我确实了解 C# 中使用的 Barrier
类。但是,在下面的代码中,我不明白为什么 SignalAndWait()
被调用了两次?任务中的调用还不够吗?该代码基本上模拟了这样的情况:三个 friend (或任务)从 A 到 B,B 到 C,还有一些从 B 回到 A 而不去 C。
请帮帮我。顺便说一句,此代码来自以下书籍:MCSD Certification Exam Toolkit
(70-483)。非常感谢!
static void Main(string[] args)
{
var participants = 5;
Barrier barrier = new Barrier(participants + 1,
b => { // This method is only called when all the paricipants arrived.
Console.WriteLine("{0} paricipants are at rendez-vous point {1}.",
b.ParticipantCount -1, // We substract the main thread.
b.CurrentPhaseNumber);
});
for (int i = 0; i < participants; i++)
{
var localCopy = i;
Task.Run(() => {
Console.WriteLine("Task {0} left point A!", localCopy);
Thread.Sleep(1000 * localCopy + 1); // Do some "work"
if (localCopy % 2 == 0) {
Console.WriteLine("Task {0} arrived at point B!", localCopy);
barrier.SignalAndWait();
}
else
{
Console.WriteLine("Task {0} changed its mind and went back!", localCopy);
barrier.RemoveParticipant();
return;
}
Thread.Sleep(1000 * (participants - localCopy)); // Do some "morework"
Console.WriteLine("Task {0} arrived at point C!", localCopy);
barrier.SignalAndWait();
});
}
Console.WriteLine("Main thread is waiting for {0} tasks!",
barrier.ParticipantCount - 1);
barrier.SignalAndWait(); // Waiting at the first phase
barrier.SignalAndWait(); // Waiting at the second phase
Console.WriteLine("Main thread is done!");
}
最佳答案
您还会看到行 Console.WriteLine("{0} paricipants are at rendez-vous point {1}.",...)
执行两次。
单个 Barrier 实例用于在 B 和 C 处会合。(剩余的)任务调用 SignalAndWait()
来标记它们到达 B 和 C,因此是两次调用。
精简代码:
if (localCopy % 2 == 0)
{
...
barrier.SignalAndWait(); // arrival at B
}
else
{
...
barrier.RemoveParticipant(); // return to A
return;
}
...
barrier.SignalAndWait(); // arrival at C
关于c# - 屏障类c#,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/24975239/