Windows 服务中的连续异步 Ping

Question

我需要持续监视主机列表。N 秒后，我需要再次检查列表。因此，我尝试在Windows服务中使用异步ping。

我试图遵循与该主题相关的其他帖子中的提示，但我的服务总是在启动后不久停止。

"OnElapsedTime"函数中的等待存在问题。

有人知道出了什么问题吗？我的代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.ServiceProcess;
using System.Text;
using System.Threading.Tasks;
using System.Timers;
using System.Net.NetworkInformation;
namespace PingAsyncService
{
public partial class HyBrazil_Ping : ServiceBase
{
Timer timer = new Timer();
List<string> IPList = new List<string>();  //List of IPs

public HyBrazil_Ping()
{
IPList.Add("192.168.0.1");
IPList.Add("192.168.0.254");
InitializeComponent();
}
protected override void OnStart(string[] args)
{
WriteToFile("Service is started at " + DateTime.Now);
timer.Elapsed += new ElapsedEventHandler(OnElapsedTime);
timer.Interval = 5000; //number in miliseconds 
timer.Enabled = true;
}
protected override void OnStop()
{
WriteToFile("Service is stopped at " + DateTime.Now);
}
private async void OnElapsedTime(object source, ElapsedEventArgs e)
{
//WriteToFile("Service is recall at " + DateTime.Now);
var ResultList = await PingAsync();
foreach(PingReply reply in ResultList)
{
WriteToFile(reply.Address.ToString() + ";" + reply.Status.ToString());
}
}
private async Task<PingReply> PingAndProcessAsync(Ping pingSender, string ip)
{
var result = await pingSender.SendPingAsync(ip, 2000);
return result;
}
private async Task<List<PingReply>> PingAsync()
{
Ping pingSender = new Ping();
var tasks = IPList.Select(ip => PingAndProcessAsync(pingSender, ip));
var results = await Task.WhenAll(tasks);
return results.ToList();
}
public void WriteToFile(string Message)
{
string path = AppDomain.CurrentDomain.BaseDirectory + "\Logs";
if (!Directory.Exists(path))
{
Directory.CreateDirectory(path);
}
string filepath = AppDomain.CurrentDomain.BaseDirectory + "\Logs\ServiceLog_" + DateTime.Now.Date.ToShortDateString().Replace('/', '_') + ".txt";
if (!File.Exists(filepath))
{
// Create a file to write to.   
using (StreamWriter sw = File.CreateText(filepath))
{
sw.WriteLine(Message);
}
}
else
{
using (StreamWriter sw = File.AppendText(filepath))
{
sw.WriteLine(Message);
}
}
}
}
}

多谢！

Answer 1

在其中一条评论中，您提到错误消息为 "异步调用已在进行中。必须先完成或取消它，然后才能调用此方法。

很有可能，Ping 对象不允许同时进行异步调用。 每次调用都使用新的 Ping 对象可能会有所帮助，如下所示。

private async Task<List<PingReply>> PingAsync()
{
// Ping pingSender = new Ping();
var tasks = IPList.Select(ip =>
{
using (var p= new Ping())
{
return PingAndProcessAsync(p, ip);
}
});
var results = await Task.WhenAll(tasks);
return results.ToList();
}