在.NET 4中实现RegEx超时

Question

平台:Silverlight 4,.NET 4

使用.NET 4.5 Developer预览版,RegEx类已得到增强,允许设置Timeout值,如果模式匹配存在问题,将阻止RegEx引擎挂起UI.

请求在.NET 4 Silverlight应用程序中实现类似功能的建议.

提前致谢.

Answer 1

通用示例:

public static R WithTimeout<R>(Func<R> proc, int duration)
{
  var wh = proc.BeginInvoke(null, null);

  if (wh.AsyncWaitHandle.WaitOne(duration))
  {
    return proc.EndInvoke(wh);
  }

  throw new TimeOutException();
}

用法:

var r = WithTimeout(() => regex.Match(foo), 1000);

更新:

正如Christian.K所指出的,异步线程仍将继续运行.

这是线程终止的地方:

public static R WithTimeout<R>(Func<R> proc, int duration)
{
  var reset = new AutoResetEvent(false);
  var r = default(R);
  Exception ex = null;

  var t = new Thread(() =>
  {
    try
    {
      r = proc();
    }
    catch (Exception e)
    {
      ex = e;
    }
    reset.Set();
  });

  t.Start();

  // not sure if this is really needed in general
  while (t.ThreadState != ThreadState.Running)
  {
    Thread.Sleep(0);
  }

  if (!reset.WaitOne(duration))
  {
    t.Abort();
    throw new TimeoutException();
  }

  if (ex != null)
  {
    throw ex;
  }

  return r;
}

更新:

修复了上面的代码段以正确处理异常.