在“System.Web”ASP.NET中,可以通过RegisterObject / QueueBackgroundWorkItem注册后台工作,以便参与IIS的关闭序列(完成90秒宽限期),但我很难找到完全等效的ASP.NET 5.
查看Microsoft.AspNet.Hosting.HostingEngine的源代码,我可以看到它通过IApplicationLifecycle.ApplicationStopping和IApplicationLifecycle.ApplicationStopped发出信号(在它之间它处理服务器和PipelineInstance),但似乎没有任何空间需要90秒的宽限期旧API中的RegisterObject.
IIS集成层尚未开源(如果有的话),因此很难看出该实现如何映射事物.
我错过了一个API吗？我应该通过CancellationToken.Register()执行阻塞关闭吗？这是“vNext”中遗漏的东西吗？
任何启蒙都会受到高度赞赏.
解决方法
我使用基于Katana的Hangfire实现作为灵感来创建以下内容.除了检查IIS Express终止时关机代码运行之外,它没有任何测试,但它可以作为概念证明.
这里的设计显然不适用于“即发即忘”任务,因为它们可以在关机前触发.但它确实适用于幂等队列处理器(假设已禁用空闲关闭超时)
public static class BackgroundServiceExtensions
{
public static void UseBackgroundService(
this IApplicationBuilder builder,Func<CancellationToken,Task> service)
{
var lifetime = (IApplicationLifetime)builder.ApplicationServices
.GetService(typeof(IApplicationLifetime));
var stoppingToken = lifetime.ApplicationStopping;
var stoppedToken = lifetime.ApplicationStopped;
// This,in particular,would need to be properly thought out,// preferably including an execution context to minimise threadpool use
// for async-heavy background services
Task serviceTask = Task.Run(() => service(stoppingToken));
stoppedToken.Register(() =>
{
try
{
// Block (with timeout) to allow graceful shutdown
if (!serviceTask.Wait(TimeSpan.FromSeconds(30)))
{
// Log: Background service didn't gracefully shutdown.
// It will be terminated with the host process
}
}
catch(Exception)
{
// Ignored
}
});
}
}
然后可以这样使用：
app.UseBackgroundService(async cancellationToken =>
{
while (!cancellationToken.IsCancellationRequested)
{
System.Diagnostics.Debug.WriteLine("Tick...");
try
{
// Use cancellationToken for anything that is (logically) cancellable
await Task.Delay(1000,cancellationToken);
}
catch(TaskCanceledException)
{ }
}
System.Diagnostics.Debug.WriteLine("Cancellation requested,shutting down...");
});
