1 | #Region "Microsoft.VisualBasic::88599e270cb8b38339065a1d671ce31f, Microsoft.VisualBasic.Core\ApplicationServices\Parallel\Tasks\AsyncHandle.vb" |
2 | |
3 | ' Author: |
4 | ' |
5 | ' asuka (amethyst.asuka@gcmodeller.org) |
6 | ' xie (genetics@smrucc.org) |
7 | ' xieguigang (xie.guigang@live.com) |
8 | ' |
9 | ' Copyright (c) 2018 GPL3 Licensed |
10 | ' |
11 | ' |
12 | ' GNU GENERAL PUBLIC LICENSE (GPL3) |
13 | ' |
14 | ' |
15 | ' This program is free software: you can redistribute it and/or modify |
16 | ' it under the terms of the GNU General Public License as published by |
17 | ' the Free Software Foundation, either version 3 of the License, or |
18 | ' (at your option) any later version. |
19 | ' |
20 | ' This program is distributed in the hope that it will be useful, |
21 | ' but WITHOUT ANY WARRANTY; without even the implied warranty of |
22 | ' MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
23 | ' GNU General Public License for more details. |
24 | ' |
25 | ' You should have received a copy of the GNU General Public License |
26 | ' along with this program. If not, see <http://www.gnu.org/licenses/>. |
27 | |
28 | |
29 | |
30 | ' /********************************************************************************/ |
31 | |
32 | ' Summaries: |
33 | |
34 | ' Class AsyncHandle |
35 | ' |
36 | ' Properties: Handle, IsCompleted, Task |
37 | ' |
38 | ' Constructor: (+1 Overloads) Sub New |
39 | ' Function: GetValue, Run |
40 | ' |
41 | ' |
42 | ' /********************************************************************************/ |
43 | |
44 | #End Region |
45 | |
46 | Namespace Parallel.Tasks |
47 | |
48 | ''' <summary> |
49 | ''' Represents the status of an asynchronous operation.(背景线程加载数据) |
50 | ''' </summary> |
51 | ''' <typeparam name="TOut"></typeparam> |
52 | ''' <remarks> |
53 | ''' 这个后台任务模块是为了更加方便的构建出匿名方法的调用过程,因为这个对象的 |
54 | ''' 工作原理是基于匿名方法的``BeginInvoke``函数来工作的。 |
55 | ''' </remarks> |
56 | Public Class AsyncHandle(Of TOut) |
57 | |
58 | ''' <summary> |
59 | ''' 封装一个方法,该方法不具有参数,且返回由<typeparamref name="TOut"></typeparamref>参数指定的类型的值。 |
60 | ''' </summary> |
61 | ''' <returns></returns> |
62 | Public ReadOnly Property Task As Func(Of TOut) |
63 | ''' <summary> |
64 | ''' 对后台任务的访问 |
65 | ''' </summary> |
66 | ''' <returns></returns> |
67 | Public ReadOnly Property Handle As IAsyncResult |
68 | |
69 | ''' <summary> |
70 | ''' Gets a value that indicates whether the asynchronous operation has completed. |
71 | ''' (获取一个值,该值指示异步操作是否已完成。) |
72 | ''' </summary> |
73 | ''' <returns></returns> |
74 | Public ReadOnly Property IsCompleted As Boolean |
75 | Get |
76 | If Handle Is Nothing Then |
77 | Return True |
78 | End If |
79 | |
80 | Return Handle.IsCompleted |
81 | End Get |
82 | End Property |
83 | |
84 | ''' <summary> |
85 | ''' Creates a new background task from a function handle. |
86 | ''' </summary> |
87 | ''' <param name="Task"></param> |
88 | Sub New(Task As Func(Of TOut)) |
89 | Me.Task = Task |
90 | End Sub |
91 | |
92 | ''' <summary> |
93 | ''' Start the background task thread.(启动后台背景线程) |
94 | ''' </summary> |
95 | ''' <returns></returns> |
96 | Public Function Run() As AsyncHandle(Of TOut) |
97 | If IsCompleted Then |
98 | _Handle = Task.BeginInvoke(Nothing, Nothing) ' 假若没有执行完毕也调用的话,会改变handle |
99 | End If |
100 | |
101 | Return Me |
102 | End Function |
103 | |
104 | ''' <summary> |
105 | ''' Current thread will be blocked at here if the background task not finished. |
106 | ''' (没有完成的时候会一直在这里阻塞当前的线程) |
107 | ''' </summary> |
108 | ''' <returns></returns> |
109 | Public Function GetValue() As TOut |
110 | If Handle Is Nothing Then |
111 | Return _Task() |
112 | Else |
113 | Return Task.EndInvoke(Handle) |
114 | End If |
115 | End Function |
116 | |
117 | Public Async Function GetValueAsyn() As Threading.Tasks.Task(Of TOut) |
118 | Return Await New Threading.Tasks.Task(Of TOut)(AddressOf GetValue) |
119 | End Function |
120 | End Class |
121 | End Namespace |