SqlConnection.RetryLogicProvider Eigenschaft

public:
 property Microsoft::Data::SqlClient::SqlRetryLogicBaseProvider ^ RetryLogicProvider { Microsoft::Data::SqlClient::SqlRetryLogicBaseProvider ^ get(); void set(Microsoft::Data::SqlClient::SqlRetryLogicBaseProvider ^ value); };

[System.ComponentModel.Browsable(false)]
public Microsoft.Data.SqlClient.SqlRetryLogicBaseProvider RetryLogicProvider { get; set; }

public Microsoft.Data.SqlClient.SqlRetryLogicBaseProvider RetryLogicProvider { get; set; }

[<System.ComponentModel.Browsable(false)>]
member this.RetryLogicProvider : Microsoft.Data.SqlClient.SqlRetryLogicBaseProvider with get, set

member this.RetryLogicProvider : Microsoft.Data.SqlClient.SqlRetryLogicBaseProvider with get, set

Public Property RetryLogicProvider As SqlRetryLogicBaseProvider

Eigenschaftswert

Wenn auf NULL (Standard) festgelegt ist, wird der nicht wiederverwertbare Standardanbieter angewendet.

Attribute

BrowsableAttribute

Hinweise

Sie müssen den Wert für diese Eigenschaft festlegen, bevor sie die Verbindung öffnen, um wirksam zu werden.

Führen Sie zum Anwenden der Wiederholungslogik die folgenden Schritte aus, bevor Sie die Verbindung öffnen:

1. Definieren Sie die Konfigurationsparameter mithilfe SqlRetryLogicOption des Typs.
2. Erstellen Sie eine SqlRetryLogicBaseProvider , indem Sie eine der folgenden statischen Methoden der SqlConfigurableRetryFactory -Klasse verwenden:
   • CreateFixedRetryProvider
   • CreateIncrementalRetryProvider
   • CreateExponentialRetryProvider
   • CreateNoneRetryProvider
3. Weisen Sie das SqlRetryLogicBaseProvider -Objekt der RetryLogicProvider -Eigenschaft zu.

Beispiel

Im folgenden Beispiel wird versucht, eine Verbindung mit einer ungültigen Datenbank zu öffnen, um eine Bedingung zu simulieren, dass der Datenbankdienst vorübergehend nicht verfügbar ist. Sie sollten die Datenbank manuell erstellen, während sie SqlConnection versucht, die Verbindung herzustellen.

using Microsoft.Data.SqlClient;

/// Detecting retriable exceptions is a vital part of the retry pattern.
/// Before applying retry logic it is important to investigate exceptions and choose a retry provider that best fits your scenario.
/// First, log your exceptions and find transient faults.
/// The purpose of this sample is to illustrate how to use this feature and the condition might not be realistic.
class RetryLogicSample
{
    private const string DefaultDB = "Northwind";
    private const string CnnStringFormat = "Server=localhost; Initial Catalog={0}; Integrated Security=true; pooling=false;";
    private const string DropDatabaseFormat = "DROP DATABASE {0}";

    // For general use
    private static SqlConnection s_generalConnection = new SqlConnection(string.Format(CnnStringFormat, DefaultDB));

    static void Main(string[] args)
    {
        // 1. Define the retry logic parameters
        var options = new SqlRetryLogicOption()
        {
            NumberOfTries = 5,
            MaxTimeInterval = TimeSpan.FromSeconds(20),
            DeltaTime = TimeSpan.FromSeconds(1)
        };

        // 2. Create a retry provider
        var provider = SqlConfigurableRetryFactory.CreateExponentialRetryProvider(options);

        // define the retrying event to report the execution attempts
        provider.Retrying += (object s, SqlRetryingEventArgs e) =>
            {
                int attempts = e.RetryCount + 1;
                Console.ForegroundColor = ConsoleColor.Yellow;
                Console.WriteLine($"attempt {attempts} - current delay time:{e.Delay} \n");
                Console.ForegroundColor = ConsoleColor.DarkGray;
                if (e.Exceptions[e.Exceptions.Count - 1] is SqlException ex)
                {
                    Console.WriteLine($"{ex.Number}-{ex.Message}\n");
                }
                else
                {
                    Console.WriteLine($"{e.Exceptions[e.Exceptions.Count - 1].Message}\n");
                }

                // It is not a good practice to do time-consuming tasks inside the retrying event which blocks the running task.
                // Use parallel programming patterns to mitigate it.
                if (e.RetryCount == provider.RetryLogic.NumberOfTries - 1)
                {
                    Console.WriteLine("This is the last chance to execute the command before throwing the exception.");
                    Console.WriteLine("Press Enter when you're ready:");
                    Console.ReadLine();
                    Console.WriteLine("continue ...");
                }
            };

        // Open the general connection.
        s_generalConnection.Open();

        try
        {
            // Assume the database is being created and other services are going to connect to it.
            RetryConnection(provider);
        }
        catch
        {
            // exception is thrown if connecting to the database isn't successful.
            throw;
        }
    }

    private static void ExecuteCommand(SqlConnection cn, string command)
    {
        using var cmd = cn.CreateCommand();
        cmd.CommandText = command;
        cmd.ExecuteNonQuery();
    }

    private static void RetryConnection(SqlRetryLogicBaseProvider provider)
    {
        // Change this if you already have a database with the same name in your database.
        string dbName = "Invalid_DB_Open";

        // Create a connection to an invalid database.
        using var cnn = new SqlConnection(string.Format(CnnStringFormat, dbName));
        // 3. Assign the `provider` to the connection
        cnn.RetryLogicProvider = provider;
        Console.WriteLine($"Connecting to the [{dbName}] ...");
        // Manually execute the following command in SSMS to create the invalid database while the SqlConnection is attempting to connect to it.
        // >> CREATE DATABASE Invalid_DB_Open;
        Console.WriteLine($"Manually, run the 'CREATE DATABASE {dbName};' in the SQL Server before exceeding the {provider.RetryLogic.NumberOfTries} attempts.");
        // the connection tries to connect to the database 5 times
        Console.WriteLine("The first attempt, before getting into the retry logic.");
        cnn.Open();
        Console.WriteLine($"Connected to the [{dbName}] successfully.");

        cnn.Close();

        // Drop it after test
        ExecuteCommand(s_generalConnection, string.Format(DropDatabaseFormat, dbName));
        Console.WriteLine($"The [{dbName}] is removed.");
    }
}

Gilt für: