Мне нравится минимизировать планирование задач, ожидающих друг друга, но не показывающих его. Как бы я изменил свой TestOption1, чтобы он возвращал задачу вызывающему методу?
[TestClass()]
public class SqlServerTests
{
public const string Membership = "Data Source=LocalHost;Initial Catalog=tempdb;Integrated Security=True;";
[TestMethod()]
public async Task ContinueWithTest()
{
using CancellationTokenSource cts = new CancellationTokenSource();
//warm up so pooling is enabled on all 3 methods
using (var con = new SqlConnection(Membership))
using (var cmd = con.CreateCommand())
{
cmd.CommandType = System.Data.CommandType.Text;
cmd.CommandText = "set nocount on";
con.Open();
cmd.ExecuteNonQuery();
}
var sw2 = System.Diagnostics.Stopwatch.StartNew();
await TestOption2(cts.Token).ConfigureAwait(false);
sw2.Stop();
//allow the benefit of the doubt for the slower and give it cashed plans
var sw3 = System.Diagnostics.Stopwatch.StartNew();
await TestOption3(cts.Token).ConfigureAwait(false);
sw3.Stop();
Assert.IsTrue(sw2.ElapsedTicks < sw3.ElapsedTicks, "Stopwatch 2 {0} Stopwatch 3 {1}", sw2, sw3);
var sw1 = System.Diagnostics.Stopwatch.StartNew();
await TestOption1(cts.Token).ConfigureAwait(false);
sw1.Stop();
Console.WriteLine($"TestOption1: No internal awaits {sw1.ElapsedTicks:N0} ticks");
Console.WriteLine($"TestOption2: 1x internal await {sw2.ElapsedTicks:N0} ticks");
Console.WriteLine($"TestOption3: 2x internal await {sw3.ElapsedTicks:N0} ticks");
Assert.IsTrue(sw1.ElapsedTicks < sw2.ElapsedTicks, "Stopwatch 1 {0} Stopwatch 2 {1}", sw1, sw2);
Assert.IsTrue(sw1.ElapsedTicks < sw3.ElapsedTicks, "Stopwatch 1 {0} Stopwatch 3 {1}", sw1, sw3);
}
private static Task TestOption1(CancellationToken cancellationToken = default)
{
using (var con = new SqlConnection(Membership))
using (var cmd = con.CreateCommand())
{
cmd.CommandType = System.Data.CommandType.Text;
cmd.CommandText = "set nocount on";
return con.OpenAsync(cancellationToken)//fails as it does not wait for the db to open....
.ContinueWith((t) => cmd.ExecuteNonQuery()
, cancellationToken
, continuationOptions: TaskContinuationOptions.ExecuteSynchronously
, scheduler: TaskScheduler.Default);
}
}
private static async Task TestOption2(CancellationToken cancellationToken = default)
{
using (var con = new SqlConnection(Membership))
using (var cmd = con.CreateCommand())
{
cmd.CommandType = System.Data.CommandType.Text;
cmd.CommandText = "set nocount on";
await con.OpenAsync(cancellationToken)
.ContinueWith((_) => cmd.ExecuteNonQuery(), cancellationToken).ConfigureAwait(false);
}
}
private static async Task TestOption3(CancellationToken cancellationToken = default)
{
using (var con = new SqlConnection(Membership))
using (var cmd = con.CreateCommand())
{
cmd.CommandType = System.Data.CommandType.Text;
cmd.CommandText = "set nocount on";
await con.OpenAsync(cancellationToken).ConfigureAwait(false);
await cmd.ExecuteNonQueryAsync().ConfigureAwait(false);
}
}
}
Я бы хотел сделать что-то подобное
[TestMethod]
public async Task TestContinueWithDelegate()
{
var data = await TestOptionReturn().ConfigureAwait(false);
Assert.IsNotNull(data);
}
private static Task<object> TestOptionReturn(CancellationToken cancellationToken = default)
{
using (var con = new SqlConnection(Membership))
using (var cmd = con.CreateCommand())
{
cmd.CommandType = System.Data.CommandType.StoredProcedure;
cmd.CommandText = "Test1";
return con.OpenAsync(cancellationToken)//fails as it does not wait for the db to open....
.ContinueWith(delegate { return cmd.ExecuteScalar(); }
, cancellationToken
, continuationOptions: TaskContinuationOptions.ExecuteSynchronously
, scheduler: TaskScheduler.Default);
}
}
Следующие тесты не пройдены, поскольку база данных не открывается 
[TestMethod] publi c asyn c Task TestContinueWithDelegate () {using CancellationTokenSource cts = new CancellationTokenSource (); var data = await TestOptioDDL (cts.Token) .ConfigureAwait (false); использование var reader = await TestOptionOutput (cts.Token) .ConfigureAwait (false); Assert.IsNotNull (данные); Assert.IsTrue (reader.Read ()); }
private static Task<object> TestOptioDDL(CancellationToken cancellationToken = default)
{
using (var con = new SqlConnection(Membership))
using (var cmd = con.CreateCommand())
{
cmd.CommandType = System.Data.CommandType.StoredProcedure;
cmd.CommandText = "TestOutput";
cmd.Parameters.Add(new SqlParameter("Data", System.Data.SqlDbType.DateTime) { IsNullable = true, Direction = System.Data.ParameterDirection.Output });
return con.OpenAsync(cancellationToken)//fails as it does not wait for the db to open....
.ContinueWith(delegate
{
cmd.ExecuteScalar();
return cmd.Parameters[0].Value;
}
, cancellationToken
, continuationOptions: TaskContinuationOptions.ExecuteSynchronously
, scheduler: TaskScheduler.Default);
}
}
private static Task<SqlDataReader> TestOptionOutput(CancellationToken cancellationToken = default)
{
using (var con = new SqlConnection(Membership))
using (var cmd = con.CreateCommand())
{
cmd.CommandType = System.Data.CommandType.Text;
cmd.CommandText = "select * from sys.databases";
cmd.Parameters.Add(new SqlParameter("Data", System.Data.SqlDbType.DateTime) { IsNullable = true, Direction = System.Data.ParameterDirection.Output });
return con.OpenAsync(cancellationToken)//fails as it does not wait for the db to open....
.ContinueWith(delegate
{
return cmd.ExecuteReader();
}
, cancellationToken
, continuationOptions: TaskContinuationOptions.ExecuteSynchronously
, scheduler: TaskScheduler.Default);
}
}