asynchronous operation completes. In this -program we define a function called <tt>print</tt> to be called when the -asynchronous wait finishes. - -\until asio::deadline_timer - -Next, instead of doing a blocking wait as in tutorial Timer.1, -we call the asio::deadline_timer::async_wait() function to perform an -asynchronous wait. When calling this function we pass the <tt>print</tt> -callback handler that was defined above. - -\skipline async_wait - -Finally, we must call the asio::io_service::run() member function -on the io_service object. - -The asio library provides a guarantee that callback handlers will <b>only</b> -be called from threads that are currently calling asio::io_service::run(). -Therefore unless the asio::io_service::run() function is called the callback for -the asynchronous wait completion will never be invoked. - -The asio::io_service::run() function will also continue to run while there is -still "work" to do. In this example, the work is the asynchronous wait on the -timer, so the call will not return until the timer has expired and the -callback has completed. - -It is important to remember to give the io_service some work to do before -calling asio::io_service::run(). For example, if we had omitted the above call -to asio::deadline_timer::async_wait(), the io_service would not have had any -work to do, and consequently asio::io_service::run() would have returned -immediately. - -\skip run -\until } - -See the \ref tuttimer2src "full source listing" \n -Return to the \ref index "tutorial index" \n -Previous: \ref tuttimer1 \n -Next: \ref tuttimer3 - -*/ - -/** -\page tuttimer2src Source listing for Timer.2 -\include timer2/timer.cpp -Return to \ref tuttimer2 -*/ - -/** -\page tuttimer3 Timer.3 - Binding arguments to a handler - -In this tutorial we will modify the program from tutorial Timer.2 so that the -timer fires once a second. This will show how to pass additional parameters to -your handler function. - -\dontinclude timer3/timer.cpp -\skip #include - -\until posix_time.hpp - -To implement a repeating timer using asio you need to change -the timer's expiry time in your callback function, and to then start a new -asynchronous wait. Obviously this means that the callback function will need -to be able to access the timer object. To this end we add two new parameters -to the <tt>print</tt> function: - -\li A pointer to a timer object. - -\li A counter so that we can stop the program when the timer fires for the -sixth time. - -\until { - -As mentioned above, this tutorial program uses a counter to -stop running when the timer fires for the sixth time. However you will observe -that there is no explicit call to ask the io_service to stop. Recall that in -tutorial Timer.2 we learnt that the asio::io_service::run() function completes -when there is no more "work" to do. By not starting a new asynchronous wait on -the timer when <tt>count</tt> reaches 5, the io_service will run out of work and -stop running. - -\until ++ - -Next we move the expiry time for the timer along by one second -from the previous expiry time. By calculating the new expiry time relative to -the old, we can ensure that the timer does not drift away from the -whole-second mark due to any delays in processing the handler. - -\until expires_at - -Then we start a new asynchronous wait on the timer. As you can -see, the \ref boost_bind function is used to associate the extra parameters -with your callback handler. The asio::deadline_timer::async_wait() function -expects a handler function (or function object) with the signature -<tt>void(const asio::error_code&)</tt>. Binding the additional parameters -converts your <tt>print</tt> function into a function object that matches the -signature correctly. - -See the <a href="http://www.boost.org/libs/bind/bind.html">Boost.Bind -documentation</a> for more information on how to use \ref boost_bind. - -In this example, the asio::placeholders::error argument to \ref boost_bind is a -named placeholder for the error object passed to the handler. When initiating -the asynchronous operation, and if using \ref boost_bind, you must specify only -the arguments that match the handler's parameter list. In tutorial Timer.4 you -will see that this placeholder may be elided if the parameter is not needed by -the callback handler. - -\until asio::io_service - -A new <tt>count</tt> variable is added so that we can stop the -program when the timer fires for the sixth time. - -\until asio::deadline_timer - -As in Step 4, when making the call to -asio::deadline_timer::async_wait() from <tt>main</tt> we bind the additional -parameters needed for the <tt>print</tt> function. - -\until run - -Finally, just to prove that the <tt>count</tt> variable was -being used in the <tt>print</tt> handler function, we will print out its new -value. - -\until } - -See the \ref tuttimer3src "full source listing" \n -Return to the \ref index "tutorial index" \n -Previous: \ref tuttimer2 \n -Next: \ref tuttimer4 - -*/ - -/** -\page tuttimer3src Source listing for Timer.3 -\include timer3/timer.cpp -Return to \ref tuttimer3 -*/ - -/** -\page tuttimer4 Timer.4 - Using a member function as a handler - -In this tutorial we will see how to use a class member function as a callback -handler. The program should execute identically to the tutorial program from -tutorial Timer.3. - -\dontinclude timer4/timer.cpp -\skip #include - -\until posix_time.hpp - -Instead of defining a free function <tt>print</tt> as the -callback handler, as we did in the earlier tutorial programs, we now define a -class called <tt>printer</tt>. - -\until public - -The constructor of this class will take a reference to the -io_service object and use it when initialising the <tt>timer_</tt> member. The -counter used to shut down the program is now also a member of the class. - -\until { - -The \ref boost_bind function works just as well with class -member functions as with free functions. Since all non-static class member -functions have an implicit <tt>this</tt> parameter, we need to bind -<tt>this</tt> to the function. As in tutorial Timer.3, \ref boost_bind -converts our callback handler (now a member function) into a function object -that can be invoked as though it has the signature <tt>void(const -asio::error_code&)</tt>. - -You will note that the asio::placeholders::error placeholder is not specified -here, as the <tt>print</tt> member function does not accept an error object as -a parameter. - -\until } - -In the class destructor we will print out the final value of -the counter. - -\until } - -The <tt>print</tt> member function is very similar to the -<tt>print</tt> function from tutorial Timer.3, except that it now operates on -the class data members instead of having the timer and counter passed in as -parameters. - -\until }; - -The <tt>main</tt> function is much simpler than before, as it -now declares a local <tt>printer</tt> object before running the io_service as -normal. - -\until } - -See the \ref tuttimer4src "full source listing" \n -Return to the \ref index "tutorial index" \n -Previous: \ref tuttimer3 \n -Next: \ref tuttimer5 \n - -*/ - -/** -\page tuttimer4src Source listing for Timer.4 -\include timer4/timer.cpp -Return to \ref tuttimer4 -*/ - -/** -\page tuttimer5 Timer.5 - Synchronising handlers in multithreaded programs - -This tutorial demonstrates the use of the asio::io_service::strand class to -synchronise callback handlers in a multithreaded program. - -The previous four tutorials avoided the issue of handler synchronisation by -calling the asio::io_service::run() function from one thread only. As you -already know, the asio library provides a guarantee that callback handlers will -<b>only</b> be called from threads that are currently calling -asio::io_service::run(). Consequently, calling asio::io_service::run() from -only one thread ensures that callback handlers cannot run concurrently. - -The single threaded approach is usually the best place to start when -developing applications using asio. The downside is the limitations it places -on programs, particularly servers, including: - -<ul> -<li>Poor responsiveness when handlers can take a long time to complete.</li> -<li>An inability to scale on multiprocessor systems.</li> -</ul> - -If you find yourself running into these limitations, an alternative approach -is to have a pool of threads calling asio::io_service::run(). However, as this -allows handlers to execute concurrently, we need a method of synchronisation -when handlers might be accessing a shared, thread-unsafe resource. - -\dontinclude timer5/timer.cpp -\skip #include - -\until posix_time.hpp - -We start by defining a class called <tt>printer</tt>, similar -to the class in the previous tutorial. This class will extend the previous -tutorial by running two timers in parallel. - -\until public - -In addition to initialising a pair of asio::deadline_timer members, the -constructor initialises the <tt>strand_</tt> member, an object of type -asio::io_service::strand. - -An asio::io_service::strand is an executor that guarantees that, for those -handlers that are dispatched through it, an executing handler will be allowed -to complete before the next one is started. This is guaranteed irrespective of -the number of threads that are calling asio::io_service::run(). Of course, the -handlers may still execute concurrently with other handlers that were -<b>not</b> dispatched through an asio::io_service::strand, or were dispatched -through a different asio::io_service::strand object. - -\until { - -When initiating the asynchronous operations, each callback handler is "bound" -to an asio::io_service::strand object. The -asio::io_service::strand::bind_executor() function returns a new handler that -automatically dispatches its contained handler through the -asio::io_service::strand object. By binding the handlers to the same -asio::io_service::strand, we are ensuring that they cannot execute -concurrently. - -\until } -\until } - -In a multithreaded program, the handlers for asynchronous -operations should be synchronised if they access shared resources. In this -tutorial, the shared resources used by the handlers (<tt>print1</tt> and -<tt>print2</tt>) are <tt>std::cout</tt> and the <tt>count_</tt> data member. - -\until }; - -The <tt>main</tt> function now causes asio::io_service::run() to -be called from two threads: the main thread and one additional thread. This is -accomplished using an asio::thread object. - -Just as it would with a call from a single thread, concurrent calls to -asio::io_service::run() will continue to execute while there is "work" left to -do. The background thread will not exit until all asynchronous operations have -completed. - -\until } - -See the \ref tuttimer5src "full source listing" \n -Return to the \ref index "tutorial index" \n -Previous: \ref tuttimer4 \n - -*/ - -/** -\page tuttimer5src Source listing for Timer.5 -\include timer5/timer.cpp -Return to \ref tuttimer5 -*/ |