VariableDispenser.LockForRead(String) 方法
定义
重要
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将变量添加到要锁定用于只读访问的变量列表。
public:
void LockForRead(System::String ^ variable);public void LockForRead (string variable);member this.LockForRead : string -> unitPublic Sub LockForRead (variable As String)参数
- variable
- String
要添加到列表中以锁定用于只读访问的变量的名称。
示例
下面的代码示例创建一个 VariableDispenser 系统变量，并将两个系统变量添加到锁定以供读取的列表，并将一个系统变量添加到锁定以供写入的列表。 然后，调用该 GetVariables 变量来锁定集合中的所有三个变量，并释放列表并可用于新变量。
using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.SqlServer.Dts.Runtime;
namespace Microsoft.SqlServer.SSIS.Sample
{
class Program
{
static void Main(string[] args)
{
Package pkg = new Package();
Variables vars = null;
VariableDispenser variableDispenser = pkg.VariableDispenser;
variableDispenser.LockForRead("System::PackageName");
variableDispenser.LockForRead("System::OfflineMode");
variableDispenser.GetVariables(ref vars);
// Verify that the variable is locked before unlocking.
Console.WriteLine("Variables are locked? {0}", vars.Locked);
foreach (Variable myVar in vars)
{
Console.WriteLine("Name {0}", myVar.Name);
Console.WriteLine("Description {0}", myVar.Description);
Console.WriteLine();
}
// Use Contains to determine whether indexing can be used.
Boolean pkgName = variableDispenser.Contains("PackageName");
String qName = variableDispenser.GetQualifiedName("PackageName");
Console.WriteLine("Contains is valid? {0}", pkgName);
Console.WriteLine("Fully qualified name is: {0}", qName);
vars.Unlock();
Console.WriteLine("Variables are locked? {0}", vars.Locked);
}
}
}
Imports System
Imports System.Collections.Generic
Imports System.Text
Imports Microsoft.SqlServer.Dts.Runtime
Namespace Microsoft.SqlServer.SSIS.Sample
Class Program
Shared Sub Main(ByVal args() As String)
Dim pkg As Package = New Package()
Dim vars As Variables = Nothing
Dim variableDispenser As VariableDispenser = pkg.VariableDispenser
variableDispenser.LockForRead("System::PackageName")
variableDispenser.LockForRead("System::OfflineMode")
variableDispenser.GetVariables( vars)
' Verify that the variable is locked before unlocking.
Console.WriteLine("Variables are locked? {0}", vars.Locked)
Dim myVar As Variable
For Each myVar In vars
Console.WriteLine("Name {0}", myVar.Name)
Console.WriteLine("Description {0}", myVar.Description)
Console.WriteLine()
Next
' Use Contains to determine whether indexing can be used.
Dim pkgName As Boolean = variableDispenser.Contains("PackageName")
Dim qName As String = variableDispenser.GetQualifiedName("PackageName")
Console.WriteLine("Contains is valid? {0}", pkgName)
Console.WriteLine("Fully qualified name is: {0}", qName)
vars.Unlock()
Console.WriteLine("Variables are locked? {0}", vars.Locked)
End Sub
End Class
End Namespace
示例输出：
Variables are locked? True
Name OfflineMode
Description The offline mode currently set for the package
Name PackageName
Description The package name
Contains is valid? True
Fully qualified name is: System::PackageName
Variables are locked? False
注解
此方法在首次调用时创建一个列表，并将给定变量添加到列表中。 在后续调用中，变量将添加到现有列表中。 此方法实际上不会锁定变量。 创建所需变量的列表后，调用 GetVariables 以锁定此列表中找到的变量。 调用之前LockForWriteGetVariables可以进行任意数量的调用LockForRead。
备注
多个客户端可以同时获取变量上的只读锁。
若要在完成后清除成功的锁，请调用 Unlock。