原文:
一种延迟方法调用的实现
需求场景
最近遇到一种场景，需要延迟某个步骤的实现，以便在延迟的过程中能够及早处理，从而取消任务。 比如，现在的服务器CPU过高了，则系统记录下来，然后开始发送邮件通知用户，但是如果在10秒之内CPU恢复了；或者我不希望用户得知这个CPU的信息，因为我就在现场，我可以及时知道怎么处理这种情况，这个时候准备拨打电话的这个方法的调用就不能被执行，需要延迟一段时间，以便能够被取消——以上场景仅供参考。
代码实现
以下是我的一个实现方式，供大家讨论，或者有更好的方式可以改进。
这种方法旨在能够方便的延迟任意方法的执行：
定义任务接口
这是一个基本的线程任务的接口，包括任务名称、线程的运行状态、启停线程。
1
interface ITask
2 {
3 string Name { get; }
4 bool IsRunning { get; }
5 void Start();
6 void Stop();
7 void Run();
2 {
3 string Name { get; }
4 bool IsRunning { get; }
5 void Start();
6 void Stop();
7 void Run();
8 }
定义延迟的信息类
保存当前需要延迟的方法，以及需要延迟的时间等
1 class LazyItem
2 {
3 private readonly int _timeout;
4 private readonly DateTime _enqueueTime;
5
6 public bool IsTimeout
7 {
8 get { return (DateTime.Now - _enqueueTime).TotalSeconds > _timeout; }
9 }
10 public string Key { get; private set; }
11 public Action Continue { get; private set; }
12
13 public LazyItem( string key, int timeout, Action continueAction)
14 {
15 _enqueueTime = DateTime.Now;
16 _timeout = timeout;
17 Key = key;
18 Continue = continueAction;
19 }
20 }
3 private readonly int _timeout;
4 private readonly DateTime _enqueueTime;
5
6 public bool IsTimeout
7 {
8 get { return (DateTime.Now - _enqueueTime).TotalSeconds > _timeout; }
9 }
10 public string Key { get; private set; }
11 public Action Continue { get; private set; }
12
13 public LazyItem( string key, int timeout, Action continueAction)
14 {
15 _enqueueTime = DateTime.Now;
16 _timeout = timeout;
17 Key = key;
18 Continue = continueAction;
19 }
20 }
延迟的实现
主要是执行一个定时的任务，去检测被延迟的方法是否达到了超时的时间，如果达到，则执行该方法。另外，提供一个可供取消方法的函数。
1 class LazyInvoker : ITask
2 {
3 public string Name
4 {
5 get { return " Lazy Invoke Task "; }
6 }
7
8 public bool IsRunning { get; private set; }
9
10 private readonly ConcurrentDictionary< string, LazyItem> _lazyActions = new ConcurrentDictionary< string, LazyItem>();
11
12 public void Start()
13 {
14 Task.Factory.StartNew(Run);
15 IsRunning = true;
16 }
17
18 public void Stop()
19 {
20 IsRunning = false;
21 }
22
23 /// <summary>
24 /// 检测被延迟的任务，达到超时时间则触发
25 /// </summary>
26 /// Created by:marvin(2014/10/11 12:14)
27 public void Run()
28 {
29 while (IsRunning)
30 {
31 CheckContinue();
32 Thread.Sleep( 1 * 1000);
33 }
34 }
35
36 private void CheckContinue()
37 {
38 if (_lazyActions.Count <= 0) return;
39
40 var removeKeys = ( from lazyItem in _lazyActions where lazyItem.Value.IsTimeout select lazyItem.Key).ToList();
41 if (removeKeys.Count <= 0) return;
42
43 foreach ( var key in removeKeys)
44 {
45 LazyItem tmp;
46 if (_lazyActions.TryRemove(key, out tmp))
47 {
48 tmp.Continue();
49 }
50 }
51 }
52
53 /// <summary>
54 /// 延迟工作
55 /// </summary>
56 /// <param name="id"> The identifier. </param>
57 /// <param name="lazyTimeout"> The lazy timeout. </param>
58 /// <param name="continueAction"> The continue action. </param>
59 /// Created by:marvin(2014/10/11 11:48)
60 public void LazyDo( string id, int lazyTimeout, Action continueAction)
61 {
62 if (!_lazyActions.ContainsKey(id))
63 {
64 if (_lazyActions.TryAdd(id, new LazyItem(id, lazyTimeout, continueAction)))
65 {
66 // Console.WriteLine("lazy action : {0} , timeout : {1}", id, lazyTimeout);
67 }
68 }
69 }
70
71 /// <summary>
72 /// 取消任务
73 /// </summary>
74 /// <param name="actionKey"> The action key. </param>
75 /// Created by:marvin(2014/10/11 12:02)
76 public void Cancel( string actionKey)
77 {
78 if (_lazyActions.ContainsKey(actionKey))
79 {
80 LazyItem tmp;
81 if (_lazyActions.TryRemove(actionKey, out tmp))
82 {
83 Console.WriteLine( " lazy action “{0}” had removed ", tmp.Key);
84 }
85 }
86 }
87 }
3 public string Name
4 {
5 get { return " Lazy Invoke Task "; }
6 }
7
8 public bool IsRunning { get; private set; }
9
10 private readonly ConcurrentDictionary< string, LazyItem> _lazyActions = new ConcurrentDictionary< string, LazyItem>();
11
12 public void Start()
13 {
14 Task.Factory.StartNew(Run);
15 IsRunning = true;
16 }
17
18 public void Stop()
19 {
20 IsRunning = false;
21 }
22
23 /// <summary>
24 /// 检测被延迟的任务，达到超时时间则触发
25 /// </summary>
26 /// Created by:marvin(2014/10/11 12:14)
27 public void Run()
28 {
29 while (IsRunning)
30 {
31 CheckContinue();
32 Thread.Sleep( 1 * 1000);
33 }
34 }
35
36 private void CheckContinue()
37 {
38 if (_lazyActions.Count <= 0) return;
39
40 var removeKeys = ( from lazyItem in _lazyActions where lazyItem.Value.IsTimeout select lazyItem.Key).ToList();
41 if (removeKeys.Count <= 0) return;
42
43 foreach ( var key in removeKeys)
44 {
45 LazyItem tmp;
46 if (_lazyActions.TryRemove(key, out tmp))
47 {
48 tmp.Continue();
49 }
50 }
51 }
52
53 /// <summary>
54 /// 延迟工作
55 /// </summary>
56 /// <param name="id"> The identifier. </param>
57 /// <param name="lazyTimeout"> The lazy timeout. </param>
58 /// <param name="continueAction"> The continue action. </param>
59 /// Created by:marvin(2014/10/11 11:48)
60 public void LazyDo( string id, int lazyTimeout, Action continueAction)
61 {
62 if (!_lazyActions.ContainsKey(id))
63 {
64 if (_lazyActions.TryAdd(id, new LazyItem(id, lazyTimeout, continueAction)))
65 {
66 // Console.WriteLine("lazy action : {0} , timeout : {1}", id, lazyTimeout);
67 }
68 }
69 }
70
71 /// <summary>
72 /// 取消任务
73 /// </summary>
74 /// <param name="actionKey"> The action key. </param>
75 /// Created by:marvin(2014/10/11 12:02)
76 public void Cancel( string actionKey)
77 {
78 if (_lazyActions.ContainsKey(actionKey))
79 {
80 LazyItem tmp;
81 if (_lazyActions.TryRemove(actionKey, out tmp))
82 {
83 Console.WriteLine( " lazy action “{0}” had removed ", tmp.Key);
84 }
85 }
86 }
87 }
测试
1 class Program
2 {
3 static void Main( string[] args)
4 {
5 var lazyInvoker = new LazyInvoker();
6 lazyInvoker.Start();
7
8 // 延迟7秒运行
9 lazyInvoker.LazyDo(Guid.NewGuid().ToString(), 7, DoSomething);
10 Thread.Sleep( 5 * 1000);
11
12 // 延迟3秒运行，但是3秒的时候被取消
13 var id = Guid.NewGuid().ToString();
14 lazyInvoker.LazyDo(id, 5, DoSomething);
15 Thread.Sleep( 3 * 1000);
16 lazyInvoker.Cancel(id);
17
18 Console.ReadKey();
19 }
20
21 private static void DoSomething()
22 {
23 Console.WriteLine( " Now time is : " + DateTime.Now.ToString( " HH:mm:ss "));
24 }
25 }
3 static void Main( string[] args)
4 {
5 var lazyInvoker = new LazyInvoker();
6 lazyInvoker.Start();
7
8 // 延迟7秒运行
9 lazyInvoker.LazyDo(Guid.NewGuid().ToString(), 7, DoSomething);
10 Thread.Sleep( 5 * 1000);
11
12 // 延迟3秒运行，但是3秒的时候被取消
13 var id = Guid.NewGuid().ToString();
14 lazyInvoker.LazyDo(id, 5, DoSomething);
15 Thread.Sleep( 3 * 1000);
16 lazyInvoker.Cancel(id);
17
18 Console.ReadKey();
19 }
20
21 private static void DoSomething()
22 {
23 Console.WriteLine( " Now time is : " + DateTime.Now.ToString( " HH:mm:ss "));
24 }
25 }
运行结果如下：
