Adding WaitAvailable to EFCore extensions

AMWD.Common.EntityFrameworkCore/Extensions/DatabaseFacadeExtensions.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Data;
 using System.Data.Common;
 using System.IO;
 using System.Linq;
@@ -28,18 +29,24 @@ namespace Microsoft.EntityFrameworkCore
 			if (database == null)
 				throw new ArgumentNullException(nameof(database));
 
-			var options = new DatabaseMigrationOptions();
-			optionsAction?.Invoke(options);
-
 			if (database.GetProviderType() == DatabaseProvider.InMemory)
 				return true;
 
+			var options = new DatabaseMigrationOptions();
+			optionsAction?.Invoke(options);
+
 			if (string.IsNullOrWhiteSpace(options.MigrationsTableName))
 				throw new ArgumentNullException(nameof(options.MigrationsTableName), $"The property {nameof(options.MigrationsTableName)} of the {nameof(options)} parameter is required.");
 
 			if (string.IsNullOrWhiteSpace(options.Path))
 				throw new ArgumentNullException(nameof(options.Path), $"The property {nameof(options.Path)} of the {nameof(options)} parameter is required.");
 
+			await database.WaitAvailableAsync(opts =>
+			{
+				opts.WaitDelay = options.WaitDelay;
+				opts.Logger = options.Logger;
+			}, cancellationToken);
+
 			var connection = database.GetDbConnection();
 			try
 			{
@@ -52,7 +59,58 @@ namespace Microsoft.EntityFrameworkCore
 			}
 			finally
 			{
-				connection.Close();
+				await connection.CloseAsync();
+			}
+		}
+
+		/// <summary>
+		/// Waits until the database connection is available.
+		/// </summary>
+		/// <param name="database">The database connection.</param>
+		/// <param name="optionsAction">An action to set additional options.</param>
+		/// <param name="cancellationToken">A cancellation token.</param>
+		/// <returns>An awaitable task to wait until the database is available.</returns>
+		public static async Task WaitAvailableAsync(this DatabaseFacade database, Action<DatabaseMigrationOptions> optionsAction = null, CancellationToken cancellationToken = default)
+		{
+			if (database == null)
+				throw new ArgumentNullException(nameof(database));
+
+			if (database.GetProviderType() == DatabaseProvider.InMemory)
+				return;
+
+			var options = new DatabaseMigrationOptions();
+			optionsAction?.Invoke(options);
+
+			options.Logger?.LogInformation("Waiting for a database connection");
+			var connection = database.GetDbConnection();
+			while (!cancellationToken.IsCancellationRequested)
+			{
+				try
+				{
+					await connection.OpenAsync(cancellationToken);
+					options.Logger?.LogInformation("Database connection available");
+					return;
+				}
+				catch
+				{
+					// keep things quiet
+					try
+					{
+						await Task.Delay(options.WaitDelay, cancellationToken);
+					}
+					catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+					{
+						return;
+					}
+					catch
+					{
+						// keep things quiet
+					}
+				}
+				finally
+				{
+					await connection.CloseAsync();
+				}
 			}
 		}