Question

我正在开发一个使用ManagementEventWatcher来监控USB事件的应用程序。代码正常工作但在某些情况下程序丢失了一些USB events。从USB列出所有事件的正确方法是什么？

我正在使用以下代码，我正在使用两个查询来监视附加和从USB分离。我需要监控许多USB端口。

USB监视器

    ManagementEventWatcher watchUSBattach = new ManagementEventWatcher();
    ManagementEventWatcher watchUSBDettach = new ManagementEventWatcher();

    WqlEventQuery queryUsbAttach = new WqlEventQuery("SELECT * FROM Win32_VolumeChangeEvent WHERE EventType = 2 ");
    watchUSBattach.EventArrived += new EventArrivedEventHandler(watchUSBEventAdd);
    watchUSBattach.Query = queryUsbAttach;
    watchUSBattach.Start();

    WqlEventQuery queryUsbDettach = new WqlEventQuery("SELECT * FROM Win32_VolumeChangeEvent WHERE EventType = 3");
    watchUSBDettach.EventArrived += new EventArrivedEventHandler(watchUSBEventDettach);
    watchUSBDettach.Query = queryUsbDettach;
    watchUSBDettach.Start();

Answer 1

在监控USB设备插入或移除时，我遇到过类似的事情。示例代码如下。当WithinInterval属性设置为1ms时，我不会错过事件，但我在WMIProviderHost和相关服务中遭受了不合理的CPU负载。如果我将它设置为更合理的值（如3秒），那么如果它们从同一设备一起发生得太快（例如，如果设备自行重置），我会错过删除/创建事件。也许您的查询默认WithinInterval太长并导致事件被删除？

WqlEventQuery q;
var scope = new ManagementScope("root\\CIMV2") 
  {Options = {EnablePrivileges = true}};

q = new WqlEventQuery
{
  EventClassName = "__InstanceCreationEvent",
  WithinInterval = TimeSpan.FromMilliseconds(1),
  Condition = @"TargetInstance ISA 'Win32_USBControllerdevice'"
};
InsertWatcher = new ManagementEventWatcher(scope, q);
InsertWatcher.EventArrived += (sender, args) =>
{
  var instance = (ManagementBaseObject) args.NewEvent["TargetInstance"];
  RaiseInserted(new PlugEventArgs {DevicePath = (string) instance["__PATH"]});
};
InsertWatcher.Start();

ManagementEventWatcher在C＃中丢失事件

1 个答案: