Compress Model XML, Stage 3: assign [MetatdataExtension].Value = null to get rid of Uncompressed XML (#333)

* Compres Model XML, Stage 3: assgin `Extension.Value = null`

* Bump version

* Remove comment in Serialize()

* .SerializeIntoStream()

* Add comment

* Add comment

* DeserializeFromStream()

* Simplify

* Bump version

Author: SergeiPavlov

Orm/Xtensive.Orm/Core/SimpleXmlSerializer.cs

@@ -34,10 +34,13 @@ public T Deserialize(string value)
     {
       ArgumentNullException.ThrowIfNull(value, "serialized");
 
-      using (var reader = new StringReader(value))
-        return (T) serializer.Deserialize(reader);
+      using StringReader reader = new(value);
+      return (T) serializer.Deserialize(reader);
     }
 
+    public T DeserializeFromStream(Stream stream) =>
+      (T) serializer.Deserialize(stream);
+
     /// <summary>
     /// Serializes value of <typeparamref name="T"/> to string.
     /// </summary>
@@ -53,5 +56,13 @@ public string Serialize(T value)
       }
       return stringWriter.ToString();
     }
+
+    public void SerializeIntoStream(T value, Stream stream)
+    {
+      ArgumentNullException.ThrowIfNull(value);
+
+      using var xmlWriter = XmlWriter.Create(stream, WriterSettings);
+      serializer.Serialize(xmlWriter, value);
+    }
   }
 }

Orm/Xtensive.Orm/Orm/Model/Stored/StoredDomainModel.cs

@@ -48,21 +48,16 @@ public sealed class StoredDomainModel
     public static StoredDomainModel Deserialize(string serialized, byte[] data)
     {
       if (data != null) {
-        string xml;
         switch (data[0]) {
           case 0:
-            xml = Encoding.UTF8.GetString(data, 1, data.Length - 1);
-            break;
+            return Serializer.Deserialize(Encoding.UTF8.GetString(data, 1, data.Length - 1));
           case 1:
             using (BrotliStream brotliStream = new(new MemoryStream(data, 1, data.Length - 1), CompressionMode.Decompress)) {
-              using StreamReader reader = new(brotliStream, Encoding.UTF8);
-              xml = reader.ReadToEnd();
+              return Serializer.DeserializeFromStream(brotliStream);
             }
-            break;
           default:
             throw new NotSupportedException("Invalid data format");
         }
-        return Serializer.Deserialize(xml);
       }
       return Serializer.Deserialize(serialized);
     }
@@ -73,17 +68,12 @@ public static StoredDomainModel Deserialize(string serialized, byte[] data)
     /// <returns>Serialized instance.</returns>
     public (string Xml, byte[] Compressed) Serialize()
     {
-      var xml = Serializer.Serialize(this);
       MemoryStream ms = new(1000);
-      ms.WriteByte(1);
+      ms.WriteByte(1);      // 1 - means Brotli method
       using (BrotliStream brotliStream = new(ms, CompressionLevel.Optimal)) {
-        brotliStream.Write(Encoding.UTF8.GetBytes(xml));
+        Serializer.SerializeIntoStream(this, brotliStream);
       }
-
-      //!!!TODO  Uncomment following line to switch to Compressed XML serialization
-      // return (null, ms.ToArray());
-
-      return (xml, ms.ToArray());
+      return (null, ms.ToArray());
     }
 
     /// <summary>

Orm/Xtensive.Orm/Orm/Upgrade/SystemUpgradeHandler.cs

@@ -200,8 +200,8 @@ private Dictionary<string, MetadataSet> BuildMetadata(Domain domain, TypeIdRegis
         // Since we support storage nodes, stored domain model and real model of a node
         // must be synchronized. So we must update types' mappings
         storedModel.UpdateMappings(UpgradeContext.NodeConfiguration);
-        var (serializedModel, compressed) = storedModel.Serialize();
-        var modelExtension = new ExtensionMetadata(WellKnown.DomainModelExtensionName, serializedModel, compressed);
+        var (_, compressed) = storedModel.Serialize();
+        var modelExtension = new ExtensionMetadata(WellKnown.DomainModelExtensionName, null, compressed);
         var indexesExtension = GetPartialIndexes(domain, types);
         metadata.Assemblies.AddRange(assemblyMetadata);
         metadata.Types.AddRange(typeMetadata);

Version.props

@@ -2,7 +2,7 @@
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
 
 <PropertyGroup>
-    <DoVersion>7.2.167</DoVersion>
+    <DoVersion>7.2.168</DoVersion>
     <DoVersionSuffix>servicetitan</DoVersionSuffix>
 </PropertyGroup>