Task.Run 方法
定義
重要
部分資訊涉及發行前產品,在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊,不做任何明確或隱含的瑕疵擔保。
將指定在 ThreadPool 執行工作排入佇列,並傳回該工作的工作或 Task<TResult> 控制代碼。
多載
Run(Func<Task>, CancellationToken) |
將指定在執行緒集區執行的工作排入佇列,並傳回 |
Run(Action, CancellationToken) |
將指定在執行緒集區執行工作排入佇列,並傳回代表該工作的 Task 物件。 取消權杖可用來在工作尚未開始之前取消工作。 |
Run(Func<Task>) |
將指定在執行緒集區執行的工作排入佇列,並傳回 |
Run(Action) |
將指定在執行緒集區執行工作排入佇列,並傳回代表該工作的 Task 物件。 |
Run<TResult>(Func<Task<TResult>>) |
將指定在執行緒集區執行的工作排入佇列,並傳回 |
Run<TResult>(Func<TResult>) |
將指定在執行緒集區執行工作排入佇列,並傳回代表該工作的 Task<TResult> 物件。 取消權杖可用來在工作尚未開始之前取消工作。 |
Run<TResult>(Func<Task<TResult>>, CancellationToken) |
將指定在執行緒集區執行的工作排入佇列,並傳回 |
Run<TResult>(Func<TResult>, CancellationToken) |
將指定在執行緒集區執行工作排入佇列,並傳回代表該工作的 |
備註
方法 Run 提供一組多載,可讓您輕鬆地使用預設值啟動工作。 這是多載的 StartNew 輕量型替代方案。
Run(Func<Task>, CancellationToken)
- 來源:
- Task.cs
- 來源:
- Task.cs
- 來源:
- Task.cs
將指定在執行緒集區執行的工作排入佇列,並傳回 function
所傳回之工作的 Proxy。 取消權杖可用來在工作尚未開始之前取消工作。
public:
static System::Threading::Tasks::Task ^ Run(Func<System::Threading::Tasks::Task ^> ^ function, System::Threading::CancellationToken cancellationToken);
public static System.Threading.Tasks.Task Run (Func<System.Threading.Tasks.Task> function, System.Threading.CancellationToken cancellationToken);
public static System.Threading.Tasks.Task Run (Func<System.Threading.Tasks.Task?> function, System.Threading.CancellationToken cancellationToken);
static member Run : Func<System.Threading.Tasks.Task> * System.Threading.CancellationToken -> System.Threading.Tasks.Task
Public Shared Function Run (function As Func(Of Task), cancellationToken As CancellationToken) As Task
參數
- cancellationToken
- CancellationToken
在工作尚未開始之前可用來取消工作的取消權杖。 Run(Func<Task>, CancellationToken) 不會將 cancellationToken
傳遞給 action
。
傳回
表示 function
所傳回工作之 Proxy 的工作。
例外狀況
function
參數為 null
。
已取消這項工作。 此例外狀況會儲存在傳回的工作中。
與 cancellationToken
相關聯的 CancellationTokenSource 已經處置。
備註
如需處理工作作業擲回之例外狀況的資訊,請參閱 例外狀況處理。
另請參閱
適用於
Run(Action, CancellationToken)
- 來源:
- Task.cs
- 來源:
- Task.cs
- 來源:
- Task.cs
將指定在執行緒集區執行工作排入佇列,並傳回代表該工作的 Task 物件。 取消權杖可用來在工作尚未開始之前取消工作。
public:
static System::Threading::Tasks::Task ^ Run(Action ^ action, System::Threading::CancellationToken cancellationToken);
public static System.Threading.Tasks.Task Run (Action action, System.Threading.CancellationToken cancellationToken);
static member Run : Action * System.Threading.CancellationToken -> System.Threading.Tasks.Task
Public Shared Function Run (action As Action, cancellationToken As CancellationToken) As Task
參數
- action
- Action
要以非同步方式執行的工作。
- cancellationToken
- CancellationToken
在工作尚未開始之前可用來取消工作的取消權杖。 Run(Action, CancellationToken) 不會將 cancellationToken
傳遞給 action
。
傳回
代表已進入佇列,並要在執行緒集區中執行之工作 (work) 的工作 (task)。
例外狀況
action
參數為 null
。
已取消這項工作。 此例外狀況會儲存在傳回的工作中。
與 cancellationToken
相關聯的 CancellationTokenSource 已經處置。
範例
下列範例會呼叫 Run(Action, CancellationToken) 方法來建立工作,以逐一查看 C:\Windows\System32 目錄中的檔案。 Lambda 表達式會呼叫 方法, Parallel.ForEach 將每個檔案的相關信息新增至 List<T> 物件。 迴圈所 Parallel.ForEach 叫用的每個中斷連結巢狀工作都會檢查取消令牌的狀態,如果要求取消,則會呼叫 CancellationToken.ThrowIfCancellationRequested 方法。 方法CancellationToken.ThrowIfCancellationRequested會在OperationCanceledException呼叫線程呼叫 Task.Wait 方法時,擲回區塊中catch
處理的例外狀況。
using System;
using System.Collections.Generic;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
public class Example
{
public static async Task Main()
{
var tokenSource = new CancellationTokenSource();
var token = tokenSource.Token;
var files = new List<Tuple<string, string, long, DateTime>>();
var t = Task.Run( () => { string dir = "C:\\Windows\\System32\\";
object obj = new Object();
if (Directory.Exists(dir)) {
Parallel.ForEach(Directory.GetFiles(dir),
f => {
if (token.IsCancellationRequested)
token.ThrowIfCancellationRequested();
var fi = new FileInfo(f);
lock(obj) {
files.Add(Tuple.Create(fi.Name, fi.DirectoryName, fi.Length, fi.LastWriteTimeUtc));
}
});
}
}
, token);
await Task.Yield();
tokenSource.Cancel();
try {
await t;
Console.WriteLine("Retrieved information for {0} files.", files.Count);
}
catch (AggregateException e) {
Console.WriteLine("Exception messages:");
foreach (var ie in e.InnerExceptions)
Console.WriteLine(" {0}: {1}", ie.GetType().Name, ie.Message);
Console.WriteLine("\nTask status: {0}", t.Status);
}
finally {
tokenSource.Dispose();
}
}
}
// The example displays the following output:
// Exception messages:
// TaskCanceledException: A task was canceled.
// TaskCanceledException: A task was canceled.
// ...
//
// Task status: Canceled
open System
open System.IO
open System.Threading
open System.Threading.Tasks
let main =
task {
use tokenSource = new CancellationTokenSource()
let token = tokenSource.Token
let files = ResizeArray()
let t =
Task.Run(
(fun () ->
let dir = "C:\\Windows\\System32\\"
let obj = obj ()
if Directory.Exists dir then
Parallel.ForEach(
Directory.GetFiles dir,
(fun f ->
if token.IsCancellationRequested then
token.ThrowIfCancellationRequested()
let fi = FileInfo f
lock obj (fun () -> files.Add(fi.Name, fi.DirectoryName, fi.Length, fi.LastWriteTimeUtc)))
)
|> ignore),
token
)
do! Task.Yield()
tokenSource.Cancel()
try
do! t
printfn $"Retrieved information for {files.Count} files."
with :? AggregateException as e ->
printfn "Exception messages:"
for ie in e.InnerExceptions do
printfn $" {ie.GetType().Name}: {ie.Message}"
printfn $"Task status: {t.Status}"
}
main.Wait()
// The example displays the following output:
// Exception messages:
// TaskCanceledException: A task was canceled.
// TaskCanceledException: A task was canceled.
// ...
//
// Task status: Canceled
Imports System.Collections.Generic
Imports System.IO
Imports System.Threading
Imports System.Threading.Tasks
Module Example
Public Sub Main()
Dim tokenSource As New CancellationTokenSource()
Dim token As CancellationToken = tokenSource.Token
Dim files As New List(Of Tuple(Of String, String, Long, Date))()
Dim t As Task = Task.Run( Sub()
Dim dir As String = "C:\Windows\System32\"
Dim obj As New Object()
If Directory.Exists(dir)Then
Parallel.ForEach(Directory.GetFiles(dir),
Sub(f)
If token.IsCancellationRequested Then
token.ThrowIfCancellationRequested()
End If
Dim fi As New FileInfo(f)
SyncLock(obj)
files.Add(Tuple.Create(fi.Name, fi.DirectoryName, fi.Length, fi.LastWriteTimeUtc))
End SyncLock
End Sub)
End If
End Sub, token)
tokenSource.Cancel()
Try
t.Wait()
Console.WriteLine("Retrieved information for {0} files.", files.Count)
Catch e As AggregateException
Console.WriteLine("Exception messages:")
For Each ie As Exception In e.InnerExceptions
Console.WriteLine(" {0}:{1}", ie.GetType().Name, ie.Message)
Next
Console.WriteLine()
Console.WriteLine("Task status: {0}", t.Status)
Finally
tokenSource.Dispose()
End Try
End Sub
End Module
' The example displays the following output:
' Exception messages:
' TaskCanceledException: A task was canceled.
'
' Task status: Canceled
備註
如果在工作開始執行之前要求取消,工作就不會執行。 而是設定為 Canceled 狀態,並擲回 TaskCanceledException 例外狀況。
方法 Run(Action, CancellationToken) 是方法的較簡單替代 TaskFactory.StartNew(Action, CancellationToken) 方法。 它會建立具有下列預設值的工作:
它會使用預設的工作排程器。
如需處理工作作業擲回之例外狀況的資訊,請參閱 例外狀況處理。
另請參閱
適用於
Run(Func<Task>)
- 來源:
- Task.cs
- 來源:
- Task.cs
- 來源:
- Task.cs
將指定在執行緒集區執行的工作排入佇列,並傳回 function
所傳回之工作的 Proxy。
public:
static System::Threading::Tasks::Task ^ Run(Func<System::Threading::Tasks::Task ^> ^ function);
public static System.Threading.Tasks.Task Run (Func<System.Threading.Tasks.Task> function);
public static System.Threading.Tasks.Task Run (Func<System.Threading.Tasks.Task?> function);
static member Run : Func<System.Threading.Tasks.Task> -> System.Threading.Tasks.Task
Public Shared Function Run (function As Func(Of Task)) As Task
參數
傳回
表示 function
所傳回工作之 Proxy 的工作。
例外狀況
function
參數為 null
。
備註
如需處理工作作業擲回之例外狀況的資訊,請參閱 例外狀況處理。
另請參閱
適用於
Run(Action)
- 來源:
- Task.cs
- 來源:
- Task.cs
- 來源:
- Task.cs
將指定在執行緒集區執行工作排入佇列,並傳回代表該工作的 Task 物件。
public:
static System::Threading::Tasks::Task ^ Run(Action ^ action);
public static System.Threading.Tasks.Task Run (Action action);
static member Run : Action -> System.Threading.Tasks.Task
Public Shared Function Run (action As Action) As Task
參數
- action
- Action
要以非同步方式執行的工作。
傳回
表示已進入佇列要在 ThreadPool 中執行之工作 (work) 的工作 (task)。
例外狀況
action
參數為 null
。
範例
下列範例會定義顯示 ShowThreadInfo
目前線程之 的方法 Thread.ManagedThreadId 。 它會直接從應用程式線程呼叫,並從傳遞至 Run(Action) 方法的委派呼叫Action。
using System;
using System.Threading;
using System.Threading.Tasks;
public class Example
{
public static void Main()
{
ShowThreadInfo("Application");
var t = Task.Run(() => ShowThreadInfo("Task") );
t.Wait();
}
static void ShowThreadInfo(String s)
{
Console.WriteLine("{0} thread ID: {1}",
s, Thread.CurrentThread.ManagedThreadId);
}
}
// The example displays the following output:
// Application thread ID: 1
// Task thread ID: 3
open System.Threading
open System.Threading.Tasks
let showThreadInfo s =
printfn $"%s{s} thread ID: {Thread.CurrentThread.ManagedThreadId}"
showThreadInfo "Application"
let t = Task.Run(fun () -> showThreadInfo "Task")
t.Wait()
// The example displays the following output:
// Application thread ID: 1
// Task thread ID: 3
Imports System.Threading
Imports System.Threading.Tasks
Module Example
Public Sub Main()
ShowThreadInfo("Application")
Dim t As Task = Task.Run(Sub() ShowThreadInfo("Task") )
t.Wait()
End Sub
Private Sub ShowThreadInfo(s As String)
Console.WriteLine("{0} Thread ID: {1}",
s, Thread.CurrentThread.ManagedThreadId)
End Sub
End Module
' The example displays output like the following:
' Application thread ID: 1
' Task thread ID: 3
下列範例與上一個範例類似,不同之處在於它會使用 Lambda 表達式來定義工作執行的程序代碼。
using System;
using System.Threading;
using System.Threading.Tasks;
public class Example
{
public static void Main()
{
Console.WriteLine("Application thread ID: {0}",
Thread.CurrentThread.ManagedThreadId);
var t = Task.Run(() => { Console.WriteLine("Task thread ID: {0}",
Thread.CurrentThread.ManagedThreadId);
} );
t.Wait();
}
}
// The example displays the following output:
// Application thread ID: 1
// Task thread ID: 3
open System.Threading
open System.Threading.Tasks
printfn $"Application thread ID: {Thread.CurrentThread.ManagedThreadId}"
let t = Task.Run(fun () -> printfn $"Task thread ID: {Thread.CurrentThread.ManagedThreadId}")
t.Wait()
// The example displays the following output:
// Application thread ID: 1
// Task thread ID: 3
Imports System.Threading
Imports System.Threading.Tasks
Module Example
Public Sub Main()
Console.WriteLine("Application thread ID: {0}",
Thread.CurrentThread.ManagedThreadId)
Dim t As Task = Task.Run(Sub()
Console.WriteLine("Task thread ID: {0}",
Thread.CurrentThread.ManagedThreadId)
End Sub)
t.Wait()
End Sub
End Module
' The example displays output like the following:
' Application thread ID: 1
' Task thread ID: 3
這些範例顯示異步工作在與主要應用程式線程不同的線程上執行。
方法的 Wait 呼叫可確保工作在應用程式結束之前完成並顯示其輸出。 否則,在工作完成之前, Main
方法可能會完成。
下列範例說明 Run(Action) 方法。 它會定義目錄名稱的陣列,並啟動個別的工作來擷取每個目錄中的檔名。 所有工作都會將檔名寫入單 ConcurrentBag<T> 一物件。 然後範例會呼叫 WaitAll(Task[]) 方法,以確保所有工作都已完成,然後顯示寫入物件 ConcurrentBag<T> 之檔名總數的計數。
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;
public class Example
{
public static void Main()
{
var list = new ConcurrentBag<string>();
string[] dirNames = { ".", ".." };
List<Task> tasks = new List<Task>();
foreach (var dirName in dirNames) {
Task t = Task.Run( () => { foreach(var path in Directory.GetFiles(dirName))
list.Add(path); } );
tasks.Add(t);
}
Task.WaitAll(tasks.ToArray());
foreach (Task t in tasks)
Console.WriteLine("Task {0} Status: {1}", t.Id, t.Status);
Console.WriteLine("Number of files read: {0}", list.Count);
}
}
// The example displays output like the following:
// Task 1 Status: RanToCompletion
// Task 2 Status: RanToCompletion
// Number of files read: 23
open System.Collections.Concurrent
open System.IO
open System.Threading.Tasks
let list = ConcurrentBag<string>()
let dirNames = [ "."; ".." ]
let tasks = ResizeArray()
for dirName in dirNames do
let t =
Task.Run(fun () ->
for path in Directory.GetFiles dirName do
list.Add path)
tasks.Add t
tasks.ToArray() |> Task.WaitAll
for t in tasks do
printfn $"Task {t.Id} Status: {t.Status}"
printfn $"Number of files read: {list.Count}"
// The example displays output like the following:
// Task 1 Status: RanToCompletion
// Task 2 Status: RanToCompletion
// Number of files read: 23
Imports System.Collections.Concurrent
Imports System.Collections.Generic
Imports System.IO
Imports System.Threading.Tasks
Module Example
Public Sub Main()
Dim list As New ConcurrentBag(Of String)()
Dim dirNames() As String = { ".", ".." }
Dim tasks As New List(Of Task)()
For Each dirName In dirNames
Dim t As Task = Task.Run( Sub()
For Each path In Directory.GetFiles(dirName)
list.Add(path)
Next
End Sub )
tasks.Add(t)
Next
Task.WaitAll(tasks.ToArray())
For Each t In tasks
Console.WriteLine("Task {0} Status: {1}", t.Id, t.Status)
Next
Console.WriteLine("Number of files read: {0}", list.Count)
End Sub
End Module
' The example displays output like the following:
' Task 1 Status: RanToCompletion
' Task 2 Status: RanToCompletion
' Number of files read: 23
備註
方法 Run 可讓您在單一方法呼叫中建立和執行工作,而且是方法的更簡單替代方案 StartNew 。 它會建立具有下列預設值的工作:
取消標記為 CancellationToken.None。
它會使用預設的工作排程器。
如需處理工作作業擲回之例外狀況的資訊,請參閱 例外狀況處理。
另請參閱
適用於
Run<TResult>(Func<Task<TResult>>)
- 來源:
- Task.cs
- 來源:
- Task.cs
- 來源:
- Task.cs
將指定在執行緒集區執行的工作排入佇列,並傳回 function
所傳回之 Task(TResult)
的 Proxy。 取消權杖可用來在工作尚未開始之前取消工作。
public:
generic <typename TResult>
static System::Threading::Tasks::Task<TResult> ^ Run(Func<System::Threading::Tasks::Task<TResult> ^> ^ function);
public static System.Threading.Tasks.Task<TResult> Run<TResult> (Func<System.Threading.Tasks.Task<TResult>> function);
public static System.Threading.Tasks.Task<TResult> Run<TResult> (Func<System.Threading.Tasks.Task<TResult>?> function);
static member Run : Func<System.Threading.Tasks.Task<'Result>> -> System.Threading.Tasks.Task<'Result>
Public Shared Function Run(Of TResult) (function As Func(Of Task(Of TResult))) As Task(Of TResult)
類型參數
- TResult
Proxy 工作傳回的結果類型。
參數
傳回
Task(TResult)
,代表 Task(TResult)
所傳回之 function
的 Proxy。
例外狀況
function
參數為 null
。
備註
如需處理工作作業擲回之例外狀況的資訊,請參閱 例外狀況處理。
另請參閱
適用於
Run<TResult>(Func<TResult>)
- 來源:
- Task.cs
- 來源:
- Task.cs
- 來源:
- Task.cs
將指定在執行緒集區執行工作排入佇列,並傳回代表該工作的 Task<TResult> 物件。 取消權杖可用來在工作尚未開始之前取消工作。
public:
generic <typename TResult>
static System::Threading::Tasks::Task<TResult> ^ Run(Func<TResult> ^ function);
public static System.Threading.Tasks.Task<TResult> Run<TResult> (Func<TResult> function);
static member Run : Func<'Result> -> System.Threading.Tasks.Task<'Result>
Public Shared Function Run(Of TResult) (function As Func(Of TResult)) As Task(Of TResult)
類型參數
- TResult
工作的傳回類型。
參數
- function
- Func<TResult>
要以非同步方式執行的工作。
傳回
代表已排入佇列要在執行緒集區中執行之工作 (work) 的工作 (task) 物件。
例外狀況
function
參數為 null
。
範例
下列範例會計算文本檔中代表已發行書籍的大約字數。 每項工作都會負責開啟檔案、以異步方式讀取其整個內容,以及使用正則表達式計算字數。 系統會 WaitAll(Task[]) 呼叫 方法,以確保所有工作都已完成,再將每本書籍的字數顯示到主控台。
using System;
using System.IO;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
public class Example
{
public static void Main()
{
string pattern = @"\p{P}*\s+";
string[] titles = { "Sister Carrie", "The Financier" };
Task<int>[] tasks = new Task<int>[titles.Length];
for (int ctr = 0; ctr < titles.Length; ctr++) {
string s = titles[ctr];
tasks[ctr] = Task.Run( () => {
// Number of words.
int nWords = 0;
// Create filename from title.
string fn = s + ".txt";
if (File.Exists(fn)) {
StreamReader sr = new StreamReader(fn);
string input = sr.ReadToEndAsync().Result;
nWords = Regex.Matches(input, pattern).Count;
}
return nWords;
} );
}
Task.WaitAll(tasks);
Console.WriteLine("Word Counts:\n");
for (int ctr = 0; ctr < titles.Length; ctr++)
Console.WriteLine("{0}: {1,10:N0} words", titles[ctr], tasks[ctr].Result);
}
}
// The example displays the following output:
// Sister Carrie: 159,374 words
// The Financier: 196,362 words
open System
open System.IO
open System.Text.RegularExpressions
open System.Threading.Tasks
let pattern = @"\p{P}*\s+"
let titles = [| "Sister Carrie"; "The Financier" |]
let tasks =
Array.map (fun title ->
Task.Run(fun () ->
// Create filename from title.
let fn = title + ".txt"
if File.Exists fn then
use sr = new StreamReader(fn)
let input = sr.ReadToEndAsync().Result
Regex.Matches(input, pattern).Count
else
0)) titles
tasks |> Seq.cast |> Array.ofSeq |> Task.WaitAll
printfn "Word Counts:\n"
for i = 0 to tasks.Length - 1 do
printfn $"%s{titles.[i]}: %10d{tasks.[i].Result} words"
// The example displays the following output:
// Sister Carrie: 159,374 words
// The Financier: 196,362 words
Imports System.IO
Imports System.Text.RegularExpressions
Imports System.Threading.Tasks
Module Example
Public Sub Main()
Dim pattern As String = "\p{P}*\s+"
Dim titles() As String = { "Sister Carrie",
"The Financier" }
Dim tasks(titles.Length - 1) As Task(Of Integer)
For ctr As Integer = 0 To titles.Length - 1
Dim s As String = titles(ctr)
tasks(ctr) = Task.Run( Function()
' Number of words.
Dim nWords As Integer = 0
' Create filename from title.
Dim fn As String = s + ".txt"
If File.Exists(fn) Then
Dim sr As New StreamReader(fn)
Dim input As String = sr.ReadToEndAsync().Result
nWords = Regex.Matches(input, pattern).Count
End If
Return nWords
End Function)
Next
Task.WaitAll(tasks)
Console.WriteLine("Word Counts:")
Console.WriteLine()
For ctr As Integer = 0 To titles.Length - 1
Console.WriteLine("{0}: {1,10:N0} words", titles(ctr), tasks(ctr).Result)
Next
End Sub
End Module
' The example displays the following output:
' Sister Carrie: 159,374 words
' The Financier: 196,362 words
正則表達式 \p{P}*\s+
會比對零、一或多個標點符號字元,後面接著一或多個空格符。 它假設相符項目的總數等於近似字數。
備註
方法是 Run 方法的較簡單替代方案 TaskFactory.StartNew(Action) 。 它會建立具有下列預設值的工作:
取消標記為 CancellationToken.None。
它會使用預設的工作排程器。
如需處理工作作業擲回之例外狀況的資訊,請參閱 例外狀況處理。
另請參閱
適用於
Run<TResult>(Func<Task<TResult>>, CancellationToken)
- 來源:
- Task.cs
- 來源:
- Task.cs
- 來源:
- Task.cs
將指定在執行緒集區執行的工作排入佇列,並傳回 function
所傳回之 Task(TResult)
的 Proxy。
public:
generic <typename TResult>
static System::Threading::Tasks::Task<TResult> ^ Run(Func<System::Threading::Tasks::Task<TResult> ^> ^ function, System::Threading::CancellationToken cancellationToken);
public static System.Threading.Tasks.Task<TResult> Run<TResult> (Func<System.Threading.Tasks.Task<TResult>> function, System.Threading.CancellationToken cancellationToken);
public static System.Threading.Tasks.Task<TResult> Run<TResult> (Func<System.Threading.Tasks.Task<TResult>?> function, System.Threading.CancellationToken cancellationToken);
static member Run : Func<System.Threading.Tasks.Task<'Result>> * System.Threading.CancellationToken -> System.Threading.Tasks.Task<'Result>
Public Shared Function Run(Of TResult) (function As Func(Of Task(Of TResult)), cancellationToken As CancellationToken) As Task(Of TResult)
類型參數
- TResult
Proxy 工作傳回的結果類型。
參數
- cancellationToken
- CancellationToken
在工作尚未開始之前可用來取消工作的取消權杖。 Run<TResult>(Func<Task<TResult>>, CancellationToken) 不會將 cancellationToken
傳遞給 action
。
傳回
Task(TResult)
,代表 Task(TResult)
所傳回之 function
的 Proxy。
例外狀況
function
參數為 null
。
已取消這項工作。 此例外狀況會儲存在傳回的工作中。
與 cancellationToken
相關聯的 CancellationTokenSource 已經處置。
備註
如需處理工作作業擲回之例外狀況的資訊,請參閱 例外狀況處理。
另請參閱
適用於
Run<TResult>(Func<TResult>, CancellationToken)
- 來源:
- Task.cs
- 來源:
- Task.cs
- 來源:
- Task.cs
將指定在執行緒集區執行工作排入佇列,並傳回代表該工作的 Task(TResult)
物件。
public:
generic <typename TResult>
static System::Threading::Tasks::Task<TResult> ^ Run(Func<TResult> ^ function, System::Threading::CancellationToken cancellationToken);
public static System.Threading.Tasks.Task<TResult> Run<TResult> (Func<TResult> function, System.Threading.CancellationToken cancellationToken);
static member Run : Func<'Result> * System.Threading.CancellationToken -> System.Threading.Tasks.Task<'Result>
Public Shared Function Run(Of TResult) (function As Func(Of TResult), cancellationToken As CancellationToken) As Task(Of TResult)
類型參數
- TResult
工作的結果類型。
參數
- function
- Func<TResult>
要以非同步方式執行的工作。
- cancellationToken
- CancellationToken
在工作尚未開始之前可用來取消工作的取消權杖。 Run<TResult>(Func<TResult>, CancellationToken) 不會將 cancellationToken
傳遞給 action
。
傳回
Task(TResult)
,代表已排入佇列要在執行緒集區中執行的工作。
例外狀況
function
參數為 null
。
已取消這項工作。 此例外狀況會儲存在傳回的工作中。
與 cancellationToken
相關聯的 CancellationTokenSource 已經處置。
範例
下列範例會建立 20 個將迴圈的工作,直到計數器遞增為 2 百萬個值為止。 當前 10 個工作達到 2 百萬個時,取消令牌會取消,而且任何計數器尚未達到 2 百萬個的工作都取消。 此範例會顯示可能的輸出。
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
public class Example
{
public static void Main()
{
var tasks = new List<Task<int>>();
var source = new CancellationTokenSource();
var token = source.Token;
int completedIterations = 0;
for (int n = 0; n <= 19; n++)
tasks.Add(Task.Run( () => { int iterations = 0;
for (int ctr = 1; ctr <= 2000000; ctr++) {
token.ThrowIfCancellationRequested();
iterations++;
}
Interlocked.Increment(ref completedIterations);
if (completedIterations >= 10)
source.Cancel();
return iterations; }, token));
Console.WriteLine("Waiting for the first 10 tasks to complete...\n");
try {
Task.WaitAll(tasks.ToArray());
}
catch (AggregateException) {
Console.WriteLine("Status of tasks:\n");
Console.WriteLine("{0,10} {1,20} {2,14:N0}", "Task Id",
"Status", "Iterations");
foreach (var t in tasks)
Console.WriteLine("{0,10} {1,20} {2,14}",
t.Id, t.Status,
t.Status != TaskStatus.Canceled ? t.Result.ToString("N0") : "n/a");
}
}
}
// The example displays output like the following:
// Waiting for the first 10 tasks to complete...
// Status of tasks:
//
// Task Id Status Iterations
// 1 RanToCompletion 2,000,000
// 2 RanToCompletion 2,000,000
// 3 RanToCompletion 2,000,000
// 4 RanToCompletion 2,000,000
// 5 RanToCompletion 2,000,000
// 6 RanToCompletion 2,000,000
// 7 RanToCompletion 2,000,000
// 8 RanToCompletion 2,000,000
// 9 RanToCompletion 2,000,000
// 10 Canceled n/a
// 11 Canceled n/a
// 12 Canceled n/a
// 13 Canceled n/a
// 14 Canceled n/a
// 15 Canceled n/a
// 16 RanToCompletion 2,000,000
// 17 Canceled n/a
// 18 Canceled n/a
// 19 Canceled n/a
// 20 Canceled n/a
open System
open System.Collections.Generic
open System.Threading
open System.Threading.Tasks
let source = new CancellationTokenSource()
let token = source.Token
let mutable completedIterations = 0
let tasks =
[| for _ = 0 to 19 do
Task.Run(
(fun () ->
let mutable iterations = 0
for _ = 1 to 2000000 do
token.ThrowIfCancellationRequested()
iterations <- iterations + 1
Interlocked.Increment &completedIterations |> ignore
if completedIterations >= 10 then
source.Cancel()
iterations),
token
)
|]
printfn "Waiting for the first 10 tasks to complete...\n"
try
tasks |> Seq.cast |> Array.ofSeq |> Task.WaitAll
with :? AggregateException ->
printfn "Status of tasks:\n"
printfn "%10s %20s %14s" "Task Id" "Status" "Iterations"
for t in tasks do
if t.Status <> TaskStatus.Canceled then
t.Result.ToString "N0"
else
"n/a"
|> printfn "%10i %20O %14s" t.Id t.Status
// The example displays output like the following:
// Waiting for the first 10 tasks to complete...
// Status of tasks:
//
// Task Id Status Iterations
// 1 RanToCompletion 2,000,000
// 2 RanToCompletion 2,000,000
// 3 RanToCompletion 2,000,000
// 4 RanToCompletion 2,000,000
// 5 RanToCompletion 2,000,000
// 6 RanToCompletion 2,000,000
// 7 RanToCompletion 2,000,000
// 8 RanToCompletion 2,000,000
// 9 RanToCompletion 2,000,000
// 10 Canceled n/a
// 11 Canceled n/a
// 12 Canceled n/a
// 13 Canceled n/a
// 14 Canceled n/a
// 15 Canceled n/a
// 16 RanToCompletion 2,000,000
// 17 Canceled n/a
// 18 Canceled n/a
// 19 Canceled n/a
// 20 Canceled n/a
Imports System.Collections.Generic
Imports System.Threading
Imports System.Threading.Tasks
Module Example
Public Sub Main()
Dim tasks As New List(Of Task(Of Integer))()
Dim source As New CancellationTokenSource
Dim token As CancellationToken = source.Token
Dim completedIterations As Integer = 0
For n As Integer = 0 To 19
tasks.Add(Task.Run( Function()
Dim iterations As Integer= 0
For ctr As Long = 1 To 2000000
token.ThrowIfCancellationRequested()
iterations += 1
Next
Interlocked.Increment(completedIterations)
If completedIterations >= 10 Then source.Cancel()
Return iterations
End Function, token))
Next
Console.WriteLine("Waiting for the first 10 tasks to complete... ")
Try
Task.WaitAll(tasks.ToArray())
Catch e As AggregateException
Console.WriteLine("Status of tasks:")
Console.WriteLine()
Console.WriteLine("{0,10} {1,20} {2,14}", "Task Id",
"Status", "Iterations")
For Each t In tasks
Console.WriteLine("{0,10} {1,20} {2,14}",
t.Id, t.Status,
If(t.Status <> TaskStatus.Canceled,
t.Result.ToString("N0"), "n/a"))
Next
End Try
End Sub
End Module
' The example displays output like the following:
' Waiting for the first 10 tasks to complete...
' Status of tasks:
'
' Task Id Status Iterations
' 1 RanToCompletion 2,000,000
' 2 RanToCompletion 2,000,000
' 3 RanToCompletion 2,000,000
' 4 RanToCompletion 2,000,000
' 5 RanToCompletion 2,000,000
' 6 RanToCompletion 2,000,000
' 7 RanToCompletion 2,000,000
' 8 RanToCompletion 2,000,000
' 9 RanToCompletion 2,000,000
' 10 Canceled n/a
' 11 Canceled n/a
' 12 Canceled n/a
' 13 Canceled n/a
' 14 Canceled n/a
' 15 Canceled n/a
' 16 RanToCompletion 2,000,000
' 17 Canceled n/a
' 18 Canceled n/a
' 19 Canceled n/a
' 20 Canceled n/a
此範例不會使用 InnerExceptions 屬性來檢查例外狀況,而是逐一查看所有工作,以判斷哪些工作已順利完成,以及哪些工作已經取消。 針對已完成的專案,它會顯示工作所傳回的值。
因為取消是合作的,所以每個工作都可以決定如何回應取消。 下列範例就像第一個範例,不同之處在於,一旦取消令牌,工作就會傳回他們已完成的反覆項目數目,而不是擲回例外狀況。
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
public class Example
{
public static void Main()
{
var tasks = new List<Task<int>>();
var source = new CancellationTokenSource();
var token = source.Token;
int completedIterations = 0;
for (int n = 0; n <= 19; n++)
tasks.Add(Task.Run( () => { int iterations = 0;
for (int ctr = 1; ctr <= 2000000; ctr++) {
if (token.IsCancellationRequested)
return iterations;
iterations++;
}
Interlocked.Increment(ref completedIterations);
if (completedIterations >= 10)
source.Cancel();
return iterations; }, token));
Console.WriteLine("Waiting for the first 10 tasks to complete...\n");
try {
Task.WaitAll(tasks.ToArray());
}
catch (AggregateException) {
Console.WriteLine("Status of tasks:\n");
Console.WriteLine("{0,10} {1,20} {2,14:N0}", "Task Id",
"Status", "Iterations");
foreach (var t in tasks)
Console.WriteLine("{0,10} {1,20} {2,14}",
t.Id, t.Status,
t.Status != TaskStatus.Canceled ? t.Result.ToString("N0") : "n/a");
}
}
}
// The example displays output like the following:
// Status of tasks:
//
// Task Id Status Iterations
// 1 RanToCompletion 2,000,000
// 2 RanToCompletion 2,000,000
// 3 RanToCompletion 2,000,000
// 4 RanToCompletion 2,000,000
// 5 RanToCompletion 2,000,000
// 6 RanToCompletion 2,000,000
// 7 RanToCompletion 2,000,000
// 8 RanToCompletion 2,000,000
// 9 RanToCompletion 2,000,000
// 10 RanToCompletion 1,658,326
// 11 RanToCompletion 1,988,506
// 12 RanToCompletion 2,000,000
// 13 RanToCompletion 1,942,246
// 14 RanToCompletion 950,108
// 15 RanToCompletion 1,837,832
// 16 RanToCompletion 1,687,182
// 17 RanToCompletion 194,548
// 18 Canceled Not Started
// 19 Canceled Not Started
// 20 Canceled Not Started
open System
open System.Collections.Generic
open System.Threading
open System.Threading.Tasks
let source = new CancellationTokenSource()
let token = source.Token
let mutable completedIterations = 0
let tasks =
[| for _ = 0 to 19 do
Task.Run(
(fun () ->
let mutable iterations = 0
for _ = 1 to 2000000 do
token.ThrowIfCancellationRequested()
iterations <- iterations + 1
Interlocked.Increment &completedIterations |> ignore
if completedIterations >= 10 then
source.Cancel()
iterations),
token
) |]
printfn "Waiting for the first 10 tasks to complete...\n"
try
tasks |> Seq.cast |> Array.ofSeq |> Task.WaitAll
with :? AggregateException ->
printfn "Status of tasks:\n"
printfn "%10s %20s %14s" "Task Id" "Status" "Iterations"
for t in tasks do
if t.Status <> TaskStatus.Canceled then
t.Result.ToString "N0"
else
"n/a"
|> printfn "%10i %20O %14s" t.Id t.Status
// The example displays output like the following:
// Status of tasks:
//
// Task Id Status Iterations
// 1 RanToCompletion 2,000,000
// 2 RanToCompletion 2,000,000
// 3 RanToCompletion 2,000,000
// 4 RanToCompletion 2,000,000
// 5 RanToCompletion 2,000,000
// 6 RanToCompletion 2,000,000
// 7 RanToCompletion 2,000,000
// 8 RanToCompletion 2,000,000
// 9 RanToCompletion 2,000,000
// 10 RanToCompletion 1,658,326
// 11 RanToCompletion 1,988,506
// 12 RanToCompletion 2,000,000
// 13 RanToCompletion 1,942,246
// 14 RanToCompletion 950,108
// 15 RanToCompletion 1,837,832
// 16 RanToCompletion 1,687,182
// 17 RanToCompletion 194,548
// 18 Canceled Not Started
// 19 Canceled Not Started
// 20 Canceled Not Started
Imports System.Collections.Generic
Imports System.Threading
Imports System.Threading.Tasks
Module Example
Public Sub Main()
Dim tasks As New List(Of Task(Of Integer))()
Dim source As New CancellationTokenSource
Dim token As CancellationToken = source.Token
Dim completedIterations As Integer = 0
For n As Integer = 0 To 19
tasks.Add(Task.Run( Function()
Dim iterations As Integer= 0
For ctr As Long = 1 To 2000000
If token.IsCancellationRequested Then
Return iterations
End If
iterations += 1
Next
Interlocked.Increment(completedIterations)
If completedIterations >= 10 Then source.Cancel()
Return iterations
End Function, token))
Next
Try
Task.WaitAll(tasks.ToArray())
Catch e As AggregateException
Console.WriteLine("Status of tasks:")
Console.WriteLine()
Console.WriteLine("{0,10} {1,20} {2,14:N0}", "Task Id",
"Status", "Iterations")
For Each t In tasks
Console.WriteLine("{0,10} {1,20} {2,14}",
t.Id, t.Status,
If(t.Status <> TaskStatus.Canceled,
t.Result.ToString("N0"), "Not Started"))
Next
End Try
End Sub
End Module
' The example displays output like the following:
' Status of tasks:
'
' Task Id Status Iterations
' 1 RanToCompletion 2,000,000
' 2 RanToCompletion 2,000,000
' 3 RanToCompletion 2,000,000
' 4 RanToCompletion 2,000,000
' 5 RanToCompletion 2,000,000
' 6 RanToCompletion 2,000,000
' 7 RanToCompletion 2,000,000
' 8 RanToCompletion 2,000,000
' 9 RanToCompletion 2,000,000
' 10 RanToCompletion 1,658,326
' 11 RanToCompletion 1,988,506
' 12 RanToCompletion 2,000,000
' 13 RanToCompletion 1,942,246
' 14 RanToCompletion 950,108
' 15 RanToCompletion 1,837,832
' 16 RanToCompletion 1,687,182
' 17 RanToCompletion 194,548
' 18 Canceled Not Started
' 19 Canceled Not Started
' 20 Canceled Not Started
此範例仍然必須處理 AggregateException 例外狀況,因為要求取消時尚未啟動的任何工作仍會擲回例外狀況。
備註
如果在工作開始執行之前要求取消,則不會執行工作。 而是設定為 Canceled 狀態,並擲回例外狀況 TaskCanceledException 。
方法是 Run 方法的較簡單替代方案 StartNew 。 它會建立具有下列預設值的工作:
它會使用預設的工作排程器。
如需處理工作作業擲回之例外狀況的資訊,請參閱 例外狀況處理。
另請參閱
適用於
意見反應
https://aka.ms/ContentUserFeedback。
即將登場:在 2024 年,我們將逐步淘汰 GitHub 問題作為內容的意見反應機制,並將它取代為新的意見反應系統。 如需詳細資訊,請參閱:提交並檢視相關的意見反應