[Java.Interop] Type & Member Remapping Support

samples/Hello/Program.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using System.Threading;
 
 using Mono.Options;
@@ -9,10 +10,13 @@ namespace Hello
 {
 	class App
 	{
+		const int N = 1000000;
+
 		public static void Main (string[] args)
 		{
 			string? jvmPath             = global::Java.InteropTests.TestJVM.GetJvmLibraryPath ();
 			bool    createMultipleVMs   = false;
+			bool    reportTiming        = false;
 			bool    showHelp            = false;
 			var options = new OptionSet () {
 				"Using the JVM from C#!",
@@ -24,6 +28,9 @@ public static void Main (string[] args)
 				{ "m",
 				  "Create multiple Java VMs.  This will likely creash.",
 				  v => createMultipleVMs = v != null },
+				{ "t",
+				  $"Timing; invoke Object.hashCode() {N} times, print average.",
+				  v => reportTiming = v != null },
 				{ "h|help",
 				  "Show this message and exit.",
 				  v => showHelp = v != null },
@@ -33,23 +40,25 @@ public static void Main (string[] args)
 				options.WriteOptionDescriptions (Console.Out);
 				return;
 			}
-			Console.WriteLine ("Hello World!");
 			var builder = new JreRuntimeOptions () {
 				JniAddNativeMethodRegistrationAttributePresent  = true,
 				JvmLibraryPath                                  = jvmPath,
 			};
 			builder.AddOption ("-Xcheck:jni");
+
 			var jvm = builder.CreateJreVM ();
-			Console.WriteLine ($"JniRuntime.CurrentRuntime == jvm? {ReferenceEquals (JniRuntime.CurrentRuntime, jvm)}");
-			foreach (var h in JniRuntime.GetAvailableInvocationPointers ()) {
-				Console.WriteLine ("PRE: GetCreatedJavaVMHandles: {0}", h);
-			}
 
-			CreateJLO ();
+			if (reportTiming) {
+				ReportTiming ();
+				return;
+			}
 
 			if (createMultipleVMs) {
 				CreateAnotherJVM ();
+				return;
 			}
+
+			CreateJLO ();
 		}
 
 		static void CreateJLO ()
@@ -58,6 +67,17 @@ static void CreateJLO ()
 			Console.WriteLine ($"binding? {jlo.ToString ()}");
 		}
 
+		static void ReportTiming ()
+		{
+			var jlo = new Java.Lang.Object ();
+			var t = Stopwatch.StartNew ();
+			for (int i = 0; i < N; ++i) {
+				jlo.GetHashCode ();
+			}
+			t.Stop ();
+			Console.WriteLine ($"Object.hashCode: {N} invocations. Total={t.Elapsed}; Average={t.Elapsed.TotalMilliseconds / (double) N}ms");
+		}
+
 		static unsafe void CreateAnotherJVM ()
 		{
 			Console.WriteLine ("Part 2!");

src/Java.Interop/Java.Interop.csproj

@@ -26,7 +26,8 @@
     <OutputPath>$(ToolOutputFullPath)</OutputPath>
     <DocumentationFile>$(ToolOutputFullPath)Java.Interop.xml</DocumentationFile>
     <JNIEnvGenPath>$(BuildToolOutputFullPath)</JNIEnvGenPath>
-    <LangVersion>8.0</LangVersion>
+    <LangVersion Condition=" '$(JIBuildingForNetCoreApp)' == 'True' ">9.0</LangVersion>
+    <LangVersion Condition=" '$(LangVersion)' == '' ">8.0</LangVersion>
     <Nullable>enable</Nullable>
     <ProduceReferenceAssembly>true</ProduceReferenceAssembly>
     <MSBuildWarningsAsMessages>NU1702</MSBuildWarningsAsMessages>

src/Java.Interop/Java.Interop/JavaArray.cs

@@ -231,9 +231,9 @@ bool IList.IsFixedSize {
 
 		object? IList.this [int index] {
 			get {return this [index];}
-#pragma warning disable 8601
+#pragma warning disable 8600,8601
 			set {this [index] = (T) value;}
-#pragma warning restore 8601
+#pragma warning restore 8600,8601
 		}
 
 		void ICollection.CopyTo (Array array, int index)

src/Java.Interop/Java.Interop/JniEnvironment.Types.cs

@@ -31,7 +31,12 @@ static Types ()
 				}
 			}
 
-			public static unsafe JniObjectReference FindClass (string classname)
+			public static JniObjectReference FindClass (string classname)
+			{
+				return TryFindClass (classname, throwOnError: true);
+			}
+
+			static unsafe JniObjectReference TryFindClass (string classname, bool throwOnError)
 			{
 				if (classname == null)
 					throw new ArgumentNullException (nameof (classname));
@@ -85,6 +90,10 @@ public static unsafe JniObjectReference FindClass (string classname)
 					}
 				}
 
+				if (!throwOnError) {
+					(pendingException as IJavaPeerable)?.Dispose ();
+					return default;
+				}
 				throw pendingException!;
 #endif  // !FEATURE_JNIENVIRONMENT_JI_PINVOKES
 #if FEATURE_JNIOBJECTREFERENCE_SAFEHANDLES
@@ -120,10 +129,27 @@ public static unsafe JniObjectReference FindClass (string classname)
 				var loadClassThrown     = new JniObjectReference (thrown, JniObjectReferenceType.Local);
 				LogCreateLocalRef (loadClassThrown);
 				pendingException    = info.Runtime.GetExceptionForThrowable (ref loadClassThrown, JniObjectReferenceOptions.CopyAndDispose);
+				if (!throwOnError) {
+					(pendingException as IJavaPeerable)?.Dispose ();
+					return default;
+				}
 				throw pendingException!;
 #endif  // !FEATURE_JNIOBJECTREFERENCE_SAFEHANDLES
 			}
 
+#if NET
+			public static bool TryFindClass (string classname, out JniObjectReference instance)
+			{
+				if (classname == null)
+					throw new ArgumentNullException (nameof (classname));
+				if (classname.Length == 0)
+					throw new ArgumentException ("'classname' cannot be a zero-length string.", nameof (classname));
+
+				instance = TryFindClass (classname, throwOnError: false);
+				return instance.IsValid;
+			}
+#endif  // NET
+
 			public static JniType? GetTypeFromInstance (JniObjectReference instance)
 			{
 				if (!instance.IsValid)

src/Java.Interop/Java.Interop/JniMemberSignature.cs

@@ -0,0 +1,134 @@
+#nullable enable
+
+#if NET
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Reflection;
+using System.Runtime.InteropServices;
+using System.Runtime.Versioning;
+
+namespace Java.Interop
+{
+	public struct JniMemberSignature : IEquatable<JniMemberSignature>
+	{
+		public   static readonly    JniMemberSignature  Empty;
+
+		string?                 memberName;
+		string?                 memberSignature;
+
+		public      string      MemberName        => memberName ?? throw new InvalidOperationException ();
+		public      string      MemberSignature   => memberSignature ?? throw new InvalidOperationException ();
+
+		public JniMemberSignature (string memberName, string memberSignature)
+		{
+			if (string.IsNullOrEmpty (memberName)) {
+				throw new ArgumentNullException (nameof (memberName));
+			}
+			if (string.IsNullOrEmpty (memberSignature)) {
+				throw new ArgumentNullException (nameof (memberSignature));
+			}
+			this.memberName         = memberName;
+			this.memberSignature    = memberSignature;
+		}
+
+		public static int GetParameterCountFromMethodSignature (string jniMethodSignature)
+		{
+			if (jniMethodSignature.Length < "()V".Length || jniMethodSignature [0] != '(' ) {
+				throw new ArgumentException (
+						$"Member signature `{jniMethodSignature}` is not a method signature.  Method signatures must start with `(`.",
+						nameof (jniMethodSignature));
+			}
+			int count = 0;
+			int index = 1;
+			while (index < jniMethodSignature.Length &&
+					jniMethodSignature [index] != ')') {
+				ExtractType (jniMethodSignature, ref index);
+				count++;
+			}
+			return count;
+		}
+
+		internal static (int StartIndex, int Length) ExtractType (string signature, ref int index)
+		{
+			AssertSignatureIndex (signature, index);
+			var i = index++;
+			switch (signature [i]) {
+			case '[':
+				if ((i+1) >= signature.Length)
+					throw new InvalidOperationException ($"Missing array type after '[' at index {i} in: `{signature}`");
+				var rest    = ExtractType (signature, ref index);
+				return (StartIndex: i, Length: index - i);
+			case 'B':
+			case 'C':
+			case 'D':
+			case 'F':
+			case 'I':
+			case 'J':
+			case 'S':
+			case 'V':
+			case 'Z':
+				return (StartIndex: i, Length: 1);
+			case 'L':
+				int depth = 0;
+				int e = index;
+				while (e < signature.Length) {
+					var c = signature [e++];
+					if (depth == 0 && c == ';')
+						break;
+				}
+				if (e > signature.Length)
+					throw new InvalidOperationException ($"Missing reference type after `{signature [i]}` at index {i} in `{signature}`!");
+				index = e;
+				return (StartIndex: i, Length: (e - i));
+			default:
+				throw new InvalidOperationException ($"Unknown JNI Type `{signature [i]}` within: `{signature}`!");
+			}
+		}
+
+		internal static void AssertSignatureIndex (string signature, int index)
+		{
+			if (signature == null)
+				throw new ArgumentNullException (nameof (signature));
+			if (signature.Length == 0)
+				throw new ArgumentException ("Descriptor cannot be empty string", nameof (signature));
+			if (index >= signature.Length)
+				throw new ArgumentException ("index >= descriptor.Length", nameof (index));
+		}
+
+		public override int GetHashCode ()
+		{
+			return (memberName?.GetHashCode () ?? 0) ^
+				(memberSignature?.GetHashCode () ?? 0);
+		}
+
+		public override bool Equals (object? obj)
+		{
+			var v = obj as JniMemberSignature?;
+			if (v.HasValue)
+				return Equals (v.Value);
+			return false;
+		}
+
+		public bool Equals (JniMemberSignature other)
+		{
+			return memberName == other.memberName &&
+				memberSignature == other.memberSignature;
+		}
+
+		public override string ToString ()
+		{
+			return $"{nameof (JniMemberSignature)} {{ " +
+				$"{nameof (MemberName)} = {(memberName == null ? "null" : "\"" + memberName + "\"")}" +
+				$", {nameof (MemberSignature)} = {(memberSignature == null ? "null" : "\"" + memberSignature + "\"")}" +
+				$"}}";
+		}
+
+		public static bool operator== (JniMemberSignature a, JniMemberSignature b) => a.Equals (b);
+		public static bool operator!= (JniMemberSignature a, JniMemberSignature b) => !a.Equals (b);
+	}
+}
+
+#endif  // NET

src/Java.Interop/Java.Interop/JniMethodInfo.cs

@@ -10,6 +10,11 @@ public sealed class JniMethodInfo
 
 		public      bool    IsStatic    {get; private set;}
 
+#if NET
+		internal    JniType?    StaticRedirect;
+		internal    int?        ParameterCount;
+#endif  //NET
+
 		internal    bool    IsValid {
 			get {return ID != IntPtr.Zero;}
 		}

src/Java.Interop/Java.Interop/JniPeerMembers.JniInstanceMethods.cs

@@ -84,14 +84,46 @@ internal JniInstanceMethods GetConstructorsForType (Type declaringType)
 		public JniMethodInfo GetMethodInfo (string encodedMember)
 		{
 			lock (InstanceMethods) {
-				if (!InstanceMethods.TryGetValue (encodedMember, out var m)) {
-					string method, signature;
-					JniPeerMembers.GetNameAndSignature (encodedMember, out method, out signature);
-					m = JniPeerType.GetInstanceMethod (method, signature);
-					InstanceMethods.Add (encodedMember, m);
+				if (InstanceMethods.TryGetValue (encodedMember, out var m)) {
+					return m;
 				}
-				return m;
 			}
+			string method, signature;
+			JniPeerMembers.GetNameAndSignature (encodedMember, out method, out signature);
+			var info = GetMethodInfo (method, signature);
+			lock (InstanceMethods) {
+				if (InstanceMethods.TryGetValue (encodedMember, out var m)) {
+					return m;
+				}
+				InstanceMethods.Add (encodedMember, info);
+			}
+			return info;
+		}
+
+		JniMethodInfo GetMethodInfo (string method, string signature)
+		{
+#if NET
+			var m              = (JniMethodInfo?) null;
+			var newMethod      = JniEnvironment.Runtime.TypeManager.GetReplacementMethodInfo (Members.JniPeerTypeName, method, signature);
+			if (newMethod.HasValue) {
+				var typeName   = newMethod.Value.TargetJniType ?? Members.JniPeerTypeName;
+				var methodName = newMethod.Value.TargetJniMethodName ?? method;
+				var methodSig  = newMethod.Value.TargetJniMethodSignature ?? signature;
+
+				using var t = new JniType (typeName);
+				if (newMethod.Value.TargetJniMethodInstanceToStatic &&
+						t.TryGetStaticMethod (methodName, methodSig, out m)) {
+					m.ParameterCount = newMethod.Value.TargetJniMethodParameterCount;
+					m.StaticRedirect = new JniType (typeName);
+					return m;
+				}
+				if (t.TryGetInstanceMethod (methodName, methodSig, out m)) {
+					return m;
+				}
+				Console.Error.WriteLine ($"warning: For declared method `{Members.JniPeerTypeName}.{method}.{signature}`, could not find requested method `{typeName}.{methodName}.{methodSig}`!");
+			}
+#endif  // NET
+			return JniPeerType.GetInstanceMethod (method, signature);
 		}
 
 		public unsafe JniObjectReference StartCreateInstance (string constructorSignature, Type declaringType, JniArgumentValue* parameters)