Make ClearRequest lazy

Author: SergeiPavlov

Orm/Xtensive.Orm/Orm/Providers/Interfaces/IPersistDescriptor.cs

@@ -14,6 +14,6 @@ public interface IPersistDescriptor
     Lazy<PersistRequest> LazyLevel1BatchStoreRequest { get; }
     Lazy<PersistRequest> LazyLevel2BatchStoreRequest { get; }
 
-    PersistRequest ClearRequest { get; }
+    Lazy<PersistRequest> ClearRequest { get; }
   }
 }

Orm/Xtensive.Orm/Orm/Providers/SqlSessionHandler.IProviderExecutor.cs

@@ -64,15 +64,15 @@ async Task IProviderExecutor.StoreAsync(IPersistDescriptor descriptor, IEnumerab
     void IProviderExecutor.Clear(IPersistDescriptor descriptor, ParameterContext parameterContext)
     {
       Prepare();
-      commandProcessor.RegisterTask(new SqlPersistTask(descriptor.ClearRequest));
+      commandProcessor.RegisterTask(new SqlPersistTask(descriptor.ClearRequest.Value));
       Execute(parameterContext);
     }
 
     /// <inheritdoc/>
     void IProviderExecutor.Overwrite(IPersistDescriptor descriptor, IEnumerable<Tuple> tuples)
     {
       Prepare();
-      commandProcessor.RegisterTask(new SqlPersistTask(descriptor.ClearRequest));
+      commandProcessor.RegisterTask(new SqlPersistTask(descriptor.ClearRequest.Value));
       Store(descriptor, tuples);
       Execute(new ParameterContext());
     }

Orm/Xtensive.Orm/Orm/Providers/TemporaryTables/TemporaryTableDescriptor.cs

@@ -56,7 +56,7 @@ public sealed class TemporaryTableDescriptor : IPersistDescriptor
     /// <summary>
     /// Gets or sets the clear reqest used to delete all data from temporary table.
     /// </summary>
-    public PersistRequest ClearRequest { get; set; }
+    public Lazy<PersistRequest> ClearRequest { get; set; }
 
     /// <summary>
     /// Gets or sets the query statement associated with this table descriptor.

Orm/Xtensive.Orm/Orm/Providers/TemporaryTables/TemporaryTableManager.cs

@@ -32,7 +32,7 @@ public class TemporaryTableManager : DomainBoundHandler
     /// <summary>
     /// Gets value indicating whether temporary tables are supported.
     /// </summary>
-    public bool Supported { get { return backEnd!=null; } }
+    public bool Supported { get { return backEnd != null; } }
 
     /// <summary>
     /// Builds the descriptor of a temporary table.
@@ -93,10 +93,13 @@ public TemporaryTableDescriptor BuildDescriptor(ModelMapping modelMapping, strin
         LazyLevel1BatchStoreRequest = CreateLazyPersistRequest(WellKnown.MultiRowInsertLevel1BatchSize),
         LazyLevel2BatchStoreRequest = CreateLazyPersistRequest(WellKnown.MultiRowInsertLevel2BatchSize),
         LazyStoreRequest = CreateLazyPersistRequest(1),
-        ClearRequest = new PersistRequest(driver, Handlers.ProviderInfo.Supports(ProviderFeatures.TruncateTable) ? SqlDdl.Truncate(table) : SqlDml.Delete(tableRef), null)
+        ClearRequest = new Lazy<PersistRequest>(() => {
+          var request = new PersistRequest(driver, Handlers.ProviderInfo.Supports(ProviderFeatures.TruncateTable) ? SqlDdl.Truncate(table) : SqlDml.Delete(tableRef), null);
+          request.Prepare();
+          return request;
+        })
       };
 
-      result.ClearRequest.Prepare();
       return result;
 
       Lazy<PersistRequest> CreateLazyPersistRequest(int batchSize) =>
@@ -147,7 +150,7 @@ protected void ExecuteNonQuery(EnumerationContext context, string statement)
     private static TemporaryTableStateRegistry GetRegistry(Session session)
     {
       var registry = session.Extensions.Get<TemporaryTableStateRegistry>();
-      if (registry==null) {
+      if (registry == null) {
         registry = new TemporaryTableStateRegistry();
         session.Extensions.Set(registry);
       }
@@ -167,7 +170,7 @@ private string[] BuildFieldNames(TupleDescriptor source) =>
           .Select(i => string.Format(ColumnNamePattern, i))
           .ToArray();
 
-    private Table CreateTemporaryTable(Schema schema, string name, TupleDescriptor source, TypeMapping[] typeMappings, string[]fieldNames, Collation collation)
+    private Table CreateTemporaryTable(Schema schema, string name, TupleDescriptor source, TypeMapping[] typeMappings, string[] fieldNames, Collation collation)
     {
       var tableName = Handlers.NameBuilder.ApplyNamingRules(string.Format(TableNamePattern, name));
       var table = backEnd.CreateTemporaryTable(schema, tableName);
@@ -178,7 +181,7 @@ private Table CreateTemporaryTable(Schema schema, string name, TupleDescriptor s
           var column = table.CreateColumn(fieldNames[fieldIndex], mapping.MapType());
           column.IsNullable = true;
           // TODO: Dmitry Maximov, remove this workaround than collation problem will be fixed
-          if (mapping.Type==WellKnownTypes.String)
+          if (mapping.Type == WellKnownTypes.String)
             column.Collation = collation;
           fieldIndex++;
         }

Orm/Xtensive.Orm/Orm/Upgrade/Internals/Metadata/MetadataWriter.cs

@@ -30,7 +30,7 @@ private sealed class Descriptor : IPersistDescriptor
       public Lazy<PersistRequest> LazyStoreRequest { get; set; }
       public Lazy<PersistRequest> LazyLevel1BatchStoreRequest { get; }
       public Lazy<PersistRequest> LazyLevel2BatchStoreRequest { get; }
-      public PersistRequest ClearRequest { get; set; }
+      public Lazy<PersistRequest> ClearRequest { get; set; }
     }
 
     private readonly StorageDriver driver;
@@ -121,7 +121,7 @@ private IPersistDescriptor CreateDescriptor(string tableName,
 
       return new Descriptor {
         LazyStoreRequest = new Lazy<PersistRequest>(storeRequest),
-        ClearRequest = clearRequest
+        ClearRequest = new Lazy<PersistRequest>(clearRequest)
       };
     }