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async.cpp
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58 lines (42 loc) · 1.49 KB
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// The program demonstrates how to create asynchronous task
// from an executor and a subflow.
#include <taskflow/taskflow.hpp>
int main() {
tf::Executor executor;
// create asynchronous tasks from the executor
// (using executor as a thread pool)
std::future<int> fu1 = executor.async([](){
std::cout << "async task returns 1\n";
return 1;
});
executor.silent_async([](){ // silent async task doesn't return any future object
std::cout << "silent async does not return\n";
});
// create async tasks with runtime
std::future<void> fu2 = executor.async([](tf::Runtime& rt){
printf("async task with a runtime: %p\n", &rt);
});
executor.silent_async([](tf::Runtime& rt){
printf("silent async task with a runtime: %p\n", &rt);
});
executor.wait_for_all(); // wait for the two async tasks to finish
// create asynchronous tasks from a subflow
// all asynchronous tasks are guaranteed to finish when the subflow joins
tf::Taskflow taskflow;
std::atomic<int> counter {0};
taskflow.emplace([&](tf::Runtime& rt){
for(int i=0; i<100; i++) {
rt.silent_async([&](){ counter.fetch_add(1, std::memory_order_relaxed); });
}
rt.corun_all();
// when subflow joins, all spawned tasks from the subflow will finish
if(counter == 100) {
std::cout << "async tasks spawned from the runtime all finish\n";
}
else {
throw std::runtime_error("this should not happen");
}
});
executor.run(taskflow).wait();
return 0;
}