英文:
context-select like features in C++
问题
想象一种情况，我想调用一个执行一些处理的函数，但是有时间限制。我可以使用context.Context和select在golang中编写一个函数。我想象的代码如下：
package mainimport ("context""fmt""time")func longRunning(ctx context.Context, msg string) {stop := make(chan bool)done := make(chan bool)go func() {for {fmt.Printf("long running calculation %v...", msg)select {case <-stop:fmt.Println("time to stop early!")returndefault:}}done <- true}()select {case <-done:returncase <-ctx.Done():stop <- truereturn}}func main() {ctx := context.Background()ctx, cancel := context.WithTimeout(ctx, 3*time.Second)defer cancel()longRunning(ctx, "wheeee")}
在C++中有没有类似的模式可以实现类似的结果？在上面的示例中，select能够以非阻塞的方式监听通道。是否可以使用某种事件文件描述符并监听事件来实现类似的功能？
任何建议或提示将不胜感激。
英文:
Imagine a situation where I'd like to call a function that does some amount of processing, but is time-bound. I could write a function in golang using context.Context and select. I'd imagine something as follows:
package mainimport ("context""fmt""time")func longRunning(ctx context.Context, msg string) {stop := make(chan bool)done := make(chan bool)go func() {for {fmt.Printf("long running calculation %v...", msg)select {case <-stop:fmt.Println("time to stop early!")returndefault:}}done <- true}()select {case <-done:returncase <-ctx.Done():stop <- truereturn}}func main() {ctx := context.Background()ctx, cancel := context.WithTimeout(ctx, 3*time.Second)defer cancel()longRunning(ctx, "wheeee")}
Is there a pattern I can use to achieve similar results in C++? in the sample above select is able to listen on a channel in a non-blocking way. Is having a eventfd file descriptor of some kind and listening to events the way to do it?
Any suggestions or tips would be much appreciated.
答案1
得分: 6
大致如下所示：
void longRunning(std::atomic<bool>& stop) {for (;;) {if (stop) return;// 做一些工作}}int main() {std::atomic<bool> stop = false;auto future = std::async(std::launch::async, longRunning, std::ref(stop));future.wait_for(std::chrono::seconds(num_seconds));stop = true;future.get(); // 等待任务完成或提前退出}
英文:
Something along these lines, perhaps:
void longRunning(std::atomic<bool>& stop) {for (;;) {if (stop) return;// Do a bit of work}}int main() {std::atomic<bool> stop = false;auto future = std::async(std::launch::async, longRunning, std::ref(stop));future.wait_for(std::chrono::seconds(num_seconds));stop = true;future.get(); // wait for the task to finish or exit early.}
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