SqlConnection.RetryLogicProvider Properti

Definisi

Ruang nama:

Microsoft.Data.SqlClient

Rakitan:

Microsoft.Data.SqlClient.dll

Paket:

Microsoft.Data.SqlClient v5.2.0

Mendapatkan atau mengatur nilai yang menentukan objek yang terikat ke SqlRetryLogicBaseProvider perintah ini.

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

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

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

Public Property RetryLogicProvider As SqlRetryLogicBaseProvider

Nilai Properti

SqlRetryLogicBaseProvider

Ketika diatur ke null (default), penyedia default yang tidak dapat dicoba akan diterapkan.

Keterangan

Anda harus mengatur nilai untuk properti ini sebelum membuka sambungan agar berlaku.

Untuk menerapkan logika coba lagi, lakukan langkah-langkah berikut sebelum membuka koneksi:

1. Tentukan parameter konfigurasi dengan menggunakan SqlRetryLogicOption jenis .
2. SqlRetryLogicBaseProvider Buat dengan menggunakan salah satu metode SqlConfigurableRetryFactory statis kelas berikut:
   • CreateFixedRetryProvider
   • CreateIncrementalRetryProvider
   • CreateExponentialRetryProvider
   • CreateNoneRetryProvider
3. Tetapkan SqlRetryLogicBaseProvider objek ke RetryLogicProvider properti .

Catatan

Mendeteksi pengecualian yang dapat dicoba ulang adalah bagian penting dari pola coba lagi. Sebelum menerapkan logika coba lagi, penting untuk menyelidiki pengecualian dan memilih penyedia coba lagi yang paling sesuai dengan skenario Anda. Pertama, catat pengecualian Anda dan temukan kesalahan sementara.

Catatan

Batas waktu koneksi dimulai ulang untuk setiap eksekusi koneksi yang terbuka. Tidak ada tumpang tindih waktu antara kedua tindakan ini.

Catatan

Penyedia logika coba lagi default tidak diaktifkan kecuali dikonfigurasi dalam file konfigurasi aplikasi. Untuk informasi selengkapnya, lihat Logika coba lagi dan file konfigurasi yang dapat dikonfigurasi.

Contoh

Sampel berikut mencoba membuka koneksi ke database yang tidak valid untuk mensimulasikan kondisi bahwa layanan database untuk sementara tidak tersedia. Anda harus membuat database secara manual saat SqlConnection mencoba membuat koneksi.

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.");
    }
}