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トップC#に関する質問先に実行されているタスクがあればキャンセルして終了を待ってから実行する

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回答編集履歴

5

修正

2018/10/18 04:36

投稿

Zuishin
Zuishin

スコア28675

answer CHANGED
@@ -21,17 +21,20 @@
21
21
 
22
22
  private void button1_Click(object sender, EventArgs e)
23
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  {
24
- Something.DoSomething(async ct =>
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+ for (int j = 0; j < 10; j++)
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  {
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- taskId++;
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- for (int i = 0; i < 100; i++)
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+ Something.DoSomething(async ct =>
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  {
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+ taskId++;
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+ for (int i = 0; i < 100; i++)
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+ {
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- if (ct.IsCancellationRequested) break;
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+ if (ct.IsCancellationRequested) break;
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- Debug.WriteLine($"{taskId}:{i}:1");
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+ Debug.WriteLine($"{taskId}:{i}:1");
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- await Task.Delay(100);
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+ await Task.Delay(100);
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- Debug.WriteLine($"{taskId}:{i}:2");
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+ Debug.WriteLine($"{taskId}:{i}:2");
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- }
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+ }
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- });
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+ });
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+ }
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  }
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  }
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40
 
@@ -39,12 +42,17 @@
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  {
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  static CancellationTokenSource cts;
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  static SemaphoreSlim semaphore = new SemaphoreSlim(1, 1);
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+ static object lockObject = new object();
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46
 
43
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  public static Task DoSomething(Func<CancellationToken, Task> action)
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  {
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+ CancellationToken token;
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+ lock (lockObject)
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+ {
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- Cancel();
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+ Cancel();
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- cts = new CancellationTokenSource();
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+ cts = new CancellationTokenSource();
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- var token = cts.Token;
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+ token = cts.Token;
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+ }
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56
  return Task.Run(async () =>
49
57
  {
50
58
  await semaphore.WaitAsync();

4

修正

2018/10/18 04:36

投稿

Zuishin
Zuishin

スコア28675

answer CHANGED
@@ -43,13 +43,14 @@
43
43
  public static Task DoSomething(Func<CancellationToken, Task> action)
44
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  {
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45
  Cancel();
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+ cts = new CancellationTokenSource();
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+ var token = cts.Token;
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  return Task.Run(async () =>
47
49
  {
48
- cts = new CancellationTokenSource();
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  await semaphore.WaitAsync();
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  try
51
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  {
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- await action(cts.Token);
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+ await action(token);
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54
  }
54
55
  finally
55
56
  {

3

順番を間違えていたので修正

2018/10/16 12:41

投稿

Zuishin
Zuishin

スコア28675

answer CHANGED
@@ -45,10 +45,10 @@
45
45
  Cancel();
46
46
  return Task.Run(async () =>
47
47
  {
48
+ cts = new CancellationTokenSource();
48
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  await semaphore.WaitAsync();
49
50
  try
50
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  {
51
- cts = new CancellationTokenSource();
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52
  await action(cts.Token);
53
53
  }
54
54
  finally

2

変更

2018/10/16 12:33

投稿

Zuishin
Zuishin

スコア28675

answer CHANGED
@@ -1,4 +1,5 @@
1
1
  みなさんならどうしますかということなので、私なら別のクラスに分離します。
2
+ コメント欄にて指摘いただいたので書き直しました。
2
3
 
3
4
  ```C#
4
5
  using System;
@@ -20,14 +21,15 @@
20
21
 
21
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  private void button1_Click(object sender, EventArgs e)
22
23
  {
23
- taskId++;
24
24
  Something.DoSomething(async ct =>
25
25
  {
26
+ taskId++;
26
27
  for (int i = 0; i < 100; i++)
27
28
  {
28
29
  if (ct.IsCancellationRequested) break;
29
- Debug.WriteLine($"{taskId}:{i}");
30
+ Debug.WriteLine($"{taskId}:{i}:1");
30
31
  await Task.Delay(100);
32
+ Debug.WriteLine($"{taskId}:{i}:2");
31
33
  }
32
34
  });
33
35
  }
@@ -36,17 +38,23 @@
36
38
  static class Something
37
39
  {
38
40
  static CancellationTokenSource cts;
41
+ static SemaphoreSlim semaphore = new SemaphoreSlim(1, 1);
39
42
 
40
43
  public static Task DoSomething(Func<CancellationToken, Task> action)
41
44
  {
42
45
  Cancel();
43
- return Task.Run(() =>
46
+ return Task.Run(async () =>
44
47
  {
45
- using (var semaphore = new Semaphore(0, 1))
48
+ await semaphore.WaitAsync();
49
+ try
46
50
  {
47
51
  cts = new CancellationTokenSource();
48
- action(cts.Token).GetAwaiter().GetResult();
52
+ await action(cts.Token);
49
53
  }
54
+ finally
55
+ {
56
+ semaphore.Release();
57
+ }
50
58
  });
51
59
  }
52
60
 

1

using を使う

2018/10/16 11:34

投稿

Zuishin
Zuishin

スコア28675

answer CHANGED
@@ -42,16 +42,11 @@
42
42
  Cancel();
43
43
  return Task.Run(() =>
44
44
  {
45
- var semaphore = new Semaphore(0, 1);
45
+ using (var semaphore = new Semaphore(0, 1))
46
- try
47
46
  {
48
47
  cts = new CancellationTokenSource();
49
48
  action(cts.Token).GetAwaiter().GetResult();
50
49
  }
51
- finally
52
- {
53
- semaphore.Release();
54
- }
55
50
  });
56
51
  }
57
52