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[illink] Redo Java.Lang.Object serialization (dotnet#5473)
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Context: dotnet#5454

The use of `DataContract` attribute on  `Java.Lang.Object` class pulls
in `System.Runtime.Serialization.Primitives` assembly.

We still need to make the `Java.Lang.Object` class serializable, so that
inherited types can be serialized. Otherwise that would lead to
`System.Runtime.Serialization.InvalidDataContractException` during
runtime.

Instead of decorating `Java.Lang.Object` with `DataContract` attribute,
use `Serializable` attribute on class and `NonSerialized` attribute on fields.

This might seem contraproductive, to use multiple attribute instances
instead of one. In real it is not and leads to size saving and getting rid
of `System.Runtime.Serialization.Primitives` assembly reference
in linked apps. Because the `Serializable` and `NonSerialized` attributes
are not present in the compiled output, instead flags are used.

The compiled `Java.Lang.Object` class IL looks like this:
```
.class public auto ansi serializable beforefieldinit Java.Lang.Object
       extends [System.Private.CoreLib]System.Object
       implements [System.Private.CoreLib]System.IDisposable,
                  Android.Runtime.IJavaObject,
                  Java.Interop.IJavaObjectEx,
                  [Java.Interop]Java.Interop.IJavaPeerable
{
  .custom instance void Android.Runtime.RegisterAttribute::.ctor(string) = ( 01 00 10 6A 61 76 61 2F 6C 61 6E 67 2F 4F 62 6A   // ...java/lang/Obj
                                                                             65 63 74 01 00 54 02 10 44 6F 4E 6F 74 47 65 6E   // ect..T..DoNotGen
                                                                             65 72 61 74 65 41 63 77 01 )                      // erateAcw.
  .field private static initonly class [Java.Interop]Java.Interop.JniPeerMembers _members
  .field private static class [System.Private.CoreLib]System.Delegate cb_equals_Ljava_lang_Object_
  .field private static class [System.Private.CoreLib]System.Delegate cb_hashCode
  .field private static class [System.Private.CoreLib]System.Delegate cb_toString
  .field private notserialized native int key_handle
  .field private notserialized native int weak_handle
  .field private notserialized int32 refs_added
  .field private notserialized valuetype Android.Runtime.JObjectRefType handle_type
  .field private notserialized native int handle
  .field private notserialized bool needsActivation
  .field private notserialized bool isProxy
...
```

The apk size savings on net6 in BuildReleaseArm64False test:
```
> apkdiff -md -e dll$ before.apk after.apk
Size difference in bytes ([*1] apk1 only, [*2] apk2 only):
  -          13 assemblies/Mono.Android.dll
    -         120 Metadata
      -          60 Stream #~ (tables)
        -           6 Table TypeRef
        -           6 Table MemberRef
        -           6 Table CustomAttribute
        -          40 Table AssemblyRef
      -          60 Stream #Strings
    Type Java.Lang.Object
      -             CustomAttribute System.Runtime.Serialization.DataContractAttribute
  -       2,583 assemblies/System.Runtime.Serialization.Primitives.dll *1
Summary:
  -       2,596 Assemblies -0.28% (of 915,384)
```

I have also added a new test for `Java.Lang.Object` class serialization with code from
old `Hello` sample.

Example of `System.Runtime.Serialization.InvalidDataContractException` during runtime,
if `Java.Lang.Object` class was not serializable:
```
I MonoDroid: Android.Runtime.JavaProxyThrowable: Exception of type 'Android.Runtime.JavaProxyThrowable' was thrown.
I MonoDroid:   --- End of managed Android.Runtime.JavaProxyThrowable stack trace ---
I MonoDroid: android.runtime.JavaProxyThrowable: System.Runtime.Serialization.InvalidDataContractException: Type 'UnnamedProject.Person' cannot inherit from a type that is not marked with DataContractAttribute or SerializableAttribute.  Consider marking the base type 'Java.Lang.Object' with DataContractAttribute or SerializableAttribute, or removing them from the derived type.
I MonoDroid:   at System.Runtime.Serialization.ClassDataContract+ClassDataContractCriticalHelper..ctor (System.Type type) [0x001c3] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.ClassDataContract..ctor (System.Type type) [0x00000] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.DataContract+DataContractCriticalHelper.CreateDataContract (System.Int32 id, System.RuntimeTypeHandle typeHandle, System.Type type) [0x000e0] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.DataContract+DataContractCriticalHelper.GetDataContractSkipValidation (System.Int32 id, System.RuntimeTypeHandle typeHandle, System.Type type) [0x0000b] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.DataContract.GetDataContractSkipValidation (System.Int32 id, System.RuntimeTypeHandle typeHandle, System.Type type) [0x00000] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.DataContract.GetDataContract (System.Int32 id, System.RuntimeTypeHandle typeHandle, System.Runtime.Serialization.SerializationMode mode) [0x00000] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.DataContract.GetDataContract (System.RuntimeTypeHandle typeHandle, System.Type type, System.Runtime.Serialization.SerializationMode mode) [0x00006] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.DataContract.GetDataContract (System.Type type) [0x00006] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.Json.DataContractJsonSerializer.get_RootContract () [0x00022] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.Json.DataContractJsonSerializer.InternalWriteObjectContent (System.Runtime.Serialization.XmlWriterDelegator writer, System.Object graph) [0x00031] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.Json.DataContractJsonSerializer.InternalWriteObject (System.Runtime.Serialization.XmlWriterDelegator writer, System.Object graph) [0x00008] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.XmlObjectSerializer.InternalWriteObject (System.Runtime.Serialization.XmlWriterDelegator writer, System.Object graph, System.Runtime.Serialization.DataContractResolver dataContractResolver) [0x00000] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions (System.Runtime.Serialization.XmlWriterDelegator writer, System.Object graph, System.Runtime.Serialization.DataContractResolver dataContractResolver) [0x00073] in <686be187480b41979dcbf5635f805a7b>:0 01-07 16:13:09.246 10624 10624 I MonoDroid:   at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions (System.Runtime.Serialization.XmlWriterDelegator writer, System.Object graph) [0x00000] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.Json.DataContractJsonSerializer.WriteObject (System.Xml.XmlDictionaryWriter writer, System.Object graph) [0x0000d] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at System.Runtime.Serialization.Json.DataContractJsonSerializer.WriteObject (System.IO.Stream stream, System.Object graph) [0x00018] in <686be187480b41979dcbf5635f805a7b>:0
I MonoDroid:   at UnnamedProject.MainActivity.TestJsonDeserializationCreatesJavaHandle () [0x00033] in <11a2c65ab60d41dea720c7638d552ce0>:0
I MonoDroid:   at UnnamedProject.MainActivity.OnCreate (Android.OS.Bundle bundle) [0x0004b] in <11a2c65ab60d41dea720c7638d552ce0>:0 01-07 16:13:09.247 10624 10624 I MonoDroid:   at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_ (System.IntPtr jnienv, System.IntPtr native__this, System.IntPtr native_savedInstanceState) [0x00012] in <3045e86f0ced43c19ee1b522f77c72d7>:0
I MonoDroid:   at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_ (System.IntPtr jnienv, System.IntPtr native__this, System.IntPtr native_savedInstanceState) [0x00012] in <3045e86f0ced43c19ee1b522f77c72d7>:0
I MonoDroid:   at (wrapper dynamic-method) Android.Runtime.DynamicMethodNameCounter.1(intptr,intptr,intptr)
I MonoDroid:     at unnamedproject.unnamedproject.MainActivity.n_onCreate(Native Method)
I MonoDroid:     at unnamedproject.unnamedproject.MainActivity.onCreate(MainActivity.java:29)
I MonoDroid:     at android.app.Activity.performCreate(Activity.java:8000)
I MonoDroid:     at android.app.Activity.performCreate(Activity.java:7984)
I MonoDroid:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
I MonoDroid:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3404)
I MonoDroid:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3595)
I MonoDroid:     at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
I MonoDroid:     at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
I MonoDroid:     at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
I MonoDroid:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
I MonoDroid:     at android.os.Handler.dispatchMessage(Handler.java:106)
I MonoDroid:     at android.os.Looper.loop(Looper.java:223)
I MonoDroid:     at android.app.ActivityThread.main(ActivityThread.java:7660)
I MonoDroid:     at java.lang.reflect.Method.invoke(Native Method)
I MonoDroid:     at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
I MonoDroid:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
I MonoDroid:
W ActivityTaskManager:   Force finishing activity UnnamedProject.UnnamedProject/unnamedproject.unnamedproject.MainActivity
```
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@radekdoulik
radekdoulik authored Jan 12, 2021
1 parent 597e716 commit 101fea2
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Showing 5 changed files with 80 additions and 10 deletions.
16 changes: 8 additions & 8 deletions src/Mono.Android/Java.Lang/Object.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,21 +12,21 @@

namespace Java.Lang {

[DataContract]
[Serializable]
public partial class Object : IDisposable, IJavaObject, IJavaObjectEx
#if JAVA_INTEROP
, IJavaPeerable
#endif // JAVA_INTEROP
{
IntPtr key_handle;
[NonSerialized] IntPtr key_handle;
#pragma warning disable CS0649, CS0169, CS0414 // Suppress fields are never used warnings, these fields are used directly by monodroid-glue.cc
IntPtr weak_handle;
int refs_added;
[NonSerialized] IntPtr weak_handle;
[NonSerialized] int refs_added;
#pragma warning restore CS0649, CS0169, CS0414
JObjectRefType handle_type;
IntPtr handle;
bool needsActivation;
bool isProxy;
[NonSerialized] JObjectRefType handle_type;
[NonSerialized] IntPtr handle;
[NonSerialized] bool needsActivation;
[NonSerialized] bool isProxy;

IntPtr IJavaObjectEx.KeyHandle {
get {return key_handle;}
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2 changes: 0 additions & 2 deletions src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/PackagingTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -89,7 +89,6 @@ public void CheckIncludedAssemblies ()
"System.Console.dll",
"System.Linq.Expressions.dll",
"System.ObjectModel.dll",
"System.Runtime.Serialization.Primitives.dll",
"System.Private.CoreLib.dll",
"System.Collections.Concurrent.dll",
"System.Collections.dll",
Expand All @@ -103,7 +102,6 @@ public void CheckIncludedAssemblies ()
"System.Core.dll",
"System.Data.dll",
"System.dll",
"System.Runtime.Serialization.dll",
"UnnamedProject.dll",
"Mono.Data.Sqlite.dll",
"Mono.Data.Sqlite.dll.config",
Expand Down
1 change: 1 addition & 0 deletions src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Resources/Base/MainActivity.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@ protected override void OnCreate (Bundle bundle)
//${AFTER_ONCREATE}
}
}
//${AFTER_MAINACTIVITY}
}


70 changes: 70 additions & 0 deletions tests/MSBuildDeviceIntegration/Tests/InstallAndRunTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -419,5 +419,75 @@ public class LinkModeFullClass {
}
}

[Test]
public void JsonDeserializationCreatesJavaHandle ([Values (false, true)] bool isRelease)
{
AssertHasDevices ();

proj = new XamarinAndroidApplicationProject () {
IsRelease = isRelease,
};

if (isRelease || !CommercialBuildAvailable) {
proj.SetAndroidSupportedAbis ("armeabi-v7a", "arm64-v8a", "x86");
}

proj.References.Add (new BuildItem.Reference ("System.Runtime.Serialization"));

if (Builder.UseDotNet)
proj.References.Add (new BuildItem.Reference ("System.Runtime.Serialization.Json"));

proj.MainActivity = proj.DefaultMainActivity.Replace ("//${AFTER_ONCREATE}",
@"TestJsonDeserializationCreatesJavaHandle();
}
void TestJsonDeserializationCreatesJavaHandle ()
{
Person p = new Person () {
Name = ""John Smith"",
Age = 900,
};
var stream = new MemoryStream ();
var serializer = new DataContractJsonSerializer (typeof (Person));
serializer.WriteObject (stream, p);
stream.Position = 0;
StreamReader sr = new StreamReader (stream);
Console.WriteLine ($""JSON Person representation: {sr.ReadToEnd ()}"");
stream.Position = 0;
Person p2 = (Person) serializer.ReadObject (stream);
Console.WriteLine ($""JSON Person parsed: Name '{p2.Name}' Age '{p2.Age}' Handle '0x{p2.Handle:X}'"");
if (p2.Name != ""John Smith"")
throw new InvalidOperationException (""JSON deserialization of Name"");
if (p2.Age != 900)
throw new InvalidOperationException (""JSON deserialization of Age"");
if (p2.Handle == IntPtr.Zero)
throw new InvalidOperationException (""Failed to instantiate new Java instance for Person!"");
Console.WriteLine ($""JSON Person deserialized OK"");").Replace ("//${AFTER_MAINACTIVITY}", @"
[DataContract]
class Person : Java.Lang.Object {
[DataMember]
public string Name;
[DataMember]
public int Age;
}").Replace ("using System;", @"using System;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Json;");
builder = CreateApkBuilder ();
Assert.IsTrue (builder.Install (proj), "Install should have succeeded.");
ClearAdbLogcat ();
AdbStartActivity ($"{proj.PackageName}/{proj.JavaPackageName}.MainActivity");
Assert.IsFalse (MonitorAdbLogcat ((line) => {
return line.Contains ("InvalidOperationException");
}, Path.Combine (Root, builder.ProjectDirectory, "startup-logcat.log"), 45), $"Output did contain InvalidOperationException!");
}
}
}
1 change: 1 addition & 0 deletions tests/api-compatibility/acceptable-breakages-vReference.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -22,3 +22,4 @@ CannotRemoveAttribute : Attribute 'System.ComponentModel.CategoryAttribute' exis
CannotRemoveAttribute : Attribute 'System.ComponentModel.CategoryAttribute' exists on 'Android.Content.ContentProviderAttribute.Icon' in the contract but not the implementation.
CannotRemoveAttribute : Attribute 'System.ComponentModel.CategoryAttribute' exists on 'Android.Content.ContentProviderAttribute.Label' in the contract but not the implementation.
CannotRemoveAttribute : Attribute 'System.ComponentModel.CategoryAttribute' exists on 'Android.Content.ContentProviderAttribute.RoundIcon' in the contract but not the implementation.
CannotRemoveAttribute : Attribute 'System.Runtime.Serialization.DataContractAttribute' exists on 'Java.Lang.Object' in the contract but not the implementation.

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