如何做一个异步的服务控制器.等待状态

Question

所以ServiceController.WaitForStatus是一个阻塞调用。如何以任务/异步方式完成？

Answer 1

ServiceController.WaitForStatus的代码是：

public void WaitForStatus(ServiceControllerStatus desiredStatus, TimeSpan timeout)
{
    DateTime utcNow = DateTime.UtcNow;
    this.Refresh();
    while (this.Status != desiredStatus)
    {
        if (DateTime.UtcNow - utcNow > timeout)
        {
            throw new TimeoutException(Res.GetString("Timeout"));
        }
        Thread.Sleep(250);
        this.Refresh();
    }
}

可以使用以下命令将其转换为基于任务的 api：

public static class ServiceControllerExtensions
{
    public static async Task WaitForStatusAsync(this ServiceController controller, ServiceControllerStatus desiredStatus, TimeSpan timeout)
    {
        var utcNow = DateTime.UtcNow;
        controller.Refresh();
        while (controller.Status != desiredStatus)
        {
            if (DateTime.UtcNow - utcNow > timeout)
            {
                throw new TimeoutException($"Failed to wait for '{controller.ServiceName}' to change status to '{desiredStatus}'.");
            }
            await Task.Delay(250)
                .ConfigureAwait(false);
            controller.Refresh();
        }
    }
}

或者支持CancellationToken

public static class ServiceControllerExtensions
{
    public static async Task WaitForStatusAsync(this ServiceController controller, ServiceControllerStatus desiredStatus, TimeSpan timeout, CancellationToken cancellationToken)
    {
        var utcNow = DateTime.UtcNow;
        controller.Refresh();
        while (controller.Status != desiredStatus)
        {
            if (DateTime.UtcNow - utcNow > timeout)
            {
                throw new TimeoutException($"Failed to wait for '{controller.ServiceName}' to change status to '{desiredStatus}'.");
            }
            await Task.Delay(250, cancellationToken)
                .ConfigureAwait(false);
            controller.Refresh();
        }
    }
}

Answer 2

编写一个扩展方法并与 Task.Run（...） 异步

public static class ServiceControllerExtensions
{
    public static async Task<ServiceControllerStatus>
        WaitForStatusAsync(
            this ServiceController controller,
            ServiceControllerStatus desiredStatus,
            int timeoutInSeconds)
    {
        _ = await Task.Run(() => controller.TryWaitForStatus(desiredStatus, timeoutInSeconds))
            .ConfigureAwait(false);
        return controller.Status;
    }
    private static bool TryWaitForStatus(this ServiceController controller, ServiceControllerStatus desiredStatus, int timeoutInSeconds = 10)
    {
        var timeout = TimeSpan.FromSeconds(timeoutInSeconds);
        try
        {
            controller.WaitForStatus(desiredStatus, timeout);
            return true;
        }
        catch(System.ServiceProcess.TimeoutException)
        {
            controller.Refresh();
            return false;
        }
    }
}