How to: Send a Message at a Regular Interval
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This example shows how to use the concurrency::timer class to send a message at a regular interval.
The following example uses a timer object to report progress during a lengthy operation. This example links the timer object to a concurrency::call object. The call object prints a progress indicator to the console at a regular interval. The concurrency::timer::start method runs the timer on a separate context. The perform_lengthy_operation function calls the concurrency::wait function on the main context to simulate a time-consuming operation.
// report-progress.cpp // compile with: /EHsc #include <agents.h> #include <iostream> using namespace concurrency; using namespace std; // Simulates a lengthy operation. void perform_lengthy_operation() { // Yield the current context for one second. wait(1000); } int wmain() { // Create a call object that prints a single character to the console. call<wchar_t> report_progress([](wchar_t c) { wcout << c; }); // Create a timer object that sends the dot character to the // call object every 100 milliseconds. timer<wchar_t> progress_timer(100, L'.', &report_progress, true); wcout << L"Performing a lengthy operation"; // Start the timer on a separate context. progress_timer.start(); // Perform a lengthy operation on the main context. perform_lengthy_operation(); // Stop the timer and print a message. progress_timer.stop(); wcout << L"done."; }
This example produces the following sample output:
Performing a lengthy operation..........done.
Copy the example code and paste it in a Visual Studio project, or paste it in a file that is named report-progress.cpp and then run the following command in a Visual Studio Command Prompt window.
cl.exe /EHsc report-progress.cpp
Asynchronous Agents Library
Asynchronous Message Blocks
Message Passing Functions