MOAR LOGGING

Context: good! https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=3201349&view=logs&j=8556562a-ae5f-5bd1-7c4d-bf1af4b6f1e1&t=a4d74fbf-7b8e-51d6-b189-8c80ca04a74a
Context:  Bad! https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=3201349&view=logs&j=8556562a-ae5f-5bd1-7c4d-bf1af4b6f1e1&t=1ce93f75-3079-5716-18de-288761bcb886

LOGGING FOR THE LOGGING GODS!

The story so far: now we have GREF logs (yay), and can thus see their
creation & destruction.

Conspicuously MISSING, however, is the handle in the exception
message!

	System.NotSupportedException: Unable to activate instance of type
	Xamarin.Forms.Performance.Integration.Droid.MainActivity from native
	handle 0xff88ad3c (key_handle 0x2629e85).

The GREF logs we have DO NOT MENTION 0xff88ad3c nor 0x2629e85.

Compare to the working (JIT-only) iteration, which has a `handle`
statement:

	handle 0x2786; key_handle 0x2629e85: Java Type: `xamarin/forms/performance/integration/MainActivity`; MCW type: `Xamarin.Forms.Performance.Integration.Droid.MainActivity`

This leaves one current scary hypothesis (good for Halloween!):
what if the instance isn't being *activated*?

When a Java Callable Wrapper constructor is executed, the Java side
invokes `mono.android.TypeManager.Activate()`, which is
`Java.Interop.TypeManager.n_Activate()`, which will NOT activate an
instance for a variety of reasons.

Is `TypeManager.n_Activate()` being executed?

If it *is* executed, does it *do* anything?

LOG THE HELL OUT OF IT.

Ditto `TypeManager.CreateInstance()`.

Additionally, update `OSBridge::_monodroid_gref_log()` so that the
message is written to *both* `grefs.txt` AND `adb logcat`, to make it
easier to reason about things when only one or the other is around.
(This should allow the `handle` statement to appear in `adb logcat`.)

Author: jonpryor

src/Mono.Android/Java.Interop/TypeManager.cs

@@ -133,13 +133,17 @@ static Type[] GetParameterTypes (string signature)
 
 		static void n_Activate (IntPtr jnienv, IntPtr jclass, IntPtr typename_ptr, IntPtr signature_ptr, IntPtr jobject, IntPtr parameters_ptr)
 		{
+			JNIEnv._monodroid_gref_log (
+					string.Format ("# jonp: n_Activate: Activating handle 0x{0} (key_handle 0x{1}).",
+						jobject.ToString ("x"), JNIEnv.IdentityHash (jobject).ToString ("x")));
 			var o   = Java.Lang.Object.PeekObject (jobject);
 			var ex  = o as IJavaObjectEx;
 			if (ex != null) {
 				if (!ex.NeedsActivation && !ex.IsProxy)
 					return;
 			}
 			if (!ActivationEnabled) {
+				JNIEnv._monodroid_gref_log ($"# jonp: n_Activate: Activation not enabled.  Bailing!");
 				if (Logger.LogGlobalRef) {
 					Logger.Log (LogLevel.Info, "monodroid-gref",
 							string.Format ("warning: Skipping managed constructor invocation for handle 0x{0} (key_handle 0x{1}). " +
@@ -151,22 +155,26 @@ static void n_Activate (IntPtr jnienv, IntPtr jclass, IntPtr typename_ptr, IntPt
 			}
 
 			Type type = Type.GetType (JNIEnv.GetString (typename_ptr, JniHandleOwnership.DoNotTransfer), throwOnError:true);
+			JNIEnv._monodroid_gref_log ($"# jonp: n_Activate: type={type}");
 			if (type.IsGenericTypeDefinition) {
 				throw new NotSupportedException (
 						"Constructing instances of generic types from Java is not supported, as the type parameters cannot be determined.",
 						CreateJavaLocationException ());
 			}
 			Type[] ptypes = GetParameterTypes (JNIEnv.GetString (signature_ptr, JniHandleOwnership.DoNotTransfer));
+			JNIEnv._monodroid_gref_log ($"# jonp: n_Activate: constructor parameter types: {string.Join (", ", (object[]) ptypes)}");
 			object[] parms = JNIEnv.GetObjectArray (parameters_ptr, ptypes);
 			ConstructorInfo cinfo = type.GetConstructor (ptypes);
 			if (cinfo == null) {
 				throw CreateMissingConstructorException (type, ptypes);
 			}
 			if (o != null) {
+				JNIEnv._monodroid_gref_log ($"# jonp: n_Activate: invoking ctor on already created instance");
 				cinfo.Invoke (o, parms);
 				return;
 			}
 			try {
+				JNIEnv._monodroid_gref_log ($"# jonp: n_Activate: creating new instance");
 				var activator = ConstructorBuilder.CreateDelegate (type, cinfo, ptypes);
 				activator (jobject, parms);
 			} catch (Exception e) {
@@ -243,6 +251,7 @@ internal static IJavaObject CreateInstance (IntPtr handle, JniHandleOwnership tr
 
 		internal static IJavaObject CreateInstance (IntPtr handle, JniHandleOwnership transfer, Type targetType)
 		{
+			JNIEnv._monodroid_gref_log ($"# jonp: CreateInstance: handle=0x{handle.ToString ("x2")}, key_handle=0x{JNIEnv.IdentityHash (handle)}");
 			Type type = null;
 			IntPtr class_ptr = JNIEnv.GetObjectClass (handle);
 			string class_name = GetClassName (class_ptr);
@@ -283,6 +292,8 @@ internal static IJavaObject CreateInstance (IntPtr handle, JniHandleOwnership tr
 				type = invokerType;
 			}
 
+			JNIEnv._monodroid_gref_log ($"# jonp: CreateInstance: type={type}");
+
 
 			IJavaObject result = null;
 

src/monodroid/jni/osbridge.cc

@@ -222,6 +222,7 @@ OSBridge::_write_stack_trace (FILE *to, const char *from)
 void
 OSBridge::_monodroid_gref_log (const char *message)
 {
+	log_info (LOG_GREF, "%s", message);
 	if (!gref_log)
 		return;
 	fprintf (gref_log, "%s", message);