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 main
import (
"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!")
return
default:
}
}
done <- true
}()
select {
case <-done:
return
case <-ctx.Done():
stop <- true
return
}
}
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 main
import (
"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!")
return
default:
}
}
done <- true
}()
select {
case <-done:
return
case <-ctx.Done():
stop <- true
return
}
}
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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