基元用户模式构造--互锁构造 Interlocked 实现的异步web请求实例

1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Net.Http;
5 using System.Text;
6 using System.Threading;
7 using System.Threading.Tasks;
8
9 namespace Test
10 {
11     enum CoordinationStatus
12     {
13         AllDone,
14         Cancel,
15         Timeout
16     }
17     class AsyncCoordinator
18     {
19         private int statusReported = 0;
20         private int op_count = 1;
21
22         private Action<CoordinationStatus> callback;
23         private Timer timer;
24
25         public void AboutToBegin(int num = 1)
26         {
27             Interlocked.Add(ref op_count, num);
28         }
29
30         public void JustToEnd()
31         {
32             if (Interlocked.Decrement(ref op_count) == 0)
33             {
34                 ReportStatus(CoordinationStatus.AllDone);
35             }
36         }
37
38         public void AllBegun(Action<CoordinationStatus> callback, int timeout = Timeout.Infinite)
39         {
40             this.callback = callback;
41             if (timeout != Timeout.Infinite)
42             {
43                 timer = new Timer(Expired, null, timeout, Timeout.Infinite);
44             }
45             JustToEnd();
46         }
47
48         private void Expired(object obj)
49         {
50             ReportStatus(CoordinationStatus.Cancel);
51         }
52         public void Cancel()
53         {
54             ReportStatus(CoordinationStatus.Cancel);
55         }
56         private void ReportStatus(CoordinationStatus status)
57         {
58             if (Interlocked.Exchange(ref statusReported, 1) == 0)
59             {
60                 callback(status);
61             }
62         }
63
64
65
66     }
67
68     class MultiWebRequests
69     {
70         private AsyncCoordinator coordinator = new AsyncCoordinator();
71
72         private Dictionary<string, object> servers = new Dictionary<string, object>(){
73             {"http://www.baidu.com",null},
74             {"http://www.sina.com",null},
75             {"http://www.qq.com",null},
76         };
77
78         public MultiWebRequests()
79         {
80
81             var http = new HttpClient();
82             foreach (var url in servers.Keys)
83             {
84                 //发送了一个请求
85                 coordinator.AboutToBegin(1);
86                 http.GetByteArrayAsync(url).ContinueWith(task => GetResult(url, task));
87             }
88             //所有请求发送完毕
89             coordinator.AllBegun(AllDone, Timeout.Infinite);
90         }
91
92         private void GetResult(string server, Task<byte[]> task)
93         {
94             object res;
95             if (task.Exception != null)
96             {
97                 res = task.Exception.InnerExceptions;
98             }
99             else
100             {
101                 res = task.Result.Length;
102             }
103             servers[server] = res;
104             //完成了一个请求
105             coordinator.JustToEnd();
106         }
107
108         public void Cancel()
109         {
110             coordinator.Cancel();
111         }
112
113         private void AllDone(CoordinationStatus status)
114         {
115             switch (status)
116             {
117                 case CoordinationStatus.AllDone:
118                     Console.WriteLine("allDone: ");
119
120                     foreach (var item in servers)
121                     {
122                         Console.Write(item.Key);
123                         object val = item.Value;
124                         if (val is Exception)
125                         {
126                             Console.WriteLine("Exception: {0}",val.GetType().Name);
127                         }
128                         else
129                         {
130                             Console.WriteLine("returned  {0:N0} bytes",val);
131                         }
132                     }
133                     break;
134                 case CoordinationStatus.Cancel:
135                     break;
136                 case CoordinationStatus.Timeout:
137                     break;
138                 default:
139                     break;
140             }
141         }
142     }
143 }